[PATCH v24 12/15] log: add optional support of syslog

[Stephen Hemminger <stephen@networkplumber.org>]

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@networkplumber.org>
Acked-by: Morten Brørup <mb@smartsharesystems.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>
Acked-by: Chengwen Feng <fengchengwen@huawei.com>
---
 app/test/test_eal_flags.c                     |  5 +-
 doc/guides/linux_gsg/linux_eal_parameters.rst | 27 ------
 doc/guides/prog_guide/log_lib.rst             | 17 ++++
 lib/eal/common/eal_common_options.c           |  5 +-
 lib/log/log.c                                 | 28 +++---
 lib/log/log_private.h                         | 17 ++++
 lib/log/log_syslog.c                          | 88 +++++++++++++++++++
 lib/log/meson.build                           |  4 +
 lib/log/version.map                           |  2 +-
 9 files changed, 150 insertions(+), 43 deletions(-)
 create mode 100644 lib/log/log_syslog.c

diff --git a/app/test/test_eal_flags.c b/app/test/test_eal_flags.c
index 40dd288d5f..06295030b2 100644
--- a/app/test/test_eal_flags.c
+++ b/app/test/test_eal_flags.c
@@ -987,9 +987,10 @@ test_misc_flags(void)
 	/* With empty --syslog */
 	const char *argv3[] = {prgname, prefix, mp_flag, "--syslog"};
 	/* With valid --syslog */
-	const char *argv4[] = {prgname, prefix, mp_flag, "--syslog", "always"};
+	const char *argv4[] = {prgname, prefix, mp_flag, "--syslog=both"};
 	/* With invalid --syslog */
-	const char *argv5[] = {prgname, prefix, mp_flag, "--syslog", "error"};
+	const char *argv5[] = {prgname, prefix, mp_flag, "--syslog=invalid"};
+
 	/* With no-sh-conf, also use no-huge to ensure this test runs on BSD */
 	const char *argv6[] = {prgname, "-m", DEFAULT_MEM_SIZE,
 			no_shconf, nosh_prefix, no_huge};
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 ec3b5c3dfd..ac1aadbef4 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    },
@@ -2215,6 +2215,9 @@ eal_common_usage(void)
 	       "                      (can be used multiple times)\n"
 	       "  --"OPT_VMWARE_TSC_MAP"    Use VMware TSC map instead of native RDTSC\n"
 	       "  --"OPT_PROC_TYPE"         Type of this process (primary|secondary|auto)\n"
+#ifndef RTE_EXEC_ENV_WINDOWS
+	       "  --"OPT_SYSLOG"[=<when>]   Enable use of syslog\n"
+#endif
 	       "  --"OPT_LOG_LEVEL"=<level> Set global log level\n"
 	       "  --"OPT_LOG_LEVEL"=<type-match>:<level>\n"
 	       "                      Set specific log level\n"
diff --git a/lib/log/log.c b/lib/log/log.c
index 6ab856272c..f748551bc0 100644
--- a/lib/log/log.c
+++ b/lib/log/log.c
@@ -12,18 +12,19 @@
 #include <regex.h>
 #include <fnmatch.h>
 #include <sys/queue.h>
+#include <unistd.h>
 
 #include <rte_common.h>
 #include <rte_log.h>
 #include <rte_per_lcore.h>
 
-#include "log_internal.h"
-#include "log_private.h"
-
 #ifdef RTE_EXEC_ENV_WINDOWS
 #include <rte_os_shim.h>
 #endif
 
+#include "log_internal.h"
+#include "log_private.h"
+
 struct rte_log_dynamic_type {
 	const char *name;
 	uint32_t loglevel;
@@ -496,20 +497,23 @@ rte_log(uint32_t level, uint32_t logtype, const char *format, ...)
 	return ret;
 }
 
-/* Placeholder */
-int
-eal_log_syslog(const char *mode __rte_unused)
-{
-	return -1;
-}
-
 /*
  * Called by rte_eal_init
  */
 void
-eal_log_init(const char *id __rte_unused)
+eal_log_init(const char *id)
 {
-	if (log_timestamp_enabled())
+	bool is_terminal;
+
+#ifdef RTE_EXEC_ENV_WINDOWS
+	is_terminal = _isatty(_fileno(stderr));
+#else
+	is_terminal = isatty(STDERR_FILENO);
+#endif
+
+	if (log_syslog_enabled(is_terminal))
+		log_syslog_open(id, is_terminal);
+	else if (log_timestamp_enabled())
 		rte_logs.print_func = log_print_with_timestamp;
 	else
 		rte_logs.print_func = vfprintf;
diff --git a/lib/log/log_private.h b/lib/log/log_private.h
index 67cfe72fc6..532a481340 100644
--- a/lib/log/log_private.h
+++ b/lib/log/log_private.h
@@ -17,4 +17,21 @@ ssize_t log_timestamp(char *tsbuf, size_t tsbuflen);
 __rte_format_printf(2, 0)
 int log_print_with_timestamp(FILE *f, const char *format, va_list ap);
 
+#ifdef RTE_EXEC_ENV_WINDOWS
+static inline bool
+log_syslog_enabled(bool is_tty __rte_unused)
+{
+	return false;
+}
+
+static inline void
+log_syslog_open(const char *id __rte_unused, bool is_terminal __rte_unused)
+{
+}
+#else
+
+bool log_syslog_enabled(bool is_tty);
+void log_syslog_open(const char *id, bool is_terminal);
+#endif
+
 #endif /* LOG_PRIVATE_H */
diff --git a/lib/log/log_syslog.c b/lib/log/log_syslog.c
new file mode 100644
index 0000000000..fb69921e05
--- /dev/null
+++ b/lib/log/log_syslog.c
@@ -0,0 +1,88 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
+#include <stdbool.h>
+#include <stdio.h>
+#include <string.h>
+#include <syslog.h>
+
+#include <rte_common.h>
+#include <rte_log.h>
+
+#include "log_internal.h"
+#include "log_private.h"
+
+static enum {
+	LOG_SYSLOG_NONE = 0,	/* do not use syslog */
+	LOG_SYSLOG_AUTO,	/* use syslog only if not a terminal */
+	LOG_SYSLOG_ALWAYS,	/* always use syslog */
+	LOG_SYSLOG_BOTH,	/* log to both syslog and stderr */
+} log_syslog_opt;
+
+int
+eal_log_syslog(const char *str)
+{
+	if (str == NULL || strcmp(str, "auto") == 0)
+		log_syslog_opt = LOG_SYSLOG_AUTO;
+	else if (strcmp(str, "both") == 0)
+		log_syslog_opt = LOG_SYSLOG_BOTH;
+	else if (strcmp(str, "always") == 0)
+		log_syslog_opt = LOG_SYSLOG_ALWAYS;
+	else
+		return -1;
+	return 0;
+}
+
+bool
+log_syslog_enabled(bool is_terminal)
+{
+	switch (log_syslog_opt) {
+	default:
+		return false;
+
+	case LOG_SYSLOG_ALWAYS:
+	case LOG_SYSLOG_BOTH:
+		return true;
+
+	case LOG_SYSLOG_AUTO:
+		return !is_terminal;
+	}
+}
+
+/*
+ * When syslog is used, the log stream is redirected to a
+ * pseudo FILE handle that calls these functions.
+ */
+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,
+};
+
+void
+log_syslog_open(const char *id, bool is_terminal)
+{
+	int flags = LOG_NDELAY | LOG_PID;
+
+	if (log_syslog_opt == LOG_SYSLOG_BOTH)
+		flags |= LOG_PERROR;
+
+	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)
+		rte_openlog_stream(log_stream);
+}
diff --git a/lib/log/meson.build b/lib/log/meson.build
index 04235f6ee5..4ac232786e 100644
--- a/lib/log/meson.build
+++ b/lib/log/meson.build
@@ -7,4 +7,8 @@ sources = files(
         'log_timestamp.c',
 )
 
+if not is_windows
+    sources += files('log_syslog.c')
+endif
+
 headers = files('rte_log.h')
diff --git a/lib/log/version.map b/lib/log/version.map
index 155f8b3bbe..8be6907840 100644
--- a/lib/log/version.map
+++ b/lib/log/version.map
@@ -29,7 +29,7 @@ INTERNAL {
 	eal_log_level2str;
 	eal_log_save_pattern;
 	eal_log_save_regexp;
-	eal_log_syslog;
+	eal_log_syslog; # WINDOWS_NO_EXPORT
 	eal_log_timestamp;
 	rte_eal_log_cleanup;
 };
-- 
2.45.2