Created
December 28, 2017 05:22
-
-
Save oraoto/d76ebf699ed1cb86faae02bc6246ff0e to your computer and use it in GitHub Desktop.
Romove BOM wih copy_file_range
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
#define _GNU_SOURCE | |
#include <fcntl.h> | |
#include <stdio.h> | |
#include <stdlib.h> | |
#include <sys/stat.h> | |
#include <sys/syscall.h> | |
#include <unistd.h> | |
static loff_t | |
copy_file_range(int fd_in, loff_t *off_in, int fd_out, | |
loff_t *off_out, size_t len, unsigned int flags) | |
{ | |
return syscall(__NR_copy_file_range, fd_in, off_in, fd_out, | |
off_out, len, flags); | |
} | |
int | |
main(int argc, char **argv) | |
{ | |
int fd_in, fd_out; | |
struct stat stat; | |
loff_t len, ret; | |
if (argc != 2) { | |
fprintf(stderr, "Usage: %s <file>\n", argv[0]); | |
exit(EXIT_FAILURE); | |
} | |
fd_in = open(argv[1], O_RDONLY); | |
if (fd_in == -1) { | |
perror("open (argv[1])"); | |
exit(EXIT_FAILURE); | |
} | |
if (fstat(fd_in, &stat) == -1) { | |
perror("fstat"); | |
exit(EXIT_FAILURE); | |
} | |
len = stat.st_size; | |
lseek(fd_in, 3, SEEK_SET); | |
char template[] = ".XXXXXX"; | |
char * temp_file = mktemp(template); | |
fd_out = open(temp_file, O_CREAT | O_WRONLY | O_TRUNC, 0644); | |
if (fd_out == -1) { | |
perror("open (argv[2])"); | |
exit(EXIT_FAILURE); | |
} | |
do { | |
ret = copy_file_range(fd_in, NULL, fd_out, NULL, len, 0); | |
if (ret == -1) { | |
perror("copy_file_range"); | |
exit(EXIT_FAILURE); | |
} | |
len -= ret; | |
} while (len > 3); | |
close(fd_in); | |
close(fd_out); | |
rename(temp_file, argv[1]); | |
exit(EXIT_SUCCESS); | |
} |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment