sortix-mirror/libc/stdlib/mkostemps.c

65 lines
1.9 KiB
C

/*
* Copyright (c) 2013, 2014, 2015 Jonas 'Sortie' Termansen.
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
* stdlib/mkostemps.c
* Make a unique temporary file path and open it.
*/
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
static const uint32_t NUM_CHARACTERS = 10 + 26 + 26;
static inline char random_character(void)
{
uint32_t index = arc4random_uniform(NUM_CHARACTERS);
if ( index < 10 )
return '0' + index;
if ( index < 10 + 26 )
return 'a' + index - 10;
if ( index < 10 + 26 + 26 )
return 'A' + index - (10 + 26);
__builtin_unreachable();
}
int mkostemps(char* templ, int suffixlen, int flags)
{
size_t templ_length = strlen(templ);
if ( templ_length < 6 ||
suffixlen < 0 ||
templ_length - 6 < (size_t) suffixlen )
return errno = EINVAL, -1;
size_t xpos = templ_length - (6 + suffixlen);
for ( size_t i = 0; i < 6; i++ )
if ( templ[xpos + i] != 'X' )
return errno = EINVAL, -1;
flags &= ~O_ACCMODE;
do
{
for ( size_t i = 0; i < 6; i++ )
templ[xpos + i] = random_character();
int fd = open(templ, flags | O_RDWR | O_EXCL | O_CREAT, 0600);
if ( 0 <= fd )
return fd;
} while ( errno == EEXIST );
memcpy(templ + xpos, "XXXXXX", 6);
return -1;
}