src/journal/journald-console.c

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