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Diffstat (limited to 'sys-utils/flock.c')
| -rw-r--r-- | sys-utils/flock.c | 380 |
1 files changed, 380 insertions, 0 deletions
diff --git a/sys-utils/flock.c b/sys-utils/flock.c new file mode 100644 index 0000000..ed25230 --- /dev/null +++ b/sys-utils/flock.c @@ -0,0 +1,380 @@ +/* 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 sig_atomic_t timeout_expired = 0; + +static void timeout_handler(int sig __attribute__((__unused__)), + siginfo_t *info, + void *context __attribute__((__unused__))) +{ + if (info->si_code == SI_TIMER) + 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[]) +{ + static timer_t t_id; + 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); + atexit(close_stdout); + + 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")); + break; + case OPT_VERBOSE: + verbose = 1; + break; + case 'V': + printf(UTIL_LINUX_VERSION); + exit(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(&t_id, &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(&t_id); + if (verbose) { + struct timeval delta; + + gettime_monotonic(&time_done); + timersub(&time_done, &time_start, &delta); + printf(_("%s: getting lock took %ld.%06ld seconds\n"), + program_invocation_short_name, delta.tv_sec, + 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; +} |