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120 lines
2.9 KiB
C
120 lines
2.9 KiB
C
/*
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* Copyright (C) 2010 Timo Teras <timo.teras@iki.fi>
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*
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* This is free software, licensed under the GNU General Public License v2.
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*/
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//config:config FLOCK
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//config: bool "flock (6.5 kb)"
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//config: default y
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//config: help
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//config: Manage locks from shell scripts
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//applet:IF_FLOCK(APPLET(flock, BB_DIR_USR_BIN, BB_SUID_DROP))
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//kbuild:lib-$(CONFIG_FLOCK) += flock.o
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//usage:#define flock_trivial_usage
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//usage: "[-sxun] FD | { FILE [-c] PROG ARGS }"
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//usage:#define flock_full_usage "\n\n"
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//usage: "[Un]lock file descriptor, or lock FILE, run PROG\n"
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//usage: "\n -s Shared lock"
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//usage: "\n -x Exclusive lock (default)"
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//usage: "\n -u Unlock FD"
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//usage: "\n -n Fail rather than wait"
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#include <sys/file.h>
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#include "libbb.h"
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int flock_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int flock_main(int argc UNUSED_PARAM, char **argv)
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{
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int mode, opt, fd;
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enum {
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OPT_s = (1 << 0),
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OPT_x = (1 << 1),
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OPT_n = (1 << 2),
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OPT_u = (1 << 3),
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OPT_c = (1 << 4),
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};
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#if ENABLE_LONG_OPTS
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static const char flock_longopts[] ALIGN1 =
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"shared\0" No_argument "s"
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"exclusive\0" No_argument "x"
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"unlock\0" No_argument "u"
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"nonblock\0" No_argument "n"
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;
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#endif
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opt = getopt32long(argv, "^+" "sxnu" "\0" "-1", flock_longopts);
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argv += optind;
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if (argv[1]) {
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fd = open(argv[0], O_RDONLY|O_NOCTTY|O_CREAT, 0666);
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if (fd < 0 && errno == EISDIR)
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fd = open(argv[0], O_RDONLY|O_NOCTTY);
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if (fd < 0)
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bb_perror_msg_and_die("can't open '%s'", argv[0]);
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//TODO? close_on_exec_on(fd);
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} else {
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fd = xatoi_positive(argv[0]);
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}
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argv++;
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/* If it is "flock FILE -c PROG", then -c isn't caught by getopt32:
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* we use "+" in order to support "flock -opt FILE PROG -with-opts",
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* we need to remove -c by hand.
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*/
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if (argv[0]
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&& argv[0][0] == '-'
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&& ( (argv[0][1] == 'c' && !argv[0][2])
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|| (ENABLE_LONG_OPTS && strcmp(argv[0] + 1, "-command") == 0)
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)
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) {
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argv++;
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if (argv[1])
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bb_simple_error_msg_and_die("-c takes only one argument");
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opt |= OPT_c;
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}
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if (OPT_s == LOCK_SH && OPT_x == LOCK_EX && OPT_n == LOCK_NB && OPT_u == LOCK_UN) {
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/* With suitably matched constants, mode setting is much simpler */
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mode = opt & (LOCK_SH + LOCK_EX + LOCK_NB + LOCK_UN);
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if (!(mode & ~LOCK_NB))
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mode |= LOCK_EX;
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} else {
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if (opt & OPT_u)
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mode = LOCK_UN;
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else if (opt & OPT_s)
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mode = LOCK_SH;
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else
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mode = LOCK_EX;
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if (opt & OPT_n)
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mode |= LOCK_NB;
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}
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if (flock(fd, mode) != 0) {
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if (errno == EWOULDBLOCK)
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return EXIT_FAILURE;
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bb_perror_nomsg_and_die();
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}
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if (argv[0]) {
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int rc;
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if (opt & OPT_c) {
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/* -c 'PROG ARGS' means "run sh -c 'PROG ARGS'" */
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argv -= 2;
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argv[0] = (char*)get_shell_name();
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argv[1] = (char*)"-c";
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/* argv[2] = "PROG ARGS"; */
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/* argv[3] = NULL; */
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}
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rc = spawn_and_wait(argv);
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if (rc < 0)
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bb_simple_perror_msg(argv[0]);
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return rc;
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}
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return EXIT_SUCCESS;
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}
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