1 files changed, 103 insertions, 0 deletions
diff --git a/src/journal/journald-console.c b/src/journal/journald-console.c
new file mode 100644
index 0000000..2035e2d
--- /dev/null
+++ b/src/journal/journald-console.c
@@ -0,0 +1,103 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <fcntl.h>
+#include <sys/socket.h>
+#include <time.h>
+
+#include "alloc-util.h"
+#include "fd-util.h"
+#include "fileio.h"
+#include "format-util.h"
+#include "io-util.h"
+#include "journald-console.h"
+#include "journald-server.h"
+#include "parse-util.h"
+#include "process-util.h"
+#include "stdio-util.h"
+#include "terminal-util.h"
+
+static bool prefix_timestamp(void) {
+
+        static int cached_printk_time = -1;
+
+        if (_unlikely_(cached_printk_time < 0)) {
+                _cleanup_free_ char *p = NULL;
+
+                cached_printk_time =
+                        read_one_line_file("/sys/module/printk/parameters/time", &p) >= 0
+                        && parse_boolean(p) > 0;
+        }
+
+        return cached_printk_time;
+}
+
+void server_forward_console(
+                Server *s,
+                int priority,
+                const char *identifier,
+                const char *message,
+                const struct ucred *ucred) {
+
+        struct iovec iovec[5];
+        struct timespec ts;
+        char tbuf[STRLEN("[] ") + DECIMAL_STR_MAX(ts.tv_sec) + DECIMAL_STR_MAX(ts.tv_nsec)-3 + 1];
+        char header_pid[STRLEN("[]: ") + DECIMAL_STR_MAX(pid_t)];
+        _cleanup_free_ char *ident_buf = NULL;
+        _cleanup_close_ int fd = -1;
+        const char *tty;
+        int n = 0;
+
+        assert(s);
+        assert(message);
+
+        if (LOG_PRI(priority) > s->max_level_console)
+                return;
+
+        /* First: timestamp */
+        if (prefix_timestamp()) {
+                assert_se(clock_gettime(CLOCK_MONOTONIC, &ts) == 0);
+                xsprintf(tbuf, "[%5"PRI_TIME".%06"PRI_NSEC"] ",
+                         ts.tv_sec,
+                         (nsec_t)ts.tv_nsec / 1000);
+
+                iovec[n++] = IOVEC_MAKE_STRING(tbuf);
+        }
+
+        /* Second: identifier and PID */
+        if (ucred) {
+                if (!identifier) {
+                        (void) get_process_comm(ucred->pid, &ident_buf);
+                        identifier = ident_buf;
+                }
+
+                xsprintf(header_pid, "["PID_FMT"]: ", ucred->pid);
+
+                if (identifier)
+                        iovec[n++] = IOVEC_MAKE_STRING(identifier);
+
+                iovec[n++] = IOVEC_MAKE_STRING(header_pid);
+        } else if (identifier) {
+                iovec[n++] = IOVEC_MAKE_STRING(identifier);
+                iovec[n++] = IOVEC_MAKE_STRING(": ");
+        }
+
+        /* Fourth: message */
+        iovec[n++] = IOVEC_MAKE_STRING(message);
+        iovec[n++] = IOVEC_MAKE_STRING("\n");
+
+        tty = s->tty_path ?: "/dev/console";
+
+        /* Before you ask: yes, on purpose we open/close the console for each log line we write individually. This is a
+         * good strategy to avoid journald getting killed by the kernel's SAK concept (it doesn't fix this entirely,
+         * but minimizes the time window the kernel might end up killing journald due to SAK). It also makes things
+         * easier for us so that we don't have to recover from hangups and suchlike triggered on the console. */
+
+        fd = open_terminal(tty, O_WRONLY|O_NOCTTY|O_CLOEXEC);
+        if (fd < 0) {
+                log_debug_errno(fd, "Failed to open %s for logging: %m", tty);
+                return;
+        }
+
+        if (writev(fd, iovec, n) < 0)
+                log_debug_errno(errno, "Failed to write to %s for logging: %m", tty);
+}