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authorDavid Oberhollenzer <david.oberhollenzer@tele2.at>2018-09-01 01:12:46 +0200
committerDavid Oberhollenzer <david.oberhollenzer@tele2.at>2018-09-01 13:03:18 +0200
commitdc30dd7530cee426bbb30425e255868ffa635c13 (patch)
tree5f8c9dce00a58bd82ece93db86c93c783a773c37 /syslogd/klogd.c
parentb0b6c68e3839656c657f83de70badace6c01675a (diff)
Add tiny klogd implementation
Signed-off-by: David Oberhollenzer <david.oberhollenzer@tele2.at>
Diffstat (limited to 'syslogd/klogd.c')
-rw-r--r--syslogd/klogd.c191
1 files changed, 191 insertions, 0 deletions
diff --git a/syslogd/klogd.c b/syslogd/klogd.c
new file mode 100644
index 0000000..ca16e4e
--- /dev/null
+++ b/syslogd/klogd.c
@@ -0,0 +1,191 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * Copyright (C) 2018 - David Oberhollenzer
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+#include <sys/klog.h>
+#include <syslog.h>
+#include <signal.h>
+#include <string.h>
+#include <stdlib.h>
+#include <getopt.h>
+#include <stdio.h>
+#include <errno.h>
+
+#include "config.h"
+
+enum {
+ KLOG_CLOSE = 0,
+ KLOG_OPEN = 1,
+ KLOG_READ = 2,
+ KLOG_CONSOLE_OFF = 6,
+ KLOG_CONSOLE_ON = 7,
+ KLOG_CONSOLE_LEVEL = 8,
+};
+
+static char log_buffer[4096];
+static sig_atomic_t running = 1;
+static int level = 0;
+
+static const struct option options[] = {
+ { "help", no_argument, NULL, 'h' },
+ { "version", no_argument, NULL, 'V' },
+ { "level", required_argument, NULL, 'l' },
+ { NULL, 0, NULL, 0 },
+};
+
+static const char *shortopt = "hVl:";
+
+static const char *versiontext =
+"klogd (Pygos init) "PACKAGE_VERSION"\n"
+"Copyright (C) 2018 David Oberhollenzer\n"
+"License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>.\n"
+"This is free software: you are free to change and redistribute it.\n"
+"There is NO WARRANTY, to the extent permitted by law.\n";
+
+static const char *helptext =
+"Usage: klogd [OPTION]... \n\n"
+"Collect printk() messages from the kernel and forward them to syslogd.\n"
+"\n"
+"The following OPTIONSs can be used:\n"
+" -l, --level <level> Minimum log level that should be printed to console.\n"
+" If not set, logging to console is turned off.\n"
+" -h, --help Print this help text and exit\n"
+" -V, --version Print version information and exit\n\n";
+
+static void process_options(int argc, char **argv)
+{
+ int c;
+
+ for (;;) {
+ c = getopt_long(argc, argv, shortopt, options, NULL);
+ if (c == -1)
+ break;
+
+ switch (c) {
+ case 'l':
+ level = strtoul(optarg, NULL, 10);
+ break;
+ case 'h':
+ fputs(helptext, stdout);
+ exit(EXIT_SUCCESS);
+ case 'V':
+ fputs(versiontext, stdout);
+ exit(EXIT_SUCCESS);
+ default:
+ fputs("Try `klogd --help' for more information\n",
+ stderr);
+ exit(EXIT_FAILURE);
+ }
+ }
+}
+
+static void sighandler(int signo)
+{
+ if (signo == SIGTERM || signo == SIGINT)
+ running = 0;
+}
+
+static void sigsetup(void)
+{
+ struct sigaction act;
+ sigset_t mask;
+
+ memset(&act, 0, sizeof(act));
+ act.sa_handler = sighandler;
+ sigaction(SIGTERM, &act, NULL);
+ sigaction(SIGINT, &act, NULL);
+
+ sigfillset(&mask);
+ sigdelset(&mask, SIGTERM);
+ sigdelset(&mask, SIGINT);
+ sigprocmask(SIG_SETMASK, &mask, NULL);
+}
+
+static void log_open(void)
+{
+ klogctl(KLOG_OPEN, NULL, 0);
+
+ if (level) {
+ klogctl(KLOG_CONSOLE_LEVEL, NULL, level);
+ } else {
+ klogctl(KLOG_CONSOLE_OFF, NULL, 0);
+ }
+
+ openlog("kernel", 0, LOG_KERN);
+}
+
+static void log_close(void)
+{
+ klogctl(KLOG_CONSOLE_ON, NULL, 0);
+ klogctl(KLOG_CLOSE, NULL, 0);
+ syslog(LOG_NOTICE, "-- klogd terminating --");
+}
+
+int main(int argc, char **argv)
+{
+ int diff, count = 0, priority, ret = EXIT_SUCCESS;
+ char *ptr, *end;
+
+ process_options(argc, argv);
+ sigsetup();
+ log_open();
+
+ /* TODO: seccomp lockdown? */
+
+ while (running) {
+ diff = klogctl(KLOG_READ, log_buffer + count,
+ sizeof(log_buffer) - 1 - count);
+
+ if (diff < 0) {
+ if (errno == EINTR)
+ continue;
+ syslog(LOG_CRIT, "klogctl read: %s", strerror(errno));
+ ret = EXIT_FAILURE;
+ break;
+ }
+
+ count += diff;
+ log_buffer[count] = '\0';
+ ptr = log_buffer;
+
+ for (;;) {
+ end = strchr(ptr, '\n');
+ if (end == NULL) {
+ count = strlen(ptr);
+ memmove(log_buffer, ptr, count);
+ break;
+ }
+
+ *(end++) = '\0';
+ priority = LOG_INFO;
+
+ if (*ptr == '<') {
+ ++ptr;
+ if (*ptr)
+ priority = strtoul(ptr, &ptr, 10);
+ if (*ptr == '>')
+ ++ptr;
+ }
+
+ if (*ptr)
+ syslog(priority, "%s", ptr);
+ ptr = end;
+ }
+ }
+
+ log_close();
+ return ret;
+}