stat: Use statx where available and support --cached

* src/stat.c: Drop statbuf argument from out_epoch_sec().
Use statx() rather than [lf]stat() where available,
so a separate call is not required to get birth time.
Set STATX_* mask bits only for things we want to print,
which can be more efficient on some file systems.
Add a new --cache= command-line option that sets the appropriate hint
flags in the statx call.  These are primarily used with network
file systems to indicate what level of cache coherency is desired.
The new option is available unconditionally for better portability,
and ignored where not implemented.
* doc/coreutils.texi: Add documention for --cached.
* man/stat.x (SEE ALSO): Mention statx().
* NEWS: Mention the new feature.

1 files changed, 422 insertions, 201 deletions

diff --git a/src/stat.c b/src/stat.c
index bb1ef1a3d..3bb84f35d 100644
--- a/src/stat.c
+++ b/src/stat.c
@@ -28,6 +28,12 @@
 # define USE_STATVFS 0
 #endif
 
+#if HAVE_STATX && defined STATX_INO
+# define USE_STATX 1
+#else
+# define USE_STATX 0
+#endif
+
 #include <stddef.h>
 #include <stdio.h>
 #include <stdalign.h>
@@ -194,6 +200,23 @@ enum
   PRINTF_OPTION = CHAR_MAX + 1
 };
 
+enum cached_mode
+{
+  cached_default,
+  cached_never,
+  cached_always
+};
+
+static char const *const cached_args[] =
+{
+  "default", "never", "always", NULL
+};
+
+static enum cached_mode const cached_modes[] =
+{
+  cached_default, cached_never, cached_always
+};
+
 static struct option const long_options[] =
 {
   {"dereference", no_argument, NULL, 'L'},
@@ -201,6 +224,7 @@ static struct option const long_options[] =
   {"format", required_argument, NULL, 'c'},
   {"printf", required_argument, NULL, PRINTF_OPTION},
   {"terse", no_argument, NULL, 't'},
+  {"cached", required_argument, NULL, 0},
   {GETOPT_HELP_OPTION_DECL},
   {GETOPT_VERSION_OPTION_DECL},
   {NULL, 0, NULL, 0}
@@ -221,6 +245,10 @@ static char const *trailing_delim = "";
 static char const *decimal_point;
 static size_t decimal_point_len;
 
+static bool
+print_stat (char *pformat, size_t prefix_len, unsigned int m,
+            int fd, char const *filename, void const *data);
+
 /* Return the type of the specified file system.
    Some systems have statfvs.f_basetype[FSTYPSZ] (AIX, HP-UX, and Solaris).
    Others have statvfs.f_fstypename[_VFS_NAMELEN] (NetBSD 3.0).
@@ -676,7 +704,6 @@ out_minus_zero (char *pformat, size_t prefix_len)
    acts like printf's %f format.  */
 static void
 out_epoch_sec (char *pformat, size_t prefix_len,
-               struct stat const *statbuf _GL_UNUSED,
                struct timespec arg)
 {
   char *dot = memchr (pformat, '.', prefix_len);
@@ -980,57 +1007,6 @@ print_mount_point:
   return fail;
 }
 
-static struct timespec
-get_birthtime (int fd, char const *filename, struct stat const *st)
-{
-  struct timespec ts = get_stat_birthtime (st);
-
-#if HAVE_GETATTRAT
-  if (ts.tv_nsec < 0)
-    {
-      nvlist_t *response;
-      if ((fd < 0
-           ? getattrat (AT_FDCWD, XATTR_VIEW_READWRITE, filename, &response)
-           : fgetattr (fd, XATTR_VIEW_READWRITE, &response))
-          == 0)
-        {
-          uint64_t *val;
-          uint_t n;
-          if (nvlist_lookup_uint64_array (response, A_CRTIME, &val, &n) == 0
-              && 2 <= n
-              && val[0] <= TYPE_MAXIMUM (time_t)
-              && val[1] < 1000000000 * 2 /* for leap seconds */)
-            {
-              ts.tv_sec = val[0];
-              ts.tv_nsec = val[1];
-            }
-          nvlist_free (response);
-        }
-    }
-#endif
-
-#if HAVE_STATX && defined STATX_BTIME
-  if (ts.tv_nsec < 0)
-    {
-      struct statx stx;
-      if ((fd < 0
-           ? statx (AT_FDCWD, filename,
-                    follow_links ? 0 : AT_SYMLINK_NOFOLLOW,
-                    STATX_BTIME, &stx)
-           : statx (fd, "", AT_EMPTY_PATH, STATX_BTIME, &stx)) == 0)
-        {
-          if ((stx.stx_mask & STATX_BTIME) && stx.stx_btime.tv_sec != 0)
-            {
-              ts.tv_sec = stx.stx_btime.tv_sec;
-              ts.tv_nsec = stx.stx_btime.tv_nsec;
-            }
-        }
-    }
-#endif
-
-  return ts;
-}
-
 /* Map a TS with negative TS.tv_nsec to {0,0}.  */
 static inline struct timespec
 neg_to_zero (struct timespec ts)
@@ -1067,139 +1043,6 @@ getenv_quoting_style (void)
 /* Equivalent to quotearg(), but explicit to avoid syntax checks.  */
 #define quoteN(x) quotearg_style (get_quoting_style (NULL), x)
 
-/* Print stat info.  Return zero upon success, nonzero upon failure.  */
-static bool
-print_stat (char *pformat, size_t prefix_len, unsigned int m,
-            int fd, char const *filename, void const *data)
-{
-  struct stat *statbuf = (struct stat *) data;
-  struct passwd *pw_ent;
-  struct group *gw_ent;
-  bool fail = false;
-
-  switch (m)
-    {
-    case 'n':
-      out_string (pformat, prefix_len, filename);
-      break;
-    case 'N':
-      out_string (pformat, prefix_len, quoteN (filename));
-      if (S_ISLNK (statbuf->st_mode))
-        {
-          char *linkname = areadlink_with_size (filename, statbuf->st_size);
-          if (linkname == NULL)
-            {
-              error (0, errno, _("cannot read symbolic link %s"),
-                     quoteaf (filename));
-              return true;
-            }
-          printf (" -> ");
-          out_string (pformat, prefix_len, quoteN (linkname));
-          free (linkname);
-        }
-      break;
-    case 'd':
-      out_uint (pformat, prefix_len, statbuf->st_dev);
-      break;
-    case 'D':
-      out_uint_x (pformat, prefix_len, statbuf->st_dev);
-      break;
-    case 'i':
-      out_uint (pformat, prefix_len, statbuf->st_ino);
-      break;
-    case 'a':
-      out_uint_o (pformat, prefix_len, statbuf->st_mode & CHMOD_MODE_BITS);
-      break;
-    case 'A':
-      out_string (pformat, prefix_len, human_access (statbuf));
-      break;
-    case 'f':
-      out_uint_x (pformat, prefix_len, statbuf->st_mode);
-      break;
-    case 'F':
-      out_string (pformat, prefix_len, file_type (statbuf));
-      break;
-    case 'h':
-      out_uint (pformat, prefix_len, statbuf->st_nlink);
-      break;
-    case 'u':
-      out_uint (pformat, prefix_len, statbuf->st_uid);
-      break;
-    case 'U':
-      pw_ent = getpwuid (statbuf->st_uid);
-      out_string (pformat, prefix_len,
-                  pw_ent ? pw_ent->pw_name : "UNKNOWN");
-      break;
-    case 'g':
-      out_uint (pformat, prefix_len, statbuf->st_gid);
-      break;
-    case 'G':
-      gw_ent = getgrgid (statbuf->st_gid);
-      out_string (pformat, prefix_len,
-                  gw_ent ? gw_ent->gr_name : "UNKNOWN");
-      break;
-    case 't':
-      out_uint_x (pformat, prefix_len, major (statbuf->st_rdev));
-      break;
-    case 'm':
-      fail |= out_mount_point (filename, pformat, prefix_len, statbuf);
-      break;
-    case 'T':
-      out_uint_x (pformat, prefix_len, minor (statbuf->st_rdev));
-      break;
-    case 's':
-      out_int (pformat, prefix_len, statbuf->st_size);
-      break;
-    case 'B':
-      out_uint (pformat, prefix_len, ST_NBLOCKSIZE);
-      break;
-    case 'b':
-      out_uint (pformat, prefix_len, ST_NBLOCKS (*statbuf));
-      break;
-    case 'o':
-      out_uint (pformat, prefix_len, ST_BLKSIZE (*statbuf));
-      break;
-    case 'w':
-      {
-        struct timespec t = get_birthtime (fd, filename, statbuf);
-        if (t.tv_nsec < 0)
-          out_string (pformat, prefix_len, "-");
-        else
-          out_string (pformat, prefix_len, human_time (t));
-      }
-      break;
-    case 'W':
-      out_epoch_sec (pformat, prefix_len, statbuf,
-                     neg_to_zero (get_birthtime (fd, filename, statbuf)));
-      break;
-    case 'x':
-      out_string (pformat, prefix_len, human_time (get_stat_atime (statbuf)));
-      break;
-    case 'X':
-      out_epoch_sec (pformat, prefix_len, statbuf, get_stat_atime (statbuf));
-      break;
-    case 'y':
-      out_string (pformat, prefix_len, human_time (get_stat_mtime (statbuf)));
-      break;
-    case 'Y':
-      out_epoch_sec (pformat, prefix_len, statbuf, get_stat_mtime (statbuf));
-      break;
-    case 'z':
-      out_string (pformat, prefix_len, human_time (get_stat_ctime (statbuf)));
-      break;
-    case 'Z':
-      out_epoch_sec (pformat, prefix_len, statbuf, get_stat_ctime (statbuf));
-      break;
-    case 'C':
-      fail |= out_file_context (pformat, prefix_len, filename);
-      break;
-    default:
-      fputc ('?', stdout);
-      break;
-    }
-  return fail;
-}
-
 /* Output a single-character \ escape.  */
 
 static void
@@ -1241,6 +1084,17 @@ print_esc_char (char c)
   putchar (c);
 }
 
+static size_t _GL_ATTRIBUTE_PURE
+format_code_offset (char const* directive)
+{
+  size_t len = strspn (directive + 1, printf_flags);
+  char const *fmt_char = directive + len + 1;
+  fmt_char += strspn (fmt_char, digits);
+  if (*fmt_char == '.')
+    fmt_char += 1 + strspn (fmt_char + 1, digits);
+  return fmt_char - directive;
+}
+
 /* Print the information specified by the format string, FORMAT,
    calling PRINT_FUNC for each %-directive encountered.
    Return zero upon success, nonzero upon failure.  */
@@ -1270,33 +1124,28 @@ print_it (char const *format, int fd, char const *filename,
         {
         case '%':
           {
-            size_t len = strspn (b + 1, printf_flags);
-            char const *fmt_char = b + len + 1;
-            fmt_char += strspn (fmt_char, digits);
-            if (*fmt_char == '.')
-              fmt_char += 1 + strspn (fmt_char + 1, digits);
-            len = fmt_char - (b + 1);
-            unsigned int fmt_code = *fmt_char;
-            memcpy (dest, b, len + 1);
-
-            b = fmt_char;
-            switch (fmt_code)
+            size_t len = format_code_offset (b);
+            char const *fmt_char = b + len;
+            memcpy (dest, b, len);
+            b += len;
+
+            switch (*fmt_char)
               {
               case '\0':
                 --b;
                 FALLTHROUGH;
               case '%':
-                if (0 < len)
+                if (1 < len)
                   {
-                    dest[len + 1] = *fmt_char;
-                    dest[len + 2] = '\0';
+                    dest[len] = *fmt_char;
+                    dest[len + 1] = '\0';
                     die (EXIT_FAILURE, 0, _("%s: invalid directive"),
                          quote (dest));
                   }
                 putchar ('%');
                 break;
               default:
-                fail |= print_func (dest, len + 1, fmt_code,
+                fail |= print_func (dest, len, to_uchar (*fmt_char),
                                     fd, filename, data);
                 break;
               }
@@ -1384,6 +1233,204 @@ do_statfs (char const *filename, char const *format)
   return ! fail;
 }
 
+struct print_args {
+  struct stat *st;
+  struct timespec btime;
+};
+
+/* Ask statx to avoid syncing? */
+static bool dont_sync;
+
+/* Ask statx to force sync? */
+static bool force_sync;
+
+#if USE_STATX
+/* Much of the format printing requires a struct stat or timespec */
+static struct timespec
+statx_timestamp_to_timespec (struct statx_timestamp tsx)
+{
+  struct timespec ts;
+
+  ts.tv_sec = tsx.tv_sec;
+  ts.tv_nsec = tsx.tv_nsec;
+  return ts;
+}
+
+static void
+statx_to_stat (struct statx *stx, struct stat *stat)
+{
+  stat->st_dev = makedev (stx->stx_dev_major, stx->stx_dev_minor);
+  stat->st_ino = stx->stx_ino;
+  stat->st_mode = stx->stx_mode;
+  stat->st_nlink = stx->stx_nlink;
+  stat->st_uid = stx->stx_uid;
+  stat->st_gid = stx->stx_gid;
+  stat->st_rdev = makedev (stx->stx_rdev_major, stx->stx_rdev_minor);
+  stat->st_size = stx->stx_size;
+  stat->st_blksize = stx->stx_blksize;
+/* define to avoid sc_prohibit_stat_st_blocks.  */
+# define SC_ST_BLOCKS st_blocks
+  stat->SC_ST_BLOCKS = stx->stx_blocks;
+  stat->st_atim = statx_timestamp_to_timespec (stx->stx_atime);
+  stat->st_mtim = statx_timestamp_to_timespec (stx->stx_mtime);
+  stat->st_ctim = statx_timestamp_to_timespec (stx->stx_ctime);
+}
+
+static unsigned int
+fmt_to_mask (char fmt)
+{
+  switch (fmt)
+    {
+    case 'N':
+      return STATX_MODE|STATX_SIZE;
+    case 'd':
+    case 'D':
+      return STATX_MODE;
+    case 'i':
+      return STATX_INO;
+    case 'a':
+    case 'A':
+      return STATX_MODE;
+    case 'f':
+      return STATX_MODE|STATX_TYPE;
+    case 'F':
+      return STATX_TYPE;
+    case 'h':
+      return STATX_NLINK;
+    case 'u':
+    case 'U':
+      return STATX_UID;
+    case 'g':
+    case 'G':
+      return STATX_GID;
+    case 'm':
+      return STATX_MODE|STATX_INO;
+    case 's':
+      return STATX_SIZE;
+    case 't':
+    case 'T':
+      return STATX_MODE;
+    case 'b':
+      return STATX_BLOCKS;
+    case 'w':
+    case 'W':
+      return STATX_BTIME;
+    case 'x':
+    case 'X':
+      return STATX_ATIME;
+    case 'y':
+    case 'Y':
+      return STATX_MTIME;
+    case 'z':
+    case 'Z':
+      return STATX_CTIME;
+    }
+  return 0;
+}
+
+static unsigned int _GL_ATTRIBUTE_PURE
+format_to_mask (char const *format)
+{
+  unsigned int mask = 0;
+  char const *b;
+
+  for (b = format; *b; b++)
+    {
+      if (*b != '%')
+        continue;
+
+      b += format_code_offset (b);
+      if (*b == '\0')
+        break;
+      mask |= fmt_to_mask (*b);
+    }
+  return mask;
+}
+
+/* statx the file and print what we find */
+static bool ATTRIBUTE_WARN_UNUSED_RESULT
+do_stat (char const *filename, char const *format, char const *format2)
+{
+  int fd = STREQ (filename, "-") ? 0 : AT_FDCWD;
+  int flags = 0;
+  struct stat st;
+  struct statx stx;
+  const char *pathname = filename;
+  struct print_args pa;
+  pa.st = &st;
+  pa.btime = (struct timespec) {-1, -1};
+
+  if (AT_FDCWD != fd)
+    {
+      pathname = "";
+      flags = AT_EMPTY_PATH;
+    }
+  else if (!follow_links)
+    {
+      flags = AT_SYMLINK_NOFOLLOW;
+    }
+
+  if (dont_sync)
+    flags |= AT_STATX_DONT_SYNC;
+  else if (force_sync)
+    flags |= AT_STATX_FORCE_SYNC;
+
+  fd = statx (fd, pathname, flags, format_to_mask (format), &stx);
+  if (fd < 0)
+    {
+      if (flags & AT_EMPTY_PATH)
+        error (0, errno, _("cannot stat standard input"));
+      else
+        error (0, errno, _("cannot statx %s"), quoteaf (filename));
+      return false;
+    }
+
+  if (S_ISBLK (stx.stx_mode) || S_ISCHR (stx.stx_mode))
+    format = format2;
+
+  statx_to_stat (&stx, &st);
+  if (stx.stx_mask & STATX_BTIME)
+    pa.btime = statx_timestamp_to_timespec (stx.stx_btime);
+
+  bool fail = print_it (format, fd, filename, print_stat, &pa);
+  return ! fail;
+}
+
+#else /* USE_STATX */
+
+static struct timespec
+get_birthtime (int fd, char const *filename, struct stat const *st)
+{
+  struct timespec ts = get_stat_birthtime (st);
+
+# if HAVE_GETATTRAT
+  if (ts.tv_nsec < 0)
+    {
+      nvlist_t *response;
+      if ((fd < 0
+           ? getattrat (AT_FDCWD, XATTR_VIEW_READWRITE, filename, &response)
+           : fgetattr (fd, XATTR_VIEW_READWRITE, &response))
+          == 0)
+        {
+          uint64_t *val;
+          uint_t n;
+          if (nvlist_lookup_uint64_array (response, A_CRTIME, &val, &n) == 0
+              && 2 <= n
+              && val[0] <= TYPE_MAXIMUM (time_t)
+              && val[1] < 1000000000 * 2 /* for leap seconds */)
+            {
+              ts.tv_sec = val[0];
+              ts.tv_nsec = val[1];
+            }
+          nvlist_free (response);
+        }
+    }
+# endif
+
+  return ts;
+}
+
+
 /* stat the file and print what we find */
 static bool ATTRIBUTE_WARN_UNUSED_RESULT
 do_stat (char const *filename, char const *format,
@@ -1391,6 +1438,9 @@ do_stat (char const *filename, char const *format,
 {
   int fd = STREQ (filename, "-") ? 0 : -1;
   struct stat statbuf;
+  struct print_args pa;
+  pa.st = &statbuf;
+  pa.btime = (struct timespec) {-1, -1};
 
   if (0 <= fd)
     {
@@ -1414,9 +1464,152 @@ do_stat (char const *filename, char const *format,
   if (S_ISBLK (statbuf.st_mode) || S_ISCHR (statbuf.st_mode))
     format = format2;
 
-  bool fail = print_it (format, fd, filename, print_stat, &statbuf);
+  bool fail = print_it (format, fd, filename, print_stat, &pa);
   return ! fail;
 }
+#endif /* USE_STATX */
+
+
+/* Print stat info.  Return zero upon success, nonzero upon failure.  */
+static bool
+print_stat (char *pformat, size_t prefix_len, unsigned int m,
+            int fd, char const *filename, void const *data)
+{
+  struct print_args *parg = (struct print_args *) data;
+  struct stat *statbuf = parg->st;
+  struct timespec btime = parg->btime;
+  struct passwd *pw_ent;
+  struct group *gw_ent;
+  bool fail = false;
+
+  switch (m)
+    {
+    case 'n':
+      out_string (pformat, prefix_len, filename);
+      break;
+    case 'N':
+      out_string (pformat, prefix_len, quoteN (filename));
+      if (S_ISLNK (statbuf->st_mode))
+        {
+          char *linkname = areadlink_with_size (filename, statbuf->st_size);
+          if (linkname == NULL)
+            {
+              error (0, errno, _("cannot read symbolic link %s"),
+                     quoteaf (filename));
+              return true;
+            }
+          printf (" -> ");
+          out_string (pformat, prefix_len, quoteN (linkname));
+          free (linkname);
+        }
+      break;
+    case 'd':
+      out_uint (pformat, prefix_len, statbuf->st_dev);
+      break;
+    case 'D':
+      out_uint_x (pformat, prefix_len, statbuf->st_dev);
+      break;
+    case 'i':
+      out_uint (pformat, prefix_len, statbuf->st_ino);
+      break;
+    case 'a':
+      out_uint_o (pformat, prefix_len, statbuf->st_mode & CHMOD_MODE_BITS);
+      break;
+    case 'A':
+      out_string (pformat, prefix_len, human_access (statbuf));
+      break;
+    case 'f':
+      out_uint_x (pformat, prefix_len, statbuf->st_mode);
+      break;
+    case 'F':
+      out_string (pformat, prefix_len, file_type (statbuf));
+      break;
+    case 'h':
+      out_uint (pformat, prefix_len, statbuf->st_nlink);
+      break;
+    case 'u':
+      out_uint (pformat, prefix_len, statbuf->st_uid);
+      break;
+    case 'U':
+      pw_ent = getpwuid (statbuf->st_uid);
+      out_string (pformat, prefix_len,
+                  pw_ent ? pw_ent->pw_name : "UNKNOWN");
+      break;
+    case 'g':
+      out_uint (pformat, prefix_len, statbuf->st_gid);
+      break;
+    case 'G':
+      gw_ent = getgrgid (statbuf->st_gid);
+      out_string (pformat, prefix_len,
+                  gw_ent ? gw_ent->gr_name : "UNKNOWN");
+      break;
+    case 'm':
+      fail |= out_mount_point (filename, pformat, prefix_len, statbuf);
+      break;
+    case 's':
+      out_int (pformat, prefix_len, statbuf->st_size);
+      break;
+    case 't':
+      out_uint_x (pformat, prefix_len, major (statbuf->st_rdev));
+      break;
+    case 'T':
+      out_uint_x (pformat, prefix_len, minor (statbuf->st_rdev));
+      break;
+    case 'B':
+      out_uint (pformat, prefix_len, ST_NBLOCKSIZE);
+      break;
+    case 'b':
+      out_uint (pformat, prefix_len, ST_NBLOCKS (*statbuf));
+      break;
+    case 'o':
+      out_uint (pformat, prefix_len, ST_BLKSIZE (*statbuf));
+      break;
+    case 'w':
+      {
+#if ! USE_STATX
+        btime = get_birthtime (fd, filename, statbuf);
+#endif
+        if (btime.tv_nsec < 0)
+          out_string (pformat, prefix_len, "-");
+        else
+          out_string (pformat, prefix_len, human_time (btime));
+      }
+      break;
+    case 'W':
+      {
+#if ! USE_STATX
+        btime = get_birthtime (fd, filename, statbuf);
+#endif
+        out_epoch_sec (pformat, prefix_len, neg_to_zero (btime));
+      }
+      break;
+    case 'x':
+      out_string (pformat, prefix_len, human_time (get_stat_atime (statbuf)));
+      break;
+    case 'X':
+      out_epoch_sec (pformat, prefix_len, get_stat_atime (statbuf));
+      break;
+    case 'y':
+      out_string (pformat, prefix_len, human_time (get_stat_mtime (statbuf)));
+      break;
+    case 'Y':
+      out_epoch_sec (pformat, prefix_len, get_stat_mtime (statbuf));
+      break;
+    case 'z':
+      out_string (pformat, prefix_len, human_time (get_stat_ctime (statbuf)));
+      break;
+    case 'Z':
+      out_epoch_sec (pformat, prefix_len, get_stat_ctime (statbuf));
+      break;
+    case 'C':
+      fail |= out_file_context (pformat, prefix_len, filename);
+      break;
+    default:
+      fputc ('?', stdout);
+      break;
+    }
+  return fail;
+}
 
 /* Return an allocated format string in static storage that
    corresponds to whether FS and TERSE options were declared.  */
@@ -1527,6 +1720,10 @@ Display file or file system status.\n\
   -f, --file-system     display file system status instead of file status\n\
 "), stdout);
       fputs (_("\
+      --cached=MODE     specify how to use cached attributes;\n\
+                          useful on remote file systems. See MODE below\n\
+"), stdout);
+      fputs (_("\
   -c  --format=FORMAT   use the specified FORMAT instead of the default;\n\
                           output a newline after each use of FORMAT\n\
       --printf=FORMAT   like --format, but interpret backslash escapes,\n\
@@ -1538,6 +1735,13 @@ Display file or file system status.\n\
       fputs (VERSION_OPTION_DESCRIPTION, stdout);
 
       fputs (_("\n\
+The --cached MODE argument can be; always, never, or default.\n\
+`always` will use cached attributes if available, while\n\
+`never` will try to synchronize with the latest attributes, and\n\
+`default` will leave it up to the underlying file system.\n\
+"), stdout);
+
+      fputs (_("\n\
 The valid format sequences for files (without --file-system):\n\
 \n\
   %a   access rights in octal (note '#' and '0' printf flags)\n\
@@ -1670,6 +1874,23 @@ main (int argc, char *argv[])
           terse = true;
           break;
 
+        case 0:
+          switch (XARGMATCH ("--cached", optarg, cached_args, cached_modes))
+            {
+              case cached_never:
+                force_sync = true;
+                dont_sync = false;
+                break;
+              case cached_always:
+                force_sync = false;
+                dont_sync = true;
+                break;
+              case cached_default:
+                force_sync = false;
+                dont_sync = false;
+            }
+          break;
+
         case_GETOPT_HELP_CHAR;
 
         case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);