src/journal/journald-console.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   This file is part of systemd.
   4
   5   Copyright 2011 Lennart Poettering
   6 ***/
   7
   8 #include <fcntl.h>
   9 #include <sys/socket.h>
  10 #include <time.h>
  11
  12 #include "alloc-util.h"
  13 #include "fd-util.h"
  14 #include "fileio.h"
  15 #include "format-util.h"
  16 #include "io-util.h"
  17 #include "journald-console.h"
  18 #include "journald-server.h"
  19 #include "parse-util.h"
  20 #include "process-util.h"
  21 #include "stdio-util.h"
  22 #include "terminal-util.h"
  23
  24 static bool prefix_timestamp(void) {
  25
  26         static int cached_printk_time = -1;
  27
  28         if (_unlikely_(cached_printk_time < 0)) {
  29                 _cleanup_free_ char *p = NULL;
  30
  31                 cached_printk_time =
  32                         read_one_line_file("/sys/module/printk/parameters/time", &p) >= 0
  33                         && parse_boolean(p) > 0;
  34         }
  35
  36         return cached_printk_time;
  37 }
  38
  39 void server_forward_console(
  40                 Server *s,
  41                 int priority,
  42                 const char *identifier,
  43                 const char *message,
  44                 const struct ucred *ucred) {
  45
  46         struct iovec iovec[5];
  47         struct timespec ts;
  48         char tbuf[STRLEN("[] ") + DECIMAL_STR_MAX(ts.tv_sec) + DECIMAL_STR_MAX(ts.tv_nsec)-3 + 1];
  49         char header_pid[STRLEN("[]: ") + DECIMAL_STR_MAX(pid_t)];
  50         _cleanup_free_ char *ident_buf = NULL;
  51         _cleanup_close_ int fd = -1;
  52         const char *tty;
  53         int n = 0;
  54
  55         assert(s);
  56         assert(message);
  57
  58         if (LOG_PRI(priority) > s->max_level_console)
  59                 return;
  60
  61         /* First: timestamp */
  62         if (prefix_timestamp()) {
  63                 assert_se(clock_gettime(CLOCK_MONOTONIC, &ts) == 0);
  64                 xsprintf(tbuf, "[%5"PRI_TIME".%06"PRI_NSEC"] ",
  65                          ts.tv_sec,
  66                          (nsec_t)ts.tv_nsec / 1000);
  67
  68                 iovec[n++] = IOVEC_MAKE_STRING(tbuf);
  69         }
  70
  71         /* Second: identifier and PID */
  72         if (ucred) {
  73                 if (!identifier) {
  74                         get_process_comm(ucred->pid, &ident_buf);
  75                         identifier = ident_buf;
  76                 }
  77
  78                 xsprintf(header_pid, "["PID_FMT"]: ", ucred->pid);
  79
  80                 if (identifier)
  81                         iovec[n++] = IOVEC_MAKE_STRING(identifier);
  82
  83                 iovec[n++] = IOVEC_MAKE_STRING(header_pid);
  84         } else if (identifier) {
  85                 iovec[n++] = IOVEC_MAKE_STRING(identifier);
  86                 iovec[n++] = IOVEC_MAKE_STRING(": ");
  87         }
  88
  89         /* Fourth: message */
  90         iovec[n++] = IOVEC_MAKE_STRING(message);
  91         iovec[n++] = IOVEC_MAKE_STRING("\n");
  92
  93         tty = s->tty_path ?: "/dev/console";
  94
  95         /* Before you ask: yes, on purpose we open/close the console for each log line we write individually. This is a
  96          * good strategy to avoid journald getting killed by the kernel's SAK concept (it doesn't fix this entirely,
  97          * but minimizes the time window the kernel might end up killing journald due to SAK). It also makes things
  98          * easier for us so that we don't have to recover from hangups and suchlike triggered on the console. */
  99
 100         fd = open_terminal(tty, O_WRONLY|O_NOCTTY|O_CLOEXEC);
 101         if (fd < 0) {
 102                 log_debug_errno(fd, "Failed to open %s for logging: %m", tty);
 103                 return;
 104         }
 105
 106         if (writev(fd, iovec, n) < 0)
 107                 log_debug_errno(errno, "Failed to write to %s for logging: %m", tty);
 108 }