1 | /*
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2 | * Copyright (C) 2010 Timo Teras <timo.teras@iki.fi>
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3 | *
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4 | * This is free software, licensed under the GNU General Public License v2.
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5 | */
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6 |
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7 | //usage:#define flock_trivial_usage
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8 | //usage: "[-sxun] FD|{FILE [-c] PROG ARGS}"
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9 | //usage:#define flock_full_usage "\n\n"
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10 | //usage: "[Un]lock file descriptor, or lock FILE, run PROG\n"
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11 | //usage: "\n -s Shared lock"
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12 | //usage: "\n -x Exclusive lock (default)"
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13 | //usage: "\n -u Unlock FD"
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14 | //usage: "\n -n Fail rather than wait"
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15 |
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16 | #include <sys/file.h>
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17 | #include "libbb.h"
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18 |
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19 | int flock_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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20 | int flock_main(int argc UNUSED_PARAM, char **argv)
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21 | {
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22 | int mode, opt, fd;
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23 | enum {
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24 | OPT_s = (1 << 0),
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25 | OPT_x = (1 << 1),
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26 | OPT_n = (1 << 2),
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27 | OPT_u = (1 << 3),
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28 | OPT_c = (1 << 4),
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29 | };
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30 |
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31 | #if ENABLE_LONG_OPTS
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32 | static const char getopt_longopts[] ALIGN1 =
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33 | "shared\0" No_argument "s"
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34 | "exclusive\0" No_argument "x"
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35 | "unlock\0" No_argument "u"
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36 | "nonblock\0" No_argument "n"
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37 | ;
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38 | applet_long_options = getopt_longopts;
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39 | #endif
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40 | opt_complementary = "-1";
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41 |
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42 | opt = getopt32(argv, "+sxnu");
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43 | argv += optind;
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44 |
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45 | if (argv[1]) {
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46 | fd = open(argv[0], O_RDONLY|O_NOCTTY|O_CREAT, 0666);
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47 | if (fd < 0 && errno == EISDIR)
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48 | fd = open(argv[0], O_RDONLY|O_NOCTTY);
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49 | if (fd < 0)
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50 | bb_perror_msg_and_die("can't open '%s'", argv[0]);
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51 | //TODO? close_on_exec_on(fd);
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52 | } else {
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53 | fd = xatoi_positive(argv[0]);
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54 | }
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55 | argv++;
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56 |
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57 | /* If it is "flock FILE -c PROG", then -c isn't caught by getopt32:
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58 | * we use "+" in order to support "flock -opt FILE PROG -with-opts",
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59 | * we need to remove -c by hand.
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60 | * TODO: in upstream, -c 'PROG ARGS' means "run sh -c 'PROG ARGS'"
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61 | */
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62 | if (argv[0]
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63 | && argv[0][0] == '-'
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64 | && ( (argv[0][1] == 'c' && !argv[0][2])
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65 | || (ENABLE_LONG_OPTS && strcmp(argv[0] + 1, "-command") == 0)
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66 | )
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67 | ) {
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68 | argv++;
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69 | }
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70 |
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71 | if (OPT_s == LOCK_SH && OPT_x == LOCK_EX && OPT_n == LOCK_NB && OPT_u == LOCK_UN) {
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72 | /* With suitably matched constants, mode setting is much simpler */
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73 | mode = opt & (LOCK_SH + LOCK_EX + LOCK_NB + LOCK_UN);
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74 | if (!(mode & ~LOCK_NB))
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75 | mode |= LOCK_EX;
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76 | } else {
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77 | if (opt & OPT_u)
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78 | mode = LOCK_UN;
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79 | else if (opt & OPT_s)
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80 | mode = LOCK_SH;
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81 | else
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82 | mode = LOCK_EX;
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83 | if (opt & OPT_n)
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84 | mode |= LOCK_NB;
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85 | }
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86 |
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87 | if (flock(fd, mode) != 0) {
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88 | if (errno == EWOULDBLOCK)
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89 | return EXIT_FAILURE;
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90 | bb_perror_nomsg_and_die();
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91 | }
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92 |
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93 | if (argv[0])
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94 | return spawn_and_wait(argv);
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95 |
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96 | return EXIT_SUCCESS;
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97 | }
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