X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;ds=sidebyside;f=lib%2Fchown.c;h=2a7bba1a6c09e1bfc4b21c4355a1e87960d62f7a;hb=da326536990b4518c6e067ef773321d2e3d20889;hp=2d3b4e8212b2f243e94791235dc1c6b9d6927daf;hpb=02276ef5a15bd1e1264d2857e86c4c9f6132ad12;p=gnulib.git

diff --git a/lib/chown.c b/lib/chown.c
index 2d3b4e821..2a7bba1a6 100644
--- a/lib/chown.c
+++ b/lib/chown.c
@@ -1,6 +1,6 @@
 /* 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.
+   Copyright (C) 1997, 2004, 2005 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
@@ -14,31 +14,89 @@
 
    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.  */
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
 
 /* written by Jim Meyering */
 
-#include <config.h>
-#include <sys/types.h>
-#ifdef HAVE_UNISTD_H
-# include <unistd.h>
+#ifdef HAVE_CONFIG_H
+# include <config.h>
 #endif
 
-/* FIXME: describe.  */
+/* 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
+
+#include <stdbool.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+
+#include "stat-macros.h"
+
+/* 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
-chown (file, gid, uid)
-     const char *file;
-     gid_t git;
-     uid_t uit;
+rpl_chown (const char *file, uid_t uid, gid_t gid)
 {
+#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 will remain unchanged.  */
-      FIXME
+      struct stat file_stats;
+
+      /* Stat file to get id(s) that should remain unchanged.  */
+      if (stat (file, &file_stats))
+	return -1;
+
+      if (gid == (gid_t) -1)
+	gid = file_stats.st_gid;
+
+      if (uid == (uid_t) -1)
+	uid = file_stats.st_uid;
     }
+#endif
 
-#undef chown
+#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 result = fchown (fd, uid, gid);
+	int saved_errno = errno;
+
+	/* POSIX says fchown can fail with errno == EINVAL on sockets,
+	   so fall back on chown in that case.  */
+	struct stat sb;
+	bool fchown_socket_failure =
+	  (result != 0 && saved_errno == EINVAL
+	   && fstat (fd, &sb) == 0 && S_ISFIFO (sb.st_mode));
+
+	close (fd);
+
+	if (! fchown_socket_failure)
+	  {
+	    errno = saved_errno;
+	    return result;
+	  }
+      }
+    else if (errno != EACCES)
+      return -1;
+  }
+#endif
 
-  return chown (file, gid, uid);
+  return chown (file, uid, gid);
 }