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- /* ----------------------------------------------------------------------- *
- *
- * Copyright 2003-2005 H. Peter Anvin - All Rights Reserved
- *
- * Permission is hereby granted, free of charge, to any person
- * obtaining a copy of this software and associated documentation
- * files (the "Software"), to deal in the Software without
- * restriction, including without limitation the rights to use,
- * copy, modify, merge, publish, distribute, sublicense, and/or
- * sell copies of the Software, and to permit persons to whom
- * the Software is furnished to do so, subject to the following
- * conditions:
- *
- * The above copyright notice and this permission notice shall
- * be included in all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
- * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
- * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
- * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
- * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
- * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
- * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
- * OTHER DEALINGS IN THE SOFTWARE.
- *
- * ----------------------------------------------------------------------- */
- #include <errno.h>
- #include <stdio.h>
- #include <stdlib.h>
- #include <unistd.h>
- #include <getopt.h>
- #include <signal.h>
- #include <ctype.h>
- #include <string.h>
- #include <paths.h>
- #include <sysexits.h>
- #include <sys/types.h>
- #include <sys/file.h>
- #include <sys/time.h>
- #include <sys/wait.h>
- #include <fcntl.h>
- #define PACKAGE_STRING "util-linux-ng 2.18"
- #define _(x) (x)
- static const struct option long_options[] = {
- { "shared", 0, NULL, 's' },
- { "exclusive", 0, NULL, 'x' },
- { "unlock", 0, NULL, 'u' },
- { "nonblocking", 0, NULL, 'n' },
- { "nb", 0, NULL, 'n' },
- { "timeout", 1, NULL, 'w' },
- { "wait", 1, NULL, 'w' },
- { "close", 0, NULL, 'o' },
- { "help", 0, NULL, 'h' },
- { "version", 0, NULL, 'V' },
- { 0, 0, 0, 0 }
- };
- const char *program;
- static void usage(int ex)
- {
- fputs("flock (" PACKAGE_STRING ")\n", stderr);
- fprintf(stderr,
- _("Usage: %1$s [-sxun][-w #] fd#\n"
- " %1$s [-sxon][-w #] file [-c] command...\n"
- " %1$s [-sxon][-w #] directory [-c] command...\n"
- " -s --shared Get a shared lock\n"
- " -x --exclusive Get an exclusive lock\n"
- " -u --unlock Remove a lock\n"
- " -n --nonblock Fail rather than wait\n"
- " -w --timeout Wait for a limited amount of time\n"
- " -o --close Close file descriptor before running command\n"
- " -c --command Run a single command string through the shell\n"
- " -h --help Display this text\n"
- " -V --version Display version\n"),
- program);
- exit(ex);
- }
- static sig_atomic_t timeout_expired = 0;
- static void timeout_handler(int sig)
- {
- (void)sig;
- timeout_expired = 1;
- }
- static char * strtotimeval(const char *str, struct timeval *tv)
- {
- char *s;
- long fs; /* Fractional seconds */
- int i;
- tv->tv_sec = strtol(str, &s, 10);
- fs = 0;
- if ( *s == '.' ) {
- s++;
- for ( i = 0 ; i < 6 ; i++ ) {
- if ( !isdigit(*s) )
- break;
- fs *= 10;
- fs += *s++ - '0';
- }
- for ( ; i < 6; i++ )
- fs *= 10;
- while ( isdigit(*s) )
- s++;
- }
- tv->tv_usec = fs;
- return s;
- }
- int main(int argc, char *argv[])
- {
- struct itimerval timeout, old_timer;
- int have_timeout = 0;
- int type = LOCK_EX;
- int block = 0;
- int fd = -1;
- int opt, ix;
- int do_close = 0;
- int err;
- int status;
- int open_flags = 0;
- char *eon;
- char **cmd_argv = NULL, *sh_c_argv[4];
- const char *filename = NULL;
- struct sigaction sa, old_sa;
- program = argv[0];
- if ( argc < 2 )
- usage(EX_USAGE);
- memset(&timeout, 0, sizeof timeout);
- optopt = 0;
- while ( (opt = getopt_long(argc, argv, "+sexnouw:hV?", long_options, &ix)) != EOF ) {
- switch(opt) {
- case 's':
- type = LOCK_SH;
- break;
- case 'e':
- case 'x':
- type = LOCK_EX;
- break;
- case 'u':
- type = LOCK_UN;
- break;
- case 'o':
- do_close = 1;
- break;
- case 'n':
- block = LOCK_NB;
- break;
- case 'w':
- have_timeout = 1;
- eon = strtotimeval(optarg, &timeout.it_value);
- if ( *eon )
- usage(EX_USAGE);
- break;
- case 'V':
- printf("flock (%s)\n", PACKAGE_STRING);
- exit(0);
- default:
- /* optopt will be set if this was an unrecognized option, i.e. *not* 'h' or '?' */
- usage(optopt ? EX_USAGE : 0);
- break;
- }
- }
- if ( argc > optind+1 ) {
- /* Run command */
- if ( !strcmp(argv[optind+1], "-c") ||
- !strcmp(argv[optind+1], "--command") ) {
- if ( argc != optind+3 ) {
- fprintf(stderr, _("%s: %s requires exactly one command argument\n"),
- program, argv[optind+1]);
- exit(EX_USAGE);
- }
- cmd_argv = sh_c_argv;
- cmd_argv[0] = getenv("SHELL");
- if ( !cmd_argv[0] || !*cmd_argv[0] )
- cmd_argv[0] = _PATH_BSHELL;
- cmd_argv[1] = "-c";
- cmd_argv[2] = argv[optind+2];
- cmd_argv[3] = 0;
- } else {
- cmd_argv = &argv[optind+1];
- }
- filename = argv[optind];
- fd = open(filename, O_RDONLY|O_NOCTTY|O_CREAT, 0666);
- /* Linux doesn't like O_CREAT on a directory, even though it should be a
- no-op */
- if (fd < 0 && errno == EISDIR)
- fd = open(filename, O_RDONLY|O_NOCTTY);
- if ( fd < 0 ) {
- err = errno;
- fprintf(stderr, _("%s: cannot open lock file %s: %s\n"),
- program, argv[optind], strerror(err));
- exit((err == ENOMEM||err == EMFILE||err == ENFILE) ? EX_OSERR :
- (err == EROFS||err == ENOSPC) ? EX_CANTCREAT :
- EX_NOINPUT);
- }
- } else if (optind < argc) {
- /* Use provided file descriptor */
- fd = (int)strtol(argv[optind], &eon, 10);
- if ( *eon || !argv[optind] ) {
- fprintf(stderr, _("%s: bad number: %s\n"), program, argv[optind]);
- exit(EX_USAGE);
- }
- } else {
- /* Bad options */
- fprintf(stderr, _("%s: requires file descriptor, file or directory\n"),
- program);
- exit(EX_USAGE);
- }
- if ( have_timeout ) {
- if ( timeout.it_value.tv_sec == 0 &&
- timeout.it_value.tv_usec == 0 ) {
- /* -w 0 is equivalent to -n; this has to be special-cased
- because setting an itimer to zero means disabled! */
- have_timeout = 0;
- block = LOCK_NB;
- } else {
- memset(&sa, 0, sizeof sa);
- sa.sa_handler = timeout_handler;
- sa.sa_flags = SA_RESETHAND;
- sigaction(SIGALRM, &sa, &old_sa);
- setitimer(ITIMER_REAL, &timeout, &old_timer);
- }
- }
- while ( flock(fd, type|block) ) {
- switch( (err = errno) ) {
- case EWOULDBLOCK: /* -n option set and failed to lock */
- exit(1);
- case EINTR: /* Signal received */
- if ( timeout_expired )
- exit(1); /* -w option set and failed to lock */
- continue; /* otherwise try again */
- case EBADF: /* since Linux 3.4 (commit 55725513) */
- /* Probably NFSv4 where flock() is emulated by fcntl().
- * Let's try to reopen in read-write mode.
- */
- if (!(open_flags & O_RDWR) &&
- type != LOCK_SH &&
- filename &&
- access(filename, R_OK | W_OK) == 0) {
- close(fd);
- open_flags = O_RDWR;
- fd = open(filename, open_flags);
- break;
- }
- /* go through */
- default: /* Other errors */
- if ( filename )
- fprintf(stderr, "%s: %s: %s\n", program, filename, strerror(err));
- else
- fprintf(stderr, "%s: %d: %s\n", program, fd, strerror(err));
- exit((err == ENOLCK||err == ENOMEM) ? EX_OSERR : EX_DATAERR);
- }
- }
- if ( have_timeout ) {
- setitimer(ITIMER_REAL, &old_timer, NULL); /* Cancel itimer */
- sigaction(SIGALRM, &old_sa, NULL); /* Cancel signal handler */
- }
- status = 0;
- if ( cmd_argv ) {
- pid_t w, f;
- /* Clear any inherited settings */
- signal(SIGCHLD, SIG_DFL);
- f = fork();
- if ( f < 0 ) {
- err = errno;
- fprintf(stderr, _("%s: fork failed: %s\n"), program, strerror(err));
- exit(EX_OSERR);
- } else if ( f == 0 ) {
- if ( do_close )
- close(fd);
- err = errno;
- execvp(cmd_argv[0], cmd_argv);
- /* execvp() failed */
- fprintf(stderr, "%s: %s: %s\n", program, cmd_argv[0], strerror(err));
- _exit((err == ENOMEM) ? EX_OSERR: EX_UNAVAILABLE);
- } else {
- do {
- w = waitpid(f, &status, 0);
- if (w == -1 && errno != EINTR)
- break;
- } while ( w != f );
- if (w == -1) {
- err = errno;
- status = EXIT_FAILURE;
- fprintf(stderr, "%s: waitpid failed: %s\n", program, strerror(err));
- } else if ( WIFEXITED(status) )
- status = WEXITSTATUS(status);
- else if ( WIFSIGNALED(status) )
- status = WTERMSIG(status) + 128;
- else
- status = EX_OSERR; /* WTF? */
- }
- }
- return status;
- }
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