OpenWrt – Rev 4
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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;
}