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/* Borrowed from glibc-2.16/sysdeps/posix/tempname.c */
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <unistd.h>
#include <errno.h>
#include <sys/time.h>
#include <fcntl.h>
#include <sys/types.h>
#include <time.h>
#include <inttypes.h>
/* Copyright (C) 1991-2001, 2006, 2007, 2009 Free Software Foundation, Inc.
This file is part of 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 Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
static const char letters[] =
"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
/* Generate a temporary file name based on TMPL. TMPL must match the
rules for mk[s]temp (i.e. end in "XXXXXX", possibly with a suffix).
*/
int
gf_mkostemp (char *tmpl, int suffixlen, int flags)
{
int len;
char *XXXXXX;
static uint64_t value;
uint64_t random_time_bits;
unsigned int count;
int fd = -1;
/* A lower bound on the number of temporary files to attempt to
generate. The maximum total number of temporary file names that
can exist for a given template is 62**6. It should never be
necessary to try all these combinations. Instead if a reasonable
number of names is tried (we define reasonable as 62**3) fail to
give the system administrator the chance to remove the problems. */
#define ATTEMPTS_MIN (62 * 62 * 62)
/* The number of times to attempt to generate a temporary file. To
conform to POSIX, this must be no smaller than TMP_MAX. */
#if ATTEMPTS_MIN < TMP_MAX
unsigned int attempts = TMP_MAX;
#else
unsigned int attempts = ATTEMPTS_MIN;
#endif
len = strlen (tmpl);
if (len < 6 + suffixlen || memcmp (&tmpl[len - 6 - suffixlen],
"XXXXXX", 6))
return -1;
/* This is where the Xs start. */
XXXXXX = &tmpl[len - 6 - suffixlen];
/* Get some more or less random data. */
# if HAVE_GETTIMEOFDAY
struct timeval tv;
gettimeofday (&tv, NULL);
random_time_bits = ((uint64_t) tv.tv_usec << 16) ^ tv.tv_sec;
# else
random_time_bits = time (NULL);
# endif
value += random_time_bits ^ getpid ();
for (count = 0; count < attempts; value += 7777, ++count) {
uint64_t v = value;
/* 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 (tmpl, (flags & ~O_ACCMODE)
| O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
if (fd >= 0)
return fd;
else if (errno != EEXIST)
return -1;
}
/* We got out of the loop because we ran out of combinations to try. */
return -1;
}
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