Work even in a chroot where d_ino values for entries in "/"

don't match the stat.st_ino values for the same names.

(__getcwd): When no d_ino value matches the target inode
number, iterate through all entries again, using lstat instead.
Reported by Kenshi Muto in http://bugs.debian.org/355810.

diff --git a/lib/getcwd.c b/lib/getcwd.c
index 739ef44c788cfd203c81beeb1646453b9c61e62a..ba226799d384c1f799dfd49e966435d1202b8a89 100644 (file)
--- a/lib/getcwd.c
+++ b/lib/getcwd.c
@@ -211,6 +211,7 @@ __getcwd (char *buf, size_t size)
       int parent_status;
       size_t dirroom;
       size_t namlen;
+      bool use_d_ino = true;
 
       /* Look at the parent directory.  */
 #ifdef AT_FDCWD
@@ -257,6 +258,21 @@ __getcwd (char *buf, size_t size)
             NULL.  */
          __set_errno (0);
          d = __readdir (dirstream);
+
+         /* When we've iterated through all directory entries without finding
+            one with a matching d_ino, rewind the stream and consider each
+            name again, but this time, using lstat.  This is necessary in a
+            chroot on at least one system (glibc-2.3.6 + linux 2.6.12), where
+            .., ../.., ../../.., etc. all had the same device number, yet the
+            d_ino values for entries in / did not match those obtained
+            via lstat.  */
+         if (d == NULL && errno == 0 && use_d_ino)
+           {
+             use_d_ino = false;
+             rewinddir (dirstream);
+             d = __readdir (dirstream);
+           }
+
          if (d == NULL)
            {
              if (errno == 0)
@@ -269,58 +285,65 @@ __getcwd (char *buf, size_t size)
              (d->d_name[1] == '\0' ||
               (d->d_name[1] == '.' && d->d_name[2] == '\0')))
            continue;
-         if (MATCHING_INO (d, thisino) || mount_point)
+
+         if (use_d_ino)
            {
-             int entry_status;
+             bool match = (MATCHING_INO (d, thisino) || mount_point);
+             if (! match)
+               continue;
+           }
+
+         {
+           int entry_status;
 #ifdef AT_FDCWD
-             entry_status = fstatat (fd, d->d_name, &st, AT_SYMLINK_NOFOLLOW);
+           entry_status = fstatat (fd, d->d_name, &st, AT_SYMLINK_NOFOLLOW);
 #else
-             /* Compute size needed for this file name, or for the file
-                name ".." in the same directory, whichever is larger.
-                Room for ".." might be needed the next time through
-                the outer loop.  */
-             size_t name_alloc = _D_ALLOC_NAMLEN (d);
-             size_t filesize = dotlen + MAX (sizeof "..", name_alloc);
-
-             if (filesize < dotlen)
-               goto memory_exhausted;
-
-             if (dotsize < filesize)
-               {
-                 /* My, what a deep directory tree you have, Grandma.  */
-                 size_t newsize = MAX (filesize, dotsize * 2);
-                 size_t i;
-                 if (newsize < dotsize)
-                   goto memory_exhausted;
-                 if (dotlist != dots)
-                   free (dotlist);
-                 dotlist = malloc (newsize);
-                 if (dotlist == NULL)
-                   goto lose;
-                 dotsize = newsize;
-
-                 i = 0;
-                 do
-                   {
-                     dotlist[i++] = '.';
-                     dotlist[i++] = '.';
-                     dotlist[i++] = '/';
-                   }
-                 while (i < dotlen);
-               }
-
-             memcpy (dotlist + dotlen, d->d_name, _D_ALLOC_NAMLEN (d));
-             entry_status = __lstat (dotlist, &st);
+           /* Compute size needed for this file name, or for the file
+              name ".." in the same directory, whichever is larger.
+              Room for ".." might be needed the next time through
+              the outer loop.  */
+           size_t name_alloc = _D_ALLOC_NAMLEN (d);
+           size_t filesize = dotlen + MAX (sizeof "..", name_alloc);
+
+           if (filesize < dotlen)
+             goto memory_exhausted;
+
+           if (dotsize < filesize)
+             {
+               /* My, what a deep directory tree you have, Grandma.  */
+               size_t newsize = MAX (filesize, dotsize * 2);
+               size_t i;
+               if (newsize < dotsize)
+                 goto memory_exhausted;
+               if (dotlist != dots)
+                 free (dotlist);
+               dotlist = malloc (newsize);
+               if (dotlist == NULL)
+                 goto lose;
+               dotsize = newsize;
+
+               i = 0;
+               do
+                 {
+                   dotlist[i++] = '.';
+                   dotlist[i++] = '.';
+                   dotlist[i++] = '/';
+                 }
+               while (i < dotlen);
+             }
+
+           memcpy (dotlist + dotlen, d->d_name, _D_ALLOC_NAMLEN (d));
+           entry_status = __lstat (dotlist, &st);
 #endif
-             /* We don't fail here if we cannot stat() a directory entry.
-                This can happen when (network) file systems fail.  If this
-                entry is in fact the one we are looking for we will find
-                out soon as we reach the end of the directory without
-                having found anything.  */
-             if (entry_status == 0 && S_ISDIR (st.st_mode)
-                 && st.st_dev == thisdev && st.st_ino == thisino)
-               break;
-           }
+           /* We don't fail here if we cannot stat() a directory entry.
+              This can happen when (network) file systems fail.  If this
+              entry is in fact the one we are looking for we will find
+              out soon as we reach the end of the directory without
+              having found anything.  */
+           if (entry_status == 0 && S_ISDIR (st.st_mode)
+               && st.st_dev == thisdev && st.st_ino == thisino)
+             break;
+         }
        }
 
       dirroom = dirp - dir;