[PATCH v12 11/14] log: add optional support of syslog

[Stephen Hemminger]

Log to syslog only if option is specified. And if syslog is used
then normally only log to syslog, don't duplicate output.
Also enables syslog support on FreeBSD.

Signed-off-by: Stephen Hemminger <stephen at networkplumber.org>
---
 doc/guides/linux_gsg/linux_eal_parameters.rst |  27 -----
 doc/guides/prog_guide/log_lib.rst             |  17 +++
 lib/eal/common/eal_common_options.c           |   2 +-
 lib/log/log.c                                 | 101 ++++++++++++++++--
 4 files changed, 111 insertions(+), 36 deletions(-)

diff --git a/doc/guides/linux_gsg/linux_eal_parameters.rst b/doc/guides/linux_gsg/linux_eal_parameters.rst
index ea8f381391..d86f94d8a8 100644
--- a/doc/guides/linux_gsg/linux_eal_parameters.rst
+++ b/doc/guides/linux_gsg/linux_eal_parameters.rst
@@ -108,30 +108,3 @@ Memory-related options
 *   ``--match-allocations``
 
     Free hugepages back to system exactly as they were originally allocated.
-
-Other options
-~~~~~~~~~~~~~
-
-*   ``--syslog <syslog facility>``
-
-    Set syslog facility. Valid syslog facilities are::
-
-        auth
-        cron
-        daemon
-        ftp
-        kern
-        lpr
-        mail
-        news
-        syslog
-        user
-        uucp
-        local0
-        local1
-        local2
-        local3
-        local4
-        local5
-        local6
-        local7
diff --git a/doc/guides/prog_guide/log_lib.rst b/doc/guides/prog_guide/log_lib.rst
index 504eefe1d2..abaedc7212 100644
--- a/doc/guides/prog_guide/log_lib.rst
+++ b/doc/guides/prog_guide/log_lib.rst
@@ -83,6 +83,23 @@ To prefix all console messages with ISO format time the syntax is::
 
 	/path/to/app --log-timestamp=iso
 
+Log output
+~~~~~~~~~~
+
+If desired, messages can be redirected to syslog (on Linux and FreeBSD) with the ``--syslog``
+option. There are three possible settings for this option:
+
+*always*
+    Redirect all log output to syslog.
+
+*auto*
+    Use console if it is a terminal, and use syslog if is not.
+
+*both*
+    Print to both console and syslog.
+
+If ``--syslog`` option is not specified, then only console (stderr) will be used.
+
 
 
 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 aa1faad45c..6f0fd151c1 100644
--- a/lib/eal/common/eal_common_options.c
+++ b/lib/eal/common/eal_common_options.c
@@ -91,7 +91,7 @@ eal_long_options[] = {
 	{OPT_PROC_TYPE,         1, NULL, OPT_PROC_TYPE_NUM        },
 	{OPT_SOCKET_MEM,        1, NULL, OPT_SOCKET_MEM_NUM       },
 	{OPT_SOCKET_LIMIT,      1, NULL, OPT_SOCKET_LIMIT_NUM     },
-	{OPT_SYSLOG,            1, NULL, OPT_SYSLOG_NUM           },
+	{OPT_SYSLOG,            2, NULL, OPT_SYSLOG_NUM           },
 	{OPT_VDEV,              1, NULL, OPT_VDEV_NUM             },
 	{OPT_VFIO_INTR,         1, NULL, OPT_VFIO_INTR_NUM        },
 	{OPT_VFIO_VF_TOKEN,     1, NULL, OPT_VFIO_VF_TOKEN_NUM    },
diff --git a/lib/log/log.c b/lib/log/log.c
index 2dca91306e..d8974c66db 100644
--- a/lib/log/log.c
+++ b/lib/log/log.c
@@ -13,15 +13,17 @@
 #include <sys/queue.h>
 #include <unistd.h>
 
+#ifdef RTE_EXEC_ENV_WINDOWS
+#include <rte_os_shim.h>
+#else
+#include <syslog.h>
+#endif
+
 #include <rte_log.h>
 #include <rte_per_lcore.h>
 
 #include "log_internal.h"
 
-#ifdef RTE_EXEC_ENV_WINDOWS
-#include <rte_os_shim.h>
-#endif
-
 struct rte_log_dynamic_type {
 	const char *name;
 	uint32_t loglevel;
@@ -36,14 +38,25 @@ enum eal_log_time_format {
 	EAL_LOG_TIMESTAMP_ISO,
 };
 
+enum eal_log_syslog {
+	EAL_LOG_SYSLOG_NONE = 0,	/* do not use syslog */
+	EAL_LOG_SYSLOG_AUTO,		/* use syslog only if not a terminal */
+	EAL_LOG_SYSLOG_ALWAYS,		/* always use syslog */
+	EAL_LOG_SYSLOG_BOTH,		/* log to both syslog and stderr */
+};
+
 typedef int (*log_print_t)(FILE *f, uint32_t level, const char *fmt, va_list ap);
 static int log_print(FILE *f, uint32_t level, const char *format, va_list ap);
 
+
 /** The rte_log structure. */
 static struct rte_logs {
 	uint32_t type;  /**< Bitfield with enabled logs. */
 	uint32_t level; /**< Log level. */
 	FILE *file;     /**< Output file set by rte_openlog_stream, or NULL. */
+#ifndef RTE_EXEC_ENV_WINDOWS
+	enum eal_log_syslog syslog_opt;
+#endif
 	log_print_t print_func;
 
 	enum eal_log_time_format time_format;
@@ -532,9 +545,23 @@ rte_log(uint32_t level, uint32_t logtype, const char *format, ...)
 
 /* Placeholder */
 int
-eal_log_syslog(const char *mode __rte_unused)
+eal_log_syslog(const char *str)
 {
+#ifdef RTE_EXEC_ENV_WINDOWS
+	RTE_SET_USED(str);
 	return -1;
+#else
+	if (str == NULL || strcmp(str, "auto") == 0)
+		/* log to syslog only if stderr is not a terminal */
+		rte_logs.syslog_opt = EAL_LOG_SYSLOG_AUTO;
+	else if (strcmp(str, "both") == 0)
+		rte_logs.syslog_opt = EAL_LOG_SYSLOG_BOTH;
+	else if (strcmp(str, "always") == 0)
+		rte_logs.syslog_opt = EAL_LOG_SYSLOG_ALWAYS;
+	else
+		return -1;
+	return 0;
+#endif
 }
 
 /* Set the log timestamp format */
@@ -706,17 +733,75 @@ log_print_with_timestamp(FILE *f, uint32_t level,
 	return log_print(f, level, format, ap);
 }
 
+#ifndef RTE_EXEC_ENV_WINDOWS
 /*
- * Called by rte_eal_init
+ * wrapper for log stream to put messages into syslog
+ * useful for cases like:
+ *   rte_hex_dump(rte_get_log_stream(), ...)
  */
-void
-eal_log_init(const char *id __rte_unused)
+static ssize_t
+syslog_log_write(__rte_unused void *c, const char *buf, size_t size)
+{
+	/* Syslog error levels are from 0 to 7, so subtract 1 to convert */
+	syslog(rte_log_cur_msg_loglevel() - 1, "%.*s", (int)size, buf);
+	return size;
+}
+
+static int
+syslog_log_close(__rte_unused void *c)
 {
+	closelog();
+	return 0;
+}
+
+static cookie_io_functions_t syslog_log_func = {
+	.write = syslog_log_write,
+	.close = syslog_log_close,
+};
+#endif
+
+
+/* Choose how log output is directed */
+static void
+log_output_selection(const char *id)
+{
+	RTE_SET_USED(id);
+
+#ifndef RTE_EXEC_ENV_WINDOWS
+	bool is_terminal = isatty(STDERR_FILENO);
+
+	if (!(rte_logs.syslog_opt == EAL_LOG_SYSLOG_NONE ||
+	      (rte_logs.syslog_opt == EAL_LOG_SYSLOG_AUTO && is_terminal))) {
+		int flags = LOG_NDELAY | LOG_PID;
+
+#ifdef LOG_PERROR
+		if (rte_logs.syslog_opt == EAL_LOG_SYSLOG_BOTH)
+			flags |= LOG_PERROR;
+#endif
+		openlog(id, flags, is_terminal ? LOG_USER : LOG_DAEMON);
+
+		/* redirect other log messages to syslog as well */
+		FILE *log_stream = fopencookie(NULL, "w", syslog_log_func);
+		if (log_stream != NULL)
+			default_log_stream = log_stream;
+		return;
+	}
+#endif
 	if (rte_logs.time_format != EAL_LOG_TIMESTAMP_NONE)
 		rte_logs.print_func = log_print_with_timestamp;
+}
 
+/*
+ * Called by rte_eal_init
+ */
+void
+eal_log_init(const char *id)
+{
+	rte_logs.print_func = log_print;
 	default_log_stream = stderr;
 
+	log_output_selection(id);
+
 #if RTE_LOG_DP_LEVEL >= RTE_LOG_DEBUG
 	RTE_LOG(NOTICE, EAL,
 		"Debug dataplane logs available - lower performance\n");
-- 
2.43.0