sdk/tools/port/mkstemps.c

   1 /* Copyright (C) 1991, 1992, 1996, 1998 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 Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the 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    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, write to the Free
  16    Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  17    Boston, MA 02110-1301, USA.
  18 */
  19
  20 #include <sys/types.h>
  21 #include <stdlib.h>
  22 #include <string.h>
  23 #include <errno.h>
  24 #include <stdio.h>
  25 #include <fcntl.h>
  26
  27 #ifdef _WIN32
  28     #include <io.h>
  29     #include <process.h>
  30 #else
  31     #include <unistd.h>
  32     #include <sys/time.h>
  33 #endif
  34
  35 /* We need to provide a type for gcc_uint64_t.  */
  36 #ifdef __GNUC__
  37 __extension__ typedef unsigned long long gcc_uint64_t;
  38 #else
  39 typedef unsigned long gcc_uint64_t;
  40 #endif
  41
  42 #ifndef TMP_MAX
  43 #define TMP_MAX 16384
  44 #endif
  45
  46 /* if O_BINARY is not defined, the system is probably not expecting any such flag */
  47 #ifndef O_BINARY
  48 #define O_BINARY 0
  49 #endif
  50
  51 /*
  52
  53 @deftypefn Replacement int mkstemps (char *@var{template}, int @var{suffix_len})
  54
  55 Generate a unique temporary file name from @var{template}.
  56 @var{template} has the form:
  57
  58 @example
  59    @var{path}/ccXXXXXX@var{suffix}
  60 @end example
  61
  62 @var{suffix_len} tells us how long @var{suffix} is (it can be zero
  63 length).  The last six characters of @var{template} before @var{suffix}
  64 must be @samp{XXXXXX}; they are replaced with a string that makes the
  65 filename unique.  Returns a file descriptor open on the file for
  66 reading and writing.
  67
  68 @end deftypefn
  69
  70 */
  71
  72 int
  73 mkstemps (
  74      char *template,
  75      int suffix_len)
  76 {
  77   static const char letters[]
  78     = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
  79   static gcc_uint64_t value;
  80 #ifdef HAVE_GETTIMEOFDAY
  81   struct timeval tv;
  82 #endif
  83   char *XXXXXX;
  84   size_t len;
  85   int count;
  86
  87   len = strlen (template);
  88
  89   if ((int) len < 6 + suffix_len
  90       || strncmp (&template[len - 6 - suffix_len], "XXXXXX", 6))
  91     {
  92       printf("wrong parameter\n");
  93       return -1;
  94     }
  95
  96   XXXXXX = &template[len - 6 - suffix_len];
  97
  98 #ifdef HAVE_GETTIMEOFDAY
  99   /* Get some more or less random data.  */
 100   gettimeofday (&tv, NULL);
 101   value += ((gcc_uint64_t) tv.tv_usec << 16) ^ tv.tv_sec ^ getpid ();
 102 #else
 103   value += getpid ();
 104 #endif
 105
 106   for (count = 0; count < TMP_MAX; ++count)
 107     {
 108       gcc_uint64_t v = value;
 109       int fd;
 110
 111       /* Fill in the random bits.  */
 112       XXXXXX[0] = letters[v % 62];
 113       v /= 62;
 114       XXXXXX[1] = letters[v % 62];
 115       v /= 62;
 116       XXXXXX[2] = letters[v % 62];
 117       v /= 62;
 118       XXXXXX[3] = letters[v % 62];
 119       v /= 62;
 120       XXXXXX[4] = letters[v % 62];
 121       v /= 62;
 122       XXXXXX[5] = letters[v % 62];
 123
 124 #ifdef VMS
 125       fd = open (template, O_RDWR|O_CREAT|O_EXCL, 0600, "fop=tmd");
 126 #else
 127       fd = open (template, O_RDWR|O_CREAT|O_EXCL|O_BINARY, 0600);
 128 #endif
 129       if (fd >= 0)
 130         /* The file does not exist.  */
 131         return fd;
 132
 133       /* This is a random value.  It is only necessary that the next
 134          TMP_MAX values generated by adding 7777 to VALUE are different
 135          with (module 2^32).  */
 136       value += 7777;
 137     }
 138
 139   /* We return the null string if we can't find a unique file name.  */
 140   template[0] = '\0';
 141   return -1;
 142 }