src/journal/cat.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include <errno.h>
   4 #include <fcntl.h>
   5 #include <getopt.h>
   6 #include <stdio.h>
   7 #include <stdlib.h>
   8 #include <unistd.h>
   9
  10 #include "sd-journal.h"
  11
  12 #include "alloc-util.h"
  13 #include "fd-util.h"
  14 #include "parse-util.h"
  15 #include "string-util.h"
  16 #include "syslog-util.h"
  17 #include "util.h"
  18 #include "terminal-util.h"
  19
  20 static const char *arg_identifier = NULL;
  21 static int arg_priority = LOG_INFO;
  22 static bool arg_level_prefix = true;
  23
  24 static int help(void) {
  25         _cleanup_free_ char *link = NULL;
  26         int r;
  27
  28         r = terminal_urlify_man("systemd-cat", "1", &link);
  29         if (r < 0)
  30                 return log_oom();
  31
  32         printf("%s [OPTIONS...] {COMMAND} ...\n\n"
  33                "Execute process with stdout/stderr connected to the journal.\n\n"
  34                "  -h --help               Show this help\n"
  35                "     --version            Show package version\n"
  36                "  -t --identifier=STRING  Set syslog identifier\n"
  37                "  -p --priority=PRIORITY  Set priority value (0..7)\n"
  38                "     --level-prefix=BOOL  Control whether level prefix shall be parsed\n"
  39                "\nSee the %s for details.\n"
  40                , program_invocation_short_name
  41                , link
  42         );
  43
  44         return 0;
  45 }
  46
  47 static int parse_argv(int argc, char *argv[]) {
  48
  49         enum {
  50                 ARG_VERSION = 0x100,
  51                 ARG_LEVEL_PREFIX
  52         };
  53
  54         static const struct option options[] = {
  55                 { "help",         no_argument,       NULL, 'h'              },
  56                 { "version",      no_argument,       NULL, ARG_VERSION      },
  57                 { "identifier",   required_argument, NULL, 't'              },
  58                 { "priority",     required_argument, NULL, 'p'              },
  59                 { "level-prefix", required_argument, NULL, ARG_LEVEL_PREFIX },
  60                 {}
  61         };
  62
  63         int c;
  64
  65         assert(argc >= 0);
  66         assert(argv);
  67
  68         while ((c = getopt_long(argc, argv, "+ht:p:", options, NULL)) >= 0)
  69
  70                 switch (c) {
  71
  72                 case 'h':
  73                         help();
  74                         return 0;
  75
  76                 case ARG_VERSION:
  77                         return version();
  78
  79                 case 't':
  80                         if (isempty(optarg))
  81                                 arg_identifier = NULL;
  82                         else
  83                                 arg_identifier = optarg;
  84                         break;
  85
  86                 case 'p':
  87                         arg_priority = log_level_from_string(optarg);
  88                         if (arg_priority < 0) {
  89                                 log_error("Failed to parse priority value.");
  90                                 return -EINVAL;
  91                         }
  92                         break;
  93
  94                 case ARG_LEVEL_PREFIX: {
  95                         int k;
  96
  97                         k = parse_boolean(optarg);
  98                         if (k < 0)
  99                                 return log_error_errno(k, "Failed to parse level prefix value.");
 100
 101                         arg_level_prefix = k;
 102                         break;
 103                 }
 104
 105                 case '?':
 106                         return -EINVAL;
 107
 108                 default:
 109                         assert_not_reached("Unhandled option");
 110                 }
 111
 112         return 1;
 113 }
 114
 115 int main(int argc, char *argv[]) {
 116         _cleanup_close_ int  fd = -1, saved_stderr = -1;
 117         int r;
 118
 119         log_parse_environment();
 120         log_open();
 121
 122         r = parse_argv(argc, argv);
 123         if (r <= 0)
 124                 goto finish;
 125
 126         fd = sd_journal_stream_fd(arg_identifier, arg_priority, arg_level_prefix);
 127         if (fd < 0) {
 128                 r = log_error_errno(fd, "Failed to create stream fd: %m");
 129                 goto finish;
 130         }
 131
 132         saved_stderr = fcntl(STDERR_FILENO, F_DUPFD_CLOEXEC, 3);
 133
 134         r = rearrange_stdio(STDIN_FILENO, fd, fd); /* Invalidates fd on succcess + error! */
 135         fd = -1;
 136         if (r < 0) {
 137                 log_error_errno(r, "Failed to rearrange stdout/stderr: %m");
 138                 goto finish;
 139         }
 140
 141         if (argc <= optind)
 142                 (void) execl("/bin/cat", "/bin/cat", NULL);
 143         else
 144                 (void) execvp(argv[optind], argv + optind);
 145         r = -errno;
 146
 147         /* Let's try to restore a working stderr, so we can print the error message */
 148         if (saved_stderr >= 0)
 149                 (void) dup3(saved_stderr, STDERR_FILENO, 0);
 150
 151         log_error_errno(r, "Failed to execute process: %m");
 152
 153 finish:
 154         return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 155 }