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 <stdio.h>
  23 #include <getopt.h>
  24 #include <assert.h>
  25 #include <unistd.h>
  26 #include <stdlib.h>
  27 #include <errno.h>
  28 #include <fcntl.h>
  29
  30 #include <systemd/sd-journal.h>
  31
  32 #include "util.h"
  33 #include "build.h"
  34
  35 static char *arg_identifier = NULL;
  36 static int arg_priority = LOG_INFO;
  37 static bool arg_level_prefix = true;
  38
  39 static int help(void) {
  40
  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         return 0;
  51 }
  52
  53 static int parse_argv(int argc, char *argv[]) {
  54
  55         enum {
  56                 ARG_VERSION = 0x100,
  57                 ARG_LEVEL_PREFIX
  58         };
  59
  60         static const struct option options[] = {
  61                 { "help",         no_argument,       NULL, 'h'              },
  62                 { "version",      no_argument,       NULL, ARG_VERSION      },
  63                 { "identifier",   required_argument, NULL, 't'              },
  64                 { "priority",     required_argument, NULL, 'p'              },
  65                 { "level-prefix", required_argument, NULL, ARG_LEVEL_PREFIX },
  66                 {}
  67         };
  68
  69         int c;
  70
  71         assert(argc >= 0);
  72         assert(argv);
  73
  74         while ((c = getopt_long(argc, argv, "+ht:p:", options, NULL)) >= 0) {
  75
  76                 switch (c) {
  77
  78                 case 'h':
  79                         return help();
  80
  81                 case ARG_VERSION:
  82                         puts(PACKAGE_STRING);
  83                         puts(SYSTEMD_FEATURES);
  84                         return 0;
  85
  86                 case 't':
  87                         free(arg_identifier);
  88                         if (isempty(optarg))
  89                                 arg_identifier = NULL;
  90                         else {
  91                                 arg_identifier = strdup(optarg);
  92                                 if (!arg_identifier)
  93                                         return log_oom();
  94                         }
  95                         break;
  96
  97                 case 'p':
  98                         arg_priority = log_level_from_string(optarg);
  99                         if (arg_priority < 0) {
 100                                 log_error("Failed to parse priority value.");
 101                                 return arg_priority;
 102                         }
 103                         break;
 104
 105                 case ARG_LEVEL_PREFIX: {
 106                         int k;
 107
 108                         k = parse_boolean(optarg);
 109                         if (k < 0) {
 110                                 log_error("Failed to parse level prefix value.");
 111                                 return k;
 112                         }
 113                         arg_level_prefix = k;
 114                         break;
 115                 }
 116
 117                 case '?':
 118                         return -EINVAL;
 119
 120                 default:
 121                         assert_not_reached("Unhandled option");
 122                 }
 123         }
 124
 125         return 1;
 126 }
 127
 128 int main(int argc, char *argv[]) {
 129         int r, fd = -1, saved_stderr = -1;
 130
 131         log_parse_environment();
 132         log_open();
 133
 134         r = parse_argv(argc, argv);
 135         if (r <= 0)
 136                 goto finish;
 137
 138         fd = sd_journal_stream_fd(arg_identifier, arg_priority, arg_level_prefix);
 139         if (fd < 0) {
 140                 log_error("Failed to create stream fd: %s", strerror(-fd));
 141                 r = fd;
 142                 goto finish;
 143         }
 144
 145         saved_stderr = fcntl(STDERR_FILENO, F_DUPFD_CLOEXEC, 3);
 146
 147         if (dup3(fd, STDOUT_FILENO, 0) < 0 ||
 148             dup3(fd, STDERR_FILENO, 0) < 0) {
 149                 log_error("Failed to duplicate fd: %m");
 150                 r = -errno;
 151                 goto finish;
 152         }
 153
 154         if (fd >= 3)
 155                 safe_close(fd);
 156
 157         fd = -1;
 158
 159         if (argc <= optind)
 160                 execl("/bin/cat", "/bin/cat", NULL);
 161         else
 162                 execvp(argv[optind], argv + optind);
 163
 164         r = -errno;
 165
 166         /* Let's try to restore a working stderr, so we can print the error message */
 167         if (saved_stderr >= 0)
 168                 dup3(saved_stderr, STDERR_FILENO, 0);
 169
 170         log_error("Failed to execute process: %s", strerror(-r));
 171
 172 finish:
 173         safe_close(fd);
 174         safe_close(saved_stderr);
 175
 176         return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 177 }