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/*
* Copyright (C) 2010 Timo Teras <timo.teras@iki.fi>
*
* This is free software, licensed under the GNU General Public License v2.
*/
//config:config FLOCK
//config: bool "flock (6.3 kb)"
//config: default y
//config: help
//config: Manage locks from shell scripts
//applet:IF_FLOCK(APPLET(flock, BB_DIR_USR_BIN, BB_SUID_DROP))
//kbuild:lib-$(CONFIG_FLOCK) += flock.o
//usage:#define flock_trivial_usage
//usage: "[-sxun] FD | { FILE [-c] PROG ARGS }"
//usage:#define flock_full_usage "\n\n"
//usage: "[Un]lock file descriptor, or lock FILE, run PROG\n"
//usage: "\n -s Shared lock"
//usage: "\n -x Exclusive lock (default)"
//usage: "\n -u Unlock FD"
//usage: "\n -n Fail rather than wait"
#include <sys/file.h>
#include "libbb.h"
int flock_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int flock_main(int argc UNUSED_PARAM, char **argv)
{
int mode, opt, fd;
enum {
OPT_s = (1 << 0),
OPT_x = (1 << 1),
OPT_n = (1 << 2),
OPT_u = (1 << 3),
OPT_c = (1 << 4),
};
#if ENABLE_LONG_OPTS
static const char flock_longopts[] ALIGN1 =
"shared\0" No_argument "s"
"exclusive\0" No_argument "x"
"unlock\0" No_argument "u"
"nonblock\0" No_argument "n"
;
#endif
opt = getopt32long(argv, "^+" "sxnu" "\0" "-1", flock_longopts);
argv += optind;
if (argv[1]) {
fd = open(argv[0], O_RDONLY|O_NOCTTY|O_CREAT, 0666);
if (fd < 0 && errno == EISDIR)
fd = open(argv[0], O_RDONLY|O_NOCTTY);
if (fd < 0)
bb_perror_msg_and_die("can't open '%s'", argv[0]);
//TODO? close_on_exec_on(fd);
} else {
fd = xatoi_positive(argv[0]);
}
argv++;
/* If it is "flock FILE -c PROG", then -c isn't caught by getopt32:
* we use "+" in order to support "flock -opt FILE PROG -with-opts",
* we need to remove -c by hand.
*/
if (argv[0]
&& argv[0][0] == '-'
&& ( (argv[0][1] == 'c' && !argv[0][2])
|| (ENABLE_LONG_OPTS && strcmp(argv[0] + 1, "-command") == 0)
)
) {
argv++;
if (argv[1])
bb_simple_error_msg_and_die("-c takes only one argument");
opt |= OPT_c;
}
if (OPT_s == LOCK_SH && OPT_x == LOCK_EX && OPT_n == LOCK_NB && OPT_u == LOCK_UN) {
/* With suitably matched constants, mode setting is much simpler */
mode = opt & (LOCK_SH + LOCK_EX + LOCK_NB + LOCK_UN);
if (!(mode & ~LOCK_NB))
mode |= LOCK_EX;
} else {
if (opt & OPT_u)
mode = LOCK_UN;
else if (opt & OPT_s)
mode = LOCK_SH;
else
mode = LOCK_EX;
if (opt & OPT_n)
mode |= LOCK_NB;
}
if (flock(fd, mode) != 0) {
if (errno == EWOULDBLOCK)
return EXIT_FAILURE;
bb_perror_nomsg_and_die();
}
if (argv[0]) {
int rc;
if (opt & OPT_c) {
/* -c 'PROG ARGS' means "run sh -c 'PROG ARGS'" */
argv -= 2;
argv[0] = (char*)get_shell_name();
argv[1] = (char*)"-c";
/* argv[2] = "PROG ARGS"; */
/* argv[3] = NULL; */
}
rc = spawn_and_wait(argv);
if (rc < 0)
bb_simple_perror_msg(argv[0]);
return rc;
}
return EXIT_SUCCESS;
}
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