63 lines
1.5 KiB
C
63 lines
1.5 KiB
C
#include <stdio.h>
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#include <stdint.h>
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#include <inttypes.h>
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#include <stdlib.h>
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#include <stddef.h>
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#include <unistd.h>
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#include <errno.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <string.h>
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#define BUF_LEN 0x10
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int main(int argc, char *argv[])
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{
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uint8_t buf[BUF_LEN + 7];
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int64_t len;
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char *path;
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if (argc != 3) {
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fprintf(stderr, "mkfilepattern filename size\n");
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exit(1);
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} else {
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path = argv[1];
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sscanf(argv[2], "%" SCNi64, &len);
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}
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int fd = open(path, O_CREAT | O_WRONLY, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
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if (fd == -1) {
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fprintf(stderr, "Can't open %s: %s\n", path, strerror(errno));
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exit(1);
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}
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for (int64_t pos = 0, count = BUF_LEN; pos < len; pos += count) {
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if (count > len - pos) {
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count = len - pos;
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}
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off_t off = 0;
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while (off < count) {
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if (pos + off < 0x100) {
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*(uint8_t*)(buf + off) = (uint8_t)(pos + off);
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off += 1;
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} else if (pos + off < 0x10000) {
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*(uint16_t*)(buf + off) = (uint16_t)(pos + off);
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off += 2;
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} else if (pos + off < 0x100000000l) {
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*(uint32_t*)(buf + off) = (uint32_t)(pos + off);
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off += 4;
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} else {
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*(uint64_t*)(buf + off) = (uint64_t)(pos + off);
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off += 8;
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}
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}
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write(fd, buf, count);
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}
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close(fd);
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return 0;
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}
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