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
index 227d9bd951eba3c7715db7c6bcd733274a346e0f..fbfa1e483831c6497a5e85b761bf7d1433934227 100644 (file)
--- 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
index b1218f6c26a61461a0e3ffdc3d25392856cc724f..de898fba1eb59c9800eaa0aa82162b5b87fdb736 100644 (file)
--- a/doc/posix-functions/readlink.texi
+++ b/doc/posix-functions/readlink.texi
@@ -10,7 +10,7 @@ Portability problems fixed by Gnulib:
 @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
index fa7c2ddcb1e6e4a74ea8a02def920c399e1c4794..e61c1a1cf70cca78e1967d7e64b7934439c79e71 100644 (file)
--- 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 @@ AC_DEFUN([gl_FUNC_READLINK],
       /* 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
index 4ce67f79d560446021bef2d735cbe83f9b631a4b..5f5e9108d31044d2a4cb7d680e779a07c627b4ed 100644 (file)
--- a/tests/test-readlink.h
+++ b/tests/test-readlink.h
@@ -52,11 +52,11 @@ test_readlink (ssize_t (*func) (char const *, char *, size_t), bool print)
   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 @@ test_readlink (ssize_t (*func) (char const *, char *, size_t), bool print)
   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.  */