# HG changeset patch
# User Eric Blake <ebb9@byu.net>
# Date 1257946442 25200
# Node ID 0583a6917a640a264dbcd4288184b0e5f1e4a17e
# Parent  2518d73aaac78289215027f361f55ec6252bbef3
readlink: detect FreeBSD bug

readlink("link-to-symlink/",buf,len) mistakenly read the contents
of "symlink", rather than failing.

* m4/readlink.m4 (gl_FUNC_READLINK): Also detect FreeBSD bug with
slash on symlink.
* doc/posix-functions/readlink.texi (readlink): Document the bug.
* tests/test-readlink.h (test_readlink): Enhance test.

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

diff --git a/ChangeLog b/ChangeLog
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,11 @@
 2009-11-11  Eric Blake  <ebb9@byu.net>
 
+	readlink: detect FreeBSD bug
+	* m4/readlink.m4 (gl_FUNC_READLINK): Also detect FreeBSD bug with
+	slash on symlink.
+	* doc/posix-functions/readlink.texi (readlink): Document the bug.
+	* tests/test-readlink.h (test_readlink): Enhance test.
+
 	symlink: detect FreeBSD bug
 	* m4/symlink.m4 (gl_FUNC_SYMLINK): Also detect FreeBSD bug with
 	slash on symlink.
diff --git a/doc/posix-functions/readlink.texi b/doc/posix-functions/readlink.texi
--- a/doc/posix-functions/readlink.texi
+++ b/doc/posix-functions/readlink.texi
@@ -10,7 +10,7 @@
 @itemize
 @item
 Some platforms mistakenly succeed on @code{readlink("link/",buf,len)}:
-Solaris 9.
+FreeBSD 7.2, Solaris 9.
 @item
 On some platforms, @code{readlink} returns @code{int} instead of
 @code{ssize_t}:
diff --git a/m4/readlink.m4 b/m4/readlink.m4
--- a/m4/readlink.m4
+++ b/m4/readlink.m4
@@ -1,4 +1,4 @@
-# readlink.m4 serial 7
+# readlink.m4 serial 8
 dnl Copyright (C) 2003, 2007, 2009 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -21,15 +21,18 @@
       /* Cause compilation failure if original declaration has wrong type.  */
       ssize_t readlink (const char *, char *, size_t);]])],
          [gl_cv_decl_readlink_works=yes], [gl_cv_decl_readlink_works=no])])
+    dnl Solaris 9 ignores trailing slash.
+    dnl FreeBSD 7.2 dereferences only one level of links with trailing slash.
     AC_CACHE_CHECK([whether readlink handles trailing slash correctly],
       [gl_cv_func_readlink_works],
       [# We have readlink, so assume ln -s works.
        ln -s conftest.no-such conftest.link
+       ln -s conftest.link conftest.lnk2
        AC_RUN_IFELSE(
          [AC_LANG_PROGRAM(
            [[#include <unistd.h>
 ]], [[char buf[20];
-      return readlink ("conftest.link/", buf, sizeof buf) != -1;]])],
+      return readlink ("conftest.lnk2/", buf, sizeof buf) != -1;]])],
          [gl_cv_func_readlink_works=yes], [gl_cv_func_readlink_works=no],
          [gl_cv_func_readlink_works="guessing no"])
       rm -f conftest.link])
diff --git a/tests/test-readlink.h b/tests/test-readlink.h
--- a/tests/test-readlink.h
+++ b/tests/test-readlink.h
@@ -52,11 +52,11 @@
   errno = 0;
   ASSERT (func (BASE "file/", buf, sizeof buf) == -1);
   ASSERT (errno == ENOTDIR);
-  ASSERT (unlink (BASE "file") == 0);
 
   /* Now test actual symlinks.  */
   if (symlink (BASE "dir", BASE "link"))
     {
+      ASSERT (unlink (BASE "file") == 0);
       if (print)
         fputs ("skipping test: symlinks not supported on this file system\n",
                stderr);
@@ -66,6 +66,17 @@
   errno = 0;
   ASSERT (func (BASE "link/", buf, sizeof buf) == -1);
   ASSERT (errno == EINVAL);
+  ASSERT (symlink (BASE "link", BASE "link2") == 0);
+  errno = 0;
+  ASSERT (func (BASE "link2/", buf, sizeof buf) == -1);
+  ASSERT (errno == EINVAL);
+  ASSERT (unlink (BASE "link2") == 0);
+  ASSERT (symlink (BASE "file", BASE "link2") == 0);
+  errno = 0;
+  ASSERT (func (BASE "link2/", buf, sizeof buf) == -1);
+  ASSERT (errno == ENOTDIR);
+  ASSERT (unlink (BASE "file") == 0);
+  ASSERT (unlink (BASE "link2") == 0);
   {
     /* Up till now, no readlink has been successful, so buf should be
        unchanged.  */