1 // SPDX-License-Identifier: GPL-2.0
2 #define _GNU_SOURCE
3 #include <errno.h>
4 #include <fcntl.h>
5 #include <limits.h>
6 #include <stdio.h>
7 #include <stdlib.h>
8 #include <unistd.h>
9 #include <sys/types.h>
10 #include <sys/stat.h>
11 
12 int main(int argc, char *argv[])
13 {
14 	int fd;
15 	size_t size;
16 	ssize_t spliced;
17 
18 	if (argc < 2) {
19 		fprintf(stderr, "Usage: %s INPUT [BYTES]\n", argv[0]);
20 		return EXIT_FAILURE;
21 	}
22 
23 	fd = open(argv[1], O_RDONLY);
24 	if (fd < 0) {
25 		perror(argv[1]);
26 		return EXIT_FAILURE;
27 	}
28 
29 	if (argc == 3)
30 		size = atol(argv[2]);
31 	else {
32 		struct stat statbuf;
33 
34 		if (fstat(fd, &statbuf) < 0) {
35 			perror(argv[1]);
36 			return EXIT_FAILURE;
37 		}
38 
39 		if (statbuf.st_size > INT_MAX) {
40 			fprintf(stderr, "%s: Too big\n", argv[1]);
41 			return EXIT_FAILURE;
42 		}
43 
44 		size = statbuf.st_size;
45 	}
46 
47 	/* splice(2) file to stdout. */
48 	spliced = splice(fd, NULL, STDOUT_FILENO, NULL,
49 		      size, SPLICE_F_MOVE);
50 	if (spliced < 0) {
51 		perror("splice");
52 		return EXIT_FAILURE;
53 	}
54 
55 	close(fd);
56 	return EXIT_SUCCESS;
57 }
58