mirror of
https://github.com/darlinghq/darling-removefile.git
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120 lines
3.3 KiB
C
120 lines
3.3 KiB
C
/* srm */
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/* Copyright (c) 2000 Matthew D. Gauthier
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* Portions copyright (c) 2007 Apple Inc. All rights reserved.
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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* IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
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* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
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* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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* OTHER DEALINGS IN THE SOFTWARE.
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*
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* Except as contained in this notice, the name of the contributors shall
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* not be used in advertising or otherwise to promote the sale, use or
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* other dealings in this Software without prior written authorization.
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*/
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#include <fcntl.h>
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#include <stdlib.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <sys/time.h>
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#include <unistd.h>
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#include "removefile.h"
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#include "removefile_priv.h"
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static void
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seed_random(removefile_state_t state) {
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#ifdef USE_ARC4RANDOM
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arc4random_stir();
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#else
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unsigned int rseed;
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struct timeval tv;
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struct timezone tz;
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if (state->urand_file != -1) {
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read(state->urand_file, &rseed, sizeof(rseed));
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} else {
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rseed = rand();
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}
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(void)gettimeofday(&tv, &tz);
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rseed ^= tv.tv_sec + tv.tv_usec + getpid();
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srand(rseed);
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#endif
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}
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void
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__removefile_init_random(const unsigned int seed, removefile_state_t state) {
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#ifdef USE_ARC4RANDOM
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arc4random_addrandom((unsigned char *)&seed, sizeof(seed));
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#else
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struct stat statbuf;
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if (stat("/dev/urandom", &statbuf) == 0 && S_ISCHR(statbuf.st_mode)) {
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state->urand_file = open("/dev/urandom", O_RDONLY);
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} else {
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srand(seed);
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}
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seed_random(state);
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#endif
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}
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char
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__removefile_random_char(removefile_state_t state) {
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#ifdef USE_ARC4RANDOM
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random_bytes_read += 4;
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return arc4random();
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#else
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char buf[4];
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if (state->urand_file != -1) {
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read(state->urand_file, &buf, 1);
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return buf[0];
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}
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return rand();
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#endif
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}
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void
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__removefile_randomize_buffer(unsigned char *buffer, size_t length, removefile_state_t state) {
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size_t i;
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#ifdef USE_ARC4RANDOM
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u_int32_t *p = (u_int32_t *)buffer;
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u_int32_t mod4length = length - (length % 4);
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for (i = 0; i < mod4length; i += 4) {
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*p++ = arc4random();
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}
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while (i < length) {
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buffer[i++] = arc4random();
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}
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state->random_bytes_read += (mod4length + ((length - mod4length) * 4));
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if (state->random_bytes_read > 512*1024*1024 /* RESEED_BYTES */) {
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state->random_bytes_read = 0;
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seed_random(state);
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}
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#else
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if (state->urand_file != -1) {
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read(state->urand_file, buffer, length);
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} else {
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for (i = 0; i < length; i++)
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buffer[i] = rand();
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}
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#endif
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}
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