/* * 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 (6.1 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 getopt_longopts[] ALIGN1 = "shared\0" No_argument "s" "exclusive\0" No_argument "x" "unlock\0" No_argument "u" "nonblock\0" No_argument "n" ; applet_long_options = getopt_longopts; #endif opt_complementary = "-1"; opt = getopt32(argv, "+sxnu"); 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_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; }