1117395Skan/* ----------------------------------------------------------------------- *
2132718Skan *
3117395Skan *   Copyright 2003-2005 H. Peter Anvin - All Rights Reserved
4117395Skan *
5132718Skan *   Permission is hereby granted, free of charge, to any person
6117395Skan *   obtaining a copy of this software and associated documentation
7132718Skan *   files (the "Software"), to deal in the Software without
8132718Skan *   restriction, including without limitation the rights to use,
9132718Skan *   copy, modify, merge, publish, distribute, sublicense, and/or
10132718Skan *   sell copies of the Software, and to permit persons to whom
11117395Skan *   the Software is furnished to do so, subject to the following
12132718Skan *   conditions:
13132718Skan *
14132718Skan *   The above copyright notice and this permission notice shall
15132718Skan *   be included in all copies or substantial portions of the Software.
16117395Skan *
17132718Skan *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
18132718Skan *   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
19169689Skan *   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
20169689Skan *   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
21117395Skan *   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
22132718Skan *   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
23117395Skan *   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
24117395Skan *   OTHER DEALINGS IN THE SOFTWARE.
25132718Skan *
26117395Skan * ----------------------------------------------------------------------- */
27117395Skan
28132718Skan#include <errno.h>
29117395Skan#include <stdio.h>
30117395Skan#include <stdlib.h>
31132718Skan#include <unistd.h>
32117395Skan#include <getopt.h>
33117395Skan#include <signal.h>
34117395Skan#include <ctype.h>
35117395Skan#include <string.h>
36117395Skan#include <paths.h>
37117395Skan#include <sysexits.h>
38117395Skan#include <sys/types.h>
39117395Skan#include <sys/file.h>
40132718Skan#include <sys/time.h>
41117395Skan#include <sys/wait.h>
42117395Skan#include <fcntl.h>
43132718Skan
44117395Skan#define PACKAGE_STRING "util-linux-ng 2.18"
45117395Skan#define _(x) (x)
46132718Skan
47117395Skanstatic 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' },
58  { 0, 0, 0, 0 }
59};
60
61const char *program;
62
63static void usage(int ex)
64{
65  fputs("flock (" PACKAGE_STRING ")\n", stderr);
66  fprintf(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"),
79	  program);
80  exit(ex);
81}
82
83
84static sig_atomic_t timeout_expired = 0;
85
86static void timeout_handler(int sig)
87{
88  (void)sig;
89
90  timeout_expired = 1;
91}
92
93
94static char * strtotimeval(const char *str, struct timeval *tv)
95{
96  char *s;
97  long fs;			/* Fractional seconds */
98  int i;
99
100  tv->tv_sec = strtol(str, &s, 10);
101  fs = 0;
102
103  if ( *s == '.' ) {
104    s++;
105
106    for ( i = 0 ; i < 6 ; i++ ) {
107      if ( !isdigit(*s) )
108	break;
109
110      fs *= 10;
111      fs += *s++ - '0';
112    }
113
114    for ( ; i < 6; i++ )
115      fs *= 10;
116
117    while ( isdigit(*s) )
118      s++;
119  }
120
121  tv->tv_usec = fs;
122  return s;
123}
124
125int main(int argc, char *argv[])
126{
127  struct itimerval timeout, old_timer;
128  int have_timeout = 0;
129  int type = LOCK_EX;
130  int block = 0;
131  int fd = -1;
132  int opt, ix;
133  int do_close = 0;
134  int err;
135  int status;
136  char *eon;
137  char **cmd_argv = NULL, *sh_c_argv[4];
138  const char *filename = NULL;
139  struct sigaction sa, old_sa;
140
141  program = argv[0];
142
143  if ( argc < 2 )
144    usage(EX_USAGE);
145
146  memset(&timeout, 0, sizeof timeout);
147
148  optopt = 0;
149  while ( (opt = getopt_long(argc, argv, "+sexnouw:hV?", long_options, &ix)) != EOF ) {
150    switch(opt) {
151    case 's':
152      type = LOCK_SH;
153      break;
154    case 'e':
155    case 'x':
156      type = LOCK_EX;
157      break;
158    case 'u':
159      type = LOCK_UN;
160      break;
161    case 'o':
162      do_close = 1;
163      break;
164    case 'n':
165      block = LOCK_NB;
166      break;
167    case 'w':
168      have_timeout = 1;
169      eon = strtotimeval(optarg, &timeout.it_value);
170      if ( *eon )
171	usage(EX_USAGE);
172      break;
173    case 'V':
174      printf("flock (%s)\n", PACKAGE_STRING);
175      exit(0);
176    default:
177      /* optopt will be set if this was an unrecognized option, i.e. *not* 'h' or '?' */
178      usage(optopt ? EX_USAGE : 0);
179      break;
180    }
181  }
182
183  if ( argc > optind+1 ) {
184    /* Run command */
185
186    if ( !strcmp(argv[optind+1], "-c") ||
187	 !strcmp(argv[optind+1], "--command") ) {
188
189      if ( argc != optind+3 ) {
190	fprintf(stderr, _("%s: %s requires exactly one command argument\n"),
191		program, argv[optind+1]);
192	exit(EX_USAGE);
193      }
194
195      cmd_argv = sh_c_argv;
196
197      cmd_argv[0] = getenv("SHELL");
198      if ( !cmd_argv[0] || !*cmd_argv[0] )
199	cmd_argv[0] = _PATH_BSHELL;
200
201      cmd_argv[1] = "-c";
202      cmd_argv[2] = argv[optind+2];
203      cmd_argv[3] = 0;
204    } else {
205      cmd_argv = &argv[optind+1];
206    }
207
208    filename = argv[optind];
209    fd = open(filename, O_RDONLY|O_NOCTTY|O_CREAT, 0666);
210    /* Linux doesn't like O_CREAT on a directory, even though it should be a
211       no-op */
212    if (fd < 0 && errno == EISDIR)
213        fd = open(filename, O_RDONLY|O_NOCTTY);
214
215    if ( fd < 0 ) {
216      err = errno;
217      fprintf(stderr, _("%s: cannot open lock file %s: %s\n"),
218	      program, argv[optind], strerror(err));
219      exit((err == ENOMEM||err == EMFILE||err == ENFILE) ? EX_OSERR :
220	   (err == EROFS||err == ENOSPC) ? EX_CANTCREAT :
221	   EX_NOINPUT);
222    }
223
224  } else if (optind < argc) {
225    /* Use provided file descriptor */
226
227    fd = (int)strtol(argv[optind], &eon, 10);
228    if ( *eon || !argv[optind] ) {
229      fprintf(stderr, _("%s: bad number: %s\n"), program, argv[optind]);
230      exit(EX_USAGE);
231    }
232
233  } else {
234    /* Bad options */
235
236    fprintf(stderr, _("%s: requires file descriptor, file or directory\n"),
237		program);
238    exit(EX_USAGE);
239  }
240
241
242  if ( have_timeout ) {
243    if ( timeout.it_value.tv_sec == 0 &&
244	 timeout.it_value.tv_usec == 0 ) {
245      /* -w 0 is equivalent to -n; this has to be special-cased
246	 because setting an itimer to zero means disabled! */
247
248      have_timeout = 0;
249      block = LOCK_NB;
250    } else {
251      memset(&sa, 0, sizeof sa);
252
253      sa.sa_handler = timeout_handler;
254      sa.sa_flags   = SA_RESETHAND;
255      sigaction(SIGALRM, &sa, &old_sa);
256
257      setitimer(ITIMER_REAL, &timeout, &old_timer);
258    }
259  }
260
261  while ( flock(fd, type|block) ) {
262    switch( (err = errno) ) {
263    case EWOULDBLOCK:		/* -n option set and failed to lock */
264      exit(1);
265    case EINTR:			/* Signal received */
266      if ( timeout_expired )
267	exit(1);		/* -w option set and failed to lock */
268      continue;			/* otherwise try again */
269    default:			/* Other errors */
270      if ( filename )
271	fprintf(stderr, "%s: %s: %s\n", program, filename, strerror(err));
272      else
273	fprintf(stderr, "%s: %d: %s\n", program, fd, strerror(err));
274      exit((err == ENOLCK||err == ENOMEM) ? EX_OSERR : EX_DATAERR);
275    }
276  }
277
278  if ( have_timeout ) {
279    setitimer(ITIMER_REAL, &old_timer, NULL); /* Cancel itimer */
280    sigaction(SIGALRM, &old_sa, NULL); /* Cancel signal handler */
281  }
282
283  status = 0;
284
285  if ( cmd_argv ) {
286    pid_t w, f;
287
288    /* Clear any inherited settings */
289    signal(SIGCHLD, SIG_DFL);
290    f = fork();
291
292    if ( f < 0 ) {
293      err = errno;
294      fprintf(stderr, _("%s: fork failed: %s\n"), program, strerror(err));
295      exit(EX_OSERR);
296    } else if ( f == 0 ) {
297      if ( do_close )
298	close(fd);
299      err = errno;
300      execvp(cmd_argv[0], cmd_argv);
301      /* execvp() failed */
302      fprintf(stderr, "%s: %s: %s\n", program, cmd_argv[0], strerror(err));
303      _exit((err == ENOMEM) ? EX_OSERR: EX_UNAVAILABLE);
304    } else {
305      do {
306	w = waitpid(f, &status, 0);
307	if (w == -1 && errno != EINTR)
308	  break;
309      } while ( w != f );
310
311      if (w == -1) {
312	err = errno;
313	status = EXIT_FAILURE;
314	fprintf(stderr, "%s: waitpid failed: %s\n", program, strerror(err));
315      } else if ( WIFEXITED(status) )
316	status = WEXITSTATUS(status);
317      else if ( WIFSIGNALED(status) )
318	status = WTERMSIG(status) + 128;
319      else
320	status = EX_OSERR;	/* WTF? */
321    }
322  }
323
324  return status;
325}
326
327