| 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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