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| 2 | |
| 3 | * Simple poll on a file.
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| 4 | *
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| 5 | * Copyright (c) 2024 Google LLC.
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| 6 |
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| 7 |
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| 8 | #include <errno.h>
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| 9 | #include <fcntl.h>
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| 10 | #include <poll.h>
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| 11 | #include <stdio.h>
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| 12 | #include <stdlib.h>
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| 13 | #include <string.h>
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| 14 | #include <unistd.h>
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| 15 |
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| 16 | #define BUFSIZE 4096
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| 17 |
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| 18 | |
| 19 | * Usage:
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| 20 | * poll [-I|-P] [-t timeout] FILE
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| 21 |
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| 22 | int main(int argc, char *argv[])
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| 23 | {
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| 24 | struct pollfd pfd = {.events = POLLIN};
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| 25 | char buf[BUFSIZE];
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| 26 | int timeout = -1;
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| 27 | int ret, opt;
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| 28 |
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| 29 | while ((opt = getopt(argc, argv, "IPt:")) != -1) {
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| 30 | switch (opt) {
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| 31 | case 'I':
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| 32 | pfd.events = POLLIN;
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| 33 | break;
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| 34 | case 'P':
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| 35 | pfd.events = POLLPRI;
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| 36 | break;
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| 37 | case 't':
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| 38 | timeout = atoi(optarg);
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| 39 | break;
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| 40 | default:
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| 41 | fprintf(stderr, "Usage: %s [-I|-P] [-t timeout] FILE\n",
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| 42 | argv[0]);
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| 43 | return -1;
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| 44 | }
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| 45 | }
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| 46 | if (optind >= argc) {
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| 47 | fprintf(stderr, "Error: Polling file is not specified\n");
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| 48 | return -1;
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| 49 | }
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| 50 |
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| 51 | pfd.fd = open(argv[optind], O_RDONLY);
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| 52 | if (pfd.fd < 0) {
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| 53 | fprintf(stderr, "failed to open %s", argv[optind]);
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| 54 | perror("open");
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| 55 | return -1;
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| 56 | }
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| 57 |
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| 58 |
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| 59 | if (pfd.events & POLLIN)
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| 60 | do {} while (read(pfd.fd, buf, BUFSIZE) == BUFSIZE);
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| 61 |
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| 62 | ret = poll(&pfd, 1, timeout);
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| 63 | if (ret < 0 && errno != EINTR) {
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| 64 | perror("poll");
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| 65 | return -1;
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| 66 | }
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| 67 | close(pfd.fd);
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| 68 |
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| 69 |
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| 70 | if (ret == 0)
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| 71 | return 1;
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| 72 |
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| 73 | return 0;
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| 74 | }
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