m4/utimes.m4

   1 # Detect some bugs in glibc's implementation of utimes.
   2 # serial 3
   3
   4 dnl Copyright (C) 2003-2005, 2009-2014 Free Software Foundation, Inc.
   5 dnl This file is free software; the Free Software Foundation
   6 dnl gives unlimited permission to copy and/or distribute it,
   7 dnl with or without modifications, as long as this notice is preserved.
   8
   9 # See if we need to work around bugs in glibc's implementation of
  10 # utimes from 2003-07-12 to 2003-09-17.
  11 # First, there was a bug that would make utimes set mtime
  12 # and atime to zero (1970-01-01) unconditionally.
  13 # Then, there was code to round rather than truncate.
  14 # Then, there was an implementation (sparc64, Linux-2.4.28, glibc-2.3.3)
  15 # that didn't honor the NULL-means-set-to-current-time semantics.
  16 # Finally, there was also a version of utimes that failed on read-only
  17 # files, while utime worked fine (linux-2.2.20, glibc-2.2.5).
  18 #
  19 # From Jim Meyering, with suggestions from Paul Eggert.
  20
  21 AC_DEFUN([gl_FUNC_UTIMES],
  22 [
  23   AC_CACHE_CHECK([whether the utimes function works],
  24                  [gl_cv_func_working_utimes],
  25   [
  26   AC_RUN_IFELSE([AC_LANG_SOURCE([[
  27 #include <sys/types.h>
  28 #include <sys/stat.h>
  29 #include <fcntl.h>
  30 #include <sys/time.h>
  31 #include <time.h>
  32 #include <unistd.h>
  33 #include <stdlib.h>
  34 #include <stdio.h>
  35 #include <utime.h>
  36
  37 static int
  38 inorder (time_t a, time_t b, time_t c)
  39 {
  40   return a <= b && b <= c;
  41 }
  42
  43 int
  44 main ()
  45 {
  46   int result = 0;
  47   char const *file = "conftest.utimes";
  48   static struct timeval timeval[2] = {{9, 10}, {999999, 999999}};
  49
  50   /* Test whether utimes() essentially works.  */
  51   {
  52     struct stat sbuf;
  53     FILE *f = fopen (file, "w");
  54     if (f == NULL)
  55       result |= 1;
  56     else if (fclose (f) != 0)
  57       result |= 1;
  58     else if (utimes (file, timeval) != 0)
  59       result |= 2;
  60     else if (lstat (file, &sbuf) != 0)
  61       result |= 1;
  62     else if (!(sbuf.st_atime == timeval[0].tv_sec
  63                && sbuf.st_mtime == timeval[1].tv_sec))
  64       result |= 4;
  65     if (unlink (file) != 0)
  66       result |= 1;
  67   }
  68
  69   /* Test whether utimes() with a NULL argument sets the file's timestamp
  70      to the current time.  Use 'fstat' as well as 'time' to
  71      determine the "current" time, to accommodate NFS file systems
  72      if there is a time skew between the host and the NFS server.  */
  73   {
  74     int fd = open (file, O_WRONLY|O_CREAT, 0644);
  75     if (fd < 0)
  76       result |= 1;
  77     else
  78       {
  79         time_t t0, t2;
  80         struct stat st0, st1, st2;
  81         if (time (&t0) == (time_t) -1)
  82           result |= 1;
  83         else if (fstat (fd, &st0) != 0)
  84           result |= 1;
  85         else if (utimes (file, timeval) != 0)
  86           result |= 2;
  87         else if (utimes (file, NULL) != 0)
  88           result |= 8;
  89         else if (fstat (fd, &st1) != 0)
  90           result |= 1;
  91         else if (write (fd, "\n", 1) != 1)
  92           result |= 1;
  93         else if (fstat (fd, &st2) != 0)
  94           result |= 1;
  95         else if (time (&t2) == (time_t) -1)
  96           result |= 1;
  97         else
  98           {
  99             int m_ok_POSIX = inorder (t0, st1.st_mtime, t2);
 100             int m_ok_NFS = inorder (st0.st_mtime, st1.st_mtime, st2.st_mtime);
 101             if (! (st1.st_atime == st1.st_mtime))
 102               result |= 16;
 103             if (! (m_ok_POSIX || m_ok_NFS))
 104               result |= 32;
 105           }
 106         if (close (fd) != 0)
 107           result |= 1;
 108       }
 109     if (unlink (file) != 0)
 110       result |= 1;
 111   }
 112
 113   /* Test whether utimes() with a NULL argument works on read-only files.  */
 114   {
 115     int fd = open (file, O_WRONLY|O_CREAT, 0444);
 116     if (fd < 0)
 117       result |= 1;
 118     else if (close (fd) != 0)
 119       result |= 1;
 120     else if (utimes (file, NULL) != 0)
 121       result |= 64;
 122     if (unlink (file) != 0)
 123       result |= 1;
 124   }
 125
 126   return result;
 127 }
 128   ]])],
 129        [gl_cv_func_working_utimes=yes],
 130        [gl_cv_func_working_utimes=no],
 131        [gl_cv_func_working_utimes=no])])
 132
 133   if test $gl_cv_func_working_utimes = yes; then
 134     AC_DEFINE([HAVE_WORKING_UTIMES], [1], [Define if utimes works properly. ])
 135   fi
 136 ])