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New file, slightly modified from libiberties

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mkstemps.c.
This commit is contained in:
Marius Vollmer 2001-06-02 12:39:09 +00:00
parent 26446f9907
commit 23cc59681b
1 changed files with 123 additions and 0 deletions
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libguile/mkstemp.c Normal file
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/* Copyright (C) 1991, 1992, 1996, 1998 Free Software Foundation, Inc.
This file is derived from mkstemps.c from the GNU Libiberty Library
which in turn is derived 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., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
#include "scmconfig.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
/* We need to provide a type for gcc_uint64_t. */
#ifdef __GNUC__
typedef unsigned long long gcc_uint64_t;
#else
typedef unsigned long gcc_uint64_t;
#endif
#ifndef TMP_MAX
#define TMP_MAX 16384
#endif
/* Generate a unique temporary file name from TEMPLATE.
TEMPLATE has the form:
<path>/ccXXXXXX
The last six characters of TEMPLATE must be "XXXXXX"; they are
replaced with a string that makes the filename unique.
Returns a file descriptor open on the file for reading and writing. */
int
mkstemp (template)
char *template;
{
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 (template);
if ((int) len < 6
|| strncmp (&template[len - 6], "XXXXXX", 6))
{
return -1;
}
XXXXXX = &template[len - 6];
#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 (template, O_RDWR|O_CREAT|O_EXCL, 0600);
if (fd >= 0)
/* The file does not exist. */
return fd;
/* 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. */
template[0] = '\0';
return -1;
}