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 void help(void) {
  40         printf("%s [OPTIONS...] {COMMAND} ...\n\n"
  41                "Execute process with stdout/stderr connected to the journal.\n\n"
  42                "  -h --help               Show this help\n"
  43                "     --version            Show package version\n"
  44                "  -t --identifier=STRING  Set syslog identifier\n"
  45                "  -p --priority=PRIORITY  Set priority value (0..7)\n"
  46                "     --level-prefix=BOOL  Control whether level prefix shall be parsed\n"
  47                , program_invocation_short_name);
  48 }
  49
  50 static int parse_argv(int argc, char *argv[]) {
  51
  52         enum {
  53                 ARG_VERSION = 0x100,
  54                 ARG_LEVEL_PREFIX
  55         };
  56
  57         static const struct option options[] = {
  58                 { "help",         no_argument,       NULL, 'h'              },
  59                 { "version",      no_argument,       NULL, ARG_VERSION      },
  60                 { "identifier",   required_argument, NULL, 't'              },
  61                 { "priority",     required_argument, NULL, 'p'              },
  62                 { "level-prefix", required_argument, NULL, ARG_LEVEL_PREFIX },
  63                 {}
  64         };
  65
  66         int c;
  67
  68         assert(argc >= 0);
  69         assert(argv);
  70
  71         while ((c = getopt_long(argc, argv, "+ht:p:", options, NULL)) >= 0)
  72
  73                 switch (c) {
  74
  75                 case 'h':
  76                         help();
  77                         return 0;
  78
  79                 case ARG_VERSION:
  80                         puts(PACKAGE_STRING);
  81                         puts(SYSTEMD_FEATURES);
  82                         return 0;
  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 arg_priority;
 100                         }
 101                         break;
 102
 103                 case ARG_LEVEL_PREFIX: {
 104                         int k;
 105
 106                         k = parse_boolean(optarg);
 107                         if (k < 0) {
 108                                 log_error("Failed to parse level prefix value.");
 109                                 return k;
 110                         }
 111                         arg_level_prefix = k;
 112                         break;
 113                 }
 114
 115                 case '?':
 116                         return -EINVAL;
 117
 118                 default:
 119                         assert_not_reached("Unhandled option");
 120                 }
 121
 122         return 1;
 123 }
 124
 125 int main(int argc, char *argv[]) {
 126         int r, fd = -1, saved_stderr = -1;
 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                 log_error_errno(fd, "Failed to create stream fd: %m");
 138                 r = fd;
 139                 goto finish;
 140         }
 141
 142         saved_stderr = fcntl(STDERR_FILENO, F_DUPFD_CLOEXEC, 3);
 143
 144         if (dup3(fd, STDOUT_FILENO, 0) < 0 ||
 145             dup3(fd, STDERR_FILENO, 0) < 0) {
 146                 log_error_errno(errno, "Failed to duplicate fd: %m");
 147                 r = -errno;
 148                 goto finish;
 149         }
 150
 151         if (fd >= 3)
 152                 safe_close(fd);
 153
 154         fd = -1;
 155
 156         if (argc <= optind)
 157                 execl("/bin/cat", "/bin/cat", NULL);
 158         else
 159                 execvp(argv[optind], argv + optind);
 160
 161         r = -errno;
 162
 163         /* Let's try to restore a working stderr, so we can print the error message */
 164         if (saved_stderr >= 0)
 165                 dup3(saved_stderr, STDERR_FILENO, 0);
 166
 167         log_error_errno(r, "Failed to execute process: %m");
 168
 169 finish:
 170         safe_close(fd);
 171         safe_close(saved_stderr);
 172
 173         return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 174 }