91 lines
2.7 KiB
C
91 lines
2.7 KiB
C
/* Copyright (C) 1991, 1992, 1996, 1998 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If not,
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write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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#include <stdlib.h>
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#include <string.h>
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#include <errno.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <sys/time.h>
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/* Generate a unique temporary file name from TEMPLATE.
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The last six characters of TEMPLATE must be "XXXXXX";
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they are replaced with a string that makes the filename unique.
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Returns a file descriptor open on the file for reading and writing. */
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int
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mkstemp (template)
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char *template;
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{
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static const char letters[62]
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= "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
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static uint64_t value;
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struct timeval tv;
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char *XXXXXX;
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size_t len;
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int count;
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len = strlen (template);
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if (len < 6 || strcmp (&template[len - 6], "XXXXXX"))
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{
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__set_errno (EINVAL);
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return -1;
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}
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/* This is where the Xs start. */
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XXXXXX = &template[len - 6];
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/* Get some more or less random data. */
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__gettimeofday (&tv, NULL);
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value += ((uint64_t) tv.tv_usec << 16) ^ tv.tv_sec ^ __getpid ();
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for (count = 0; count < TMP_MAX; ++count)
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{
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uint64_t v = value;
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int fd;
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/* Fill in the random bits. */
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XXXXXX[0] = letters[v % 62];
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v /= 62;
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XXXXXX[1] = letters[v % 62];
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v /= 62;
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XXXXXX[2] = letters[v % 62];
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v /= 62;
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XXXXXX[3] = letters[v % 62];
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v /= 62;
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XXXXXX[4] = letters[v % 62];
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v /= 62;
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XXXXXX[5] = letters[v % 62];
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fd = __open (template, O_RDWR|O_CREAT|O_EXCL, 0600);
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if (fd >= 0)
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/* The file does not exist. */
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return fd;
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/* This is a random value. It is only necessary that the next
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TMP_MAX values generated by adding 7777 to VALUE are different
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with (module 2^32). */
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value += 7777;
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}
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/* We return the null string if we can't find a unique file name. */
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template[0] = '\0';
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return -1;
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}
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