1 /* ----------------------------------------------------------------------- *
3 * Copyright 2003-2005 H. Peter Anvin - All Rights Reserved
5 * Permission is hereby granted, free of charge, to any person
6 * obtaining a copy of this software and associated documentation
7 * files (the "Software"), to deal in the Software without
8 * restriction, including without limitation the rights to use,
9 * copy, modify, merge, publish, distribute, sublicense, and/or
10 * sell copies of the Software, and to permit persons to whom
11 * the Software is furnished to do so, subject to the following
14 * The above copyright notice and this permission notice shall
15 * be included in all copies or substantial portions of the Software.
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
18 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
19 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
20 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
21 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
22 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
23 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
24 * OTHER DEALINGS IN THE SOFTWARE.
26 * ----------------------------------------------------------------------- */
38 #include <sys/types.h>
44 #define PACKAGE_STRING "util-linux-ng 2.18"
47 static const struct option long_options
[] = {
48 { "shared", 0, NULL
, 's' },
49 { "exclusive", 0, NULL
, 'x' },
50 { "unlock", 0, NULL
, 'u' },
51 { "nonblocking", 0, NULL
, 'n' },
52 { "nb", 0, NULL
, 'n' },
53 { "timeout", 1, NULL
, 'w' },
54 { "wait", 1, NULL
, 'w' },
55 { "close", 0, NULL
, 'o' },
56 { "help", 0, NULL
, 'h' },
57 { "version", 0, NULL
, 'V' },
63 static void usage(int ex
)
65 fputs("flock (" PACKAGE_STRING
")\n", stderr
);
67 _("Usage: %1$s [-sxun][-w #] fd#\n"
68 " %1$s [-sxon][-w #] file [-c] command...\n"
69 " %1$s [-sxon][-w #] directory [-c] command...\n"
70 " -s --shared Get a shared lock\n"
71 " -x --exclusive Get an exclusive lock\n"
72 " -u --unlock Remove a lock\n"
73 " -n --nonblock Fail rather than wait\n"
74 " -w --timeout Wait for a limited amount of time\n"
75 " -o --close Close file descriptor before running command\n"
76 " -c --command Run a single command string through the shell\n"
77 " -h --help Display this text\n"
78 " -V --version Display version\n"),
84 static sig_atomic_t timeout_expired
= 0;
86 static void timeout_handler(int sig
)
94 static char * strtotimeval(const char *str
, struct timeval
*tv
)
97 long fs
; /* Fractional seconds */
100 tv
->tv_sec
= strtol(str
, &s
, 10);
106 for ( i
= 0 ; i
< 6 ; i
++ ) {
117 while ( isdigit(*s
) )
125 int main(int argc
, char *argv
[])
127 struct itimerval timeout
, old_timer
;
128 int have_timeout
= 0;
138 char **cmd_argv
= NULL
, *sh_c_argv
[4];
139 const char *filename
= NULL
;
140 struct sigaction sa
, old_sa
;
147 memset(&timeout
, 0, sizeof timeout
);
150 while ( (opt
= getopt_long(argc
, argv
, "+sexnouw:hV?", long_options
, &ix
)) != EOF
) {
170 eon
= strtotimeval(optarg
, &timeout
.it_value
);
175 printf("flock (%s)\n", PACKAGE_STRING
);
178 /* optopt will be set if this was an unrecognized option, i.e. *not* 'h' or '?' */
179 usage(optopt
? EX_USAGE
: 0);
184 if ( argc
> optind
+1 ) {
187 if ( !strcmp(argv
[optind
+1], "-c") ||
188 !strcmp(argv
[optind
+1], "--command") ) {
190 if ( argc
!= optind
+3 ) {
191 fprintf(stderr
, _("%s: %s requires exactly one command argument\n"),
192 program
, argv
[optind
+1]);
196 cmd_argv
= sh_c_argv
;
198 cmd_argv
[0] = getenv("SHELL");
199 if ( !cmd_argv
[0] || !*cmd_argv
[0] )
200 cmd_argv
[0] = _PATH_BSHELL
;
203 cmd_argv
[2] = argv
[optind
+2];
206 cmd_argv
= &argv
[optind
+1];
209 filename
= argv
[optind
];
210 fd
= open(filename
, O_RDONLY
|O_NOCTTY
|O_CREAT
, 0666);
211 /* Linux doesn't like O_CREAT on a directory, even though it should be a
213 if (fd
< 0 && errno
== EISDIR
)
214 fd
= open(filename
, O_RDONLY
|O_NOCTTY
);
218 fprintf(stderr
, _("%s: cannot open lock file %s: %s\n"),
219 program
, argv
[optind
], strerror(err
));
220 exit((err
== ENOMEM
||err
== EMFILE
||err
== ENFILE
) ? EX_OSERR
:
221 (err
== EROFS
||err
== ENOSPC
) ? EX_CANTCREAT
:
225 } else if (optind
< argc
) {
226 /* Use provided file descriptor */
228 fd
= (int)strtol(argv
[optind
], &eon
, 10);
229 if ( *eon
|| !argv
[optind
] ) {
230 fprintf(stderr
, _("%s: bad number: %s\n"), program
, argv
[optind
]);
237 fprintf(stderr
, _("%s: requires file descriptor, file or directory\n"),
243 if ( have_timeout
) {
244 if ( timeout
.it_value
.tv_sec
== 0 &&
245 timeout
.it_value
.tv_usec
== 0 ) {
246 /* -w 0 is equivalent to -n; this has to be special-cased
247 because setting an itimer to zero means disabled! */
252 memset(&sa
, 0, sizeof sa
);
254 sa
.sa_handler
= timeout_handler
;
255 sa
.sa_flags
= SA_RESETHAND
;
256 sigaction(SIGALRM
, &sa
, &old_sa
);
258 setitimer(ITIMER_REAL
, &timeout
, &old_timer
);
262 while ( flock(fd
, type
|block
) ) {
263 switch( (err
= errno
) ) {
264 case EWOULDBLOCK
: /* -n option set and failed to lock */
266 case EINTR
: /* Signal received */
267 if ( timeout_expired
)
268 exit(1); /* -w option set and failed to lock */
269 continue; /* otherwise try again */
270 case EBADF
: /* since Linux 3.4 (commit 55725513) */
271 /* Probably NFSv4 where flock() is emulated by fcntl().
272 * Let's try to reopen in read-write mode.
274 if (!(open_flags
& O_RDWR
) &&
277 access(filename
, R_OK
| W_OK
) == 0) {
281 fd
= open(filename
, open_flags
);
285 default: /* Other errors */
287 fprintf(stderr
, "%s: %s: %s\n", program
, filename
, strerror(err
));
289 fprintf(stderr
, "%s: %d: %s\n", program
, fd
, strerror(err
));
290 exit((err
== ENOLCK
||err
== ENOMEM
) ? EX_OSERR
: EX_DATAERR
);
294 if ( have_timeout
) {
295 setitimer(ITIMER_REAL
, &old_timer
, NULL
); /* Cancel itimer */
296 sigaction(SIGALRM
, &old_sa
, NULL
); /* Cancel signal handler */
304 /* Clear any inherited settings */
305 signal(SIGCHLD
, SIG_DFL
);
310 fprintf(stderr
, _("%s: fork failed: %s\n"), program
, strerror(err
));
312 } else if ( f
== 0 ) {
316 execvp(cmd_argv
[0], cmd_argv
);
317 /* execvp() failed */
318 fprintf(stderr
, "%s: %s: %s\n", program
, cmd_argv
[0], strerror(err
));
319 _exit((err
== ENOMEM
) ? EX_OSERR
: EX_UNAVAILABLE
);
322 w
= waitpid(f
, &status
, 0);
323 if (w
== -1 && errno
!= EINTR
)
329 status
= EXIT_FAILURE
;
330 fprintf(stderr
, "%s: waitpid failed: %s\n", program
, strerror(err
));
331 } else if ( WIFEXITED(status
) )
332 status
= WEXITSTATUS(status
);
333 else if ( WIFSIGNALED(status
) )
334 status
= WTERMSIG(status
) + 128;
336 status
= EX_OSERR
; /* WTF? */