Use mmap and cache the view buffer for get_view

This patch uses mmap if it is available and works.  It also caches the
view buffer for get_view.

	* configure.ac: Add AC_FUNC_MMAP.
	* config.in: Regenerated.
	* configure: Likewise.
	* plugin.c: Include <sys/mman.h>.
	(MAP_FAILED): New.  Defined if not defined.
	(PROT_READ): Likewise.
	(MAP_PRIVATE): Likewise.
	(view_buffer_t): New.
	(plugin_input_file_t): Add view_buffer.
	(get_view): Try mmap and cache the view buffer.
	(plugin_maybe_claim): Initialize view_buffer.

1 files changed, 182 insertions, 0 deletions

diff --git a/ld/configure b/ld/configure
index 8a7bd207c53..7af2626d5bc 100755
--- a/ld/configure
+++ b/ld/configure
@@ -16549,6 +16549,188 @@ fi
 fi
 
 
+for ac_header in stdlib.h unistd.h
+do :
+  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
+ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
+eval as_val=\$$as_ac_Header
+   if test "x$as_val" = x""yes; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+
+done
+
+for ac_func in getpagesize
+do :
+  ac_fn_c_check_func "$LINENO" "getpagesize" "ac_cv_func_getpagesize"
+if test "x$ac_cv_func_getpagesize" = x""yes; then :
+  cat >>confdefs.h <<_ACEOF
+#define HAVE_GETPAGESIZE 1
+_ACEOF
+
+fi
+done
+
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for working mmap" >&5
+$as_echo_n "checking for working mmap... " >&6; }
+if test "${ac_cv_func_mmap_fixed_mapped+set}" = set; then :
+  $as_echo_n "(cached) " >&6
+else
+  if test "$cross_compiling" = yes; then :
+  ac_cv_func_mmap_fixed_mapped=no
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+$ac_includes_default
+/* malloc might have been renamed as rpl_malloc. */
+#undef malloc
+
+/* Thanks to Mike Haertel and Jim Avera for this test.
+   Here is a matrix of mmap possibilities:
+	mmap private not fixed
+	mmap private fixed at somewhere currently unmapped
+	mmap private fixed at somewhere already mapped
+	mmap shared not fixed
+	mmap shared fixed at somewhere currently unmapped
+	mmap shared fixed at somewhere already mapped
+   For private mappings, we should verify that changes cannot be read()
+   back from the file, nor mmap's back from the file at a different
+   address.  (There have been systems where private was not correctly
+   implemented like the infamous i386 svr4.0, and systems where the
+   VM page cache was not coherent with the file system buffer cache
+   like early versions of FreeBSD and possibly contemporary NetBSD.)
+   For shared mappings, we should conversely verify that changes get
+   propagated back to all the places they're supposed to be.
+
+   Grep wants private fixed already mapped.
+   The main things grep needs to know about mmap are:
+   * does it exist and is it safe to write into the mmap'd area
+   * how to use it (BSD variants)  */
+
+#include <fcntl.h>
+#include <sys/mman.h>
+
+#if !defined STDC_HEADERS && !defined HAVE_STDLIB_H
+char *malloc ();
+#endif
+
+/* This mess was copied from the GNU getpagesize.h.  */
+#ifndef HAVE_GETPAGESIZE
+/* Assume that all systems that can run configure have sys/param.h.  */
+# ifndef HAVE_SYS_PARAM_H
+#  define HAVE_SYS_PARAM_H 1
+# endif
+
+# ifdef _SC_PAGESIZE
+#  define getpagesize() sysconf(_SC_PAGESIZE)
+# else /* no _SC_PAGESIZE */
+#  ifdef HAVE_SYS_PARAM_H
+#   include <sys/param.h>
+#   ifdef EXEC_PAGESIZE
+#    define getpagesize() EXEC_PAGESIZE
+#   else /* no EXEC_PAGESIZE */
+#    ifdef NBPG
+#     define getpagesize() NBPG * CLSIZE
+#     ifndef CLSIZE
+#      define CLSIZE 1
+#     endif /* no CLSIZE */
+#    else /* no NBPG */
+#     ifdef NBPC
+#      define getpagesize() NBPC
+#     else /* no NBPC */
+#      ifdef PAGESIZE
+#       define getpagesize() PAGESIZE
+#      endif /* PAGESIZE */
+#     endif /* no NBPC */
+#    endif /* no NBPG */
+#   endif /* no EXEC_PAGESIZE */
+#  else /* no HAVE_SYS_PARAM_H */
+#   define getpagesize() 8192	/* punt totally */
+#  endif /* no HAVE_SYS_PARAM_H */
+# endif /* no _SC_PAGESIZE */
+
+#endif /* no HAVE_GETPAGESIZE */
+
+int
+main ()
+{
+  char *data, *data2, *data3;
+  int i, pagesize;
+  int fd;
+
+  pagesize = getpagesize ();
+
+  /* First, make a file with some known garbage in it. */
+  data = (char *) malloc (pagesize);
+  if (!data)
+    return 1;
+  for (i = 0; i < pagesize; ++i)
+    *(data + i) = rand ();
+  umask (0);
+  fd = creat ("conftest.mmap", 0600);
+  if (fd < 0)
+    return 1;
+  if (write (fd, data, pagesize) != pagesize)
+    return 1;
+  close (fd);
+
+  /* Next, try to mmap the file at a fixed address which already has
+     something else allocated at it.  If we can, also make sure that
+     we see the same garbage.  */
+  fd = open ("conftest.mmap", O_RDWR);
+  if (fd < 0)
+    return 1;
+  data2 = (char *) malloc (2 * pagesize);
+  if (!data2)
+    return 1;
+  data2 += (pagesize - ((long int) data2 & (pagesize - 1))) & (pagesize - 1);
+  if (data2 != mmap (data2, pagesize, PROT_READ | PROT_WRITE,
+		     MAP_PRIVATE | MAP_FIXED, fd, 0L))
+    return 1;
+  for (i = 0; i < pagesize; ++i)
+    if (*(data + i) != *(data2 + i))
+      return 1;
+
+  /* Finally, make sure that changes to the mapped area do not
+     percolate back to the file as seen by read().  (This is a bug on
+     some variants of i386 svr4.0.)  */
+  for (i = 0; i < pagesize; ++i)
+    *(data2 + i) = *(data2 + i) + 1;
+  data3 = (char *) malloc (pagesize);
+  if (!data3)
+    return 1;
+  if (read (fd, data3, pagesize) != pagesize)
+    return 1;
+  for (i = 0; i < pagesize; ++i)
+    if (*(data + i) != *(data3 + i))
+      return 1;
+  close (fd);
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_run "$LINENO"; then :
+  ac_cv_func_mmap_fixed_mapped=yes
+else
+  ac_cv_func_mmap_fixed_mapped=no
+fi
+rm -f core *.core core.conftest.* gmon.out bb.out conftest$ac_exeext \
+  conftest.$ac_objext conftest.beam conftest.$ac_ext
+fi
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_func_mmap_fixed_mapped" >&5
+$as_echo "$ac_cv_func_mmap_fixed_mapped" >&6; }
+if test $ac_cv_func_mmap_fixed_mapped = yes; then
+
+$as_echo "#define HAVE_MMAP 1" >>confdefs.h
+
+fi
+rm -f conftest.mmap
+
+
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for library containing dlopen" >&5
 $as_echo_n "checking for library containing dlopen... " >&6; }
 if test "${ac_cv_search_dlopen+set}" = set; then :