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- #define _GNU_SOURCE
- #include <stdlib.h>
- #include <stdio.h>
- #include <unistd.h>
- #include <fcntl.h>
- #include <limits.h>
- #include <err.h>
- int main(int argc, char *argv[])
- {
- // Just a MB less than LONG_MAX
- size_t size = LONG_MAX - (1024 * 1024);
- int in, pipefd[2], r;
- in = open(argv[1], O_RDONLY);
- if (in < 0)
- err(1, "open");
- r = pipe(pipefd);
- if (r < 0)
- err(1, "pipe");
- r = fork();
- if (r < 0)
- err(1, "fork");
- if (!r) {
- // Discard data from pipe
- char *buffer = malloc(1024 * 1024);
- while (read(pipefd[0], buffer, 1024 * 1024) > 0)
- /* do nothing */ ;
- return 0;
- }
- // splice data from file to pipe
- for (ssize_t copied = 1; copied; ) {
- copied = splice(in, NULL, pipefd[1], NULL, size, 0);
- if (copied < 0) {
- perror("splice");
- // splice() will fail when file pos + size exceeds LONG_MAX
- fprintf(stderr, "Failed to splice %zu bytes at offset %ld\n", size, lseek(in, 0, SEEK_CUR));
- return 1;
- }
- }
- return 0;
- }
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