150 lines
3.7 KiB
C
150 lines
3.7 KiB
C
/* Copyright (C) 1991-2020 Free Software Foundation, Inc.
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This file is derived from mkstemp.c from 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., 51 Franklin Street - Fifth Floor,
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Boston, MA 02110-1301, USA. */
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include <sys/types.h>
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#ifdef HAVE_STDLIB_H
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#include <stdlib.h>
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#endif
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#ifdef HAVE_STRING_H
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#include <string.h>
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#endif
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#include <errno.h>
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#include <stdio.h>
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#include <fcntl.h>
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#ifdef HAVE_UNISTD_H
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#include <unistd.h>
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#endif
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#ifdef HAVE_SYS_TIME_H
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#include <sys/time.h>
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#elif HAVE_TIME_H
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#include <time.h>
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#endif
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#include "ansidecl.h"
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/* We need to provide a type for gcc_uint64_t. */
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#ifdef __GNUC__
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__extension__ typedef unsigned long long gcc_uint64_t;
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#else
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typedef unsigned long gcc_uint64_t;
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#endif
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#ifndef TMP_MAX
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#define TMP_MAX 16384
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#endif
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#ifndef O_BINARY
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# define O_BINARY 0
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#endif
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/*
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@deftypefn Replacement int mkstemps (char *@var{pattern}, int @var{suffix_len})
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Generate a unique temporary file name from @var{pattern}.
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@var{pattern} has the form:
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@example
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@var{path}/ccXXXXXX@var{suffix}
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@end example
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@var{suffix_len} tells us how long @var{suffix} is (it can be zero
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length). The last six characters of @var{pattern} before @var{suffix}
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must be @samp{XXXXXX}; they are replaced with a string that makes the
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filename unique. Returns a file descriptor open on the file for
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reading and writing.
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@end deftypefn
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*/
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int
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mkstemps (char *pattern, int suffix_len)
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{
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static const char letters[]
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= "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
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static gcc_uint64_t value;
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#ifdef HAVE_GETTIMEOFDAY
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struct timeval tv;
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#endif
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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 (pattern);
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if ((int) len < 6 + suffix_len
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|| strncmp (&pattern[len - 6 - suffix_len], "XXXXXX", 6))
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{
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return -1;
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}
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XXXXXX = &pattern[len - 6 - suffix_len];
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#ifdef HAVE_GETTIMEOFDAY
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/* Get some more or less random data. */
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gettimeofday (&tv, NULL);
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value += ((gcc_uint64_t) tv.tv_usec << 16) ^ tv.tv_sec ^ getpid ();
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#else
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value += getpid ();
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#endif
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for (count = 0; count < TMP_MAX; ++count)
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{
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gcc_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 (pattern, O_BINARY|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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if (errno != EEXIST
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#ifdef EISDIR
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&& errno != EISDIR
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#endif
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)
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/* Fatal error (EPERM, ENOSPC etc). Doesn't make sense to loop. */
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break;
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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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pattern[0] = '\0';
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return -1;
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}
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