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