compat/mkstemps.c

   1 /* Copyright (C) 1991, 1992, 1996, 1998, 2004 Free Software Foundation, Inc.
   2    This file is derived from mkstemp.c from the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Library General Public License as
   6    published by the Free Software Foundation; either version 2 of the
   7    License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Library General Public License for more details.
  13
  14    You should have received a copy of the GNU Library General Public
  15    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  16    write to the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
  17    Boston, MA 02110-1301, USA.  */
  18 /*
  19  * This file was copied on 2013-08-03 from:
  20  * https://raw.github.com/mirrors/gcc/master/libiberty/mkstemps.c
  21  */
  22
  23 #ifdef HAVE_CONFIG_H
  24 #include "config.h"
  25 #endif
  26
  27 #include "compat.h"
  28
  29 #include <sys/types.h>
  30 #ifdef HAVE_STDLIB_H
  31 #include <stdlib.h>
  32 #endif
  33 #ifdef HAVE_STRING_H
  34 #include <string.h>
  35 #endif
  36 #include <errno.h>
  37 #include <stdio.h>
  38 #include <fcntl.h>
  39 #ifdef HAVE_UNISTD_H
  40 #include <unistd.h>
  41 #endif
  42 #ifdef HAVE_SYS_TIME_H
  43 #include <sys/time.h>
  44 #endif
  45
  46 /* We need to provide a type for gcc_uint64_t.  */
  47 #ifdef __GNUC__
  48 __extension__ typedef unsigned long long gcc_uint64_t;
  49 #else
  50 typedef unsigned long gcc_uint64_t;
  51 #endif
  52
  53 #ifndef TMP_MAX
  54 #define TMP_MAX 16384
  55 #endif
  56
  57 #ifndef O_BINARY
  58 # define O_BINARY 0
  59 #endif
  60
  61 /*
  62
  63 @deftypefn Replacement int mkstemps (char *@var{pattern}, int @var{suffix_len})
  64
  65 Generate a unique temporary file name from @var{pattern}.
  66 @var{pattern} has the form:
  67
  68 @example
  69    @var{path}/ccXXXXXX@var{suffix}
  70 @end example
  71
  72 @var{suffix_len} tells us how long @var{suffix} is (it can be zero
  73 length).  The last six characters of @var{pattern} before @var{suffix}
  74 must be @samp{XXXXXX}; they are replaced with a string that makes the
  75 filename unique.  Returns a file descriptor open on the file for
  76 reading and writing.
  77
  78 @end deftypefn
  79
  80 */
  81
  82 int
  83 compat_mkstemps (char *pattern, int suffix_len)
  84 {
  85   static const char letters[]
  86     = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
  87   static gcc_uint64_t value;
  88 #ifdef HAVE_GETTIMEOFDAY
  89   struct timeval tv;
  90 #endif
  91   char *XXXXXX;
  92   size_t len;
  93   int count;
  94
  95   len = strlen (pattern);
  96
  97   if ((int) len < 6 + suffix_len
  98       || strncmp (&pattern[len - 6 - suffix_len], "XXXXXX", 6))
  99     {
 100       return -1;
 101     }
 102
 103   XXXXXX = &pattern[len - 6 - suffix_len];
 104
 105 #ifdef HAVE_GETTIMEOFDAY
 106   /* Get some more or less random data.  */
 107   gettimeofday (&tv, NULL);
 108   value += ((gcc_uint64_t) tv.tv_usec << 16) ^ tv.tv_sec ^ getpid ();
 109 #else
 110   value += getpid ();
 111 #endif
 112
 113   for (count = 0; count < TMP_MAX; ++count)
 114     {
 115       gcc_uint64_t v = value;
 116       int fd;
 117
 118       /* Fill in the random bits.  */
 119       XXXXXX[0] = letters[v % 62];
 120       v /= 62;
 121       XXXXXX[1] = letters[v % 62];
 122       v /= 62;
 123       XXXXXX[2] = letters[v % 62];
 124       v /= 62;
 125       XXXXXX[3] = letters[v % 62];
 126       v /= 62;
 127       XXXXXX[4] = letters[v % 62];
 128       v /= 62;
 129       XXXXXX[5] = letters[v % 62];
 130
 131       fd = open (pattern, O_BINARY|O_RDWR|O_CREAT|O_EXCL, 0600);
 132       if (fd >= 0)
 133         /* The file does not exist.  */
 134         return fd;
 135       if (errno != EEXIST
 136 #ifdef EISDIR
 137           && errno != EISDIR
 138 #endif
 139          )
 140         /* Fatal error (EPERM, ENOSPC etc).  Doesn't make sense to loop.  */
 141         break;
 142
 143       /* This is a random value.  It is only necessary that the next
 144          TMP_MAX values generated by adding 7777 to VALUE are different
 145          with (module 2^32).  */
 146       value += 7777;
 147     }
 148
 149   /* We return the null string if we can't find a unique file name.  */
 150   pattern[0] = '\0';
 151   return -1;
 152 }