src/journal/cat.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   Copyright 2012 Lennart Poettering
   4 ***/
   5
   6 #include <errno.h>
   7 #include <fcntl.h>
   8 #include <getopt.h>
   9 #include <stdio.h>
  10 #include <stdlib.h>
  11 #include <unistd.h>
  12
  13 #include "sd-journal.h"
  14
  15 #include "fd-util.h"
  16 #include "parse-util.h"
  17 #include "string-util.h"
  18 #include "syslog-util.h"
  19 #include "util.h"
  20
  21 static const char *arg_identifier = NULL;
  22 static int arg_priority = LOG_INFO;
  23 static bool arg_level_prefix = true;
  24
  25 static void help(void) {
  26         printf("%s [OPTIONS...] {COMMAND} ...\n\n"
  27                "Execute process with stdout/stderr connected to the journal.\n\n"
  28                "  -h --help               Show this help\n"
  29                "     --version            Show package version\n"
  30                "  -t --identifier=STRING  Set syslog identifier\n"
  31                "  -p --priority=PRIORITY  Set priority value (0..7)\n"
  32                "     --level-prefix=BOOL  Control whether level prefix shall be parsed\n"
  33                , program_invocation_short_name);
  34 }
  35
  36 static int parse_argv(int argc, char *argv[]) {
  37
  38         enum {
  39                 ARG_VERSION = 0x100,
  40                 ARG_LEVEL_PREFIX
  41         };
  42
  43         static const struct option options[] = {
  44                 { "help",         no_argument,       NULL, 'h'              },
  45                 { "version",      no_argument,       NULL, ARG_VERSION      },
  46                 { "identifier",   required_argument, NULL, 't'              },
  47                 { "priority",     required_argument, NULL, 'p'              },
  48                 { "level-prefix", required_argument, NULL, ARG_LEVEL_PREFIX },
  49                 {}
  50         };
  51
  52         int c;
  53
  54         assert(argc >= 0);
  55         assert(argv);
  56
  57         while ((c = getopt_long(argc, argv, "+ht:p:", options, NULL)) >= 0)
  58
  59                 switch (c) {
  60
  61                 case 'h':
  62                         help();
  63                         return 0;
  64
  65                 case ARG_VERSION:
  66                         return version();
  67
  68                 case 't':
  69                         if (isempty(optarg))
  70                                 arg_identifier = NULL;
  71                         else
  72                                 arg_identifier = optarg;
  73                         break;
  74
  75                 case 'p':
  76                         arg_priority = log_level_from_string(optarg);
  77                         if (arg_priority < 0) {
  78                                 log_error("Failed to parse priority value.");
  79                                 return -EINVAL;
  80                         }
  81                         break;
  82
  83                 case ARG_LEVEL_PREFIX: {
  84                         int k;
  85
  86                         k = parse_boolean(optarg);
  87                         if (k < 0)
  88                                 return log_error_errno(k, "Failed to parse level prefix value.");
  89
  90                         arg_level_prefix = k;
  91                         break;
  92                 }
  93
  94                 case '?':
  95                         return -EINVAL;
  96
  97                 default:
  98                         assert_not_reached("Unhandled option");
  99                 }
 100
 101         return 1;
 102 }
 103
 104 int main(int argc, char *argv[]) {
 105         _cleanup_close_ int  fd = -1, saved_stderr = -1;
 106         int r;
 107
 108         log_parse_environment();
 109         log_open();
 110
 111         r = parse_argv(argc, argv);
 112         if (r <= 0)
 113                 goto finish;
 114
 115         fd = sd_journal_stream_fd(arg_identifier, arg_priority, arg_level_prefix);
 116         if (fd < 0) {
 117                 r = log_error_errno(fd, "Failed to create stream fd: %m");
 118                 goto finish;
 119         }
 120
 121         saved_stderr = fcntl(STDERR_FILENO, F_DUPFD_CLOEXEC, 3);
 122
 123         r = rearrange_stdio(STDIN_FILENO, fd, fd); /* Invalidates fd on succcess + error! */
 124         fd = -1;
 125         if (r < 0) {
 126                 log_error_errno(r, "Failed to rearrange stdout/stderr: %m");
 127                 goto finish;
 128         }
 129
 130         if (argc <= optind)
 131                 (void) execl("/bin/cat", "/bin/cat", NULL);
 132         else
 133                 (void) execvp(argv[optind], argv + optind);
 134         r = -errno;
 135
 136         /* Let's try to restore a working stderr, so we can print the error message */
 137         if (saved_stderr >= 0)
 138                 (void) dup3(saved_stderr, STDERR_FILENO, 0);
 139
 140         log_error_errno(r, "Failed to execute process: %m");
 141
 142 finish:
 143         return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 144 }