Merge remote-tracking branch 'savannah/master' into native-comp

38 files changed, 1575 insertions, 358 deletions

diff --git a/lib/_Noreturn.h b/lib/_Noreturn.h
index 38afe1d5672..fb718bc0691 100644
--- a/lib/_Noreturn.h
+++ b/lib/_Noreturn.h
@@ -26,14 +26,16 @@
        AIX system header files and several gnulib header files use precisely
        this syntax with 'extern'.  */
 #  define _Noreturn [[noreturn]]
-# elif ((!defined __cplusplus || defined __clang__)                     \
-        && (201112 <= (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0)  \
-            || 4 < __GNUC__ + (7 <= __GNUC_MINOR__) \
-            || (defined __apple_build_version__ \
-                ? 6000000 <= __apple_build_version__ \
-                : 3 < __clang_major__ + (5 <= __clang_minor__))))
+# elif ((!defined __cplusplus || defined __clang__) \
+        && (201112 <= (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) \
+            || (!defined __STRICT_ANSI__ \
+                && (__4 < __GNUC__ + (7 <= __GNUC_MINOR__) \
+                    || (defined __apple_build_version__ \
+                        ? 6000000 <= __apple_build_version__ \
+                        : 3 < __clang_major__ + (5 <= __clang_minor__))))))
    /* _Noreturn works as-is.  */
-# elif 2 < __GNUC__ + (8 <= __GNUC_MINOR__) || 0x5110 <= __SUNPRO_C
+# elif (2 < __GNUC__ + (8 <= __GNUC_MINOR__) || defined __clang__ \
+        || 0x5110 <= __SUNPRO_C)
 #  define _Noreturn __attribute__ ((__noreturn__))
 # elif 1200 <= (defined _MSC_VER ? _MSC_VER : 0)
 #  define _Noreturn __declspec (noreturn)
diff --git a/lib/canonicalize-lgpl.c b/lib/canonicalize-lgpl.c
index b6dc3a447ab..b7dba08994d 100644
--- a/lib/canonicalize-lgpl.c
+++ b/lib/canonicalize-lgpl.c
@@ -85,10 +85,6 @@
 # define IF_LINT(Code) /* empty */
 #endif
 
-/* True if adding two valid object sizes might overflow idx_t.
-   As a practical matter, this cannot happen on 64-bit machines.  */
-enum { NARROW_ADDRESSES = IDX_MAX >> 31 >> 31 == 0 };
-
 #ifndef DOUBLE_SLASH_IS_DISTINCT_ROOT
 # define DOUBLE_SLASH_IS_DISTINCT_ROOT false
 #endif
@@ -145,11 +141,11 @@ suffix_requires_dir_check (char const *end)
    macOS 10.13 <https://bugs.gnu.org/30350>, and should also work on
    platforms like AIX 7.2 that need at least "/.".  */
 
-#if defined _LIBC || defined LSTAT_FOLLOWS_SLASHED_SYMLINK
+# if defined _LIBC || defined LSTAT_FOLLOWS_SLASHED_SYMLINK
 static char const dir_suffix[] = "/";
-#else
+# else
 static char const dir_suffix[] = "/./";
-#endif
+# endif
 
 /* Return true if DIR is a searchable dir, false (setting errno) otherwise.
    DIREND points to the NUL byte at the end of the DIR string.
@@ -191,13 +187,13 @@ get_path_max (void)
    to pacify GCC is known; even an explicit #pragma does not pacify GCC.
    When the GCC bug is fixed this workaround should be limited to the
    broken GCC versions.  */
-#if __GNUC_PREREQ (10, 1)
-# if defined GCC_LINT || defined lint
+# if __GNUC_PREREQ (10, 1)
+#  if defined GCC_LINT || defined lint
 __attribute__ ((__noinline__))
-# elif __OPTIMIZE__ && !__NO_INLINE__
-#  define GCC_BOGUS_WRETURN_LOCAL_ADDR
+#  elif __OPTIMIZE__ && !__NO_INLINE__
+#   define GCC_BOGUS_WRETURN_LOCAL_ADDR
+#  endif
 # endif
-#endif
 static char *
 realpath_stk (const char *name, char *resolved,
               struct scratch_buffer *rname_buf)
@@ -343,7 +339,7 @@ realpath_stk (const char *name, char *resolved,
               if (end_in_extra_buffer)
                 end_idx = end - extra_buf;
               size_t len = strlen (end);
-              if (NARROW_ADDRESSES && INT_ADD_OVERFLOW (len, n))
+              if (INT_ADD_OVERFLOW (len, n))
                 {
                   __set_errno (ENOMEM);
                   goto error_nomem;
@@ -443,7 +439,8 @@ __realpath (const char *name, char *resolved)
 }
 libc_hidden_def (__realpath)
 versioned_symbol (libc, __realpath, realpath, GLIBC_2_3);
-#endif /* !FUNC_REALPATH_WORKS || defined _LIBC */
+
+#endif /* defined _LIBC || !FUNC_REALPATH_WORKS */
 
 
 #if SHLIB_COMPAT(libc, GLIBC_2_0, GLIBC_2_3)
diff --git a/lib/cdefs.h b/lib/cdefs.h
index 2a3dc9666b9..17a0919cd83 100644
--- a/lib/cdefs.h
+++ b/lib/cdefs.h
@@ -25,7 +25,7 @@
 
 /* The GNU libc does not support any K&R compilers or the traditional mode
    of ISO C compilers anymore.  Check for some of the combinations not
-   anymore supported.  */
+   supported anymore.  */
 #if defined __GNUC__ && !defined __STDC__
 # error "You need a ISO C conforming compiler to use the glibc headers"
 #endif
@@ -34,31 +34,26 @@
 #undef	__P
 #undef	__PMT
 
-/* Compilers that are not clang may object to
-       #if defined __clang__ && __has_attribute(...)
-   even though they do not need to evaluate the right-hand side of the &&.  */
-#if defined __clang__ && defined __has_attribute
-# define __glibc_clang_has_attribute(name) __has_attribute (name)
+/* Compilers that lack __has_attribute may object to
+       #if defined __has_attribute && __has_attribute (...)
+   even though they do not need to evaluate the right-hand side of the &&.
+   Similarly for __has_builtin, etc.  */
+#if (defined __has_attribute \
+     && (!defined __clang_minor__ \
+         || 3 < __clang_major__ + (5 <= __clang_minor__)))
+# define __glibc_has_attribute(attr) __has_attribute (attr)
 #else
-# define __glibc_clang_has_attribute(name) 0
+# define __glibc_has_attribute(attr) 0
 #endif
-
-/* Compilers that are not clang may object to
-       #if defined __clang__ && __has_builtin(...)
-   even though they do not need to evaluate the right-hand side of the &&.  */
-#if defined __clang__ && defined __has_builtin
-# define __glibc_clang_has_builtin(name) __has_builtin (name)
+#ifdef __has_builtin
+# define __glibc_has_builtin(name) __has_builtin (name)
 #else
-# define __glibc_clang_has_builtin(name) 0
+# define __glibc_has_builtin(name) 0
 #endif
-
-/* Compilers that are not clang may object to
-       #if defined __clang__ && __has_extension(...)
-   even though they do not need to evaluate the right-hand side of the &&.  */
-#if defined __clang__ && defined __has_extension
-# define __glibc_clang_has_extension(ext) __has_extension (ext)
+#ifdef __has_extension
+# define __glibc_has_extension(ext) __has_extension (ext)
 #else
-# define __glibc_clang_has_extension(ext) 0
+# define __glibc_has_extension(ext) 0
 #endif
 
 #if defined __GNUC__ || defined __clang__
@@ -74,22 +69,26 @@
 # endif
 
 /* GCC can always grok prototypes.  For C++ programs we add throw()
-   to help it optimize the function calls.  But this works only with
+   to help it optimize the function calls.  But this only works with
    gcc 2.8.x and egcs.  For gcc 3.4 and up we even mark C functions
    as non-throwing using a function attribute since programs can use
    the -fexceptions options for C code as well.  */
 # if !defined __cplusplus \
-     && (__GNUC_PREREQ (3, 4) || __glibc_clang_has_attribute (__nothrow__))
+     && (__GNUC_PREREQ (3, 4) || __glibc_has_attribute (__nothrow__))
 #  define __THROW	__attribute__ ((__nothrow__ __LEAF))
 #  define __THROWNL	__attribute__ ((__nothrow__))
 #  define __NTH(fct)	__attribute__ ((__nothrow__ __LEAF)) fct
 #  define __NTHNL(fct)  __attribute__ ((__nothrow__)) fct
 # else
 #  if defined __cplusplus && (__GNUC_PREREQ (2,8) || __clang_major >= 4)
-#   define __THROW	throw ()
-#   define __THROWNL	throw ()
-#   define __NTH(fct)	__LEAF_ATTR fct throw ()
-#   define __NTHNL(fct) fct throw ()
+#   if __cplusplus >= 201103L
+#    define __THROW	noexcept (true)
+#   else
+#    define __THROW	throw ()
+#   endif
+#   define __THROWNL	__THROW
+#   define __NTH(fct)	__LEAF_ATTR fct __THROW
+#   define __NTHNL(fct) fct __THROW
 #  else
 #   define __THROW
 #   define __THROWNL
@@ -142,24 +141,20 @@
 #define __bos(ptr) __builtin_object_size (ptr, __USE_FORTIFY_LEVEL > 1)
 #define __bos0(ptr) __builtin_object_size (ptr, 0)
 
+/* Use __builtin_dynamic_object_size at _FORTIFY_SOURCE=3 when available.  */
+#if __USE_FORTIFY_LEVEL == 3 && __glibc_clang_prereq (9, 0)
+# define __glibc_objsize0(__o) __builtin_dynamic_object_size (__o, 0)
+# define __glibc_objsize(__o) __builtin_dynamic_object_size (__o, 1)
+#else
+# define __glibc_objsize0(__o) __bos0 (__o)
+# define __glibc_objsize(__o) __bos (__o)
+#endif
+
 #if __GNUC_PREREQ (4,3)
-# define __warndecl(name, msg) \
-  extern void name (void) __attribute__((__warning__ (msg)))
 # define __warnattr(msg) __attribute__((__warning__ (msg)))
 # define __errordecl(name, msg) \
   extern void name (void) __attribute__((__error__ (msg)))
-#elif __glibc_clang_has_attribute (__diagnose_if__) && 0
-/* These definitions are not enabled, because they produce bogus warnings
-   in the glibc Fortify functions.  These functions are written in a style
-   that works with GCC.  In order to work with clang, these functions would
-   need to be modified.  */
-# define __warndecl(name, msg) \
-  extern void name (void) __attribute__((__diagnose_if__ (1, msg, "warning")))
-# define __warnattr(msg) __attribute__((__diagnose_if__ (1, msg, "warning")))
-# define __errordecl(name, msg) \
-  extern void name (void) __attribute__((__diagnose_if__ (1, msg, "error")))
 #else
-# define __warndecl(name, msg) extern void name (void)
 # define __warnattr(msg)
 # define __errordecl(name, msg) extern void name (void)
 #endif
@@ -233,7 +228,7 @@
 /* At some point during the gcc 2.96 development the `malloc' attribute
    for functions was introduced.  We don't want to use it unconditionally
    (although this would be possible) since it generates warnings.  */
-#if __GNUC_PREREQ (2,96) || __glibc_clang_has_attribute (__malloc__)
+#if __GNUC_PREREQ (2,96) || __glibc_has_attribute (__malloc__)
 # define __attribute_malloc__ __attribute__ ((__malloc__))
 #else
 # define __attribute_malloc__ /* Ignore */
@@ -251,23 +246,31 @@
 /* At some point during the gcc 2.96 development the `pure' attribute
    for functions was introduced.  We don't want to use it unconditionally
    (although this would be possible) since it generates warnings.  */
-#if __GNUC_PREREQ (2,96) || __glibc_clang_has_attribute (__pure__)
+#if __GNUC_PREREQ (2,96) || __glibc_has_attribute (__pure__)
 # define __attribute_pure__ __attribute__ ((__pure__))
 #else
 # define __attribute_pure__ /* Ignore */
 #endif
 
 /* This declaration tells the compiler that the value is constant.  */
-#if __GNUC_PREREQ (2,5) || __glibc_clang_has_attribute (__const__)
+#if __GNUC_PREREQ (2,5) || __glibc_has_attribute (__const__)
 # define __attribute_const__ __attribute__ ((__const__))
 #else
 # define __attribute_const__ /* Ignore */
 #endif
 
+#if defined __STDC_VERSION__ && 201710L < __STDC_VERSION__
+# define __attribute_maybe_unused__ [[__maybe_unused__]]
+#elif __GNUC_PREREQ (2,7) || __glibc_has_attribute (__unused__)
+# define __attribute_maybe_unused__ __attribute__ ((__unused__))
+#else
+# define __attribute_maybe_unused__ /* Ignore */
+#endif
+
 /* At some point during the gcc 3.1 development the `used' attribute
    for functions was introduced.  We don't want to use it unconditionally
    (although this would be possible) since it generates warnings.  */
-#if __GNUC_PREREQ (3,1) || __glibc_clang_has_attribute (__used__)
+#if __GNUC_PREREQ (3,1) || __glibc_has_attribute (__used__)
 # define __attribute_used__ __attribute__ ((__used__))
 # define __attribute_noinline__ __attribute__ ((__noinline__))
 #else
@@ -276,7 +279,7 @@
 #endif
 
 /* Since version 3.2, gcc allows marking deprecated functions.  */
-#if __GNUC_PREREQ (3,2) || __glibc_clang_has_attribute (__deprecated__)
+#if __GNUC_PREREQ (3,2) || __glibc_has_attribute (__deprecated__)
 # define __attribute_deprecated__ __attribute__ ((__deprecated__))
 #else
 # define __attribute_deprecated__ /* Ignore */
@@ -285,8 +288,8 @@
 /* Since version 4.5, gcc also allows one to specify the message printed
    when a deprecated function is used.  clang claims to be gcc 4.2, but
    may also support this feature.  */
-#if __GNUC_PREREQ (4,5) || \
-    __glibc_clang_has_extension (__attribute_deprecated_with_message__)
+#if __GNUC_PREREQ (4,5) \
+    || __glibc_has_extension (__attribute_deprecated_with_message__)
 # define __attribute_deprecated_msg__(msg) \
 	 __attribute__ ((__deprecated__ (msg)))
 #else
@@ -299,7 +302,7 @@
    If several `format_arg' attributes are given for the same function, in
    gcc-3.0 and older, all but the last one are ignored.  In newer gccs,
    all designated arguments are considered.  */
-#if __GNUC_PREREQ (2,8) || __glibc_clang_has_attribute (__format_arg__)
+#if __GNUC_PREREQ (2,8) || __glibc_has_attribute (__format_arg__)
 # define __attribute_format_arg__(x) __attribute__ ((__format_arg__ (x)))
 #else
 # define __attribute_format_arg__(x) /* Ignore */
@@ -309,7 +312,7 @@
    attribute for functions was introduced.  We don't want to use it
    unconditionally (although this would be possible) since it
    generates warnings.  */
-#if __GNUC_PREREQ (2,97) || __glibc_clang_has_attribute (__format__)
+#if __GNUC_PREREQ (2,97) || __glibc_has_attribute (__format__)
 # define __attribute_format_strfmon__(a,b) \
   __attribute__ ((__format__ (__strfmon__, a, b)))
 #else
@@ -317,19 +320,21 @@
 #endif
 
 /* The nonnull function attribute marks pointer parameters that
-   must not be NULL.  Do not define __nonnull if it is already defined,
-   for portability when this file is used in Gnulib.  */
+   must not be NULL.  */
 #ifndef __nonnull
-# if __GNUC_PREREQ (3,3) || __glibc_clang_has_attribute (__nonnull__)
+# if __GNUC_PREREQ (3,3) || __glibc_has_attribute (__nonnull__)
 #  define __nonnull(params) __attribute__ ((__nonnull__ params))
 # else
 #  define __nonnull(params)
 # endif
+#elif !defined __GLIBC__
+# undef __nonnull
+# define __nonnull(params) _GL_ATTRIBUTE_NONNULL (params)
 #endif
 
 /* If fortification mode, we warn about unused results of certain
    function calls which can lead to problems.  */
-#if __GNUC_PREREQ (3,4) || __glibc_clang_has_attribute (__warn_unused_result__)
+#if __GNUC_PREREQ (3,4) || __glibc_has_attribute (__warn_unused_result__)
 # define __attribute_warn_unused_result__ \
    __attribute__ ((__warn_unused_result__))
 # if defined __USE_FORTIFY_LEVEL && __USE_FORTIFY_LEVEL > 0
@@ -343,7 +348,7 @@
 #endif
 
 /* Forces a function to be always inlined.  */
-#if __GNUC_PREREQ (3,2) || __glibc_clang_has_attribute (__always_inline__)
+#if __GNUC_PREREQ (3,2) || __glibc_has_attribute (__always_inline__)
 /* The Linux kernel defines __always_inline in stddef.h (283d7573), and
    it conflicts with this definition.  Therefore undefine it first to
    allow either header to be included first.  */
@@ -356,7 +361,7 @@
 
 /* Associate error messages with the source location of the call site rather
    than with the source location inside the function.  */
-#if __GNUC_PREREQ (4,3) || __glibc_clang_has_attribute (__artificial__)
+#if __GNUC_PREREQ (4,3) || __glibc_has_attribute (__artificial__)
 # define __attribute_artificial__ __attribute__ ((__artificial__))
 #else
 # define __attribute_artificial__ /* Ignore */
@@ -433,7 +438,7 @@
 # endif
 #endif
 
-#if (__GNUC__ >= 3) || __glibc_clang_has_builtin (__builtin_expect)
+#if (__GNUC__ >= 3) || __glibc_has_builtin (__builtin_expect)
 # define __glibc_unlikely(cond)	__builtin_expect ((cond), 0)
 # define __glibc_likely(cond)	__builtin_expect ((cond), 1)
 #else
@@ -441,12 +446,6 @@
 # define __glibc_likely(cond)	(cond)
 #endif
 
-#ifdef __has_attribute
-# define __glibc_has_attribute(attr)	__has_attribute (attr)
-#else
-# define __glibc_has_attribute(attr)	0
-#endif
-
 #if (!defined _Noreturn \
      && (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) < 201112 \
      &&  !(__GNUC_PREREQ (4,7) \
@@ -467,6 +466,16 @@
 # define __attribute_nonstring__
 #endif
 
+/* Undefine (also defined in libc-symbols.h).  */
+#undef __attribute_copy__
+#if __GNUC_PREREQ (9, 0)
+/* Copies attributes from the declaration or type referenced by
+   the argument.  */
+# define __attribute_copy__(arg) __attribute__ ((__copy__ (arg)))
+#else
+# define __attribute_copy__(arg)
+#endif
+
 #if (!defined _Static_assert && !defined __cplusplus \
      && (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) < 201112 \
      && (!(__GNUC_PREREQ (4, 6) || __clang_major__ >= 4) \
@@ -483,7 +492,37 @@
 # include <bits/long-double.h>
 #endif
 
-#if defined __LONG_DOUBLE_MATH_OPTIONAL && defined __NO_LONG_DOUBLE_MATH
+#if __LDOUBLE_REDIRECTS_TO_FLOAT128_ABI == 1
+# ifdef __REDIRECT
+
+/* Alias name defined automatically.  */
+#  define __LDBL_REDIR(name, proto) ... unused__ldbl_redir
+#  define __LDBL_REDIR_DECL(name) \
+  extern __typeof (name) name __asm (__ASMNAME ("__" #name "ieee128"));
+
+/* Alias name defined automatically, with leading underscores.  */
+#  define __LDBL_REDIR2_DECL(name) \
+  extern __typeof (__##name) __##name \
+    __asm (__ASMNAME ("__" #name "ieee128"));
+
+/* Alias name defined manually.  */
+#  define __LDBL_REDIR1(name, proto, alias) ... unused__ldbl_redir1
+#  define __LDBL_REDIR1_DECL(name, alias) \
+  extern __typeof (name) name __asm (__ASMNAME (#alias));
+
+#  define __LDBL_REDIR1_NTH(name, proto, alias) \
+  __REDIRECT_NTH (name, proto, alias)
+#  define __REDIRECT_NTH_LDBL(name, proto, alias) \
+  __LDBL_REDIR1_NTH (name, proto, __##alias##ieee128)
+
+/* Unused.  */
+#  define __REDIRECT_LDBL(name, proto, alias) ... unused__redirect_ldbl
+#  define __LDBL_REDIR_NTH(name, proto) ... unused__ldbl_redir_nth
+
+# else
+_Static_assert (0, "IEEE 128-bits long double requires redirection on this platform");
+# endif
+#elif defined __LONG_DOUBLE_MATH_OPTIONAL && defined __NO_LONG_DOUBLE_MATH
 # define __LDBL_COMPAT 1
 # ifdef __REDIRECT
 #  define __LDBL_REDIR1(name, proto, alias) __REDIRECT (name, proto, alias)
@@ -492,6 +531,8 @@
 #  define __LDBL_REDIR1_NTH(name, proto, alias) __REDIRECT_NTH (name, proto, alias)
 #  define __LDBL_REDIR_NTH(name, proto) \
   __LDBL_REDIR1_NTH (name, proto, __nldbl_##name)
+#  define __LDBL_REDIR2_DECL(name) \
+  extern __typeof (__##name) __##name __asm (__ASMNAME ("__nldbl___" #name));
 #  define __LDBL_REDIR1_DECL(name, alias) \
   extern __typeof (name) name __asm (__ASMNAME (#alias));
 #  define __LDBL_REDIR_DECL(name) \
@@ -502,11 +543,13 @@
   __LDBL_REDIR1_NTH (name, proto, __nldbl_##alias)
 # endif
 #endif
-#if !defined __LDBL_COMPAT || !defined __REDIRECT
+#if (!defined __LDBL_COMPAT && __LDOUBLE_REDIRECTS_TO_FLOAT128_ABI == 0) \
+    || !defined __REDIRECT
 # define __LDBL_REDIR1(name, proto, alias) name proto
 # define __LDBL_REDIR(name, proto) name proto
 # define __LDBL_REDIR1_NTH(name, proto, alias) name proto __THROW
 # define __LDBL_REDIR_NTH(name, proto) name proto __THROW
+# define __LDBL_REDIR2_DECL(name)
 # define __LDBL_REDIR_DECL(name)
 # ifdef __REDIRECT
 #  define __REDIRECT_LDBL(name, proto, alias) __REDIRECT (name, proto, alias)
@@ -537,7 +580,7 @@
    check is required to enable the use of generic selection.  */
 #if !defined __cplusplus \
     && (__GNUC_PREREQ (4, 9) \
-	|| __glibc_clang_has_extension (c_generic_selections) \
+	|| __glibc_has_extension (c_generic_selections) \
 	|| (!defined __GNUC__ && defined __STDC_VERSION__ \
 	    && __STDC_VERSION__ >= 201112L))
 # define __HAVE_GENERIC_SELECTION 1
@@ -545,4 +588,23 @@
 # define __HAVE_GENERIC_SELECTION 0
 #endif
 
+#if __GNUC_PREREQ (10, 0)
+/* Designates a 1-based positional argument ref-index of pointer type
+   that can be used to access size-index elements of the pointed-to
+   array according to access mode, or at least one element when
+   size-index is not provided:
+     access (access-mode, <ref-index> [, <size-index>])  */
+#define __attr_access(x) __attribute__ ((__access__ x))
+#else
+#  define __attr_access(x)
+#endif
+
+/* Specify that a function such as setjmp or vfork may return
+   twice.  */
+#if __GNUC_PREREQ (4, 1)
+# define __attribute_returns_twice__ __attribute__ ((__returns_twice__))
+#else
+# define __attribute_returns_twice__ /* Ignore.  */
+#endif
+
 #endif	 /* sys/cdefs.h */
diff --git a/lib/dirent.in.h b/lib/dirent.in.h
index 2e2c5119a11..4666972b150 100644
--- a/lib/dirent.in.h
+++ b/lib/dirent.in.h
@@ -154,7 +154,8 @@ _GL_WARN_ON_USE (closedir, "closedir is not portable - "
 /* Return the file descriptor associated with the given directory stream,
    or -1 if none exists.  */
 # if @REPLACE_DIRFD@
-#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+/* On kLIBC, dirfd() is a macro that does not work.  Undefine it.  */
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE) || defined dirfd
 #   undef dirfd
 #   define dirfd rpl_dirfd
 #  endif
diff --git a/lib/dynarray.h b/lib/dynarray.h
new file mode 100644
index 00000000000..6da3e87e55f
--- /dev/null
+++ b/lib/dynarray.h
@@ -0,0 +1,31 @@
+/* Type-safe arrays which grow dynamically.
+   Copyright 2021 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+/* Written by Paul Eggert, 2021.  */
+
+#ifndef _GL_DYNARRAY_H
+#define _GL_DYNARRAY_H
+
+#include <libc-config.h>
+
+#define __libc_dynarray_at_failure gl_dynarray_at_failure
+#define __libc_dynarray_emplace_enlarge gl_dynarray_emplace_enlarge
+#define __libc_dynarray_finalize gl_dynarray_finalize
+#define __libc_dynarray_resize_clear gl_dynarray_resize_clear
+#define __libc_dynarray_resize gl_dynarray_resize
+#include <malloc/dynarray.h>
+
+#endif /* _GL_DYNARRAY_H */
diff --git a/lib/explicit_bzero.c b/lib/explicit_bzero.c
index feea4446c06..f50ed0875d7 100644
--- a/lib/explicit_bzero.c
+++ b/lib/explicit_bzero.c
@@ -54,11 +54,21 @@ explicit_bzero (void *s, size_t len)
   explicit_memset (s, '\0', len);
 #elif HAVE_MEMSET_S
   (void) memset_s (s, len, '\0', len);
-#else
+#elif defined __GNUC__ && !defined __clang__
   memset (s, '\0', len);
-# if defined __GNUC__ && !defined __clang__
   /* Compiler barrier.  */
   asm volatile ("" ::: "memory");
-# endif
+#elif defined __clang__
+  memset (s, '\0', len);
+  /* Compiler barrier.  */
+  /* With asm ("" ::: "memory") LLVM analyzes uses of 's' and finds that the
+     whole thing is dead and eliminates it.  Use 'g' to work around this
+     problem.  See <https://bugs.llvm.org/show_bug.cgi?id=15495#c11>.  */
+  __asm__ volatile ("" : : "g"(s) : "memory");
+#else
+  /* Invoke memset through a volatile function pointer.  This defeats compiler
+     optimizations.  */
+  void * (* const volatile volatile_memset) (void *, int, size_t) = memset;
+  (void) volatile_memset (s, '\0', len);
 #endif
 }
diff --git a/lib/fchmodat.c b/lib/fchmodat.c
index d27c0d7734a..eb6e2242fdd 100644
--- a/lib/fchmodat.c
+++ b/lib/fchmodat.c
@@ -38,6 +38,7 @@ orig_fchmodat (int dir, char const *file, mode_t mode, int flags)
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <unistd.h>
 
 #ifdef __osf__
@@ -63,6 +64,22 @@ orig_fchmodat (int dir, char const *file, mode_t mode, int flags)
 int
 fchmodat (int dir, char const *file, mode_t mode, int flags)
 {
+# if HAVE_NEARLY_WORKING_FCHMODAT
+  /* Correct the trailing slash handling.  */
+  size_t len = strlen (file);
+  if (len && file[len - 1] == '/')
+    {
+      struct stat st;
+      if (fstatat (dir, file, &st, flags & AT_SYMLINK_NOFOLLOW) < 0)
+        return -1;
+      if (!S_ISDIR (st.st_mode))
+        {
+          errno = ENOTDIR;
+          return -1;
+        }
+    }
+# endif
+
 # if NEED_FCHMODAT_NONSYMLINK_FIX
   if (flags == AT_SYMLINK_NOFOLLOW)
     {
diff --git a/lib/free.c b/lib/free.c
index 135c3eb16bc..5c89787aba1 100644
--- a/lib/free.c
+++ b/lib/free.c
@@ -27,7 +27,21 @@ void
 rpl_free (void *p)
 #undef free
 {
+#if defined __GNUC__ && !defined __clang__
+  /* An invalid GCC optimization
+     <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98396>
+     would optimize away the assignments in the code below, when link-time
+     optimization (LTO) is enabled.  Make the code more complicated, so that
+     GCC does not grok how to optimize it.  */
+  int err[2];
+  err[0] = errno;
+  err[1] = errno;
+  errno = 0;
+  free (p);
+  errno = err[errno == 0];
+#else
   int err = errno;
   free (p);
   errno = err;
+#endif
 }
diff --git a/lib/gnulib.mk.in b/lib/gnulib.mk.in
index c457ac61209..07736f9b8bc 100644
--- a/lib/gnulib.mk.in
+++ b/lib/gnulib.mk.in
@@ -516,6 +516,7 @@ GNULIB_SYMLINK = @GNULIB_SYMLINK@
 GNULIB_SYMLINKAT = @GNULIB_SYMLINKAT@
 GNULIB_SYSTEM_POSIX = @GNULIB_SYSTEM_POSIX@
 GNULIB_TIMEGM = @GNULIB_TIMEGM@
+GNULIB_TIMESPEC_GET = @GNULIB_TIMESPEC_GET@
 GNULIB_TIME_R = @GNULIB_TIME_R@
 GNULIB_TIME_RZ = @GNULIB_TIME_RZ@
 GNULIB_TMPFILE = @GNULIB_TMPFILE@
@@ -746,6 +747,7 @@ HAVE_SYS_SELECT_H = @HAVE_SYS_SELECT_H@
 HAVE_SYS_TIME_H = @HAVE_SYS_TIME_H@
 HAVE_SYS_TYPES_H = @HAVE_SYS_TYPES_H@
 HAVE_TIMEGM = @HAVE_TIMEGM@
+HAVE_TIMESPEC_GET = @HAVE_TIMESPEC_GET@
 HAVE_TIMEZONE_T = @HAVE_TIMEZONE_T@
 HAVE_TYPE_VOLATILE_SIG_ATOMIC_T = @HAVE_TYPE_VOLATILE_SIG_ATOMIC_T@
 HAVE_UNISTD_H = @HAVE_UNISTD_H@
@@ -949,6 +951,7 @@ REPLACE_FCNTL = @REPLACE_FCNTL@
 REPLACE_FDOPEN = @REPLACE_FDOPEN@
 REPLACE_FDOPENDIR = @REPLACE_FDOPENDIR@
 REPLACE_FFLUSH = @REPLACE_FFLUSH@
+REPLACE_FFSLL = @REPLACE_FFSLL@
 REPLACE_FOPEN = @REPLACE_FOPEN@
 REPLACE_FPRINTF = @REPLACE_FPRINTF@
 REPLACE_FPURGE = @REPLACE_FPURGE@
@@ -989,7 +992,9 @@ REPLACE_MEMCHR = @REPLACE_MEMCHR@
 REPLACE_MEMMEM = @REPLACE_MEMMEM@
 REPLACE_MKDIR = @REPLACE_MKDIR@
 REPLACE_MKFIFO = @REPLACE_MKFIFO@
+REPLACE_MKFIFOAT = @REPLACE_MKFIFOAT@
 REPLACE_MKNOD = @REPLACE_MKNOD@
+REPLACE_MKNODAT = @REPLACE_MKNODAT@
 REPLACE_MKSTEMP = @REPLACE_MKSTEMP@
 REPLACE_MKTIME = @REPLACE_MKTIME@
 REPLACE_NANOSLEEP = @REPLACE_NANOSLEEP@
@@ -1087,6 +1092,7 @@ SYSTEM_TYPE = @SYSTEM_TYPE@
 SYS_TIME_H_DEFINES_STRUCT_TIMESPEC = @SYS_TIME_H_DEFINES_STRUCT_TIMESPEC@
 TERMCAP_OBJ = @TERMCAP_OBJ@
 TIME_H_DEFINES_STRUCT_TIMESPEC = @TIME_H_DEFINES_STRUCT_TIMESPEC@
+TIME_H_DEFINES_TIME_UTC = @TIME_H_DEFINES_TIME_UTC@
 TOOLKIT_LIBW = @TOOLKIT_LIBW@
 UINT32_MAX_LT_UINTMAX_MAX = @UINT32_MAX_LT_UINTMAX_MAX@
 UINT64_MAX_EQ_ULONG_MAX = @UINT64_MAX_EQ_ULONG_MAX@
@@ -1171,6 +1177,7 @@ gl_GNULIB_ENABLED_a9786850e999ae65a836a6041e8e5ed1 = @gl_GNULIB_ENABLED_a9786850
 gl_GNULIB_ENABLED_be453cec5eecf5731a274f2de7f2db36 = @gl_GNULIB_ENABLED_be453cec5eecf5731a274f2de7f2db36@
 gl_GNULIB_ENABLED_cloexec = @gl_GNULIB_ENABLED_cloexec@
 gl_GNULIB_ENABLED_dirfd = @gl_GNULIB_ENABLED_dirfd@
+gl_GNULIB_ENABLED_dynarray = @gl_GNULIB_ENABLED_dynarray@
 gl_GNULIB_ENABLED_euidaccess = @gl_GNULIB_ENABLED_euidaccess@
 gl_GNULIB_ENABLED_getdtablesize = @gl_GNULIB_ENABLED_getdtablesize@
 gl_GNULIB_ENABLED_getgroups = @gl_GNULIB_ENABLED_getgroups@
@@ -1584,6 +1591,20 @@ EXTRA_libgnu_a_SOURCES += dup2.c
 endif
 ## end   gnulib module dup2
 
+## begin gnulib module dynarray
+ifeq (,$(OMIT_GNULIB_MODULE_dynarray))
+
+ifneq (,$(gl_GNULIB_ENABLED_dynarray))
+libgnu_a_SOURCES += malloc/dynarray_at_failure.c                 malloc/dynarray_emplace_enlarge.c                 malloc/dynarray_finalize.c                 malloc/dynarray_resize.c                 malloc/dynarray_resize_clear.c
+
+endif
+EXTRA_DIST += dynarray.h malloc/dynarray-skeleton.c malloc/dynarray.h
+
+EXTRA_libgnu_a_SOURCES += malloc/dynarray-skeleton.c
+
+endif
+## end   gnulib module dynarray
+
 ## begin gnulib module eloop-threshold
 ifeq (,$(OMIT_GNULIB_MODULE_eloop-threshold))
 
@@ -3036,6 +3057,7 @@ string.h: string.in.h $(top_builddir)/config.status $(CXXDEFS_H) $(ARG_NONNULL_H
 	      -e 's|@''HAVE_SIGDESCR_NP''@|$(HAVE_SIGDESCR_NP)|g' \
 	      -e 's|@''HAVE_DECL_STRSIGNAL''@|$(HAVE_DECL_STRSIGNAL)|g' \
 	      -e 's|@''HAVE_STRVERSCMP''@|$(HAVE_STRVERSCMP)|g' \
+	      -e 's|@''REPLACE_FFSLL''@|$(REPLACE_FFSLL)|g' \
 	      -e 's|@''REPLACE_MEMCHR''@|$(REPLACE_MEMCHR)|g' \
 	      -e 's|@''REPLACE_MEMMEM''@|$(REPLACE_MEMMEM)|g' \
 	      -e 's|@''REPLACE_STPNCPY''@|$(REPLACE_STPNCPY)|g' \
@@ -3237,7 +3259,9 @@ sys/stat.h: sys_stat.in.h $(top_builddir)/config.status $(CXXDEFS_H) $(ARG_NONNU
 	      -e 's|@''REPLACE_LSTAT''@|$(REPLACE_LSTAT)|g' \
 	      -e 's|@''REPLACE_MKDIR''@|$(REPLACE_MKDIR)|g' \
 	      -e 's|@''REPLACE_MKFIFO''@|$(REPLACE_MKFIFO)|g' \
+	      -e 's|@''REPLACE_MKFIFOAT''@|$(REPLACE_MKFIFOAT)|g' \
 	      -e 's|@''REPLACE_MKNOD''@|$(REPLACE_MKNOD)|g' \
+	      -e 's|@''REPLACE_MKNODAT''@|$(REPLACE_MKNODAT)|g' \
 	      -e 's|@''REPLACE_STAT''@|$(REPLACE_STAT)|g' \
 	      -e 's|@''REPLACE_UTIMENSAT''@|$(REPLACE_UTIMENSAT)|g' \
 	      -e '/definitions of _GL_FUNCDECL_RPL/r $(CXXDEFS_H)' \
@@ -3350,6 +3374,7 @@ time.h: time.in.h $(top_builddir)/config.status $(CXXDEFS_H) $(ARG_NONNULL_H) $(
 	      -e 's/@''GNULIB_STRFTIME''@/$(GNULIB_STRFTIME)/g' \
 	      -e 's/@''GNULIB_STRPTIME''@/$(GNULIB_STRPTIME)/g' \
 	      -e 's/@''GNULIB_TIMEGM''@/$(GNULIB_TIMEGM)/g' \
+	      -e 's/@''GNULIB_TIMESPEC_GET''@/$(GNULIB_TIMESPEC_GET)/g' \
 	      -e 's/@''GNULIB_TIME_R''@/$(GNULIB_TIME_R)/g' \
 	      -e 's/@''GNULIB_TIME_RZ''@/$(GNULIB_TIME_RZ)/g' \
 	      -e 's/@''GNULIB_TZSET''@/$(GNULIB_TZSET)/g' \
@@ -3358,6 +3383,7 @@ time.h: time.in.h $(top_builddir)/config.status $(CXXDEFS_H) $(ARG_NONNULL_H) $(
 	      -e 's|@''HAVE_NANOSLEEP''@|$(HAVE_NANOSLEEP)|g' \
 	      -e 's|@''HAVE_STRPTIME''@|$(HAVE_STRPTIME)|g' \
 	      -e 's|@''HAVE_TIMEGM''@|$(HAVE_TIMEGM)|g' \
+	      -e 's|@''HAVE_TIMESPEC_GET''@|$(HAVE_TIMESPEC_GET)|g' \
 	      -e 's|@''HAVE_TIMEZONE_T''@|$(HAVE_TIMEZONE_T)|g' \
 	      -e 's|@''REPLACE_CTIME''@|$(REPLACE_CTIME)|g' \
 	      -e 's|@''REPLACE_GMTIME''@|$(REPLACE_GMTIME)|g' \
@@ -3372,6 +3398,7 @@ time.h: time.in.h $(top_builddir)/config.status $(CXXDEFS_H) $(ARG_NONNULL_H) $(
 	      -e 's|@''SYS_TIME_H_DEFINES_STRUCT_TIMESPEC''@|$(SYS_TIME_H_DEFINES_STRUCT_TIMESPEC)|g' \
 	      -e 's|@''TIME_H_DEFINES_STRUCT_TIMESPEC''@|$(TIME_H_DEFINES_STRUCT_TIMESPEC)|g' \
 	      -e 's|@''UNISTD_H_DEFINES_STRUCT_TIMESPEC''@|$(UNISTD_H_DEFINES_STRUCT_TIMESPEC)|g' \
+	      -e 's|@''TIME_H_DEFINES_TIME_UTC''@|$(TIME_H_DEFINES_TIME_UTC)|g' \
 	      -e '/definitions of _GL_FUNCDECL_RPL/r $(CXXDEFS_H)' \
 	      -e '/definition of _GL_ARG_NONNULL/r $(ARG_NONNULL_H)' \
 	      -e '/definition of _GL_WARN_ON_USE/r $(WARN_ON_USE_H)' \
diff --git a/lib/libc-config.h b/lib/libc-config.h
index d4e29951f35..c0eac707cfd 100644
--- a/lib/libc-config.h
+++ b/lib/libc-config.h
@@ -71,107 +71,112 @@
 # endif
 #endif
 
-
-/* Prepare to include <cdefs.h>, which is our copy of glibc
-   <sys/cdefs.h>.  */
+#ifndef __attribute_maybe_unused__
+/* <sys/cdefs.h> either does not exist, or is too old for Gnulib.
+   Prepare to include <cdefs.h>, which is Gnulib's version of a
+   more-recent glibc <sys/cdefs.h>.  */
 
 /* Define _FEATURES_H so that <cdefs.h> does not include <features.h>.  */
-#ifndef _FEATURES_H
-# define _FEATURES_H 1
-#endif
+# ifndef _FEATURES_H
+#  define _FEATURES_H 1
+# endif
 /* Define __WORDSIZE so that <cdefs.h> does not attempt to include
    nonexistent files.  Make it a syntax error, since Gnulib does not
    use __WORDSIZE now, and if Gnulib uses it later the syntax error
    will let us know that __WORDSIZE needs configuring.  */
-#ifndef __WORDSIZE
-# define __WORDSIZE %%%
-#endif
+# ifndef __WORDSIZE
+#  define __WORDSIZE %%%
+# endif
 /* Undef the macros unconditionally defined by our copy of glibc
    <sys/cdefs.h>, so that they do not clash with any system-defined
    versions.  */
-#undef _SYS_CDEFS_H
-#undef __ASMNAME
-#undef __ASMNAME2
-#undef __BEGIN_DECLS
-#undef __CONCAT
-#undef __END_DECLS
-#undef __HAVE_GENERIC_SELECTION
-#undef __LDBL_COMPAT
-#undef __LDBL_REDIR
-#undef __LDBL_REDIR1
-#undef __LDBL_REDIR1_DECL
-#undef __LDBL_REDIR1_NTH
-#undef __LDBL_REDIR_DECL
-#undef __LDBL_REDIR_NTH
-#undef __LEAF
-#undef __LEAF_ATTR
-#undef __NTH
-#undef __NTHNL
-#undef __P
-#undef __PMT
-#undef __REDIRECT
-#undef __REDIRECT_LDBL
-#undef __REDIRECT_NTH
-#undef __REDIRECT_NTHNL
-#undef __REDIRECT_NTH_LDBL
-#undef __STRING
-#undef __THROW
-#undef __THROWNL
-#undef __always_inline
-#undef __attribute__
-#undef __attribute_alloc_size__
-#undef __attribute_artificial__
-#undef __attribute_const__
-#undef __attribute_deprecated__
-#undef __attribute_deprecated_msg__
-#undef __attribute_format_arg__
-#undef __attribute_format_strfmon__
-#undef __attribute_malloc__
-#undef __attribute_noinline__
-#undef __attribute_nonstring__
-#undef __attribute_pure__
-#undef __attribute_used__
-#undef __attribute_warn_unused_result__
-#undef __bos
-#undef __bos0
-#undef __errordecl
-#undef __extension__
-#undef __extern_always_inline
-#undef __extern_inline
-#undef __flexarr
-#undef __fortify_function
-#undef __glibc_c99_flexarr_available
-#undef __glibc_clang_has_extension
-#undef __glibc_likely
-#undef __glibc_macro_warning
-#undef __glibc_macro_warning1
-#undef __glibc_unlikely
-#undef __inline
-#undef __ptr_t
-#undef __restrict
-#undef __restrict_arr
-#undef __va_arg_pack
-#undef __va_arg_pack_len
-#undef __warnattr
-#undef __warndecl
+# undef _SYS_CDEFS_H
+# undef __ASMNAME
+# undef __ASMNAME2
+# undef __BEGIN_DECLS
+# undef __CONCAT
+# undef __END_DECLS
+# undef __HAVE_GENERIC_SELECTION
+# undef __LDBL_COMPAT
+# undef __LDBL_REDIR
+# undef __LDBL_REDIR1
+# undef __LDBL_REDIR1_DECL
+# undef __LDBL_REDIR1_NTH
+# undef __LDBL_REDIR2_DECL
+# undef __LDBL_REDIR_DECL
+# undef __LDBL_REDIR_NTH
+# undef __LEAF
+# undef __LEAF_ATTR
+# undef __NTH
+# undef __NTHNL
+# undef __REDIRECT
+# undef __REDIRECT_LDBL
+# undef __REDIRECT_NTH
+# undef __REDIRECT_NTHNL
+# undef __REDIRECT_NTH_LDBL
+# undef __STRING
+# undef __THROW
+# undef __THROWNL
+# undef __attr_access
+# undef __attribute__
+# undef __attribute_alloc_size__
+# undef __attribute_artificial__
+# undef __attribute_const__
+# undef __attribute_deprecated__
+# undef __attribute_deprecated_msg__
+# undef __attribute_format_arg__
+# undef __attribute_format_strfmon__
+# undef __attribute_malloc__
+# undef __attribute_noinline__
+# undef __attribute_nonstring__
+# undef __attribute_pure__
+# undef __attribute_returns_twice__
+# undef __attribute_used__
+# undef __attribute_warn_unused_result__
+# undef __bos
+# undef __bos0
+# undef __errordecl
+# undef __extension__
+# undef __extern_always_inline
+# undef __extern_inline
+# undef __flexarr
+# undef __fortify_function
+# undef __glibc_c99_flexarr_available
+# undef __glibc_has_attribute
+# undef __glibc_has_builtin
+# undef __glibc_has_extension
+# undef __glibc_macro_warning
+# undef __glibc_macro_warning1
+# undef __glibc_objsize
+# undef __glibc_objsize0
+# undef __glibc_unlikely
+# undef __inline
+# undef __ptr_t
+# undef __restrict
+# undef __restrict_arr
+# undef __va_arg_pack
+# undef __va_arg_pack_len
+# undef __warnattr
 
 /* Include our copy of glibc <sys/cdefs.h>.  */
-#include <cdefs.h>
+# include <cdefs.h>
 
 /* <cdefs.h> __inline is too pessimistic for non-GCC.  */
-#undef __inline
-#ifndef HAVE___INLINE
-# if 199901 <= __STDC_VERSION__ || defined inline
-#  define __inline inline
-# else
-#  define __inline
+# undef __inline
+# ifndef HAVE___INLINE
+#  if 199901 <= __STDC_VERSION__ || defined inline
+#   define __inline inline
+#  else
+#   define __inline
+#  endif
 # endif
-#endif
+
+#endif /* defined __glibc_likely */
 
 
 /* A substitute for glibc <libc-symbols.h>, good enough for Gnulib.  */
 #define attribute_hidden
-#define libc_hidden_proto(name, ...)
+#define libc_hidden_proto(name)
 #define libc_hidden_def(name)
 #define libc_hidden_weak(name)
 #define libc_hidden_ver(local, name)
diff --git a/lib/malloc/dynarray-skeleton.c b/lib/malloc/dynarray-skeleton.c
new file mode 100644
index 00000000000..4995fd1c049
--- /dev/null
+++ b/lib/malloc/dynarray-skeleton.c
@@ -0,0 +1,525 @@
+/* Type-safe arrays which grow dynamically.
+   Copyright (C) 2017-2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public
+   License as published by the Free Software Foundation; either
+   version 3 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received a copy of the GNU General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+/* Pre-processor macros which act as parameters:
+
+   DYNARRAY_STRUCT
+      The struct tag of dynamic array to be defined.
+   DYNARRAY_ELEMENT
+      The type name of the element type.  Elements are copied
+      as if by memcpy, and can change address as the dynamic
+      array grows.
+   DYNARRAY_PREFIX
+      The prefix of the functions which are defined.
+
+   The following parameters are optional:
+
+   DYNARRAY_ELEMENT_FREE
+      DYNARRAY_ELEMENT_FREE (E) is evaluated to deallocate the
+      contents of elements. E is of type  DYNARRAY_ELEMENT *.
+   DYNARRAY_ELEMENT_INIT
+      DYNARRAY_ELEMENT_INIT (E) is evaluated to initialize a new
+      element.  E is of type  DYNARRAY_ELEMENT *.
+      If DYNARRAY_ELEMENT_FREE but not DYNARRAY_ELEMENT_INIT is
+      defined, new elements are automatically zero-initialized.
+      Otherwise, new elements have undefined contents.
+   DYNARRAY_INITIAL_SIZE
+      The size of the statically allocated array (default:
+      at least 2, more elements if they fit into 128 bytes).
+      Must be a preprocessor constant.  If DYNARRAY_INITIAL_SIZE is 0,
+      there is no statically allocated array at, and all non-empty
+      arrays are heap-allocated.
+   DYNARRAY_FINAL_TYPE
+      The name of the type which holds the final array.  If not
+      defined, is PREFIX##finalize not provided.  DYNARRAY_FINAL_TYPE
+      must be a struct type, with members of type DYNARRAY_ELEMENT and
+      size_t at the start (in this order).
+
+   These macros are undefined after this header file has been
+   included.
+
+   The following types are provided (their members are private to the
+   dynarray implementation):
+
+     struct DYNARRAY_STRUCT
+
+   The following functions are provided:
+
+     void DYNARRAY_PREFIX##init (struct DYNARRAY_STRUCT *);
+     void DYNARRAY_PREFIX##free (struct DYNARRAY_STRUCT *);
+     bool DYNARRAY_PREFIX##has_failed (const struct DYNARRAY_STRUCT *);
+     void DYNARRAY_PREFIX##mark_failed (struct DYNARRAY_STRUCT *);
+     size_t DYNARRAY_PREFIX##size (const struct DYNARRAY_STRUCT *);
+     DYNARRAY_ELEMENT *DYNARRAY_PREFIX##begin (const struct DYNARRAY_STRUCT *);
+     DYNARRAY_ELEMENT *DYNARRAY_PREFIX##end (const struct DYNARRAY_STRUCT *);
+     DYNARRAY_ELEMENT *DYNARRAY_PREFIX##at (struct DYNARRAY_STRUCT *, size_t);
+     void DYNARRAY_PREFIX##add (struct DYNARRAY_STRUCT *, DYNARRAY_ELEMENT);
+     DYNARRAY_ELEMENT *DYNARRAY_PREFIX##emplace (struct DYNARRAY_STRUCT *);
+     bool DYNARRAY_PREFIX##resize (struct DYNARRAY_STRUCT *, size_t);
+     void DYNARRAY_PREFIX##remove_last (struct DYNARRAY_STRUCT *);
+     void DYNARRAY_PREFIX##clear (struct DYNARRAY_STRUCT *);
+
+   The following functions are provided are provided if the
+   prerequisites are met:
+
+     bool DYNARRAY_PREFIX##finalize (struct DYNARRAY_STRUCT *,
+                                     DYNARRAY_FINAL_TYPE *);
+       (if DYNARRAY_FINAL_TYPE is defined)
+     DYNARRAY_ELEMENT *DYNARRAY_PREFIX##finalize (struct DYNARRAY_STRUCT *,
+                                                  size_t *);
+       (if DYNARRAY_FINAL_TYPE is not defined)
+*/
+
+#include <malloc/dynarray.h>
+
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+
+#ifndef DYNARRAY_STRUCT
+# error "DYNARRAY_STRUCT must be defined"
+#endif
+
+#ifndef DYNARRAY_ELEMENT
+# error "DYNARRAY_ELEMENT must be defined"
+#endif
+
+#ifndef DYNARRAY_PREFIX
+# error "DYNARRAY_PREFIX must be defined"
+#endif
+
+#ifdef DYNARRAY_INITIAL_SIZE
+# if DYNARRAY_INITIAL_SIZE < 0
+#  error "DYNARRAY_INITIAL_SIZE must be non-negative"
+# endif
+# if DYNARRAY_INITIAL_SIZE > 0
+#  define DYNARRAY_HAVE_SCRATCH 1
+# else
+#  define DYNARRAY_HAVE_SCRATCH 0
+# endif
+#else
+/* Provide a reasonable default which limits the size of
+   DYNARRAY_STRUCT.  */
+# define DYNARRAY_INITIAL_SIZE \
+  (sizeof (DYNARRAY_ELEMENT) > 64 ? 2 : 128 / sizeof (DYNARRAY_ELEMENT))
+# define DYNARRAY_HAVE_SCRATCH 1
+#endif
+
+/* Public type definitions.  */
+
+/* All fields of this struct are private to the implementation.  */
+struct DYNARRAY_STRUCT
+{
+  union
+  {
+    struct dynarray_header dynarray_abstract;
+    struct
+    {
+      /* These fields must match struct dynarray_header.  */
+      size_t used;
+      size_t allocated;
+      DYNARRAY_ELEMENT *array;
+    } dynarray_header;
+  } u;
+
+#if DYNARRAY_HAVE_SCRATCH
+  /* Initial inline allocation.  */
+  DYNARRAY_ELEMENT scratch[DYNARRAY_INITIAL_SIZE];
+#endif
+};
+
+/* Internal use only: Helper macros.  */
+
+/* Ensure macro-expansion of DYNARRAY_PREFIX.  */
+#define DYNARRAY_CONCAT0(prefix, name) prefix##name
+#define DYNARRAY_CONCAT1(prefix, name) DYNARRAY_CONCAT0(prefix, name)
+#define DYNARRAY_NAME(name) DYNARRAY_CONCAT1(DYNARRAY_PREFIX, name)
+
+/* Use DYNARRAY_FREE instead of DYNARRAY_NAME (free),
+   so that Gnulib does not change 'free' to 'rpl_free'.  */
+#define DYNARRAY_FREE DYNARRAY_CONCAT1 (DYNARRAY_NAME (f), ree)
+
+/* Address of the scratch buffer if any.  */
+#if DYNARRAY_HAVE_SCRATCH
+# define DYNARRAY_SCRATCH(list) (list)->scratch
+#else
+# define DYNARRAY_SCRATCH(list) NULL
+#endif
+
+/* Internal use only: Helper functions.  */
+
+/* Internal function.  Call DYNARRAY_ELEMENT_FREE with the array
+   elements.  Name mangling needed due to the DYNARRAY_ELEMENT_FREE
+   macro expansion.  */
+static inline void
+DYNARRAY_NAME (free__elements__) (DYNARRAY_ELEMENT *__dynarray_array,
+                                  size_t __dynarray_used)
+{
+#ifdef DYNARRAY_ELEMENT_FREE
+  for (size_t __dynarray_i = 0; __dynarray_i < __dynarray_used; ++__dynarray_i)
+    DYNARRAY_ELEMENT_FREE (&__dynarray_array[__dynarray_i]);
+#endif /* DYNARRAY_ELEMENT_FREE */
+}
+
+/* Internal function.  Free the non-scratch array allocation.  */
+static inline void
+DYNARRAY_NAME (free__array__) (struct DYNARRAY_STRUCT *list)
+{
+#if DYNARRAY_HAVE_SCRATCH
+  if (list->u.dynarray_header.array != list->scratch)
+    free (list->u.dynarray_header.array);
+#else
+  free (list->u.dynarray_header.array);
+#endif
+}
+
+/* Public functions.  */
+
+/* Initialize a dynamic array object.  This must be called before any
+   use of the object.  */
+__nonnull ((1))
+static void
+DYNARRAY_NAME (init) (struct DYNARRAY_STRUCT *list)
+{
+  list->u.dynarray_header.used = 0;
+  list->u.dynarray_header.allocated = DYNARRAY_INITIAL_SIZE;
+  list->u.dynarray_header.array = DYNARRAY_SCRATCH (list);
+}
+
+/* Deallocate the dynamic array and its elements.  */
+__attribute_maybe_unused__ __nonnull ((1))
+static void
+DYNARRAY_FREE (struct DYNARRAY_STRUCT *list)
+{
+  DYNARRAY_NAME (free__elements__)
+    (list->u.dynarray_header.array, list->u.dynarray_header.used);
+  DYNARRAY_NAME (free__array__) (list);
+  DYNARRAY_NAME (init) (list);
+}
+
+/* Return true if the dynamic array is in an error state.  */
+__nonnull ((1))
+static inline bool
+DYNARRAY_NAME (has_failed) (const struct DYNARRAY_STRUCT *list)
+{
+  return list->u.dynarray_header.allocated == __dynarray_error_marker ();
+}
+
+/* Mark the dynamic array as failed.  All elements are deallocated as
+   a side effect.  */
+__nonnull ((1))
+static void
+DYNARRAY_NAME (mark_failed) (struct DYNARRAY_STRUCT *list)
+{
+  DYNARRAY_NAME (free__elements__)
+    (list->u.dynarray_header.array, list->u.dynarray_header.used);
+  DYNARRAY_NAME (free__array__) (list);
+  list->u.dynarray_header.array = DYNARRAY_SCRATCH (list);
+  list->u.dynarray_header.used = 0;
+  list->u.dynarray_header.allocated = __dynarray_error_marker ();
+}
+
+/* Return the number of elements which have been added to the dynamic
+   array.  */
+__nonnull ((1))
+static inline size_t
+DYNARRAY_NAME (size) (const struct DYNARRAY_STRUCT *list)
+{
+  return list->u.dynarray_header.used;
+}
+
+/* Return a pointer to the array element at INDEX.  Terminate the
+   process if INDEX is out of bounds.  */
+__nonnull ((1))
+static inline DYNARRAY_ELEMENT *
+DYNARRAY_NAME (at) (struct DYNARRAY_STRUCT *list, size_t index)
+{
+  if (__glibc_unlikely (index >= DYNARRAY_NAME (size) (list)))
+    __libc_dynarray_at_failure (DYNARRAY_NAME (size) (list), index);
+  return list->u.dynarray_header.array + index;
+}
+
+/* Return a pointer to the first array element, if any.  For a
+   zero-length array, the pointer can be NULL even though the dynamic
+   array has not entered the failure state.  */
+__nonnull ((1))
+static inline DYNARRAY_ELEMENT *
+DYNARRAY_NAME (begin) (struct DYNARRAY_STRUCT *list)
+{
+  return list->u.dynarray_header.array;
+}
+
+/* Return a pointer one element past the last array element.  For a
+   zero-length array, the pointer can be NULL even though the dynamic
+   array has not entered the failure state.  */
+__nonnull ((1))
+static inline DYNARRAY_ELEMENT *
+DYNARRAY_NAME (end) (struct DYNARRAY_STRUCT *list)
+{
+  return list->u.dynarray_header.array + list->u.dynarray_header.used;
+}
+
+/* Internal function.  Slow path for the add function below.  */
+static void
+DYNARRAY_NAME (add__) (struct DYNARRAY_STRUCT *list, DYNARRAY_ELEMENT item)
+{
+  if (__glibc_unlikely
+      (!__libc_dynarray_emplace_enlarge (&list->u.dynarray_abstract,
+                                         DYNARRAY_SCRATCH (list),
+                                         sizeof (DYNARRAY_ELEMENT))))
+    {
+      DYNARRAY_NAME (mark_failed) (list);
+      return;
+    }
+
+  /* Copy the new element and increase the array length.  */
+  list->u.dynarray_header.array[list->u.dynarray_header.used++] = item;
+}
+
+/* Add ITEM at the end of the array, enlarging it by one element.
+   Mark *LIST as failed if the dynamic array allocation size cannot be
+   increased.  */
+__nonnull ((1))
+static inline void
+DYNARRAY_NAME (add) (struct DYNARRAY_STRUCT *list, DYNARRAY_ELEMENT item)
+{
+  /* Do nothing in case of previous error.  */
+  if (DYNARRAY_NAME (has_failed) (list))
+    return;
+
+  /* Enlarge the array if necessary.  */
+  if (__glibc_unlikely (list->u.dynarray_header.used
+                        == list->u.dynarray_header.allocated))
+    {
+      DYNARRAY_NAME (add__) (list, item);
+      return;
+    }
+
+  /* Copy the new element and increase the array length.  */
+  list->u.dynarray_header.array[list->u.dynarray_header.used++] = item;
+}
+
+/* Internal function.  Building block for the emplace functions below.
+   Assumes space for one more element in *LIST.  */
+static inline DYNARRAY_ELEMENT *
+DYNARRAY_NAME (emplace__tail__) (struct DYNARRAY_STRUCT *list)
+{
+  DYNARRAY_ELEMENT *result
+    = &list->u.dynarray_header.array[list->u.dynarray_header.used];
+  ++list->u.dynarray_header.used;
+#if defined (DYNARRAY_ELEMENT_INIT)
+  DYNARRAY_ELEMENT_INIT (result);
+#elif defined (DYNARRAY_ELEMENT_FREE)
+  memset (result, 0, sizeof (*result));
+#endif
+  return result;
+}
+
+/* Internal function.  Slow path for the emplace function below.  */
+static DYNARRAY_ELEMENT *
+DYNARRAY_NAME (emplace__) (struct DYNARRAY_STRUCT *list)
+{
+  if (__glibc_unlikely
+      (!__libc_dynarray_emplace_enlarge (&list->u.dynarray_abstract,
+                                         DYNARRAY_SCRATCH (list),
+                                         sizeof (DYNARRAY_ELEMENT))))
+    {
+      DYNARRAY_NAME (mark_failed) (list);
+      return NULL;
+    }
+  return DYNARRAY_NAME (emplace__tail__) (list);
+}
+
+/* Allocate a place for a new element in *LIST and return a pointer to
+   it.  The pointer can be NULL if the dynamic array cannot be
+   enlarged due to a memory allocation failure.  */
+__attribute_maybe_unused__ __attribute_warn_unused_result__ __nonnull ((1))
+static
+/* Avoid inlining with the larger initialization code.  */
+#if !(defined (DYNARRAY_ELEMENT_INIT) || defined (DYNARRAY_ELEMENT_FREE))
+inline
+#endif
+DYNARRAY_ELEMENT *
+DYNARRAY_NAME (emplace) (struct DYNARRAY_STRUCT *list)
+{
+  /* Do nothing in case of previous error.  */
+  if (DYNARRAY_NAME (has_failed) (list))
+    return NULL;
+
+  /* Enlarge the array if necessary.  */
+  if (__glibc_unlikely (list->u.dynarray_header.used
+                        == list->u.dynarray_header.allocated))
+    return (DYNARRAY_NAME (emplace__) (list));
+  return DYNARRAY_NAME (emplace__tail__) (list);
+}
+
+/* Change the size of *LIST to SIZE.  If SIZE is larger than the
+   existing size, new elements are added (which can be initialized).
+   Otherwise, the list is truncated, and elements are freed.  Return
+   false on memory allocation failure (and mark *LIST as failed).  */
+__attribute_maybe_unused__ __nonnull ((1))
+static bool
+DYNARRAY_NAME (resize) (struct DYNARRAY_STRUCT *list, size_t size)
+{
+  if (size > list->u.dynarray_header.used)
+    {
+      bool ok;
+#if defined (DYNARRAY_ELEMENT_INIT)
+      /* The new elements have to be initialized.  */
+      size_t old_size = list->u.dynarray_header.used;
+      ok = __libc_dynarray_resize (&list->u.dynarray_abstract,
+                                   size, DYNARRAY_SCRATCH (list),
+                                   sizeof (DYNARRAY_ELEMENT));
+      if (ok)
+        for (size_t i = old_size; i < size; ++i)
+          {
+            DYNARRAY_ELEMENT_INIT (&list->u.dynarray_header.array[i]);
+          }
+#elif defined (DYNARRAY_ELEMENT_FREE)
+      /* Zero initialization is needed so that the elements can be
+         safely freed.  */
+      ok = __libc_dynarray_resize_clear
+        (&list->u.dynarray_abstract, size,
+         DYNARRAY_SCRATCH (list), sizeof (DYNARRAY_ELEMENT));
+#else
+      ok =  __libc_dynarray_resize (&list->u.dynarray_abstract,
+                                    size, DYNARRAY_SCRATCH (list),
+                                    sizeof (DYNARRAY_ELEMENT));
+#endif
+      if (__glibc_unlikely (!ok))
+        DYNARRAY_NAME (mark_failed) (list);
+      return ok;
+    }
+  else
+    {
+      /* The list has shrunk in size.  Free the removed elements.  */
+      DYNARRAY_NAME (free__elements__)
+        (list->u.dynarray_header.array + size,
+         list->u.dynarray_header.used - size);
+      list->u.dynarray_header.used = size;
+      return true;
+    }
+}
+
+/* Remove the last element of LIST if it is present.  */
+__attribute_maybe_unused__ __nonnull ((1))
+static void
+DYNARRAY_NAME (remove_last) (struct DYNARRAY_STRUCT *list)
+{
+  /* used > 0 implies that the array is the non-failed state.  */
+  if (list->u.dynarray_header.used > 0)
+    {
+      size_t new_length = list->u.dynarray_header.used - 1;
+#ifdef DYNARRAY_ELEMENT_FREE
+      DYNARRAY_ELEMENT_FREE (&list->u.dynarray_header.array[new_length]);
+#endif
+      list->u.dynarray_header.used = new_length;
+    }
+}
+
+/* Remove all elements from the list.  The elements are freed, but the
+   list itself is not.  */
+__attribute_maybe_unused__ __nonnull ((1))
+static void
+DYNARRAY_NAME (clear) (struct DYNARRAY_STRUCT *list)
+{
+  /* free__elements__ does nothing if the list is in the failed
+     state.  */
+  DYNARRAY_NAME (free__elements__)
+    (list->u.dynarray_header.array, list->u.dynarray_header.used);
+  list->u.dynarray_header.used = 0;
+}
+
+#ifdef DYNARRAY_FINAL_TYPE
+/* Transfer the dynamic array to a permanent location at *RESULT.
+   Returns true on success on false on allocation failure.  In either
+   case, *LIST is re-initialized and can be reused.  A NULL pointer is
+   stored in *RESULT if LIST refers to an empty list.  On success, the
+   pointer in *RESULT is heap-allocated and must be deallocated using
+   free.  */
+__attribute_maybe_unused__ __attribute_warn_unused_result__ __nonnull ((1, 2))
+static bool
+DYNARRAY_NAME (finalize) (struct DYNARRAY_STRUCT *list,
+                          DYNARRAY_FINAL_TYPE *result)
+{
+  struct dynarray_finalize_result res;
+  if (__libc_dynarray_finalize (&list->u.dynarray_abstract,
+                                DYNARRAY_SCRATCH (list),
+                                sizeof (DYNARRAY_ELEMENT), &res))
+    {
+      /* On success, the result owns all the data.  */
+      DYNARRAY_NAME (init) (list);
+      *result = (DYNARRAY_FINAL_TYPE) { res.array, res.length };
+      return true;
+    }
+  else
+    {
+      /* On error, we need to free all data.  */
+      DYNARRAY_FREE (list);
+      errno = ENOMEM;
+      return false;
+    }
+}
+#else /* !DYNARRAY_FINAL_TYPE */
+/* Transfer the dynamic array to a heap-allocated array and return a
+   pointer to it.  The pointer is NULL if memory allocation fails, or
+   if the array is empty, so this function should be used only for
+   arrays which are known not be empty (usually because they always
+   have a sentinel at the end).  If LENGTHP is not NULL, the array
+   length is written to *LENGTHP.  *LIST is re-initialized and can be
+   reused.  */
+__attribute_maybe_unused__ __attribute_warn_unused_result__ __nonnull ((1))
+static DYNARRAY_ELEMENT *
+DYNARRAY_NAME (finalize) (struct DYNARRAY_STRUCT *list, size_t *lengthp)
+{
+  struct dynarray_finalize_result res;
+  if (__libc_dynarray_finalize (&list->u.dynarray_abstract,
+                                DYNARRAY_SCRATCH (list),
+                                sizeof (DYNARRAY_ELEMENT), &res))
+    {
+      /* On success, the result owns all the data.  */
+      DYNARRAY_NAME (init) (list);
+      if (lengthp != NULL)
+        *lengthp = res.length;
+      return res.array;
+    }
+  else
+    {
+      /* On error, we need to free all data.  */
+      DYNARRAY_FREE (list);
+      errno = ENOMEM;
+      return NULL;
+    }
+}
+#endif /* !DYNARRAY_FINAL_TYPE */
+
+/* Undo macro definitions.  */
+
+#undef DYNARRAY_CONCAT0
+#undef DYNARRAY_CONCAT1
+#undef DYNARRAY_NAME
+#undef DYNARRAY_SCRATCH
+#undef DYNARRAY_HAVE_SCRATCH
+
+#undef DYNARRAY_STRUCT
+#undef DYNARRAY_ELEMENT
+#undef DYNARRAY_PREFIX
+#undef DYNARRAY_ELEMENT_FREE
+#undef DYNARRAY_ELEMENT_INIT
+#undef DYNARRAY_INITIAL_SIZE
+#undef DYNARRAY_FINAL_TYPE
diff --git a/lib/malloc/dynarray.h b/lib/malloc/dynarray.h
new file mode 100644
index 00000000000..84e4394bf32
--- /dev/null
+++ b/lib/malloc/dynarray.h
@@ -0,0 +1,178 @@
+/* Type-safe arrays which grow dynamically.  Shared definitions.
+   Copyright (C) 2017-2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public
+   License as published by the Free Software Foundation; either
+   version 3 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received a copy of the GNU General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+/* To use the dynarray facility, you need to include
+   <malloc/dynarray-skeleton.c> and define the parameter macros
+   documented in that file.
+
+   A minimal example which provides a growing list of integers can be
+   defined like this:
+
+     struct int_array
+     {
+       // Pointer to result array followed by its length,
+       // as required by DYNARRAY_FINAL_TYPE.
+       int *array;
+       size_t length;
+     };
+
+     #define DYNARRAY_STRUCT dynarray_int
+     #define DYNARRAY_ELEMENT int
+     #define DYNARRAY_PREFIX dynarray_int_
+     #define DYNARRAY_FINAL_TYPE struct int_array
+     #include <malloc/dynarray-skeleton.c>
+
+   To create a three-element array with elements 1, 2, 3, use this
+   code:
+
+     struct dynarray_int dyn;
+     dynarray_int_init (&dyn);
+     for (int i = 1; i <= 3; ++i)
+       {
+         int *place = dynarray_int_emplace (&dyn);
+         assert (place != NULL);
+         *place = i;
+       }
+     struct int_array result;
+     bool ok = dynarray_int_finalize (&dyn, &result);
+     assert (ok);
+     assert (result.length == 3);
+     assert (result.array[0] == 1);
+     assert (result.array[1] == 2);
+     assert (result.array[2] == 3);
+     free (result.array);
+
+   If the elements contain resources which must be freed, define
+   DYNARRAY_ELEMENT_FREE appropriately, like this:
+
+     struct str_array
+     {
+       char **array;
+       size_t length;
+     };
+
+     #define DYNARRAY_STRUCT dynarray_str
+     #define DYNARRAY_ELEMENT char *
+     #define DYNARRAY_ELEMENT_FREE(ptr) free (*ptr)
+     #define DYNARRAY_PREFIX dynarray_str_
+     #define DYNARRAY_FINAL_TYPE struct str_array
+     #include <malloc/dynarray-skeleton.c>
+
+   Compared to scratch buffers, dynamic arrays have the following
+   features:
+
+   - They have an element type, and are not just an untyped buffer of
+     bytes.
+
+   - When growing, previously stored elements are preserved.  (It is
+     expected that scratch_buffer_grow_preserve and
+     scratch_buffer_set_array_size eventually go away because all
+     current users are moved to dynamic arrays.)
+
+   - Scratch buffers have a more aggressive growth policy because
+     growing them typically means a retry of an operation (across an
+     NSS service module boundary), which is expensive.
+
+   - For the same reason, scratch buffers have a much larger initial
+     stack allocation.  */
+
+#ifndef _DYNARRAY_H
+#define _DYNARRAY_H
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <string.h>
+
+struct dynarray_header
+{
+  size_t used;
+  size_t allocated;
+  void *array;
+};
+
+/* Marker used in the allocated member to indicate that an error was
+   encountered.  */
+static inline size_t
+__dynarray_error_marker (void)
+{
+  return -1;
+}
+
+/* Internal function.  See the has_failed function in
+   dynarray-skeleton.c.  */
+static inline bool
+__dynarray_error (struct dynarray_header *list)
+{
+  return list->allocated == __dynarray_error_marker ();
+}
+
+/* Internal function.  Enlarge the dynamically allocated area of the
+   array to make room for one more element.  SCRATCH is a pointer to
+   the scratch area (which is not heap-allocated and must not be
+   freed).  ELEMENT_SIZE is the size, in bytes, of one element.
+   Return false on failure, true on success.  */
+bool __libc_dynarray_emplace_enlarge (struct dynarray_header *,
+                                      void *scratch, size_t element_size);
+
+/* Internal function.  Enlarge the dynamically allocated area of the
+   array to make room for at least SIZE elements (which must be larger
+   than the existing used part of the dynamic array).  SCRATCH is a
+   pointer to the scratch area (which is not heap-allocated and must
+   not be freed).  ELEMENT_SIZE is the size, in bytes, of one element.
+   Return false on failure, true on success.  */
+bool __libc_dynarray_resize (struct dynarray_header *, size_t size,
+                             void *scratch, size_t element_size);
+
+/* Internal function.  Like __libc_dynarray_resize, but clear the new
+   part of the dynamic array.  */
+bool __libc_dynarray_resize_clear (struct dynarray_header *, size_t size,
+                                   void *scratch, size_t element_size);
+
+/* Internal type.  */
+struct dynarray_finalize_result
+{
+  void *array;
+  size_t length;
+};
+
+/* Internal function.  Copy the dynamically-allocated area to an
+   explicitly-sized heap allocation.  SCRATCH is a pointer to the
+   embedded scratch space.  ELEMENT_SIZE is the size, in bytes, of the
+   element type.  On success, true is returned, and pointer and length
+   are written to *RESULT.  On failure, false is returned.  The caller
+   has to take care of some of the memory management; this function is
+   expected to be called from dynarray-skeleton.c.  */
+bool __libc_dynarray_finalize (struct dynarray_header *list, void *scratch,
+                               size_t element_size,
+                               struct dynarray_finalize_result *result);
+
+
+/* Internal function.  Terminate the process after an index error.
+   SIZE is the number of elements of the dynamic array.  INDEX is the
+   lookup index which triggered the failure.  */
+_Noreturn void __libc_dynarray_at_failure (size_t size, size_t index);
+
+#ifndef _ISOMAC
+libc_hidden_proto (__libc_dynarray_emplace_enlarge)
+libc_hidden_proto (__libc_dynarray_resize)
+libc_hidden_proto (__libc_dynarray_resize_clear)
+libc_hidden_proto (__libc_dynarray_finalize)
+libc_hidden_proto (__libc_dynarray_at_failure)
+#endif
+
+#endif /* _DYNARRAY_H */
diff --git a/lib/malloc/dynarray_at_failure.c b/lib/malloc/dynarray_at_failure.c
new file mode 100644
index 00000000000..a4424593748
--- /dev/null
+++ b/lib/malloc/dynarray_at_failure.c
@@ -0,0 +1,35 @@
+/* Report an dynamic array index out of bounds condition.
+   Copyright (C) 2017-2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public
+   License as published by the Free Software Foundation; either
+   version 3 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received a copy of the GNU General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <dynarray.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+void
+__libc_dynarray_at_failure (size_t size, size_t index)
+{
+#ifdef _LIBC
+  char buf[200];
+  __snprintf (buf, sizeof (buf), "Fatal glibc error: "
+              "array index %zu not less than array length %zu\n",
+              index, size);
+#else
+ abort ();
+#endif
+}
+libc_hidden_def (__libc_dynarray_at_failure)
diff --git a/lib/malloc/dynarray_emplace_enlarge.c b/lib/malloc/dynarray_emplace_enlarge.c
new file mode 100644
index 00000000000..7ac4b6db403
--- /dev/null
+++ b/lib/malloc/dynarray_emplace_enlarge.c
@@ -0,0 +1,73 @@
+/* Increase the size of a dynamic array in preparation of an emplace operation.
+   Copyright (C) 2017-2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public
+   License as published by the Free Software Foundation; either
+   version 3 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received a copy of the GNU General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <dynarray.h>
+#include <errno.h>
+#include <intprops.h>
+#include <stdlib.h>
+#include <string.h>
+
+bool
+__libc_dynarray_emplace_enlarge (struct dynarray_header *list,
+                                 void *scratch, size_t element_size)
+{
+  size_t new_allocated;
+  if (list->allocated == 0)
+    {
+      /* No scratch buffer provided.  Choose a reasonable default
+         size.  */
+      if (element_size < 4)
+        new_allocated = 16;
+      else if (element_size < 8)
+        new_allocated = 8;
+      else
+        new_allocated = 4;
+    }
+  else
+    /* Increase the allocated size, using an exponential growth
+       policy.  */
+    {
+      new_allocated = list->allocated + list->allocated / 2 + 1;
+      if (new_allocated <= list->allocated)
+        {
+          /* Overflow.  */
+          __set_errno (ENOMEM);
+          return false;
+        }
+    }
+
+  size_t new_size;
+  if (INT_MULTIPLY_WRAPV (new_allocated, element_size, &new_size))
+    return false;
+  void *new_array;
+  if (list->array == scratch)
+    {
+      /* The previous array was not heap-allocated.  */
+      new_array = malloc (new_size);
+      if (new_array != NULL && list->array != NULL)
+        memcpy (new_array, list->array, list->used * element_size);
+    }
+  else
+    new_array = realloc (list->array, new_size);
+  if (new_array == NULL)
+    return false;
+  list->array = new_array;
+  list->allocated = new_allocated;
+  return true;
+}
+libc_hidden_def (__libc_dynarray_emplace_enlarge)
diff --git a/lib/malloc/dynarray_finalize.c b/lib/malloc/dynarray_finalize.c
new file mode 100644
index 00000000000..be9441e313d
--- /dev/null
+++ b/lib/malloc/dynarray_finalize.c
@@ -0,0 +1,62 @@
+/* Copy the dynamically-allocated area to an explicitly-sized heap allocation.
+   Copyright (C) 2017-2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public
+   License as published by the Free Software Foundation; either
+   version 3 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received a copy of the GNU General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <dynarray.h>
+#include <stdlib.h>
+#include <string.h>
+
+bool
+__libc_dynarray_finalize (struct dynarray_header *list,
+                          void *scratch, size_t element_size,
+                          struct dynarray_finalize_result *result)
+{
+  if (__dynarray_error (list))
+    /* The caller will reported the deferred error.  */
+    return false;
+
+  size_t used = list->used;
+
+  /* Empty list.  */
+  if (used == 0)
+    {
+      /* An empty list could still be backed by a heap-allocated
+         array.  Free it if necessary.  */
+      if (list->array != scratch)
+        free (list->array);
+      *result = (struct dynarray_finalize_result) { NULL, 0 };
+      return true;
+    }
+
+  size_t allocation_size = used * element_size;
+  void *heap_array = malloc (allocation_size);
+  if (heap_array != NULL)
+    {
+      /* The new array takes ownership of the strings.  */
+      if (list->array != NULL)
+        memcpy (heap_array, list->array, allocation_size);
+      if (list->array != scratch)
+        free (list->array);
+      *result = (struct dynarray_finalize_result)
+        { .array = heap_array, .length = used };
+      return true;
+    }
+  else
+    /* The caller will perform the freeing operation.  */
+    return false;
+}
+libc_hidden_def (__libc_dynarray_finalize)
diff --git a/lib/malloc/dynarray_resize.c b/lib/malloc/dynarray_resize.c
new file mode 100644
index 00000000000..92bbddd4461
--- /dev/null
+++ b/lib/malloc/dynarray_resize.c
@@ -0,0 +1,64 @@
+/* Increase the size of a dynamic array.
+   Copyright (C) 2017-2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public
+   License as published by the Free Software Foundation; either
+   version 3 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received a copy of the GNU General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <dynarray.h>
+#include <errno.h>
+#include <intprops.h>
+#include <stdlib.h>
+#include <string.h>
+
+bool
+__libc_dynarray_resize (struct dynarray_header *list, size_t size,
+                        void *scratch, size_t element_size)
+{
+  /* The existing allocation provides sufficient room.  */
+  if (size <= list->allocated)
+    {
+      list->used = size;
+      return true;
+    }
+
+  /* Otherwise, use size as the new allocation size.  The caller is
+     expected to provide the final size of the array, so there is no
+     over-allocation here.  */
+
+  size_t new_size_bytes;
+  if (INT_MULTIPLY_WRAPV (size, element_size, &new_size_bytes))
+    {
+      /* Overflow.  */
+      __set_errno (ENOMEM);
+      return false;
+    }
+  void *new_array;
+  if (list->array == scratch)
+    {
+      /* The previous array was not heap-allocated.  */
+      new_array = malloc (new_size_bytes);
+      if (new_array != NULL && list->array != NULL)
+        memcpy (new_array, list->array, list->used * element_size);
+    }
+  else
+    new_array = realloc (list->array, new_size_bytes);
+  if (new_array == NULL)
+    return false;
+  list->array = new_array;
+  list->allocated = size;
+  list->used = size;
+  return true;
+}
+libc_hidden_def (__libc_dynarray_resize)
diff --git a/lib/malloc/dynarray_resize_clear.c b/lib/malloc/dynarray_resize_clear.c
new file mode 100644
index 00000000000..99c2cc87c31
--- /dev/null
+++ b/lib/malloc/dynarray_resize_clear.c
@@ -0,0 +1,35 @@
+/* Increase the size of a dynamic array and clear the new part.
+   Copyright (C) 2017-2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public
+   License as published by the Free Software Foundation; either
+   version 3 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received a copy of the GNU General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <dynarray.h>
+#include <string.h>
+
+bool
+__libc_dynarray_resize_clear (struct dynarray_header *list, size_t size,
+                              void *scratch, size_t element_size)
+{
+  size_t old_size = list->used;
+  if (!__libc_dynarray_resize (list, size, scratch, element_size))
+    return false;
+  /* __libc_dynarray_resize already checked for overflow.  */
+  char *array = list->array;
+  memset (array + (old_size * element_size), 0,
+          (size - old_size) * element_size);
+  return true;
+}
+libc_hidden_def (__libc_dynarray_resize_clear)
diff --git a/lib/malloc/scratch_buffer_grow.c b/lib/malloc/scratch_buffer_grow.c
index 41befe3d65f..e7606d81cd7 100644
--- a/lib/malloc/scratch_buffer_grow.c
+++ b/lib/malloc/scratch_buffer_grow.c
@@ -1,5 +1,5 @@
 /* Variable-sized buffer with on-stack default allocation.
-   Copyright (C) 2015-2020 Free Software Foundation, Inc.
+   Copyright (C) 2015-2021 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
diff --git a/lib/malloc/scratch_buffer_grow_preserve.c b/lib/malloc/scratch_buffer_grow_preserve.c
index aef232938d5..59f8c710001 100644
--- a/lib/malloc/scratch_buffer_grow_preserve.c
+++ b/lib/malloc/scratch_buffer_grow_preserve.c
@@ -1,5 +1,5 @@
 /* Variable-sized buffer with on-stack default allocation.
-   Copyright (C) 2015-2020 Free Software Foundation, Inc.
+   Copyright (C) 2015-2021 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
diff --git a/lib/malloc/scratch_buffer_set_array_size.c b/lib/malloc/scratch_buffer_set_array_size.c
index 5f5e4c24f5a..e2b9f31211a 100644
--- a/lib/malloc/scratch_buffer_set_array_size.c
+++ b/lib/malloc/scratch_buffer_set_array_size.c
@@ -1,5 +1,5 @@
 /* Variable-sized buffer with on-stack default allocation.
-   Copyright (C) 2015-2020 Free Software Foundation, Inc.
+   Copyright (C) 2015-2021 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
diff --git a/lib/mini-gmp.c b/lib/mini-gmp.c
index d34fe525e4c..de061e673ac 100644
--- a/lib/mini-gmp.c
+++ b/lib/mini-gmp.c
@@ -4521,7 +4521,7 @@ mpz_export (void *r, size_t *countp, int order, size_t size, int endian,
   mp_size_t un;
 
   if (nails != 0)
-    gmp_die ("mpz_import: Nails not supported.");
+    gmp_die ("mpz_export: Nails not supported.");
 
   assert (order == 1 || order == -1);
   assert (endian >= -1 && endian <= 1);
diff --git a/lib/mktime-internal.h b/lib/mktime-internal.h
index b765a37ee34..9c447bd7b05 100644
--- a/lib/mktime-internal.h
+++ b/lib/mktime-internal.h
@@ -1,5 +1,5 @@
 /* Internals of mktime and related functions
-   Copyright 2016-2020 Free Software Foundation, Inc.
+   Copyright 2016-2021 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
    Contributed by Paul Eggert <eggert@cs.ucla.edu>.
 
diff --git a/lib/nstrftime.c b/lib/nstrftime.c
index 8ba6975552b..2f5e4fbe639 100644
--- a/lib/nstrftime.c
+++ b/lib/nstrftime.c
@@ -19,7 +19,7 @@
 # define USE_IN_EXTENDED_LOCALE_MODEL 1
 # define HAVE_STRUCT_ERA_ENTRY 1
 # define HAVE_TM_GMTOFF 1
-# define HAVE_TM_ZONE 1
+# define HAVE_STRUCT_TM_TM_ZONE 1
 # define HAVE_TZNAME 1
 # include "../locale/localeinfo.h"
 #else
@@ -499,7 +499,7 @@ __strftime_internal (STREAM_OR_CHAR_T *s, STRFTIME_ARG (size_t maxsize)
 #endif
 
   zone = NULL;
-#if HAVE_TM_ZONE
+#if HAVE_STRUCT_TM_TM_ZONE
   /* The POSIX test suite assumes that setting
      the environment variable TZ to a new value before calling strftime()
      will influence the result (the %Z format) even if the information in
@@ -516,7 +516,7 @@ __strftime_internal (STREAM_OR_CHAR_T *s, STRFTIME_ARG (size_t maxsize)
     }
   else
     {
-# if !HAVE_TM_ZONE
+# if !HAVE_STRUCT_TM_TM_ZONE
       /* Infer the zone name from *TZ instead of from TZNAME.  */
       tzname_vec = tz->tzname_copy;
 # endif
diff --git a/lib/regex.c b/lib/regex.c
index 88173bb1052..f76a416b3b5 100644
--- a/lib/regex.c
+++ b/lib/regex.c
@@ -1,5 +1,5 @@
 /* Extended regular expression matching and search library.
-   Copyright (C) 2002-2020 Free Software Foundation, Inc.
+   Copyright (C) 2002-2021 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
    Contributed by Isamu Hasegawa <isamu@yamato.ibm.com>.
 
diff --git a/lib/regex_internal.h b/lib/regex_internal.h
index be2fa4fe78e..4c634edcbfa 100644
--- a/lib/regex_internal.h
+++ b/lib/regex_internal.h
@@ -32,6 +32,7 @@
 #include <stdbool.h>
 #include <stdint.h>
 
+#include <dynarray.h>
 #include <intprops.h>
 #include <verify.h>
 
@@ -444,25 +445,6 @@ typedef struct re_dfa_t re_dfa_t;
 #define re_string_skip_bytes(pstr,idx) ((pstr)->cur_idx += (idx))
 #define re_string_set_index(pstr,idx) ((pstr)->cur_idx = (idx))
 
-#if defined _LIBC || HAVE_ALLOCA
-# include <alloca.h>
-#endif
-
-#ifndef _LIBC
-# if HAVE_ALLOCA
-/* The OS usually guarantees only one guard page at the bottom of the stack,
-   and a page size can be as small as 4096 bytes.  So we cannot safely
-   allocate anything larger than 4096 bytes.  Also care for the possibility
-   of a few compiler-allocated temporary stack slots.  */
-#  define __libc_use_alloca(n) ((n) < 4032)
-# else
-/* alloca is implemented with malloc, so just use malloc.  */
-#  define __libc_use_alloca(n) 0
-#  undef alloca
-#  define alloca(n) malloc (n)
-# endif
-#endif
-
 #ifdef _LIBC
 # define MALLOC_0_IS_NONNULL 1
 #elif !defined MALLOC_0_IS_NONNULL
@@ -848,12 +830,14 @@ re_string_elem_size_at (const re_string_t *pstr, Idx idx)
 }
 #endif /* RE_ENABLE_I18N */
 
-#ifndef FALLTHROUGH
-# if (__GNUC__ >= 7) || (__clang_major__ >= 10)
+#ifdef _LIBC
+# if __GNUC__ >= 7
 #  define FALLTHROUGH __attribute__ ((__fallthrough__))
 # else
 #  define FALLTHROUGH ((void) 0)
 # endif
+#else
+# include "attribute.h"
 #endif
 
 #endif /*  _REGEX_INTERNAL_H */
diff --git a/lib/regexec.c b/lib/regexec.c
index 395e37db591..15dc57bd0e6 100644
--- a/lib/regexec.c
+++ b/lib/regexec.c
@@ -1,5 +1,5 @@
 /* Extended regular expression matching and search library.
-   Copyright (C) 2002-2020 Free Software Foundation, Inc.
+   Copyright (C) 2002-2021 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
    Contributed by Isamu Hasegawa <isamu@yamato.ibm.com>.
 
@@ -1355,6 +1355,12 @@ pop_fail_stack (struct re_fail_stack_t *fs, Idx *pidx, Idx nregs,
   return fs->stack[num].node;
 }
 
+
+#define DYNARRAY_STRUCT  regmatch_list
+#define DYNARRAY_ELEMENT regmatch_t
+#define DYNARRAY_PREFIX  regmatch_list_
+#include <malloc/dynarray-skeleton.c>
+
 /* Set the positions where the subexpressions are starts/ends to registers
    PMATCH.
    Note: We assume that pmatch[0] is already set, and
@@ -1370,8 +1376,8 @@ set_regs (const regex_t *preg, const re_match_context_t *mctx, size_t nmatch,
   re_node_set eps_via_nodes;
   struct re_fail_stack_t *fs;
   struct re_fail_stack_t fs_body = { 0, 2, NULL };
-  regmatch_t *prev_idx_match;
-  bool prev_idx_match_malloced = false;
+  struct regmatch_list prev_match;
+  regmatch_list_init (&prev_match);
 
   DEBUG_ASSERT (nmatch > 1);
   DEBUG_ASSERT (mctx->state_log != NULL);
@@ -1388,18 +1394,13 @@ set_regs (const regex_t *preg, const re_match_context_t *mctx, size_t nmatch,
   cur_node = dfa->init_node;
   re_node_set_init_empty (&eps_via_nodes);
 
-  if (__libc_use_alloca (nmatch * sizeof (regmatch_t)))
-    prev_idx_match = (regmatch_t *) alloca (nmatch * sizeof (regmatch_t));
-  else
+  if (!regmatch_list_resize (&prev_match, nmatch))
     {
-      prev_idx_match = re_malloc (regmatch_t, nmatch);
-      if (prev_idx_match == NULL)
-	{
-	  free_fail_stack_return (fs);
-	  return REG_ESPACE;
-	}
-      prev_idx_match_malloced = true;
+      regmatch_list_free (&prev_match);
+      free_fail_stack_return (fs);
+      return REG_ESPACE;
     }
+  regmatch_t *prev_idx_match = regmatch_list_begin (&prev_match);
   memcpy (prev_idx_match, pmatch, sizeof (regmatch_t) * nmatch);
 
   for (idx = pmatch[0].rm_so; idx <= pmatch[0].rm_eo ;)
@@ -1417,8 +1418,7 @@ set_regs (const regex_t *preg, const re_match_context_t *mctx, size_t nmatch,
 	      if (reg_idx == nmatch)
 		{
 		  re_node_set_free (&eps_via_nodes);
-		  if (prev_idx_match_malloced)
-		    re_free (prev_idx_match);
+		  regmatch_list_free (&prev_match);
 		  return free_fail_stack_return (fs);
 		}
 	      cur_node = pop_fail_stack (fs, &idx, nmatch, pmatch,
@@ -1427,8 +1427,7 @@ set_regs (const regex_t *preg, const re_match_context_t *mctx, size_t nmatch,
 	  else
 	    {
 	      re_node_set_free (&eps_via_nodes);
-	      if (prev_idx_match_malloced)
-		re_free (prev_idx_match);
+	      regmatch_list_free (&prev_match);
 	      return REG_NOERROR;
 	    }
 	}
@@ -1442,8 +1441,7 @@ set_regs (const regex_t *preg, const re_match_context_t *mctx, size_t nmatch,
 	  if (__glibc_unlikely (cur_node == -2))
 	    {
 	      re_node_set_free (&eps_via_nodes);
-	      if (prev_idx_match_malloced)
-		re_free (prev_idx_match);
+	      regmatch_list_free (&prev_match);
 	      free_fail_stack_return (fs);
 	      return REG_ESPACE;
 	    }
@@ -1453,15 +1451,13 @@ set_regs (const regex_t *preg, const re_match_context_t *mctx, size_t nmatch,
 	  else
 	    {
 	      re_node_set_free (&eps_via_nodes);
-	      if (prev_idx_match_malloced)
-		re_free (prev_idx_match);
+	      regmatch_list_free (&prev_match);
 	      return REG_NOMATCH;
 	    }
 	}
     }
   re_node_set_free (&eps_via_nodes);
-  if (prev_idx_match_malloced)
-    re_free (prev_idx_match);
+  regmatch_list_free (&prev_match);
   return free_fail_stack_return (fs);
 }
 
@@ -3251,7 +3247,7 @@ expand_bkref_cache (re_match_context_t *mctx, re_node_set *cur_nodes,
 /* Build transition table for the state.
    Return true if successful.  */
 
-static bool
+static bool __attribute_noinline__
 build_trtable (const re_dfa_t *dfa, re_dfastate_t *state)
 {
   reg_errcode_t err;
@@ -3259,36 +3255,20 @@ build_trtable (const re_dfa_t *dfa, re_dfastate_t *state)
   int ch;
   bool need_word_trtable = false;
   bitset_word_t elem, mask;
-  bool dests_node_malloced = false;
-  bool dest_states_malloced = false;
   Idx ndests; /* Number of the destination states from 'state'.  */
   re_dfastate_t **trtable;
-  re_dfastate_t **dest_states = NULL, **dest_states_word, **dest_states_nl;
-  re_node_set follows, *dests_node;
-  bitset_t *dests_ch;
+  re_dfastate_t *dest_states[SBC_MAX];
+  re_dfastate_t *dest_states_word[SBC_MAX];
+  re_dfastate_t *dest_states_nl[SBC_MAX];
+  re_node_set follows;
   bitset_t acceptable;
 
-  struct dests_alloc
-  {
-    re_node_set dests_node[SBC_MAX];
-    bitset_t dests_ch[SBC_MAX];
-  } *dests_alloc;
-
   /* We build DFA states which corresponds to the destination nodes
      from 'state'.  'dests_node[i]' represents the nodes which i-th
      destination state contains, and 'dests_ch[i]' represents the
      characters which i-th destination state accepts.  */
-  if (__libc_use_alloca (sizeof (struct dests_alloc)))
-    dests_alloc = (struct dests_alloc *) alloca (sizeof (struct dests_alloc));
-  else
-    {
-      dests_alloc = re_malloc (struct dests_alloc, 1);
-      if (__glibc_unlikely (dests_alloc == NULL))
-	return false;
-      dests_node_malloced = true;
-    }
-  dests_node = dests_alloc->dests_node;
-  dests_ch = dests_alloc->dests_ch;
+  re_node_set dests_node[SBC_MAX];
+  bitset_t dests_ch[SBC_MAX];
 
   /* Initialize transition table.  */
   state->word_trtable = state->trtable = NULL;
@@ -3298,8 +3278,6 @@ build_trtable (const re_dfa_t *dfa, re_dfastate_t *state)
   ndests = group_nodes_into_DFAstates (dfa, state, dests_node, dests_ch);
   if (__glibc_unlikely (ndests <= 0))
     {
-      if (dests_node_malloced)
-	re_free (dests_alloc);
       /* Return false in case of an error, true otherwise.  */
       if (ndests == 0)
 	{
@@ -3314,38 +3292,14 @@ build_trtable (const re_dfa_t *dfa, re_dfastate_t *state)
 
   err = re_node_set_alloc (&follows, ndests + 1);
   if (__glibc_unlikely (err != REG_NOERROR))
-    goto out_free;
-
-  /* Avoid arithmetic overflow in size calculation.  */
-  size_t ndests_max
-    = ((SIZE_MAX - (sizeof (re_node_set) + sizeof (bitset_t)) * SBC_MAX)
-       / (3 * sizeof (re_dfastate_t *)));
-  if (__glibc_unlikely (ndests_max < ndests))
-    goto out_free;
-
-  if (__libc_use_alloca ((sizeof (re_node_set) + sizeof (bitset_t)) * SBC_MAX
-			 + ndests * 3 * sizeof (re_dfastate_t *)))
-    dest_states = (re_dfastate_t **)
-      alloca (ndests * 3 * sizeof (re_dfastate_t *));
-  else
     {
-      dest_states = re_malloc (re_dfastate_t *, ndests * 3);
-      if (__glibc_unlikely (dest_states == NULL))
-	{
-out_free:
-	  if (dest_states_malloced)
-	    re_free (dest_states);
-	  re_node_set_free (&follows);
-	  for (i = 0; i < ndests; ++i)
-	    re_node_set_free (dests_node + i);
-	  if (dests_node_malloced)
-	    re_free (dests_alloc);
-	  return false;
-	}
-      dest_states_malloced = true;
+    out_free:
+      re_node_set_free (&follows);
+      for (i = 0; i < ndests; ++i)
+	re_node_set_free (dests_node + i);
+      return false;
     }
-  dest_states_word = dest_states + ndests;
-  dest_states_nl = dest_states_word + ndests;
+
   bitset_empty (acceptable);
 
   /* Then build the states for all destinations.  */
@@ -3470,16 +3424,9 @@ out_free:
 	  }
     }
 
-  if (dest_states_malloced)
-    re_free (dest_states);
-
   re_node_set_free (&follows);
   for (i = 0; i < ndests; ++i)
     re_node_set_free (dests_node + i);
-
-  if (dests_node_malloced)
-    re_free (dests_alloc);
-
   return true;
 }
 
diff --git a/lib/scratch_buffer.h b/lib/scratch_buffer.h
index 3e2b5ef27db..603b0d65d0a 100644
--- a/lib/scratch_buffer.h
+++ b/lib/scratch_buffer.h
@@ -21,6 +21,7 @@
 
 #include <libc-config.h>
 
+#define __libc_scratch_buffer_dupfree gl_scratch_buffer_dupfree
 #define __libc_scratch_buffer_grow gl_scratch_buffer_grow
 #define __libc_scratch_buffer_grow_preserve gl_scratch_buffer_grow_preserve
 #define __libc_scratch_buffer_set_array_size gl_scratch_buffer_set_array_size
diff --git a/lib/stddef.in.h b/lib/stddef.in.h
index ba7195a9102..0f506a5b18b 100644
--- a/lib/stddef.in.h
+++ b/lib/stddef.in.h
@@ -49,6 +49,23 @@
 
 # ifndef _@GUARD_PREFIX@_STDDEF_H
 
+/* On AIX 7.2, with xlc in 64-bit mode, <stddef.h> defines max_align_t to a
+   type with alignment 4, but 'long' has alignment 8.  */
+#  if defined _AIX && defined _ARCH_PPC64
+#   if !GNULIB_defined_max_align_t
+#    ifdef _MAX_ALIGN_T
+/* /usr/include/stddef.h has already defined max_align_t.  Override it.  */
+typedef long rpl_max_align_t;
+#     define max_align_t rpl_max_align_t
+#    else
+/* Prevent /usr/include/stddef.h from defining max_align_t.  */
+typedef long max_align_t;
+#     define _MAX_ALIGN_T
+#    endif
+#    define GNULIB_defined_max_align_t 1
+#   endif
+#  endif
+
 /* The include_next requires a split double-inclusion guard.  */
 
 #  @INCLUDE_NEXT@ @NEXT_STDDEF_H@
@@ -86,8 +103,10 @@
    we are currently compiling with gcc.
    On MSVC, max_align_t is defined only in C++ mode, after <cstddef> was
    included.  Its definition is good since it has an alignment of 8 (on x86
-   and x86_64).  */
-#if defined _MSC_VER && defined __cplusplus
+   and x86_64).
+   Similarly on OS/2 kLIBC.  */
+#if (defined _MSC_VER || (defined __KLIBC__ && !defined __LIBCN__)) \
+    && defined __cplusplus
 # include <cstddef>
 #else
 # if ! (@HAVE_MAX_ALIGN_T@ || defined _GCC_MAX_ALIGN_T)
diff --git a/lib/string.in.h b/lib/string.in.h
index 9f68e77c767..c76c1820b36 100644
--- a/lib/string.in.h
+++ b/lib/string.in.h
@@ -69,6 +69,14 @@
 # include <unistd.h>
 #endif
 
+/* AIX 7.2 declares ffsl and ffsll in <strings.h>, not in <string.h>.  */
+/* But in any case avoid namespace pollution on glibc systems.  */
+#if ((@GNULIB_FFSL@ || @GNULIB_FFSLL@ || defined GNULIB_POSIXCHECK) \
+     && defined _AIX) \
+    && ! defined __GLIBC__
+# include <strings.h>
+#endif
+
 /* The definitions of _GL_FUNCDECL_RPL etc. are copied here.  */
 
 /* The definition of _GL_ARG_NONNULL is copied here.  */
@@ -110,10 +118,18 @@ _GL_WARN_ON_USE (ffsl, "ffsl is not portable - use the ffsl module");
 
 /* Find the index of the least-significant set bit.  */
 #if @GNULIB_FFSLL@
-# if !@HAVE_FFSLL@
+# if @REPLACE_FFSLL@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   define ffsll rpl_ffsll
+#  endif
+_GL_FUNCDECL_RPL (ffsll, int, (long long int i));
+_GL_CXXALIAS_RPL (ffsll, int, (long long int i));
+# else
+#  if !@HAVE_FFSLL@
 _GL_FUNCDECL_SYS (ffsll, int, (long long int i));
-# endif
+#  endif
 _GL_CXXALIAS_SYS (ffsll, int, (long long int i));
+# endif
 _GL_CXXALIASWARN (ffsll);
 #elif defined GNULIB_POSIXCHECK
 # undef ffsll
diff --git a/lib/sys_stat.in.h b/lib/sys_stat.in.h
index ccdb5cbd143..13d12943cd0 100644
--- a/lib/sys_stat.in.h
+++ b/lib/sys_stat.in.h
@@ -713,11 +713,21 @@ _GL_WARN_ON_USE (mkfifo, "mkfifo is not portable - "
 
 
 #if @GNULIB_MKFIFOAT@
-# if !@HAVE_MKFIFOAT@
+# if @REPLACE_MKFIFOAT@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   undef mkfifoat
+#   define mkfifoat rpl_mkfifoat
+#  endif
+_GL_FUNCDECL_RPL (mkfifoat, int, (int fd, char const *file, mode_t mode)
+                                 _GL_ARG_NONNULL ((2)));
+_GL_CXXALIAS_RPL (mkfifoat, int, (int fd, char const *file, mode_t mode));
+# else
+#  if !@HAVE_MKFIFOAT@
 _GL_FUNCDECL_SYS (mkfifoat, int, (int fd, char const *file, mode_t mode)
                                  _GL_ARG_NONNULL ((2)));
-# endif
+#  endif
 _GL_CXXALIAS_SYS (mkfifoat, int, (int fd, char const *file, mode_t mode));
+# endif
 _GL_CXXALIASWARN (mkfifoat);
 #elif defined GNULIB_POSIXCHECK
 # undef mkfifoat
@@ -756,13 +766,25 @@ _GL_WARN_ON_USE (mknod, "mknod is not portable - "
 
 
 #if @GNULIB_MKNODAT@
-# if !@HAVE_MKNODAT@
+# if @REPLACE_MKNODAT@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   undef mknodat
+#   define mknodat rpl_mknodat
+#  endif
+_GL_FUNCDECL_RPL (mknodat, int,
+                  (int fd, char const *file, mode_t mode, dev_t dev)
+                  _GL_ARG_NONNULL ((2)));
+_GL_CXXALIAS_RPL (mknodat, int,
+                  (int fd, char const *file, mode_t mode, dev_t dev));
+# else
+#  if !@HAVE_MKNODAT@
 _GL_FUNCDECL_SYS (mknodat, int,
                   (int fd, char const *file, mode_t mode, dev_t dev)
                   _GL_ARG_NONNULL ((2)));
-# endif
+#  endif
 _GL_CXXALIAS_SYS (mknodat, int,
                   (int fd, char const *file, mode_t mode, dev_t dev));
+# endif
 _GL_CXXALIASWARN (mknodat);
 #elif defined GNULIB_POSIXCHECK
 # undef mknodat
diff --git a/lib/tempname.c b/lib/tempname.c
index 3d91deef1e1..e243483eaf8 100644
--- a/lib/tempname.c
+++ b/lib/tempname.c
@@ -22,6 +22,7 @@
 
 #include <sys/types.h>
 #include <assert.h>
+#include <stdbool.h>
 
 #include <errno.h>
 
@@ -61,7 +62,8 @@
 # define __gen_tempname gen_tempname
 # define __mkdir mkdir
 # define __open open
-# define __lxstat64(version, file, buf) lstat (file, buf)
+# define __lstat64(file, buf) lstat (file, buf)
+# define __stat64(file, buf) stat (file, buf)
 # define __getrandom getrandom
 # define __clock_gettime64 clock_gettime
 # define __timespec64 timespec
@@ -76,13 +78,14 @@ typedef uint_fast64_t random_value;
 #define BASE_62_POWER (62LL * 62 * 62 * 62 * 62 * 62 * 62 * 62 * 62 * 62)
 
 static random_value
-random_bits (random_value var)
+random_bits (random_value var, bool use_getrandom)
 {
   random_value r;
-  if (__getrandom (&r, sizeof r, 0) == sizeof r)
+  /* Without GRND_NONBLOCK it can be blocked for minutes on some systems.  */
+  if (use_getrandom && __getrandom (&r, sizeof r, GRND_NONBLOCK) == sizeof r)
     return r;
 #if _LIBC || (defined CLOCK_MONOTONIC && HAVE_CLOCK_GETTIME)
-  /* Add entropy if getrandom is not supported.  */
+  /* Add entropy if getrandom did not work.  */
   struct __timespec64 tv;
   __clock_gettime64 (CLOCK_MONOTONIC, &tv);
   var ^= tv.tv_nsec;
@@ -96,7 +99,7 @@ static int
 direxists (const char *dir)
 {
   struct_stat64 buf;
-  return __xstat64 (_STAT_VER, dir, &buf) == 0 && S_ISDIR (buf.st_mode);
+  return __stat64 (dir, &buf) == 0 && S_ISDIR (buf.st_mode);
 }
 
 /* Path search algorithm, for tmpnam, tmpfile, etc.  If DIR is
@@ -188,7 +191,7 @@ try_nocreate (char *tmpl, void *flags _GL_UNUSED)
 {
   struct_stat64 st;
 
-  if (__lxstat64 (_STAT_VER, tmpl, &st) == 0 || errno == EOVERFLOW)
+  if (__lstat64 (tmpl, &st) == 0 || errno == EOVERFLOW)
     __set_errno (EEXIST);
   return errno == ENOENT ? 0 : -1;
 }
@@ -267,6 +270,13 @@ try_tempname_len (char *tmpl, int suffixlen, void *args,
   /* How many random base-62 digits can currently be extracted from V.  */
   int vdigits = 0;
 
+  /* Whether to consume entropy when acquiring random bits.  On the
+     first try it's worth the entropy cost with __GT_NOCREATE, which
+     is inherently insecure and can use the entropy to make it a bit
+     less secure.  On the (rare) second and later attempts it might
+     help against DoS attacks.  */
+  bool use_getrandom = tryfunc == try_nocreate;
+
   /* Least unfair value for V.  If V is less than this, V can generate
      BASE_62_DIGITS digits fairly.  Otherwise it might be biased.  */
   random_value const unfair_min
@@ -290,7 +300,10 @@ try_tempname_len (char *tmpl, int suffixlen, void *args,
           if (vdigits == 0)
             {
               do
-                v = random_bits (v);
+                {
+                  v = random_bits (v, use_getrandom);
+                  use_getrandom = true;
+                }
               while (unfair_min <= v);
 
               vdigits = BASE_62_DIGITS;
diff --git a/lib/time-internal.h b/lib/time-internal.h
index 63a3f9e3db1..067ee729eda 100644
--- a/lib/time-internal.h
+++ b/lib/time-internal.h
@@ -24,7 +24,7 @@ struct tm_zone
      members are zero.  */
   struct tm_zone *next;
 
-#if HAVE_TZNAME && !HAVE_TM_ZONE
+#if HAVE_TZNAME && !HAVE_STRUCT_TM_TM_ZONE
   /* Copies of recent strings taken from tzname[0] and tzname[1].
      The copies are in ABBRS, so that they survive tzset.  Null if unknown.  */
   char *tzname_copy[2];
diff --git a/lib/time.in.h b/lib/time.in.h
index 958dc0bd292..1385980cdf5 100644
--- a/lib/time.in.h
+++ b/lib/time.in.h
@@ -101,6 +101,25 @@ struct __time_t_must_be_integral {
 #  define GNULIB_defined_struct_time_t_must_be_integral 1
 # endif
 
+/* Define TIME_UTC, a positive integer constant used for timespec_get().  */
+# if ! @TIME_H_DEFINES_TIME_UTC@
+#  if !GNULIB_defined_TIME_UTC
+#   define TIME_UTC 1
+#   define GNULIB_defined_TIME_UTC 1
+#  endif
+# endif
+
+/* Set *TS to the current time, and return BASE.
+   Upon failure, return 0.  */
+# if @GNULIB_TIMESPEC_GET@
+#  if ! @HAVE_TIMESPEC_GET@
+_GL_FUNCDECL_SYS (timespec_get, int, (struct timespec *ts, int base)
+                                     _GL_ARG_NONNULL ((1)));
+#  endif
+_GL_CXXALIAS_SYS (timespec_get, int, (struct timespec *ts, int base));
+_GL_CXXALIASWARN (timespec_get);
+# endif
+
 /* Sleep for at least RQTP seconds unless interrupted,  If interrupted,
    return -1 and store the remaining time into RMTP.  See
    <https://pubs.opengroup.org/onlinepubs/9699919799/functions/nanosleep.html>.  */
diff --git a/lib/time_rz.c b/lib/time_rz.c
index 65e20cc5661..3ac053c6219 100644
--- a/lib/time_rz.c
+++ b/lib/time_rz.c
@@ -71,7 +71,7 @@ tzalloc (char const *name)
   if (tz)
     {
       tz->next = NULL;
-#if HAVE_TZNAME && !HAVE_TM_ZONE
+#if HAVE_TZNAME && !HAVE_STRUCT_TM_TM_ZONE
       tz->tzname_copy[0] = tz->tzname_copy[1] = NULL;
 #endif
       tz->tz_is_set = !!name;
@@ -83,13 +83,13 @@ tzalloc (char const *name)
 }
 
 /* Save into TZ any nontrivial time zone abbreviation used by TM, and
-   update *TM (if HAVE_TM_ZONE) or *TZ (if !HAVE_TM_ZONE &&
-   HAVE_TZNAME) if they use the abbreviation.  Return true if
-   successful, false (setting errno) otherwise.  */
+   update *TM (if HAVE_STRUCT_TM_TM_ZONE) or *TZ (if
+   !HAVE_STRUCT_TM_TM_ZONE && HAVE_TZNAME) if they use the abbreviation.
+   Return true if successful, false (setting errno) otherwise.  */
 static bool
 save_abbr (timezone_t tz, struct tm *tm)
 {
-#if HAVE_TM_ZONE || HAVE_TZNAME
+#if HAVE_STRUCT_TM_TM_ZONE || HAVE_TZNAME
   char const *zone = NULL;
   char *zone_copy = (char *) "";
 
@@ -97,7 +97,7 @@ save_abbr (timezone_t tz, struct tm *tm)
   int tzname_index = -1;
 # endif
 
-# if HAVE_TM_ZONE
+# if HAVE_STRUCT_TM_TM_ZONE
   zone = tm->tm_zone;
 # endif
 
@@ -145,7 +145,7 @@ save_abbr (timezone_t tz, struct tm *tm)
     }
 
   /* Replace the zone name so that its lifetime matches that of TZ.  */
-# if HAVE_TM_ZONE
+# if HAVE_STRUCT_TM_TM_ZONE
   tm->tm_zone = zone_copy;
 # else
   if (0 <= tzname_index)
@@ -303,7 +303,7 @@ mktime_z (timezone_t tz, struct tm *tm)
           tm_1.tm_isdst = tm->tm_isdst;
           time_t t = mktime (&tm_1);
           bool ok = 0 <= tm_1.tm_yday;
-#if HAVE_TM_ZONE || HAVE_TZNAME
+#if HAVE_STRUCT_TM_TM_ZONE || HAVE_TZNAME
           ok = ok && save_abbr (tz, &tm_1);
 #endif
           if (revert_tz (old_tz) && ok)
diff --git a/lib/timegm.c b/lib/timegm.c
index fa30943084d..e4127e71c0b 100644
--- a/lib/timegm.c
+++ b/lib/timegm.c
@@ -1,6 +1,6 @@
 /* Convert UTC calendar time to simple time.  Like mktime but assumes UTC.
 
-   Copyright (C) 1994-2020 Free Software Foundation, Inc.
+   Copyright (C) 1994-2021 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
diff --git a/lib/utimens.c b/lib/utimens.c
index 5bbae058132..44d1ea003e2 100644
--- a/lib/utimens.c
+++ b/lib/utimens.c
@@ -27,6 +27,7 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <stdbool.h>
+#include <string.h>
 #include <sys/stat.h>
 #include <sys/time.h>
 #include <unistd.h>
@@ -52,7 +53,9 @@
 
 /* Avoid recursion with rpl_futimens or rpl_utimensat.  */
 #undef futimens
-#undef utimensat
+#if !HAVE_NEARLY_WORKING_UTIMENSAT
+# undef utimensat
+#endif
 
 /* Solaris 9 mistakenly succeeds when given a non-directory with a
    trailing slash.  Force the use of rpl_stat for a fix.  */
@@ -246,6 +249,20 @@ fdutimens (int fd, char const *file, struct timespec const timespec[2])
 # if HAVE_UTIMENSAT
       if (fd < 0)
         {
+#  if defined __APPLE__ && defined __MACH__
+          size_t len = strlen (file);
+          if (len > 0 && file[len - 1] == '/')
+            {
+              struct stat statbuf;
+              if (stat (file, &statbuf) < 0)
+                return -1;
+              if (!S_ISDIR (statbuf.st_mode))
+                {
+                  errno = ENOTDIR;
+                  return -1;
+                }
+            }
+#  endif
           result = utimensat (AT_FDCWD, file, ts, 0);
 #  ifdef __linux__
           /* Work around a kernel bug:
diff --git a/lib/utimensat.c b/lib/utimensat.c
index 2cea64f6982..9fdecd681f6 100644
--- a/lib/utimensat.c
+++ b/lib/utimensat.c
@@ -24,14 +24,40 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
 
 #include "stat-time.h"
 #include "timespec.h"
 #include "utimens.h"
 
-#if HAVE_UTIMENSAT
+#if HAVE_NEARLY_WORKING_UTIMENSAT
 
+/* Use the original utimensat(), but correct the trailing slash handling.  */
+int
+rpl_utimensat (int fd, char const *file, struct timespec const times[2],
+               int flag)
 # undef utimensat
+{
+  size_t len = strlen (file);
+  if (len && file[len - 1] == '/')
+    {
+      struct stat st;
+      if (fstatat (fd, file, &st, flag & AT_SYMLINK_NOFOLLOW) < 0)
+        return -1;
+      if (!S_ISDIR (st.st_mode))
+        {
+          errno = ENOTDIR;
+          return -1;
+        }
+    }
+
+  return utimensat (fd, file, times, flag);
+}
+
+#else
+
+# if HAVE_UTIMENSAT
 
 /* If we have a native utimensat, but are compiling this file, then
    utimensat was defined to rpl_utimensat by our replacement
@@ -42,24 +68,25 @@
    local_utimensat provides the fallback manipulation.  */
 
 static int local_utimensat (int, char const *, struct timespec const[2], int);
-# define AT_FUNC_NAME local_utimensat
+#  define AT_FUNC_NAME local_utimensat
 
 /* Like utimensat, but work around native bugs.  */
 
 int
 rpl_utimensat (int fd, char const *file, struct timespec const times[2],
                int flag)
+#  undef utimensat
 {
-# if defined __linux__ || defined __sun
+#  if defined __linux__ || defined __sun
   struct timespec ts[2];
-# endif
+#  endif
 
   /* See comments in utimens.c for details.  */
   static int utimensat_works_really; /* 0 = unknown, 1 = yes, -1 = no.  */
   if (0 <= utimensat_works_really)
     {
       int result;
-# if defined __linux__ || defined __sun
+#  if defined __linux__ || defined __sun
       struct stat st;
       /* As recently as Linux kernel 2.6.32 (Dec 2009), several file
          systems (xfs, ntfs-3g) have bugs with a single UTIME_OMIT,
@@ -90,7 +117,7 @@ rpl_utimensat (int fd, char const *file, struct timespec const times[2],
             ts[1] = times[1];
           times = ts;
         }
-#  ifdef __hppa__
+#   ifdef __hppa__
       /* Linux kernel 2.6.22.19 on hppa does not reject invalid tv_nsec
          values.  */
       else if (times
@@ -104,8 +131,36 @@ rpl_utimensat (int fd, char const *file, struct timespec const times[2],
           errno = EINVAL;
           return -1;
         }
+#   endif
+#  endif
+#  if defined __APPLE__ && defined __MACH__
+      /* macOS 10.13 does not reject invalid tv_nsec values either.  */
+      if (times
+          && ((times[0].tv_nsec != UTIME_OMIT
+               && times[0].tv_nsec != UTIME_NOW
+               && ! (0 <= times[0].tv_nsec
+                     && times[0].tv_nsec < TIMESPEC_HZ))
+              || (times[1].tv_nsec != UTIME_OMIT
+                  && times[1].tv_nsec != UTIME_NOW
+                  && ! (0 <= times[1].tv_nsec
+                        && times[1].tv_nsec < TIMESPEC_HZ))))
+        {
+          errno = EINVAL;
+          return -1;
+        }
+      size_t len = strlen (file);
+      if (len > 0 && file[len - 1] == '/')
+        {
+          struct stat statbuf;
+          if (fstatat (fd, file, &statbuf, 0) < 0)
+            return -1;
+          if (!S_ISDIR (statbuf.st_mode))
+            {
+              errno = ENOTDIR;
+              return -1;
+            }
+        }
 #  endif
-# endif
       result = utimensat (fd, file, times, flag);
       /* Linux kernel 2.6.25 has a bug where it returns EINVAL for
          UTIME_NOW or UTIME_OMIT with non-zero tv_sec, which
@@ -129,11 +184,11 @@ rpl_utimensat (int fd, char const *file, struct timespec const times[2],
   return local_utimensat (fd, file, times, flag);
 }
 
-#else /* !HAVE_UTIMENSAT */
+# else /* !HAVE_UTIMENSAT */
 
-# define AT_FUNC_NAME utimensat
+#  define AT_FUNC_NAME utimensat
 
-#endif /* !HAVE_UTIMENSAT */
+# endif /* !HAVE_UTIMENSAT */
 
 /* Set the access and modification timestamps of FILE to be
    TIMESPEC[0] and TIMESPEC[1], respectively; relative to directory
@@ -146,15 +201,17 @@ rpl_utimensat (int fd, char const *file, struct timespec const times[2],
    Return 0 on success, -1 (setting errno) on failure.  */
 
 /* AT_FUNC_NAME is now utimensat or local_utimensat.  */
-#define AT_FUNC_F1 lutimens
-#define AT_FUNC_F2 utimens
-#define AT_FUNC_USE_F1_COND AT_SYMLINK_NOFOLLOW
-#define AT_FUNC_POST_FILE_PARAM_DECLS , struct timespec const ts[2], int flag
-#define AT_FUNC_POST_FILE_ARGS        , ts
-#include "at-func.c"
-#undef AT_FUNC_NAME
-#undef AT_FUNC_F1
-#undef AT_FUNC_F2
-#undef AT_FUNC_USE_F1_COND
-#undef AT_FUNC_POST_FILE_PARAM_DECLS
-#undef AT_FUNC_POST_FILE_ARGS
+# define AT_FUNC_F1 lutimens
+# define AT_FUNC_F2 utimens
+# define AT_FUNC_USE_F1_COND AT_SYMLINK_NOFOLLOW
+# define AT_FUNC_POST_FILE_PARAM_DECLS , struct timespec const ts[2], int flag
+# define AT_FUNC_POST_FILE_ARGS        , ts
+# include "at-func.c"
+# undef AT_FUNC_NAME
+# undef AT_FUNC_F1
+# undef AT_FUNC_F2
+# undef AT_FUNC_USE_F1_COND
+# undef AT_FUNC_POST_FILE_PARAM_DECLS
+# undef AT_FUNC_POST_FILE_ARGS
+
+#endif /* !HAVE_NEARLY_WORKING_UTIMENSAT */
diff --git a/lib/verify.h b/lib/verify.h
index 3cdcdca5671..65514c34b9e 100644
--- a/lib/verify.h
+++ b/lib/verify.h
@@ -22,16 +22,10 @@
 
 
 /* Define _GL_HAVE__STATIC_ASSERT to 1 if _Static_assert (R, DIAGNOSTIC)
-   works as per C11.  This is supported by GCC 4.6.0 and later, in C
-   mode, and by clang (also in C++ mode).
+   works as per C11.  This is supported by GCC 4.6.0+ and by clang 4+.
 
    Define _GL_HAVE__STATIC_ASSERT1 to 1 if _Static_assert (R) works as
-   per C2X.  This is supported by GCC 9.1 and later, and by clang in
-   C++1z mode.
-
-   Define _GL_HAVE_STATIC_ASSERT1 if static_assert (R) works as per
-   C++17.  This is supported by GCC 9.1 and later, and by clang in
-   C++1z mode.
+   per C2X.  This is supported by GCC 9.1+.
 
    Support compilers claiming conformance to the relevant standard,
    and also support GCC when not pedantic.  If we were willing to slow
@@ -47,18 +41,6 @@
       || (!defined __STRICT_ANSI__ && 9 <= __GNUC__))
 #  define _GL_HAVE__STATIC_ASSERT1 1
 # endif
-#else
-# if 4 <= __clang_major__
-#  define _GL_HAVE__STATIC_ASSERT 1
-# endif
-# if 4 <= __clang_major__ && 201411 <= __cpp_static_assert
-#  define _GL_HAVE__STATIC_ASSERT1 1
-# endif
-# if 201703L <= __cplusplus \
-     || 9 <= __GNUC__ \
-     || (4 <= __clang_major__ && 201411 <= __cpp_static_assert)
-#  define _GL_HAVE_STATIC_ASSERT1 1
-# endif
 #endif
 
 /* FreeBSD 9.1 <sys/cdefs.h>, included by <stddef.h> and lots of other
@@ -225,7 +207,9 @@ template <int w>
    Unfortunately, unlike C11, this implementation must appear as an
    ordinary declaration, and cannot appear inside struct { ... }.  */
 
-#if defined _GL_HAVE__STATIC_ASSERT
+#if 200410 <= __cpp_static_assert
+# define _GL_VERIFY(R, DIAGNOSTIC, ...) static_assert (R, DIAGNOSTIC)
+#elif defined _GL_HAVE__STATIC_ASSERT
 # define _GL_VERIFY(R, DIAGNOSTIC, ...) _Static_assert (R, DIAGNOSTIC)
 #else
 # define _GL_VERIFY(R, DIAGNOSTIC, ...)                                \
@@ -239,7 +223,7 @@ template <int w>
 #  define _Static_assert(...) \
      _GL_VERIFY (__VA_ARGS__, "static assertion failed", -)
 # endif
-# if !defined _GL_HAVE_STATIC_ASSERT1 && !defined static_assert
+# if __cpp_static_assert < 201411 && !defined static_assert
 #  define static_assert _Static_assert /* C11 requires this #define.  */
 # endif
 #endif