* src/fileio.c (check_writable) [CYGWIN]: Return non-zero if UID or

GID is unknown (Bug#10257).

2 files changed, 20 insertions, 3 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 98e87ef4306..e25f0c68ce0 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,8 @@
+2011-12-17  Ken Brown  <kbrown@cornell.edu>
+
+        * fileio.c (check_writable) [CYGWIN]: Return non-zero if UID or
+        GID is unknown (Bug#10257).
+
 2011-12-17  Paul Eggert  <eggert@cs.ucla.edu>
 
         * s/gnu-linux.h: Fix mark_memory typo (Bug#10286).
diff --git a/src/fileio.c b/src/fileio.c
index fb021cee5a4..3306085491e 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -2416,15 +2416,27 @@ check_writable (const char *filename)
   return (st.st_mode & S_IWRITE || S_ISDIR (st.st_mode));
 #else /* not MSDOS */
 #ifdef HAVE_EUIDACCESS
-  return (euidaccess (filename, 2) >= 0);
-#else
+  int res = (euidaccess (filename, 2) >= 0);
+#ifdef CYGWIN
+  /* euidaccess may have returned failure because Cygwin couldn't
+     determine the file's UID or GID; if so, we return success. */
+  if (!res)
+    {
+      struct stat st;
+      if (stat (filename, &st) < 0)
+        return 0;
+      res = (st.st_uid == -1 || st.st_gid == -1);
+    }
+#endif /* CYGWIN */
+  return res;
+#else /* not HAVE_EUIDACCESS */
   /* Access isn't quite right because it uses the real uid
      and we really want to test with the effective uid.
      But Unix doesn't give us a right way to do it.
      Opening with O_WRONLY could work for an ordinary file,
      but would lose for directories.  */
   return (access (filename, 2) >= 0);
-#endif
+#endif /* not HAVE_EUIDACCESS */
 #endif /* not MSDOS */
 }