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