src/journal/cat.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2012 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU Lesser General Public License as published by
  10   the Free Software Foundation; either version 2.1 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   Lesser General Public License for more details.
  17
  18   You should have received a copy of the GNU Lesser General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <errno.h>
  23 #include <fcntl.h>
  24 #include <getopt.h>
  25 #include <stdio.h>
  26 #include <stdlib.h>
  27 #include <unistd.h>
  28
  29 #include "sd-journal.h"
  30
  31 #include "fd-util.h"
  32 #include "parse-util.h"
  33 #include "string-util.h"
  34 #include "util.h"
  35
  36 static char *arg_identifier = NULL;
  37 static int arg_priority = LOG_INFO;
  38 static bool arg_level_prefix = true;
  39
  40 static void help(void) {
  41         printf("%s [OPTIONS...] {COMMAND} ...\n\n"
  42                "Execute process with stdout/stderr connected to the journal.\n\n"
  43                "  -h --help               Show this help\n"
  44                "     --version            Show package version\n"
  45                "  -t --identifier=STRING  Set syslog identifier\n"
  46                "  -p --priority=PRIORITY  Set priority value (0..7)\n"
  47                "     --level-prefix=BOOL  Control whether level prefix shall be parsed\n"
  48                , program_invocation_short_name);
  49 }
  50
  51 static int parse_argv(int argc, char *argv[]) {
  52
  53         enum {
  54                 ARG_VERSION = 0x100,
  55                 ARG_LEVEL_PREFIX
  56         };
  57
  58         static const struct option options[] = {
  59                 { "help",         no_argument,       NULL, 'h'              },
  60                 { "version",      no_argument,       NULL, ARG_VERSION      },
  61                 { "identifier",   required_argument, NULL, 't'              },
  62                 { "priority",     required_argument, NULL, 'p'              },
  63                 { "level-prefix", required_argument, NULL, ARG_LEVEL_PREFIX },
  64                 {}
  65         };
  66
  67         int c;
  68
  69         assert(argc >= 0);
  70         assert(argv);
  71
  72         while ((c = getopt_long(argc, argv, "+ht:p:", options, NULL)) >= 0)
  73
  74                 switch (c) {
  75
  76                 case 'h':
  77                         help();
  78                         return 0;
  79
  80                 case ARG_VERSION:
  81                         return version();
  82
  83                 case 't':
  84                         free(arg_identifier);
  85                         if (isempty(optarg))
  86                                 arg_identifier = NULL;
  87                         else {
  88                                 arg_identifier = strdup(optarg);
  89                                 if (!arg_identifier)
  90                                         return log_oom();
  91                         }
  92                         break;
  93
  94                 case 'p':
  95                         arg_priority = log_level_from_string(optarg);
  96                         if (arg_priority < 0) {
  97                                 log_error("Failed to parse priority value.");
  98                                 return -EINVAL;
  99                         }
 100                         break;
 101
 102                 case ARG_LEVEL_PREFIX: {
 103                         int k;
 104
 105                         k = parse_boolean(optarg);
 106                         if (k < 0)
 107                                 return log_error_errno(k, "Failed to parse level prefix value.");
 108
 109                         arg_level_prefix = k;
 110                         break;
 111                 }
 112
 113                 case '?':
 114                         return -EINVAL;
 115
 116                 default:
 117                         assert_not_reached("Unhandled option");
 118                 }
 119
 120         return 1;
 121 }
 122
 123 int main(int argc, char *argv[]) {
 124         _cleanup_close_ int  fd = -1, saved_stderr = -1;
 125         int r;
 126
 127         log_parse_environment();
 128         log_open();
 129
 130         r = parse_argv(argc, argv);
 131         if (r <= 0)
 132                 goto finish;
 133
 134         fd = sd_journal_stream_fd(arg_identifier, arg_priority, arg_level_prefix);
 135         if (fd < 0) {
 136                 r = log_error_errno(fd, "Failed to create stream fd: %m");
 137                 goto finish;
 138         }
 139
 140         saved_stderr = fcntl(STDERR_FILENO, F_DUPFD_CLOEXEC, 3);
 141
 142         if (dup3(fd, STDOUT_FILENO, 0) < 0 ||
 143             dup3(fd, STDERR_FILENO, 0) < 0) {
 144                 r = log_error_errno(errno, "Failed to duplicate fd: %m");
 145                 goto finish;
 146         }
 147
 148         if (fd >= 3)
 149                 safe_close(fd);
 150         fd = -1;
 151
 152         if (argc <= optind)
 153                 (void) execl("/bin/cat", "/bin/cat", NULL);
 154         else
 155                 (void) execvp(argv[optind], argv + optind);
 156         r = -errno;
 157
 158         /* Let's try to restore a working stderr, so we can print the error message */
 159         if (saved_stderr >= 0)
 160                 (void) dup3(saved_stderr, STDERR_FILENO, 0);
 161
 162         log_error_errno(r, "Failed to execute process: %m");
 163
 164 finish:
 165         return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 166 }