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- #include <stdlib.h>
- #include <stdio.h>
- #include <fcntl.h>
- #include <unistd.h>
-
- #include "common.h"
-
- /* Sends the contents of `fname` to `device`, expecting every sent byte to be
- * echoed back verbatim. Compare every echoed byte with the one sent and bail
- * out if a mismatch is detected. When the whole file is sent, push a null char
- * to indicate EOF to the receiving end.
- *
- * It is recommended that you send contents that has gone through `ttysafe`.
- */
- int main(int argc, char **argv)
- {
- if (argc != 3) {
- fprintf(stderr, "Usage: ./pingpong device fname\n");
- return 1;
- }
- FILE *fp = fopen(argv[2], "r");
- if (!fp) {
- fprintf(stderr, "Can't open %s.\n", argv[2]);
- return 1;
- }
- int fd = open(argv[1], O_RDWR|O_NOCTTY|O_NONBLOCK);
- printf("Press a key...\n");
- getchar();
- unsigned char c;
- // empty the recv buffer
- while (read(fd, &c, 1) == 1) usleep(1000);
- int returncode = 0;
- while (fread(&c, 1, 1, fp)) {
- putchar('.');
- fflush(stdout);
- write(fd, &c, 1);
- usleep(1000); // let it breathe
- unsigned char c2;
- while (read(fd, &c2, 1) != 1); // read echo
- if (c != c2) {
- // mismatch!
- unsigned int pos = ftell(fp);
- fprintf(stderr, "Mismatch at byte %d! %d != %d.\n", pos, c, c2);
- returncode = 1;
- break;
- }
- }
- // To close the receiving loop on the other side, we send a straight null
- c = 0;
- write(fd, &c, 1);
- printf("Done!\n");
- fclose(fp);
- return returncode;
- }
-
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