[PATCH v20 13/14] log: add support for systemd journal

[Stephen Hemminger]

If DPDK application is being run as a systemd service, then
it can use the journal protocol which allows putting more information
in the log such as priority and other information.

The use of journal protocol is automatically detected and
handled.  Rather than having a dependency on libsystemd,
just use the protocol directly as defined in:
	https://systemd.io/JOURNAL_NATIVE_PROTOCOL/

Signed-off-by: Stephen Hemminger <stephen at networkplumber.org>
---
 doc/guides/prog_guide/log_lib.rst   |  14 ++
 lib/eal/common/eal_common_options.c |  11 ++
 lib/eal/common/eal_options.h        |   2 +
 lib/log/log.c                       |   5 +
 lib/log/log_internal.h              |   3 +
 lib/log/log_journal.c               | 200 ++++++++++++++++++++++++++++
 lib/log/log_private.h               |   2 +
 lib/log/log_stubs.c                 |  11 +-
 lib/log/meson.build                 |  10 +-
 lib/log/version.map                 |   1 +
 10 files changed, 255 insertions(+), 4 deletions(-)
 create mode 100644 lib/log/log_journal.c

diff --git a/doc/guides/prog_guide/log_lib.rst b/doc/guides/prog_guide/log_lib.rst
index abaedc7212..476dedb097 100644
--- a/doc/guides/prog_guide/log_lib.rst
+++ b/doc/guides/prog_guide/log_lib.rst
@@ -100,6 +100,20 @@ option. There are three possible settings for this option:
 
 If ``--syslog`` option is not specified, then only console (stderr) will be used.
 
+Messages can be redirected to systemd journal which is an enhanced version of syslog with the ``--log-journal`` option.
+
+There are three possible settings for this option:
+
+*auto*
+    If stderr is redirected to journal by ``systemd`` service
+    then use journal socket to instead of stderr for log.
+    This is the default.
+
+*never*
+    Do not try to use journal.
+
+*always*
+    Always try to direct messages to journal socket.
 
 
 Using Logging APIs to Generate Log Messages
diff --git a/lib/eal/common/eal_common_options.c b/lib/eal/common/eal_common_options.c
index 9ca7db04aa..9a82118184 100644
--- a/lib/eal/common/eal_common_options.c
+++ b/lib/eal/common/eal_common_options.c
@@ -74,6 +74,7 @@ eal_long_options[] = {
 	{OPT_IOVA_MODE,	        1, NULL, OPT_IOVA_MODE_NUM        },
 	{OPT_LCORES,            1, NULL, OPT_LCORES_NUM           },
 	{OPT_LOG_LEVEL,         1, NULL, OPT_LOG_LEVEL_NUM        },
+	{OPT_LOG_JOURNAL,	2, NULL, OPT_LOG_JOURNAL_NUM	  },
 	{OPT_LOG_TIMESTAMP,     2, NULL, OPT_LOG_TIMESTAMP_NUM    },
 	{OPT_TRACE,             1, NULL, OPT_TRACE_NUM            },
 	{OPT_TRACE_DIR,         1, NULL, OPT_TRACE_DIR_NUM        },
@@ -1617,6 +1618,7 @@ eal_log_level_parse(int argc, char * const argv[])
 		switch (opt) {
 		case OPT_LOG_LEVEL_NUM:
 		case OPT_SYSLOG_NUM:
+		case OPT_LOG_JOURNAL_NUM:
 		case OPT_LOG_TIMESTAMP_NUM:
 			if (eal_parse_common_option(opt, optarg, internal_conf) < 0)
 				return -1;
@@ -1843,6 +1845,14 @@ eal_parse_common_option(int opt, const char *optarg,
 			return -1;
 		}
 		break;
+
+	case OPT_LOG_JOURNAL_NUM:
+		if (eal_log_journal(optarg) < 0) {
+			EAL_LOG(ERR, "invalid parameters for --"
+				OPT_LOG_JOURNAL);
+			return -1;
+		}
+		break;
 #endif
 
 	case OPT_LOG_LEVEL_NUM:
@@ -2223,6 +2233,7 @@ eal_common_usage(void)
 	       "  --"OPT_PROC_TYPE"         Type of this process (primary|secondary|auto)\n"
 #ifndef RTE_EXEC_ENV_WINDOWS
 	       "  --"OPT_SYSLOG"[=<when>]   Enable use of syslog\n"
+	       "  --"OPT_LOG_JOURNAL"[=<when>]  Enable use of systemd journal\n"
 #endif
 	       "  --"OPT_LOG_LEVEL"=<level> Set global log level\n"
 	       "  --"OPT_LOG_LEVEL"=<type-match>:<level>\n"
diff --git a/lib/eal/common/eal_options.h b/lib/eal/common/eal_options.h
index e24c9eca53..c5a1c70288 100644
--- a/lib/eal/common/eal_options.h
+++ b/lib/eal/common/eal_options.h
@@ -35,6 +35,8 @@ enum {
 	OPT_LCORES_NUM,
 #define OPT_LOG_LEVEL         "log-level"
 	OPT_LOG_LEVEL_NUM,
+#define OPT_LOG_JOURNAL       "log-journal"
+	OPT_LOG_JOURNAL_NUM,
 #define OPT_LOG_TIMESTAMP     "log-timestamp"
 	OPT_LOG_TIMESTAMP_NUM,
 #define OPT_TRACE             "trace"
diff --git a/lib/log/log.c b/lib/log/log.c
index 4430b251a1..13d68402d9 100644
--- a/lib/log/log.c
+++ b/lib/log/log.c
@@ -508,6 +508,11 @@ eal_log_init(const char *id)
 #else
 	bool is_terminal = isatty(STDERR_FILENO);
 
+#ifdef RTE_EXEC_ENV_LINUX
+	if (log_journal_enabled())
+		log_journal_open(id);
+	else
+#endif
 	if (log_syslog_enabled(is_terminal))
 		log_syslog_open(id, is_terminal);
 	else
diff --git a/lib/log/log_internal.h b/lib/log/log_internal.h
index 7c7d44eed2..82fdc21ac2 100644
--- a/lib/log/log_internal.h
+++ b/lib/log/log_internal.h
@@ -29,6 +29,9 @@ int eal_log_save_pattern(const char *pattern, uint32_t level);
 __rte_internal
 int eal_log_syslog(const char *name);
 
+__rte_internal
+int eal_log_journal(const char *opt);
+
 /*
  * Convert log level to string.
  */
diff --git a/lib/log/log_journal.c b/lib/log/log_journal.c
new file mode 100644
index 0000000000..2475174fce
--- /dev/null
+++ b/lib/log/log_journal.c
@@ -0,0 +1,200 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
+
+#include <limits.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/uio.h>
+#include <sys/un.h>
+#include <unistd.h>
+
+#include <rte_common.h>
+#include <rte_log.h>
+
+#include "log_internal.h"
+#include "log_private.h"
+
+static enum {
+	LOG_JOURNAL_NEVER = 0,	/* do not use journal */
+	LOG_JOURNAL_AUTO,	/* use if stderr is set to journal */
+	LOG_JOURNAL_ALWAYS,	/* always try to use journal */
+} log_journal_opt = LOG_JOURNAL_AUTO;
+
+static int log_journal_fd = -1;
+
+int
+eal_log_journal(const char *str)
+{
+	if (str == NULL || strcmp(str, "auto") == 0)
+		log_journal_opt = LOG_JOURNAL_AUTO;
+	else if (strcmp(str, "always") == 0)
+		log_journal_opt = LOG_JOURNAL_ALWAYS;
+	else if (strcmp(str, "never") == 0)
+		log_journal_opt = LOG_JOURNAL_NEVER;
+	else
+		return -1;
+	return 0;
+}
+
+/*
+ * send structured message using journal protocol
+ * See: https://systemd.io/JOURNAL_NATIVE_PROTOCOL/
+ */
+static int
+journal_send(const char *buf, size_t len)
+{
+	struct iovec iov[4];
+	unsigned int n = 0;
+	int priority = rte_log_cur_msg_loglevel() - 1;
+	char msg[] = "MESSAGE=";
+	char newline = '\n';
+	char pbuf[16];	/* "PRIORITY=N\n" */
+
+	iov[n].iov_base = msg;
+	iov[n++].iov_len = strlen(msg);
+
+	iov[n].iov_base = (char *)(uintptr_t)buf;
+	iov[n++].iov_len = len;
+
+	/* if message doesn't end with newline, one will be applied. */
+	if (buf[len - 1] != '\n') {
+		iov[n].iov_base = &newline;
+		iov[n++].iov_len = 1;
+	}
+
+	/* priority value between 0 ("emerg") and 7 ("debug") */
+	iov[n].iov_base = pbuf;
+	iov[n++].iov_len = snprintf(pbuf, sizeof(pbuf),
+				    "PRIORITY=%d\n", priority);
+
+	return writev(log_journal_fd, iov, n);
+}
+
+
+/* wrapper for log stream to put messages into journal */
+static ssize_t
+journal_log_write(__rte_unused void *c, const char *buf, size_t size)
+{
+	return journal_send(buf, size);
+}
+
+static int
+journal_log_close(__rte_unused void *c)
+{
+	close(log_journal_fd);
+	log_journal_fd = -1;
+	return 0;
+}
+
+static cookie_io_functions_t journal_log_func = {
+	.write = journal_log_write,
+	.close = journal_log_close,
+};
+
+/*
+ * Check if stderr is going to system journal.
+ * This is the documented way to handle systemd journal
+ *
+ * See: https://systemd.io/JOURNAL_NATIVE_PROTOCOL/
+ *
+ */
+static bool
+is_journal(int fd)
+{
+	char *jenv, *endp = NULL;
+	struct stat st;
+	unsigned long dev, ino;
+
+	jenv = getenv("JOURNAL_STREAM");
+	if (jenv == NULL)
+		return false;
+
+	if (fstat(fd, &st) < 0)
+		return false;
+
+	/* systemd sets colon-separated list of device and inode number */
+	dev = strtoul(jenv, &endp, 10);
+	if (endp == NULL || *endp != ':')
+		return false;	/* missing colon */
+
+	ino = strtoul(endp + 1, NULL, 10);
+
+	return dev == st.st_dev && ino == st.st_ino;
+}
+
+/* Connect to systemd's journal service */
+static int
+open_journal(void)
+{
+	struct sockaddr_un sun = {
+		.sun_family = AF_UNIX,
+		.sun_path = "/run/systemd/journal/socket",
+	};
+	int s;
+
+	s = socket(AF_UNIX, SOCK_DGRAM, 0);
+	if (s < 0) {
+		perror("socket");
+		return -1;
+	}
+
+	if (connect(s, (struct sockaddr *)&sun, sizeof(sun)) < 0) {
+		perror("connect");
+		close(s);
+		return -1;
+	}
+
+	return s;
+}
+
+bool log_journal_enabled(void)
+{
+	if (log_journal_opt == LOG_JOURNAL_NEVER)
+		return false;
+
+	if (log_journal_opt == LOG_JOURNAL_AUTO &&
+	    !is_journal(STDERR_FILENO))
+		return false;
+
+	log_journal_fd = open_journal();
+	if (log_journal_fd < 0)
+		return false;
+
+	return true;
+}
+
+void log_journal_open(const char *id)
+{
+	FILE *log_stream;
+	char *syslog_id = NULL;
+	ssize_t len;
+
+	/* Send identifier as first message */
+	len = asprintf(&syslog_id, "SYSLOG_IDENTIFIER=%s\nSYSLOG_PID=%u",
+		       id, getpid());
+	if (len == 0)
+		goto error;
+
+	if (write(log_journal_fd, syslog_id, len) != len) {
+		perror("write");
+		goto error;
+	}
+
+	free(syslog_id);
+
+	/* redirect other log messages to journal */
+	log_stream = fopencookie(NULL, "w", journal_log_func);
+	if (log_stream != NULL) {
+		rte_openlog_stream(log_stream);
+		return;
+	}
+
+error:
+	free(syslog_id);
+	close(log_journal_fd);
+	log_journal_fd = -1;
+}
diff --git a/lib/log/log_private.h b/lib/log/log_private.h
index c4eb533529..91976ab313 100644
--- a/lib/log/log_private.h
+++ b/lib/log/log_private.h
@@ -20,5 +20,7 @@ int log_print_with_timestamp(FILE *f, const char *format, va_list ap);
 bool log_syslog_enabled(bool is_tty);
 void log_syslog_open(const char *id, bool is_terminal);
 
+bool log_journal_enabled(void);
+void log_journal_open(const char *id);
 
 #endif /* LOG_PRIVATE_H */
diff --git a/lib/log/log_stubs.c b/lib/log/log_stubs.c
index cb34217af8..6b2099f57b 100644
--- a/lib/log/log_stubs.c
+++ b/lib/log/log_stubs.c
@@ -20,9 +20,18 @@
 #include "log_internal.h"
 #include "log_private.h"
 
-/* Stubs for Windows */
+#ifdef RTE_EXEC_ENV_WINDOWS
 int
 eal_log_syslog(const char *str __rte_unused)
 {
 	return -1;
 }
+#endif
+
+#ifndef RTE_EXEC_ENV_LINUX
+int
+eal_log_journal(const char *str __rte_unused)
+{
+	return -1;
+}
+#endif
diff --git a/lib/log/meson.build b/lib/log/meson.build
index 37507299e7..0a80027326 100644
--- a/lib/log/meson.build
+++ b/lib/log/meson.build
@@ -7,10 +7,14 @@ sources = files(
         'log_timestamp.c',
 )
 
-if is_windows
-	sources += files('log_stubs.c')
-else
+if not is_windows
 	sources += files('log_syslog.c')
 endif
 
+if is_linux
+    sources += files('log_journal.c')
+else
+	sources += files('log_stubs.c')
+endif
+
 headers = files('rte_log.h')
diff --git a/lib/log/version.map b/lib/log/version.map
index 14d6681a5f..7af97ece43 100644
--- a/lib/log/version.map
+++ b/lib/log/version.map
@@ -26,6 +26,7 @@ INTERNAL {
 	global:
 
 	eal_log_init;
+	eal_log_journal;
 	eal_log_level2str;
 	eal_log_save_pattern;
 	eal_log_save_regexp;
-- 
2.43.0