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/* Copyright (c) 2018, Curtis McEnroe <programble@gmail.com>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <err.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sysexits.h>
#include <unistd.h>
static const uint8_t SIGNATURE[] = { 0x89, 'P', 'N', 'G', '\r', '\n', 0x1A, '\n' };
static const uint8_t IEND[] = { 'I', 'E', 'N', 'D' };
static unsigned counter;
static char path[FILENAME_MAX];
static int fd;
static void next(const char *prefix) {
if (counter++) {
int error = close(fd);
if (error) err(EX_IOERR, "%s", path);
}
snprintf(path, sizeof(path), "%s%04u.png", prefix, counter);
fd = open(path, O_WRONLY | O_CREAT | O_EXCL, 0644);
if (fd < 0) err(EX_CANTCREAT, "%s", path);
printf("%s\n", path);
}
static void writeAll(const uint8_t *buf, size_t size) {
while (size) {
ssize_t writeSize = write(fd, buf, size);
if (writeSize < 0) err(EX_IOERR, "%s", path);
buf += writeSize;
size -= writeSize;
}
}
int main(int argc, char *argv[]) {
const char *prefix = (argc > 1) ? argv[1] : "";
for (;;) {
uint8_t buf[4096];
ssize_t size = read(STDIN_FILENO, buf, sizeof(buf));
if (size < 0) err(EX_IOERR, "read");
if (!size) return EX_OK;
const uint8_t *signature = memmem(buf, size, SIGNATURE, sizeof(SIGNATURE));
if (signature) {
writeAll(buf, signature - buf);
next(prefix);
writeAll(signature, size - (signature - buf));
} else {
const uint8_t *iend = memmem(buf, size, IEND, sizeof(IEND));
if (iend && iend - buf < size - 8) {
warnx("trailing data, a PNG may be skipped");
}
writeAll(buf, size);
}
}
}
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