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Timo Teras892d4b62010-03-18 22:45:35 +01001/*
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 */
Pere Orga5bc8c002011-04-11 03:29:49 +02006
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"
Pere Orga5bc8c002011-04-11 03:29:49 +020011//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
Timo Teras892d4b62010-03-18 22:45:35 +010016#include <sys/file.h>
17#include "libbb.h"
18
19int flock_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
20int 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
Denys Vlasenkob7c9fb22011-02-03 00:05:48 +010032 static const char getopt_longopts[] ALIGN1 =
Timo Teras892d4b62010-03-18 22:45:35 +010033 "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 {
Denys Vlasenko77832482010-08-12 14:14:45 +020053 fd = xatoi_positive(argv[0]);
Timo Teras892d4b62010-03-18 22:45:35 +010054 }
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}