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-rw-r--r--sys-utils/flock.c385
1 files changed, 385 insertions, 0 deletions
diff --git a/sys-utils/flock.c b/sys-utils/flock.c
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--- /dev/null
+++ b/sys-utils/flock.c
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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 <ctype.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <getopt.h>
+#include <paths.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sysexits.h>
+#include <sys/file.h>
+#include <sys/stat.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#include "c.h"
+#include "nls.h"
+#include "strutils.h"
+#include "closestream.h"
+#include "monotonic.h"
+#include "timer.h"
+
+static void __attribute__((__noreturn__)) usage(void)
+{
+ fputs(USAGE_HEADER, stdout);
+ printf(
+ _(" %1$s [options] <file>|<directory> <command> [<argument>...]\n"
+ " %1$s [options] <file>|<directory> -c <command>\n"
+ " %1$s [options] <file descriptor number>\n"),
+ program_invocation_short_name);
+
+ fputs(USAGE_SEPARATOR, stdout);
+ fputs(_("Manage file locks from shell scripts.\n"), stdout);
+
+ fputs(USAGE_OPTIONS, stdout);
+ fputs(_( " -s, --shared get a shared lock\n"), stdout);
+ fputs(_( " -x, --exclusive get an exclusive lock (default)\n"), stdout);
+ fputs(_( " -u, --unlock remove a lock\n"), stdout);
+ fputs(_( " -n, --nonblock fail rather than wait\n"), stdout);
+ fputs(_( " -w, --timeout <secs> wait for a limited amount of time\n"), stdout);
+ fputs(_( " -E, --conflict-exit-code <number> exit code after conflict or timeout\n"), stdout);
+ fputs(_( " -o, --close close file descriptor before running command\n"), stdout);
+ fputs(_( " -c, --command <command> run a single command string through the shell\n"), stdout);
+ fputs(_( " -F, --no-fork execute command without forking\n"), stdout);
+ fputs(_( " --verbose increase verbosity\n"), stdout);
+ fputs(USAGE_SEPARATOR, stdout);
+ printf(USAGE_HELP_OPTIONS(26));
+ printf(USAGE_MAN_TAIL("flock(1)"));
+ exit(EXIT_SUCCESS);
+}
+
+static volatile sig_atomic_t timeout_expired = 0;
+
+static void timeout_handler(int sig __attribute__((__unused__)),
+ siginfo_t *info,
+ void *context __attribute__((__unused__)))
+{
+#ifdef HAVE_TIMER_CREATE
+ if (info->si_code == SI_TIMER)
+#endif
+ timeout_expired = 1;
+}
+
+static int open_file(const char *filename, int *flags)
+{
+
+ int fd;
+ int fl = *flags == 0 ? O_RDONLY : *flags;
+
+ errno = 0;
+ fl |= O_NOCTTY | O_CREAT;
+ fd = open(filename, fl, 0666);
+
+ /* Linux doesn't like O_CREAT on a directory, even though it
+ * should be a no-op; POSIX doesn't allow O_RDWR or O_WRONLY
+ */
+ if (fd < 0 && errno == EISDIR) {
+ fl = O_RDONLY | O_NOCTTY;
+ fd = open(filename, fl);
+ }
+ if (fd < 0) {
+ warn(_("cannot open lock file %s"), filename);
+ if (errno == ENOMEM || errno == EMFILE || errno == ENFILE)
+ exit(EX_OSERR);
+ if (errno == EROFS || errno == ENOSPC)
+ exit(EX_CANTCREAT);
+ exit(EX_NOINPUT);
+ }
+ *flags = fl;
+ return fd;
+}
+
+static void __attribute__((__noreturn__)) run_program(char **cmd_argv)
+{
+ execvp(cmd_argv[0], cmd_argv);
+
+ warn(_("failed to execute %s"), cmd_argv[0]);
+ _exit((errno == ENOMEM) ? EX_OSERR : EX_UNAVAILABLE);
+}
+
+int main(int argc, char *argv[])
+{
+ struct ul_timer timer;
+ struct itimerval timeout;
+ int have_timeout = 0;
+ int type = LOCK_EX;
+ int block = 0;
+ int open_flags = 0;
+ int fd = -1;
+ int opt, ix;
+ int do_close = 0;
+ int no_fork = 0;
+ int status;
+ int verbose = 0;
+ struct timeval time_start, time_done;
+ /*
+ * The default exit code for lock conflict or timeout
+ * is specified in man flock.1
+ */
+ int conflict_exit_code = 1;
+ char **cmd_argv = NULL, *sh_c_argv[4];
+ const char *filename = NULL;
+ enum {
+ OPT_VERBOSE = CHAR_MAX + 1
+ };
+ static const struct option long_options[] = {
+ {"shared", no_argument, NULL, 's'},
+ {"exclusive", no_argument, NULL, 'x'},
+ {"unlock", no_argument, NULL, 'u'},
+ {"nonblocking", no_argument, NULL, 'n'},
+ {"nb", no_argument, NULL, 'n'},
+ {"timeout", required_argument, NULL, 'w'},
+ {"wait", required_argument, NULL, 'w'},
+ {"conflict-exit-code", required_argument, NULL, 'E'},
+ {"close", no_argument, NULL, 'o'},
+ {"no-fork", no_argument, NULL, 'F'},
+ {"verbose", no_argument, NULL, OPT_VERBOSE},
+ {"help", no_argument, NULL, 'h'},
+ {"version", no_argument, NULL, 'V'},
+ {NULL, 0, NULL, 0}
+ };
+
+ setlocale(LC_ALL, "");
+ bindtextdomain(PACKAGE, LOCALEDIR);
+ textdomain(PACKAGE);
+ close_stdout_atexit();
+
+ strutils_set_exitcode(EX_USAGE);
+
+ if (argc < 2) {
+ warnx(_("not enough arguments"));
+ errtryhelp(EX_USAGE);
+ }
+
+ memset(&timeout, 0, sizeof timeout);
+
+ optopt = 0;
+ while ((opt =
+ getopt_long(argc, argv, "+sexnoFuw:E: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 'F':
+ no_fork = 1;
+ break;
+ case 'n':
+ block = LOCK_NB;
+ break;
+ case 'w':
+ have_timeout = 1;
+ strtotimeval_or_err(optarg, &timeout.it_value,
+ _("invalid timeout value"));
+ break;
+ case 'E':
+ conflict_exit_code = strtos32_or_err(optarg,
+ _("invalid exit code"));
+ if (conflict_exit_code < 0 || conflict_exit_code > 255)
+ errx(EX_USAGE, _("exit code out of range (expected 0 to 255)"));
+ break;
+ case OPT_VERBOSE:
+ verbose = 1;
+ break;
+
+ case 'V':
+ print_version(EX_OK);
+ case 'h':
+ usage();
+ default:
+ errtryhelp(EX_USAGE);
+ }
+ }
+
+ if (no_fork && do_close)
+ errx(EX_USAGE,
+ _("the --no-fork and --close options are incompatible"));
+
+ if (argc > optind + 1) {
+ /* Run command */
+ if (!strcmp(argv[optind + 1], "-c") ||
+ !strcmp(argv[optind + 1], "--command")) {
+ if (argc != optind + 3)
+ errx(EX_USAGE,
+ _("%s requires exactly one command argument"),
+ argv[optind + 1]);
+ 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] = NULL;
+ } else {
+ cmd_argv = &argv[optind + 1];
+ }
+
+ filename = argv[optind];
+ fd = open_file(filename, &open_flags);
+
+ } else if (optind < argc) {
+ /* Use provided file descriptor */
+ fd = strtos32_or_err(argv[optind], _("bad file descriptor"));
+ } else {
+ /* Bad options */
+ errx(EX_USAGE, _("requires file descriptor, file or directory"));
+ }
+
+ 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
+ if (setup_timer(&timer, &timeout, &timeout_handler))
+ err(EX_OSERR, _("cannot set up timer"));
+ }
+
+ if (verbose)
+ gettime_monotonic(&time_start);
+ while (flock(fd, type | block)) {
+ switch (errno) {
+ case EWOULDBLOCK:
+ /* -n option set and failed to lock. */
+ if (verbose)
+ warnx(_("failed to get lock"));
+ exit(conflict_exit_code);
+ case EINTR:
+ /* Signal received */
+ if (timeout_expired) {
+ /* -w option set and failed to lock. */
+ if (verbose)
+ warnx(_("timeout while waiting to get lock"));
+ exit(conflict_exit_code);
+ }
+ /* otherwise try again */
+ continue;
+ case EIO:
+ 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_file(filename, &open_flags);
+
+ if (open_flags & O_RDWR)
+ break;
+ }
+ /* fallthrough */
+ default:
+ /* Other errors */
+ if (filename)
+ warn("%s", filename);
+ else
+ warn("%d", fd);
+ exit((errno == ENOLCK
+ || errno == ENOMEM) ? EX_OSERR : EX_DATAERR);
+ }
+ }
+
+ if (have_timeout)
+ cancel_timer(&timer);
+ if (verbose) {
+ struct timeval delta;
+
+ gettime_monotonic(&time_done);
+ timersub(&time_done, &time_start, &delta);
+ printf(_("%s: getting lock took %"PRId64".%06"PRId64" seconds\n"),
+ program_invocation_short_name,
+ (int64_t) delta.tv_sec,
+ (int64_t) delta.tv_usec);
+ }
+ status = EX_OK;
+
+ if (cmd_argv) {
+ pid_t w, f;
+ /* Clear any inherited settings */
+ signal(SIGCHLD, SIG_DFL);
+ if (verbose)
+ printf(_("%s: executing %s\n"), program_invocation_short_name, cmd_argv[0]);
+
+ if (!no_fork) {
+ f = fork();
+ if (f < 0)
+ err(EX_OSERR, _("fork failed"));
+
+ /* child */
+ else if (f == 0) {
+ if (do_close)
+ close(fd);
+ run_program(cmd_argv);
+
+ /* parent */
+ } else {
+ do {
+ w = waitpid(f, &status, 0);
+ if (w == -1 && errno != EINTR)
+ break;
+ } while (w != f);
+
+ if (w == -1) {
+ status = EXIT_FAILURE;
+ warn(_("waitpid failed"));
+ } else if (WIFEXITED(status))
+ status = WEXITSTATUS(status);
+ else if (WIFSIGNALED(status))
+ status = WTERMSIG(status) + 128;
+ else
+ /* WTF? */
+ status = EX_OSERR;
+ }
+
+ } else
+ /* no-fork execution */
+ run_program(cmd_argv);
+ }
+
+ return status;
+}
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