* lib/getcwd.c (__getcwd): Don't assume getcwd (NULL, 0) works

[gnulib.git] / lib / getcwd.c

diff --git a/lib/getcwd.c b/lib/getcwd.c
index dea0ebc..3ccfbdf 100644 (file)
--- a/lib/getcwd.c
+++ b/lib/getcwd.c
@@ -19,6 +19,7 @@
 #if !_LIBC
 # include <config.h>
 # include <unistd.h>
+# include "dirfd.h"
 #endif
 
 #include <errno.h>
@@ -140,24 +141,6 @@ __getcwd (char *buf, size_t size)
   size_t allocated = size;
   size_t used;
 
-#if HAVE_PARTLY_WORKING_GETCWD
-  /* The system getcwd works, except it sometimes fails when it
-     shouldn't, setting errno to ERANGE, ENAMETOOLONG, or ENOENT.  If
-     AT_FDCWD is not defined, the algorithm below is O(N**2) and this
-     is much slower than the system getcwd (at least on GNU/Linux).
-     So trust the system getcwd's results unless they look
-     suspicious.
-
-     Use the system getcwd even if we have openat support, since the
-     system getcwd works even when a parent is unreadable, while the
-     openat-based approach does not.  */
-
-# undef getcwd
-  dir = getcwd (buf, size);
-  if (dir || (errno != ERANGE && !is_ENAMETOOLONG (errno) && errno != ENOENT))
-    return dir;
-#endif
-
   if (size == 0)
     {
       if (buf != NULL)
@@ -178,6 +161,30 @@ __getcwd (char *buf, size_t size)
   else
     dir = buf;
 
+#if HAVE_PARTLY_WORKING_GETCWD
+  /* The system getcwd works, except it sometimes fails when it
+     shouldn't, setting errno to ERANGE, ENAMETOOLONG, or ENOENT.  If
+     AT_FDCWD is not defined, the algorithm below is O(N**2) and this
+     is much slower than the system getcwd (at least on GNU/Linux).
+     So trust the system getcwd's results unless they look
+     suspicious.
+
+     Use the system getcwd even if we have openat support, since the
+     system getcwd works even when a parent is unreadable, while the
+     openat-based approach does not.  */
+
+# undef getcwd
+  if (getcwd (dir, allocated))
+    {
+      if (buf == NULL && size == 0)
+       buf = realloc (dir, strlen (dir) + 1);
+      return (buf ? buf : dir);
+    }
+
+  if (! (errno == ERANGE || is_ENAMETOOLONG (errno) || errno == ENOENT))
+    return NULL;
+#endif
+
   dirp = dir + allocated;
   *--dirp = '\0';