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/* Rename two files atomically, swapping one for the other.
* Copyright (C) 2015 Peter Wu <peter@lekensteyn.nl>
*/
#define _GNU_SOURCE
#include <unistd.h>
#include <sys/syscall.h>
#include <linux/fs.h> /* for RENAME_* */
#include <fcntl.h> /* for AT_* */
#include <stdio.h>
#include <errno.h>
int renameat2(int olddirfd, const char *oldpath,
int newdirfd, const char *newpath, unsigned int flags)
{
long r;
r = syscall(SYS_renameat2, olddirfd, oldpath, newdirfd, newpath, flags);
return (int)r;
}
int main(int argc, char **argv)
{
int olddirfd, newdirfd;
const char *oldpath, *newpath;
unsigned flags;
int r;
if (argc - 1 < 2) {
fprintf(stderr, "Usage: %s file1 file2\n", argv[0]);
fprintf(stderr, "Atomically swaps file1 and file2.\n");
return 1;
}
olddirfd = AT_FDCWD;
newdirfd = AT_FDCWD;
oldpath = argv[1];
newpath = argv[2];
flags = RENAME_EXCHANGE;
r = renameat2(olddirfd, oldpath, newdirfd, newpath, flags);
if (r < 0) {
if (errno == ENOSYS) {
fprintf(stderr, "renameat2 syscall not available!"
" You need Linux 3.15 or newer.\n");
} else {
perror("renameat2 failed");
}
}
return r < 0 ? 1 : 0;
}
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