umka/tools/mkfilepattern.c

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