stat: detect FreeBSD bug

Like Solaris 9, FreeBSD 7.2 mistakenly allows stat("link-to-file/").
Unlike Solaris, it correctly forbids stat("file/").  A number of
interfaces are affected (such as utimes), but replacing stat is
enough to catch several by reusing the Solaris 9 fixes.

* m4/stat.m4 (gl_FUNC_STAT): Also detect FreeBSD bug with slash on
symlink.
* doc/posix-functions/stat.texi (stat): Document the bug.
* tests/test-stat.h (test_stat_func): Add argument.
* tests/test-stat.c (main): Adjust caller.
* tests/test-fstatat.c (main): Likewise.
* modules/stat-tests (Depends-on): Add stdbool, symlink.
Reported by Jim Meyering.

Signed-off-by: Eric Blake <ebb9@byu.net>

3 files changed, 59 insertions, 17 deletions

diff --git a/tests/test-fstatat.c b/tests/test-fstatat.c
index ad5434e081..e965997b29 100644
--- a/tests/test-fstatat.c
+++ b/tests/test-fstatat.c
@@ -35,11 +35,11 @@
   do                                                                         \
     {                                                                        \
       if (!(expr))                                                           \
-	{                                                                    \
-	  fprintf (stderr, "%s:%d: assertion failed\n", __FILE__, __LINE__);  \
-	  fflush (stderr);                                                   \
-	  abort ();                                                          \
-	}                                                                    \
+        {                                                                    \
+          fprintf (stderr, "%s:%d: assertion failed\n", __FILE__, __LINE__);  \
+          fflush (stderr);                                                   \
+          abort ();                                                          \
+        }                                                                    \
     }                                                                        \
   while (0)
 
@@ -68,11 +68,11 @@ int
 main (void)
 {
   int result;
-  ASSERT (test_stat_func (do_stat) == 0);
-  result = test_lstat_func (do_lstat, false);
+  result = test_stat_func (do_stat, false);
+  ASSERT (test_lstat_func (do_lstat, false) == result);
   dfd = open (".", O_RDONLY);
   ASSERT (0 <= dfd);
-  ASSERT (test_stat_func (do_stat) == 0);
+  ASSERT (test_stat_func (do_stat, false) == result);
   ASSERT (test_lstat_func (do_lstat, false) == result);
   ASSERT (close (dfd) == 0);
 
@@ -80,6 +80,6 @@ main (void)
 
   if (result == 77)
     fputs ("skipping test: symlinks not supported on this file system\n",
-	   stderr);
+           stderr);
   return result;
 }
diff --git a/tests/test-stat.c b/tests/test-stat.c
index 61a9d90182..fc11731467 100644
--- a/tests/test-stat.c
+++ b/tests/test-stat.c
@@ -22,6 +22,7 @@
 
 #include <fcntl.h>
 #include <errno.h>
+#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
@@ -33,11 +34,11 @@
   do                                                                         \
     {                                                                        \
       if (!(expr))                                                           \
-	{                                                                    \
-	  fprintf (stderr, "%s:%d: assertion failed\n", __FILE__, __LINE__);  \
-	  fflush (stderr);                                                   \
-	  abort ();                                                          \
-	}                                                                    \
+        {                                                                    \
+          fprintf (stderr, "%s:%d: assertion failed\n", __FILE__, __LINE__);  \
+          fflush (stderr);                                                   \
+          abort ();                                                          \
+        }                                                                    \
     }                                                                        \
   while (0)
 
@@ -56,5 +57,5 @@ do_stat (char const *name, struct stat *st)
 int
 main (void)
 {
-  return test_stat_func (do_stat);
+  return test_stat_func (do_stat, true);
 }
diff --git a/tests/test-stat.h b/tests/test-stat.h
index 17bb43fe47..8f7897cabb 100644
--- a/tests/test-stat.h
+++ b/tests/test-stat.h
@@ -19,10 +19,11 @@
 /* This file is designed to test both stat(n,buf) and
    fstatat(AT_FDCWD,n,buf,0).  FUNC is the function to test.  Assumes
    that BASE and ASSERT are already defined, and that appropriate
-   headers are already included.  */
+   headers are already included.  If PRINT, warn before skipping
+   symlink tests with status 77.  */
 
 static int
-test_stat_func (int (*func) (char const *, struct stat *))
+test_stat_func (int (*func) (char const *, struct stat *), bool print)
 {
   struct stat st1;
   struct stat st2;
@@ -53,7 +54,47 @@ test_stat_func (int (*func) (char const *, struct stat *))
   errno = 0;
   ASSERT (func (BASE "file/", &st1) == -1);
   ASSERT (errno == ENOTDIR);
+
+  /* Now for some symlink tests, where supported.  We set up:
+     link1 -> directory
+     link2 -> file
+     link3 -> dangling
+     link4 -> loop
+     then test behavior with trailing slash.
+  */
+  if (symlink (".", BASE "link1") != 0)
+    {
+      ASSERT (unlink (BASE "file") == 0);
+      if (print)
+        fputs ("skipping test: symlinks not supported on this file system\n",
+               stderr);
+      return 77;
+    }
+  ASSERT (symlink (BASE "file", BASE "link2") == 0);
+  ASSERT (symlink (BASE "nosuch", BASE "link3") == 0);
+  ASSERT (symlink (BASE "link4", BASE "link4") == 0);
+
+  ASSERT (func (BASE "link1/", &st1) == 0);
+  ASSERT (S_ISDIR (st1.st_mode));
+
+  errno = 0;
+  ASSERT (func (BASE "link2/", &st1) == -1);
+  ASSERT (errno == ENOTDIR);
+
+  errno = 0;
+  ASSERT (func (BASE "link3/", &st1) == -1);
+  ASSERT (errno == ENOENT);
+
+  errno = 0;
+  ASSERT (func (BASE "link4/", &st1) == -1);
+  ASSERT (errno == ELOOP);
+
+  /* Cleanup.  */
   ASSERT (unlink (BASE "file") == 0);
+  ASSERT (unlink (BASE "link1") == 0);
+  ASSERT (unlink (BASE "link2") == 0);
+  ASSERT (unlink (BASE "link3") == 0);
+  ASSERT (unlink (BASE "link4") == 0);
 
   return 0;
 }