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/* Copyright (C) 1991, 1992, 1996, 1998, 2004 Free Software Foundation, Inc.

   This file is derived from mkstemp.c from the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Library General Public License as

   published by the Free Software Foundation; either version 2 of the

   License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public

   License along with the GNU C Library; see the file COPYING.LIB.  If not,

   write to the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor,

   Boston, MA 02110-1301, USA.  */

#ifdef HAVE_CONFIG_H

#include "config.h"

#endif

#include <sys/types.h>

#ifdef HAVE_STDLIB_H

#include <stdlib.h>

#endif

#ifdef HAVE_STRING_H

#include <string.h>

#endif

#include <errno.h>

#include <stdio.h>

#include <fcntl.h>

#ifdef HAVE_UNISTD_H

#include <unistd.h>

#endif

#ifdef HAVE_SYS_TIME_H

#include <sys/time.h>

#endif

#include "ansidecl.h"

/* We need to provide a type for gcc_uint64_t.  */

#ifdef __GNUC__

__extension__ typedef unsigned long long gcc_uint64_t;

#else

typedef unsigned long gcc_uint64_t;

#endif

#ifndef TMP_MAX

#define TMP_MAX 16384

#endif

#ifndef O_BINARY

# define O_BINARY 0

#endif

/*

@deftypefn Replacement int mkstemps (char *@var{pattern}, int @var{suffix_len})

Generate a unique temporary file name from @var{pattern}.

@var{pattern} has the form:

@example

   @var{path}/ccXXXXXX@var{suffix}

@end example

@var{suffix_len} tells us how long @var{suffix} is (it can be zero

length).  The last six characters of @var{pattern} before @var{suffix}

must be @samp{XXXXXX}; they are replaced with a string that makes the

filename unique.  Returns a file descriptor open on the file for

reading and writing.

@end deftypefn

*/

int

mkstemps (char *pattern, int suffix_len)

{

  static const char letters[]

    = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";

  static gcc_uint64_t value;

#ifdef HAVE_GETTIMEOFDAY

  struct timeval tv;

#endif

  char *XXXXXX;

  size_t len;

  int count;

  len = strlen (pattern);

  if ((int) len < 6 + suffix_len

      || strncmp (&pattern[len - 6 - suffix_len], "XXXXXX", 6))

    {

      return -1;

    }

  XXXXXX = &pattern[len - 6 - suffix_len];

#ifdef HAVE_GETTIMEOFDAY

  /* Get some more or less random data.  */

  gettimeofday (&tv, NULL);

  value += ((gcc_uint64_t) tv.tv_usec << 16) ^ tv.tv_sec ^ getpid ();

#else

  value += getpid ();

#endif

  for (count = 0; count < TMP_MAX; ++count)

    {

      gcc_uint64_t v = value;

      int fd;

      /* Fill in the random bits.  */

      XXXXXX[0] = letters[v % 62];

      v /= 62;

      XXXXXX[1] = letters[v % 62];

      v /= 62;

      XXXXXX[2] = letters[v % 62];

      v /= 62;

      XXXXXX[3] = letters[v % 62];

      v /= 62;

      XXXXXX[4] = letters[v % 62];

      v /= 62;

      XXXXXX[5] = letters[v % 62];

      fd = open (pattern, O_BINARY|O_RDWR|O_CREAT|O_EXCL, 0600);

      if (fd >= 0)

        /* The file does not exist.  */

        return fd;

      if (errno != EEXIST

#ifdef EISDIR

          && errno != EISDIR

#endif

         )

        /* Fatal error (EPERM, ENOSPC etc).  Doesn't make sense to loop.  */

        break;

      /* This is a random value.  It is only necessary that the next

         TMP_MAX values generated by adding 7777 to VALUE are different

         with (module 2^32).  */

      value += 7777;

    }

  /* We return the null string if we can't find a unique file name.  */

  pattern[0] = '\0';

  return -1;

}