gnulib/import/m4/getcwd-abort-bug.m4

   1 # serial 7
   2 # Determine whether getcwd aborts when the length of the working directory
   3 # name is unusually large.  Any length between 4k and 16k trigger the bug
   4 # when using glibc-2.4.90-9 or older.
   5
   6 # Copyright (C) 2006, 2009-2016 Free Software Foundation, Inc.
   7 # This file is free software; the Free Software Foundation
   8 # gives unlimited permission to copy and/or distribute it,
   9 # with or without modifications, as long as this notice is preserved.
  10
  11 # From Jim Meyering
  12
  13 # gl_FUNC_GETCWD_ABORT_BUG([ACTION-IF-FOUND[, ACTION-IF-NOT-FOUND]])
  14 AC_DEFUN([gl_FUNC_GETCWD_ABORT_BUG],
  15 [
  16   AC_CHECK_DECLS_ONCE([getcwd])
  17   AC_CHECK_HEADERS_ONCE([unistd.h])
  18   AC_REQUIRE([gl_PATHMAX_SNIPPET_PREREQ])
  19   AC_CHECK_FUNCS([getpagesize])
  20   AC_CACHE_CHECK([whether getcwd aborts when 4k < cwd_length < 16k],
  21     gl_cv_func_getcwd_abort_bug,
  22     [# Remove any remnants of a previous test.
  23      rm -rf confdir-14B---
  24      # Arrange for deletion of the temporary directory this test creates.
  25      ac_clean_files="$ac_clean_files confdir-14B---"
  26      dnl Please keep this in sync with tests/test-getcwd.c.
  27      AC_RUN_IFELSE(
  28        [AC_LANG_SOURCE(
  29           [[
  30 #include <errno.h>
  31 #include <stdlib.h>
  32 #if HAVE_UNISTD_H
  33 # include <unistd.h>
  34 #else /* on Windows with MSVC */
  35 # include <direct.h>
  36 #endif
  37 #include <string.h>
  38 #include <sys/stat.h>
  39
  40 ]gl_PATHMAX_SNIPPET[
  41
  42 /* Don't get link errors because mkdir is redefined to rpl_mkdir.  */
  43 #undef mkdir
  44
  45 #ifndef S_IRWXU
  46 # define S_IRWXU 0700
  47 #endif
  48
  49 /* FIXME: skip the run-test altogether on systems without getpagesize.  */
  50 #if ! HAVE_GETPAGESIZE
  51 # define getpagesize() 0
  52 #endif
  53
  54 /* This size is chosen to be larger than PATH_MAX (4k), yet smaller than
  55    the 16kB pagesize on ia64 linux.  Those conditions make the code below
  56    trigger a bug in glibc's getcwd implementation before 2.4.90-10.  */
  57 #define TARGET_LEN (5 * 1024)
  58
  59 int
  60 main ()
  61 {
  62   char *cwd;
  63   size_t initial_cwd_len;
  64   int fail = 0;
  65
  66   /* The bug is triggered when PATH_MAX < getpagesize (), so skip
  67      this relatively expensive and invasive test if that's not true.  */
  68 #ifdef PATH_MAX
  69   int bug_possible = PATH_MAX < getpagesize ();
  70 #else
  71   int bug_possible = 0;
  72 #endif
  73   if (! bug_possible)
  74     return 0;
  75
  76   cwd = getcwd (NULL, 0);
  77   if (cwd == NULL)
  78     return 2;
  79
  80   initial_cwd_len = strlen (cwd);
  81   free (cwd);
  82
  83   if (1)
  84     {
  85       static char const dir_name[] = "confdir-14B---";
  86       size_t desired_depth = ((TARGET_LEN - 1 - initial_cwd_len)
  87                               / sizeof dir_name);
  88       size_t d;
  89       for (d = 0; d < desired_depth; d++)
  90         {
  91           if (mkdir (dir_name, S_IRWXU) < 0 || chdir (dir_name) < 0)
  92             {
  93               if (! (errno == ERANGE || errno == ENAMETOOLONG
  94                      || errno == ENOENT))
  95                 fail = 3; /* Unable to construct deep hierarchy.  */
  96               break;
  97             }
  98         }
  99
 100       /* If libc has the bug in question, this invocation of getcwd
 101          results in a failed assertion.  */
 102       cwd = getcwd (NULL, 0);
 103       if (cwd == NULL)
 104         fail = 4; /* getcwd didn't assert, but it failed for a long name
 105                      where the answer could have been learned.  */
 106       free (cwd);
 107
 108       /* Call rmdir first, in case the above chdir failed.  */
 109       rmdir (dir_name);
 110       while (0 < d--)
 111         {
 112           if (chdir ("..") < 0)
 113             {
 114               fail = 5;
 115               break;
 116             }
 117           rmdir (dir_name);
 118         }
 119     }
 120
 121   return fail;
 122 }
 123           ]])],
 124     [gl_cv_func_getcwd_abort_bug=no],
 125     [dnl An abort will provoke an exit code of something like 134 (128 + 6).
 126      dnl An exit code of 4 can also occur (in OpenBSD 4.9, NetBSD 5.1 for
 127      dnl example): getcwd (NULL, 0) fails rather than returning a string
 128      dnl longer than PATH_MAX.  This may be POSIX compliant (in some
 129      dnl interpretations of POSIX).  But gnulib's getcwd module wants to
 130      dnl provide a non-NULL value in this case.
 131      ret=$?
 132      if test $ret -ge 128 || test $ret = 4; then
 133        gl_cv_func_getcwd_abort_bug=yes
 134      else
 135        gl_cv_func_getcwd_abort_bug=no
 136      fi],
 137     [gl_cv_func_getcwd_abort_bug=yes])
 138   ])
 139   AS_IF([test $gl_cv_func_getcwd_abort_bug = yes], [$1], [$2])
 140 ])