tar-1.29HEADtar-1.29master

1 files changed, 140 insertions, 0 deletions

diff --git a/m4/getcwd-abort-bug.m4 b/m4/getcwd-abort-bug.m4
new file mode 100644
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+++ b/m4/getcwd-abort-bug.m4
@@ -0,0 +1,140 @@
+# serial 7
+# Determine whether getcwd aborts when the length of the working directory
+# name is unusually large.  Any length between 4k and 16k trigger the bug
+# when using glibc-2.4.90-9 or older.
+
+# Copyright (C) 2006, 2009-2015 Free Software Foundation, Inc.
+# This file is free software; the Free Software Foundation
+# gives unlimited permission to copy and/or distribute it,
+# with or without modifications, as long as this notice is preserved.
+
+# From Jim Meyering
+
+# gl_FUNC_GETCWD_ABORT_BUG([ACTION-IF-FOUND[, ACTION-IF-NOT-FOUND]])
+AC_DEFUN([gl_FUNC_GETCWD_ABORT_BUG],
+[
+  AC_CHECK_DECLS_ONCE([getcwd])
+  AC_CHECK_HEADERS_ONCE([unistd.h])
+  AC_REQUIRE([gl_PATHMAX_SNIPPET_PREREQ])
+  AC_CHECK_FUNCS([getpagesize])
+  AC_CACHE_CHECK([whether getcwd aborts when 4k < cwd_length < 16k],
+    gl_cv_func_getcwd_abort_bug,
+    [# Remove any remnants of a previous test.
+     rm -rf confdir-14B---
+     # Arrange for deletion of the temporary directory this test creates.
+     ac_clean_files="$ac_clean_files confdir-14B---"
+     dnl Please keep this in sync with tests/test-getcwd.c.
+     AC_RUN_IFELSE(
+       [AC_LANG_SOURCE(
+          [[
+#include <errno.h>
+#include <stdlib.h>
+#if HAVE_UNISTD_H
+# include <unistd.h>
+#else /* on Windows with MSVC */
+# include <direct.h>
+#endif
+#include <string.h>
+#include <sys/stat.h>
+
+]gl_PATHMAX_SNIPPET[
+
+/* Don't get link errors because mkdir is redefined to rpl_mkdir.  */
+#undef mkdir
+
+#ifndef S_IRWXU
+# define S_IRWXU 0700
+#endif
+
+/* FIXME: skip the run-test altogether on systems without getpagesize.  */
+#if ! HAVE_GETPAGESIZE
+# define getpagesize() 0
+#endif
+
+/* This size is chosen to be larger than PATH_MAX (4k), yet smaller than
+   the 16kB pagesize on ia64 linux.  Those conditions make the code below
+   trigger a bug in glibc's getcwd implementation before 2.4.90-10.  */
+#define TARGET_LEN (5 * 1024)
+
+int
+main ()
+{
+  char *cwd;
+  size_t initial_cwd_len;
+  int fail = 0;
+
+  /* The bug is triggered when PATH_MAX < getpagesize (), so skip
+     this relatively expensive and invasive test if that's not true.  */
+#ifdef PATH_MAX
+  int bug_possible = PATH_MAX < getpagesize ();
+#else
+  int bug_possible = 0;
+#endif
+  if (! bug_possible)
+    return 0;
+
+  cwd = getcwd (NULL, 0);
+  if (cwd == NULL)
+    return 2;
+
+  initial_cwd_len = strlen (cwd);
+  free (cwd);
+
+  if (1)
+    {
+      static char const dir_name[] = "confdir-14B---";
+      size_t desired_depth = ((TARGET_LEN - 1 - initial_cwd_len)
+                              / sizeof dir_name);
+      size_t d;
+      for (d = 0; d < desired_depth; d++)
+        {
+          if (mkdir (dir_name, S_IRWXU) < 0 || chdir (dir_name) < 0)
+            {
+              if (! (errno == ERANGE || errno == ENAMETOOLONG
+                     || errno == ENOENT))
+                fail = 3; /* Unable to construct deep hierarchy.  */
+              break;
+            }
+        }
+
+      /* If libc has the bug in question, this invocation of getcwd
+         results in a failed assertion.  */
+      cwd = getcwd (NULL, 0);
+      if (cwd == NULL)
+        fail = 4; /* getcwd didn't assert, but it failed for a long name
+                     where the answer could have been learned.  */
+      free (cwd);
+
+      /* Call rmdir first, in case the above chdir failed.  */
+      rmdir (dir_name);
+      while (0 < d--)
+        {
+          if (chdir ("..") < 0)
+            {
+              fail = 5;
+              break;
+            }
+          rmdir (dir_name);
+        }
+    }
+
+  return fail;
+}
+          ]])],
+    [gl_cv_func_getcwd_abort_bug=no],
+    [dnl An abort will provoke an exit code of something like 134 (128 + 6).
+     dnl An exit code of 4 can also occur (in OpenBSD 4.9, NetBSD 5.1 for
+     dnl example): getcwd (NULL, 0) fails rather than returning a string
+     dnl longer than PATH_MAX.  This may be POSIX compliant (in some
+     dnl interpretations of POSIX).  But gnulib's getcwd module wants to
+     dnl provide a non-NULL value in this case.
+     ret=$?
+     if test $ret -ge 128 || test $ret = 4; then
+       gl_cv_func_getcwd_abort_bug=yes
+     else
+       gl_cv_func_getcwd_abort_bug=no
+     fi],
+    [gl_cv_func_getcwd_abort_bug=yes])
+  ])
+  AS_IF([test $gl_cv_func_getcwd_abort_bug = yes], [$1], [$2])
+])