blob: 05a747f724b678a0bc6cfeca032f4f42ad4b2783
1 | /* |
2 | * Copyright (C) 2010 Timo Teras <timo.teras@iki.fi> |
3 | * |
4 | * This is free software, licensed under the GNU General Public License v2. |
5 | */ |
6 | |
7 | //usage:#define flock_trivial_usage |
8 | //usage: "[-sxun] FD|{FILE [-c] PROG ARGS}" |
9 | //usage:#define flock_full_usage "\n\n" |
10 | //usage: "[Un]lock file descriptor, or lock FILE, run PROG\n" |
11 | //usage: "\n -s Shared lock" |
12 | //usage: "\n -x Exclusive lock (default)" |
13 | //usage: "\n -u Unlock FD" |
14 | //usage: "\n -n Fail rather than wait" |
15 | |
16 | #include <sys/file.h> |
17 | #include "libbb.h" |
18 | |
19 | int flock_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
20 | int flock_main(int argc UNUSED_PARAM, char **argv) |
21 | { |
22 | int mode, opt, fd; |
23 | enum { |
24 | OPT_s = (1 << 0), |
25 | OPT_x = (1 << 1), |
26 | OPT_n = (1 << 2), |
27 | OPT_u = (1 << 3), |
28 | OPT_c = (1 << 4), |
29 | }; |
30 | |
31 | #if ENABLE_LONG_OPTS |
32 | static const char getopt_longopts[] ALIGN1 = |
33 | "shared\0" No_argument "s" |
34 | "exclusive\0" No_argument "x" |
35 | "unlock\0" No_argument "u" |
36 | "nonblock\0" No_argument "n" |
37 | ; |
38 | applet_long_options = getopt_longopts; |
39 | #endif |
40 | opt_complementary = "-1"; |
41 | |
42 | opt = getopt32(argv, "+sxnu"); |
43 | argv += optind; |
44 | |
45 | if (argv[1]) { |
46 | fd = open(argv[0], O_RDONLY|O_NOCTTY|O_CREAT, 0666); |
47 | if (fd < 0 && errno == EISDIR) |
48 | fd = open(argv[0], O_RDONLY|O_NOCTTY); |
49 | if (fd < 0) |
50 | bb_perror_msg_and_die("can't open '%s'", argv[0]); |
51 | //TODO? close_on_exec_on(fd); |
52 | } else { |
53 | fd = xatoi_positive(argv[0]); |
54 | } |
55 | argv++; |
56 | |
57 | /* If it is "flock FILE -c PROG", then -c isn't caught by getopt32: |
58 | * we use "+" in order to support "flock -opt FILE PROG -with-opts", |
59 | * we need to remove -c by hand. |
60 | * TODO: in upstream, -c 'PROG ARGS' means "run sh -c 'PROG ARGS'" |
61 | */ |
62 | if (argv[0] |
63 | && argv[0][0] == '-' |
64 | && ( (argv[0][1] == 'c' && !argv[0][2]) |
65 | || (ENABLE_LONG_OPTS && strcmp(argv[0] + 1, "-command") == 0) |
66 | ) |
67 | ) { |
68 | argv++; |
69 | } |
70 | |
71 | if (OPT_s == LOCK_SH && OPT_x == LOCK_EX && OPT_n == LOCK_NB && OPT_u == LOCK_UN) { |
72 | /* With suitably matched constants, mode setting is much simpler */ |
73 | mode = opt & (LOCK_SH + LOCK_EX + LOCK_NB + LOCK_UN); |
74 | if (!(mode & ~LOCK_NB)) |
75 | mode |= LOCK_EX; |
76 | } else { |
77 | if (opt & OPT_u) |
78 | mode = LOCK_UN; |
79 | else if (opt & OPT_s) |
80 | mode = LOCK_SH; |
81 | else |
82 | mode = LOCK_EX; |
83 | if (opt & OPT_n) |
84 | mode |= LOCK_NB; |
85 | } |
86 | |
87 | if (flock(fd, mode) != 0) { |
88 | if (errno == EWOULDBLOCK) |
89 | return EXIT_FAILURE; |
90 | bb_perror_nomsg_and_die(); |
91 | } |
92 | |
93 | if (argv[0]) |
94 | return spawn_and_wait(argv); |
95 | |
96 | return EXIT_SUCCESS; |
97 | } |
98 |