X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=lib%2Fchown.c;h=b212198552be6b581207b9ef3514f1a6f11012e4;hb=23eecb48e39afd0d267d64d40ba6bf97aa865e13;hp=63b89c27e8a03ba6783fa793ff6a2db9b2fc2ff5;hpb=67f394c1d2be473276ccd5e071f986511a13e212;p=gnulib.git

diff --git a/lib/chown.c b/lib/chown.c
index 63b89c27e..b21219855 100644
--- a/lib/chown.c
+++ b/lib/chown.c
@@ -1,11 +1,12 @@
 /* provide consistent interface to chown for systems that don't interpret
-   an ID of -1 as meaning `don't change the corresponding ID'.
-   Copyright (C) 1997 Free Software Foundation, Inc.
+   an ID of -1 as meaning "don't change the corresponding ID".
 
-   This program is free software; you can redistribute it and/or modify
+   Copyright (C) 1997, 2004-2007, 2009-2013 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 2, or (at your option)
-   any later version.
+   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
@@ -13,46 +14,143 @@
    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, write to the Free Software Foundation,
-   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
 /* written by Jim Meyering */
 
 #include <config.h>
 
-/* Disable the definition of chown to rpl_chown (from config.h) in this
-   file.  Otherwise, we'd get conflicting prototypes for rpl_chown on
-   most systems.  */
-#undef chown
+/* Specification.  */
+#include <unistd.h>
 
-#include <sys/types.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdbool.h>
+#include <string.h>
 #include <sys/stat.h>
-#if HAVE_UNISTD_H
-# include <unistd.h>
-#endif
 
-/* FIXME: describe.  */
+#if !HAVE_CHOWN
 
+/* Simple stub that always fails with ENOSYS, for mingw.  */
 int
-rpl_chown (file, uid, gid)
-     const char *file;
-     uid_t uid;
-     gid_t gid;
+chown (const char *file _GL_UNUSED, uid_t uid _GL_UNUSED,
+       gid_t gid _GL_UNUSED)
 {
-  if (gid == (gid_t) -1 || uid == (uid_t) -1)
+  errno = ENOSYS;
+  return -1;
+}
+
+#else /* HAVE_CHOWN */
+
+/* Below we refer to the system's chown().  */
+# undef chown
+
+/* The results of open() in this file are not used with fchdir,
+   therefore save some unnecessary work in fchdir.c.  */
+# undef open
+# undef close
+
+/* Provide a more-closely POSIX-conforming version of chown on
+   systems with one or both of the following problems:
+   - chown doesn't treat an ID of -1 as meaning
+   "don't change the corresponding ID".
+   - chown doesn't dereference symlinks.  */
+
+int
+rpl_chown (const char *file, uid_t uid, gid_t gid)
+{
+  struct stat st;
+  bool stat_valid = false;
+  int result;
+
+# if CHOWN_CHANGE_TIME_BUG
+  if (gid != (gid_t) -1 || uid != (uid_t) -1)
     {
-      struct stat file_stats;
+      if (stat (file, &st))
+        return -1;
+      stat_valid = true;
+    }
+# endif
 
+# if CHOWN_FAILS_TO_HONOR_ID_OF_NEGATIVE_ONE
+  if (gid == (gid_t) -1 || uid == (uid_t) -1)
+    {
       /* Stat file to get id(s) that should remain unchanged.  */
-      if (stat (file, &file_stats))
-	return 1;
-
+      if (!stat_valid && stat (file, &st))
+        return -1;
       if (gid == (gid_t) -1)
-	gid = file_stats.st_gid;
-
+        gid = st.st_gid;
       if (uid == (uid_t) -1)
-	uid = file_stats.st_uid;
+        uid = st.st_uid;
+    }
+# endif
+
+# if CHOWN_MODIFIES_SYMLINK
+  {
+    /* Handle the case in which the system-supplied chown function
+       does *not* follow symlinks.  Instead, it changes permissions
+       on the symlink itself.  To work around that, we open the
+       file (but this can fail due to lack of read or write permission) and
+       use fchown on the resulting descriptor.  */
+    int open_flags = O_NONBLOCK | O_NOCTTY;
+    int fd = open (file, O_RDONLY | open_flags);
+    if (0 <= fd
+        || (errno == EACCES
+            && 0 <= (fd = open (file, O_WRONLY | open_flags))))
+      {
+        int saved_errno;
+        bool fchown_socket_failure;
+
+        result = fchown (fd, uid, gid);
+        saved_errno = errno;
+
+        /* POSIX says fchown can fail with errno == EINVAL on sockets
+           and pipes, so fall back on chown in that case.  */
+        fchown_socket_failure =
+          (result != 0 && saved_errno == EINVAL
+           && fstat (fd, &st) == 0
+           && (S_ISFIFO (st.st_mode) || S_ISSOCK (st.st_mode)));
+
+        close (fd);
+
+        if (! fchown_socket_failure)
+          {
+            errno = saved_errno;
+            return result;
+          }
+      }
+    else if (errno != EACCES)
+      return -1;
+  }
+# endif
+
+# if CHOWN_TRAILING_SLASH_BUG
+  if (!stat_valid)
+    {
+      size_t len = strlen (file);
+      if (len && file[len - 1] == '/' && stat (file, &st))
+        return -1;
     }
+# endif
 
-  return chown (file, uid, gid);
+  result = chown (file, uid, gid);
+
+# if CHOWN_CHANGE_TIME_BUG
+  if (result == 0 && stat_valid
+      && (uid == st.st_uid || uid == (uid_t) -1)
+      && (gid == st.st_gid || gid == (gid_t) -1))
+    {
+      /* No change in ownership, but at least one argument was not -1,
+         so we are required to update ctime.  Since chown succeeded,
+         we assume that chmod will do likewise.  Fortunately, on all
+         known systems where a 'no-op' chown skips the ctime update, a
+         'no-op' chmod still does the trick.  */
+      result = chmod (file, st.st_mode & (S_IRWXU | S_IRWXG | S_IRWXO
+                                          | S_ISUID | S_ISGID | S_ISVTX));
+    }
+# endif
+
+  return result;
 }
+
+#endif /* HAVE_CHOWN */