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 "syslog-util.h"
  35 #include "util.h"
  36
  37 static char *arg_identifier = NULL;
  38 static int arg_priority = LOG_INFO;
  39 static bool arg_level_prefix = true;
  40
  41 static void help(void) {
  42         printf("%s [OPTIONS...] {COMMAND} ...\n\n"
  43                "Execute process with stdout/stderr connected to the journal.\n\n"
  44                "  -h --help               Show this help\n"
  45                "     --version            Show package version\n"
  46                "  -t --identifier=STRING  Set syslog identifier\n"
  47                "  -p --priority=PRIORITY  Set priority value (0..7)\n"
  48                "     --level-prefix=BOOL  Control whether level prefix shall be parsed\n"
  49                , program_invocation_short_name);
  50 }
  51
  52 static int parse_argv(int argc, char *argv[]) {
  53
  54         enum {
  55                 ARG_VERSION = 0x100,
  56                 ARG_LEVEL_PREFIX
  57         };
  58
  59         static const struct option options[] = {
  60                 { "help",         no_argument,       NULL, 'h'              },
  61                 { "version",      no_argument,       NULL, ARG_VERSION      },
  62                 { "identifier",   required_argument, NULL, 't'              },
  63                 { "priority",     required_argument, NULL, 'p'              },
  64                 { "level-prefix", required_argument, NULL, ARG_LEVEL_PREFIX },
  65                 {}
  66         };
  67
  68         int c;
  69
  70         assert(argc >= 0);
  71         assert(argv);
  72
  73         while ((c = getopt_long(argc, argv, "+ht:p:", options, NULL)) >= 0)
  74
  75                 switch (c) {
  76
  77                 case 'h':
  78                         help();
  79                         return 0;
  80
  81                 case ARG_VERSION:
  82                         return version();
  83
  84                 case 't':
  85                         free(arg_identifier);
  86                         if (isempty(optarg))
  87                                 arg_identifier = NULL;
  88                         else {
  89                                 arg_identifier = strdup(optarg);
  90                                 if (!arg_identifier)
  91                                         return log_oom();
  92                         }
  93                         break;
  94
  95                 case 'p':
  96                         arg_priority = log_level_from_string(optarg);
  97                         if (arg_priority < 0) {
  98                                 log_error("Failed to parse priority value.");
  99                                 return -EINVAL;
 100                         }
 101                         break;
 102
 103                 case ARG_LEVEL_PREFIX: {
 104                         int k;
 105
 106                         k = parse_boolean(optarg);
 107                         if (k < 0)
 108                                 return log_error_errno(k, "Failed to parse level prefix value.");
 109
 110                         arg_level_prefix = k;
 111                         break;
 112                 }
 113
 114                 case '?':
 115                         return -EINVAL;
 116
 117                 default:
 118                         assert_not_reached("Unhandled option");
 119                 }
 120
 121         return 1;
 122 }
 123
 124 int main(int argc, char *argv[]) {
 125         _cleanup_close_ int  fd = -1, saved_stderr = -1;
 126         int r;
 127
 128         log_parse_environment();
 129         log_open();
 130
 131         r = parse_argv(argc, argv);
 132         if (r <= 0)
 133                 goto finish;
 134
 135         fd = sd_journal_stream_fd(arg_identifier, arg_priority, arg_level_prefix);
 136         if (fd < 0) {
 137                 r = log_error_errno(fd, "Failed to create stream fd: %m");
 138                 goto finish;
 139         }
 140
 141         saved_stderr = fcntl(STDERR_FILENO, F_DUPFD_CLOEXEC, 3);
 142
 143         if (dup3(fd, STDOUT_FILENO, 0) < 0 ||
 144             dup3(fd, STDERR_FILENO, 0) < 0) {
 145                 r = log_error_errno(errno, "Failed to duplicate fd: %m");
 146                 goto finish;
 147         }
 148
 149         if (fd >= 3)
 150                 safe_close(fd);
 151         fd = -1;
 152
 153         if (argc <= optind)
 154                 (void) execl("/bin/cat", "/bin/cat", NULL);
 155         else
 156                 (void) execvp(argv[optind], argv + optind);
 157         r = -errno;
 158
 159         /* Let's try to restore a working stderr, so we can print the error message */
 160         if (saved_stderr >= 0)
 161                 (void) dup3(saved_stderr, STDERR_FILENO, 0);
 162
 163         log_error_errno(r, "Failed to execute process: %m");
 164
 165 finish:
 166         return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 167 }