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 "string-util.h"
  32 #include "util.h"
  33
  34 static char *arg_identifier = NULL;
  35 static int arg_priority = LOG_INFO;
  36 static bool arg_level_prefix = true;
  37
  38 static void help(void) {
  39         printf("%s [OPTIONS...] {COMMAND} ...\n\n"
  40                "Execute process with stdout/stderr connected to the journal.\n\n"
  41                "  -h --help               Show this help\n"
  42                "     --version            Show package version\n"
  43                "  -t --identifier=STRING  Set syslog identifier\n"
  44                "  -p --priority=PRIORITY  Set priority value (0..7)\n"
  45                "     --level-prefix=BOOL  Control whether level prefix shall be parsed\n"
  46                , program_invocation_short_name);
  47 }
  48
  49 static int parse_argv(int argc, char *argv[]) {
  50
  51         enum {
  52                 ARG_VERSION = 0x100,
  53                 ARG_LEVEL_PREFIX
  54         };
  55
  56         static const struct option options[] = {
  57                 { "help",         no_argument,       NULL, 'h'              },
  58                 { "version",      no_argument,       NULL, ARG_VERSION      },
  59                 { "identifier",   required_argument, NULL, 't'              },
  60                 { "priority",     required_argument, NULL, 'p'              },
  61                 { "level-prefix", required_argument, NULL, ARG_LEVEL_PREFIX },
  62                 {}
  63         };
  64
  65         int c;
  66
  67         assert(argc >= 0);
  68         assert(argv);
  69
  70         while ((c = getopt_long(argc, argv, "+ht:p:", options, NULL)) >= 0)
  71
  72                 switch (c) {
  73
  74                 case 'h':
  75                         help();
  76                         return 0;
  77
  78                 case ARG_VERSION:
  79                         return version();
  80
  81                 case 't':
  82                         free(arg_identifier);
  83                         if (isempty(optarg))
  84                                 arg_identifier = NULL;
  85                         else {
  86                                 arg_identifier = strdup(optarg);
  87                                 if (!arg_identifier)
  88                                         return log_oom();
  89                         }
  90                         break;
  91
  92                 case 'p':
  93                         arg_priority = log_level_from_string(optarg);
  94                         if (arg_priority < 0) {
  95                                 log_error("Failed to parse priority value.");
  96                                 return -EINVAL;
  97                         }
  98                         break;
  99
 100                 case ARG_LEVEL_PREFIX: {
 101                         int k;
 102
 103                         k = parse_boolean(optarg);
 104                         if (k < 0)
 105                                 return log_error_errno(k, "Failed to parse level prefix value.");
 106
 107                         arg_level_prefix = k;
 108                         break;
 109                 }
 110
 111                 case '?':
 112                         return -EINVAL;
 113
 114                 default:
 115                         assert_not_reached("Unhandled option");
 116                 }
 117
 118         return 1;
 119 }
 120
 121 int main(int argc, char *argv[]) {
 122         _cleanup_close_ int  fd = -1, saved_stderr = -1;
 123         int r;
 124
 125         log_parse_environment();
 126         log_open();
 127
 128         r = parse_argv(argc, argv);
 129         if (r <= 0)
 130                 goto finish;
 131
 132         fd = sd_journal_stream_fd(arg_identifier, arg_priority, arg_level_prefix);
 133         if (fd < 0) {
 134                 r = log_error_errno(fd, "Failed to create stream fd: %m");
 135                 goto finish;
 136         }
 137
 138         saved_stderr = fcntl(STDERR_FILENO, F_DUPFD_CLOEXEC, 3);
 139
 140         if (dup3(fd, STDOUT_FILENO, 0) < 0 ||
 141             dup3(fd, STDERR_FILENO, 0) < 0) {
 142                 r = log_error_errno(errno, "Failed to duplicate fd: %m");
 143                 goto finish;
 144         }
 145
 146         if (fd >= 3)
 147                 safe_close(fd);
 148         fd = -1;
 149
 150         if (argc <= optind)
 151                 (void) execl("/bin/cat", "/bin/cat", NULL);
 152         else
 153                 (void) execvp(argv[optind], argv + optind);
 154         r = -errno;
 155
 156         /* Let's try to restore a working stderr, so we can print the error message */
 157         if (saved_stderr >= 0)
 158                 (void) dup3(saved_stderr, STDERR_FILENO, 0);
 159
 160         log_error_errno(r, "Failed to execute process: %m");
 161
 162 finish:
 163         return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 164 }