src/journal/journald-console.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2011 Lennart Poettering
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <fcntl.h>
  21 #include <sys/socket.h>
  22 #include <time.h>
  23
  24 #include "alloc-util.h"
  25 #include "fd-util.h"
  26 #include "fileio.h"
  27 #include "format-util.h"
  28 #include "io-util.h"
  29 #include "journald-console.h"
  30 #include "journald-server.h"
  31 #include "parse-util.h"
  32 #include "process-util.h"
  33 #include "stdio-util.h"
  34 #include "terminal-util.h"
  35
  36 static bool prefix_timestamp(void) {
  37
  38         static int cached_printk_time = -1;
  39
  40         if (_unlikely_(cached_printk_time < 0)) {
  41                 _cleanup_free_ char *p = NULL;
  42
  43                 cached_printk_time =
  44                         read_one_line_file("/sys/module/printk/parameters/time", &p) >= 0
  45                         && parse_boolean(p) > 0;
  46         }
  47
  48         return cached_printk_time;
  49 }
  50
  51 void server_forward_console(
  52                 Server *s,
  53                 int priority,
  54                 const char *identifier,
  55                 const char *message,
  56                 const struct ucred *ucred) {
  57
  58         struct iovec iovec[5];
  59         struct timespec ts;
  60         char tbuf[sizeof("[] ")-1 + DECIMAL_STR_MAX(ts.tv_sec) + DECIMAL_STR_MAX(ts.tv_nsec)-3 + 1];
  61         char header_pid[sizeof("[]: ")-1 + DECIMAL_STR_MAX(pid_t)];
  62         int n = 0, fd;
  63         _cleanup_free_ char *ident_buf = NULL;
  64         const char *tty;
  65
  66         assert(s);
  67         assert(message);
  68
  69         if (LOG_PRI(priority) > s->max_level_console)
  70                 return;
  71
  72         /* First: timestamp */
  73         if (prefix_timestamp()) {
  74                 assert_se(clock_gettime(CLOCK_MONOTONIC, &ts) == 0);
  75                 xsprintf(tbuf, "[%5"PRI_TIME".%06"PRI_NSEC"] ",
  76                          ts.tv_sec,
  77                          (nsec_t)ts.tv_nsec / 1000);
  78                 IOVEC_SET_STRING(iovec[n++], tbuf);
  79         }
  80
  81         /* Second: identifier and PID */
  82         if (ucred) {
  83                 if (!identifier) {
  84                         get_process_comm(ucred->pid, &ident_buf);
  85                         identifier = ident_buf;
  86                 }
  87
  88                 xsprintf(header_pid, "["PID_FMT"]: ", ucred->pid);
  89
  90                 if (identifier)
  91                         IOVEC_SET_STRING(iovec[n++], identifier);
  92
  93                 IOVEC_SET_STRING(iovec[n++], header_pid);
  94         } else if (identifier) {
  95                 IOVEC_SET_STRING(iovec[n++], identifier);
  96                 IOVEC_SET_STRING(iovec[n++], ": ");
  97         }
  98
  99         /* Fourth: message */
 100         IOVEC_SET_STRING(iovec[n++], message);
 101         IOVEC_SET_STRING(iovec[n++], "\n");
 102
 103         tty = s->tty_path ? s->tty_path : "/dev/console";
 104
 105         /* Before you ask: yes, on purpose we open/close the console for each log line we write individually. This is a
 106          * good strategy to avoid journald getting killed by the kernel's SAK concept (it doesn't fix this entirely,
 107          * but minimizes the time window the kernel might end up killing journald due to SAK). It also makes things
 108          * easier for us so that we don't have to recover from hangups and suchlike triggered on the console. */
 109
 110         fd = open_terminal(tty, O_WRONLY|O_NOCTTY|O_CLOEXEC);
 111         if (fd < 0) {
 112                 log_debug_errno(fd, "Failed to open %s for logging: %m", tty);
 113                 return;
 114         }
 115
 116         if (writev(fd, iovec, n) < 0)
 117                 log_debug_errno(errno, "Failed to write to %s for logging: %m", tty);
 118
 119         safe_close(fd);
 120 }