Log: new logging library API

Prepare to migrate away from GLib.  Currently, we're still using GLib
as a backend.

1 files changed, 350 insertions, 0 deletions

diff --git a/src/LogInit.cxx b/src/LogInit.cxx
new file mode 100644
index 000000000..d5e5c1d1f
--- /dev/null
+++ b/src/LogInit.cxx
@@ -0,0 +1,350 @@
+/*
+ * Copyright (C) 2003-2013 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * 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 2 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, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "config.h"
+#include "LogInit.hxx"
+#include "Log.hxx"
+#include "ConfigData.hxx"
+#include "ConfigGlobal.hxx"
+#include "ConfigOption.hxx"
+#include "system/fd_util.h"
+#include "system/FatalError.hxx"
+#include "fs/Path.hxx"
+#include "fs/FileSystem.hxx"
+#include "util/Error.hxx"
+#include "util/Domain.hxx"
+#include "system/FatalError.hxx"
+
+#include <assert.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <string.h>
+#include <stdarg.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <unistd.h>
+#include <errno.h>
+#include <glib.h>
+
+#ifdef HAVE_SYSLOG
+#include <syslog.h>
+#endif
+
+#define LOG_LEVEL_SECURE G_LOG_LEVEL_INFO
+
+#define LOG_DATE_BUF_SIZE 16
+#define LOG_DATE_LEN (LOG_DATE_BUF_SIZE - 1)
+
+static constexpr Domain log_domain("log");
+
+static GLogLevelFlags log_threshold = G_LOG_LEVEL_MESSAGE;
+
+static const char *log_charset;
+
+static bool stdout_mode = true;
+static int out_fd;
+static Path out_path = Path::Null();
+
+static void redirect_logs(int fd)
+{
+	assert(fd >= 0);
+	if (dup2(fd, STDOUT_FILENO) < 0)
+		FatalSystemError("Failed to dup2 stdout");
+	if (dup2(fd, STDERR_FILENO) < 0)
+		FatalSystemError("Failed to dup2 stderr");
+}
+
+static const char *log_date(void)
+{
+	static char buf[LOG_DATE_BUF_SIZE];
+	time_t t = time(NULL);
+	strftime(buf, LOG_DATE_BUF_SIZE, "%b %d %H:%M : ", localtime(&t));
+	return buf;
+}
+
+/**
+ * Determines the length of the string excluding trailing whitespace
+ * characters.
+ */
+static int
+chomp_length(const char *p)
+{
+	size_t length = strlen(p);
+
+	while (length > 0 && g_ascii_isspace(p[length - 1]))
+		--length;
+
+	return (int)length;
+}
+
+static void
+file_log_func(const gchar *domain,
+	      GLogLevelFlags log_level,
+	      const gchar *message, gcc_unused gpointer user_data)
+{
+	char *converted;
+
+	if (log_level > log_threshold)
+		return;
+
+	if (log_charset != NULL) {
+		converted = g_convert_with_fallback(message, -1,
+						    log_charset, "utf-8",
+						    NULL, NULL, NULL, NULL);
+		if (converted != NULL)
+			message = converted;
+	} else
+		converted = NULL;
+
+	if (domain == nullptr)
+		domain = "";
+
+	fprintf(stderr, "%s%s%s%.*s\n",
+		stdout_mode ? "" : log_date(),
+		domain, *domain == 0 ? "" : ": ",
+		chomp_length(message), message);
+
+	g_free(converted);
+}
+
+static void
+log_init_stdout(void)
+{
+	g_log_set_default_handler(file_log_func, NULL);
+}
+
+static int
+open_log_file(void)
+{
+	assert(!out_path.IsNull());
+
+	return OpenFile(out_path, O_CREAT | O_WRONLY | O_APPEND, 0666);
+}
+
+static bool
+log_init_file(unsigned line, Error &error)
+{
+	assert(!out_path.IsNull());
+
+	out_fd = open_log_file();
+	if (out_fd < 0) {
+		const std::string out_path_utf8 = out_path.ToUTF8();
+		error.FormatErrno("failed to open log file \"%s\" (config line %u)",
+				  out_path_utf8.c_str(), line);
+		return false;
+	}
+
+	g_log_set_default_handler(file_log_func, NULL);
+	return true;
+}
+
+#ifdef HAVE_SYSLOG
+
+static int
+glib_to_syslog_level(GLogLevelFlags log_level)
+{
+	switch (log_level & G_LOG_LEVEL_MASK) {
+	case G_LOG_LEVEL_ERROR:
+	case G_LOG_LEVEL_CRITICAL:
+		return LOG_ERR;
+
+	case G_LOG_LEVEL_WARNING:
+		return LOG_WARNING;
+
+	case G_LOG_LEVEL_MESSAGE:
+		return LOG_NOTICE;
+
+	case G_LOG_LEVEL_INFO:
+		return LOG_INFO;
+
+	case G_LOG_LEVEL_DEBUG:
+		return LOG_DEBUG;
+
+	default:
+		return LOG_NOTICE;
+	}
+}
+
+static void
+syslog_log_func(const gchar *domain,
+		GLogLevelFlags log_level, const gchar *message,
+		gcc_unused gpointer user_data)
+{
+	if (stdout_mode) {
+		/* fall back to the file log function during
+		   startup */
+		file_log_func(domain, log_level,
+			      message, user_data);
+		return;
+	}
+
+	if (log_level > log_threshold)
+		return;
+
+	if (domain == nullptr)
+		domain = "";
+
+	syslog(glib_to_syslog_level(log_level), "%s%s%.*s",
+	       domain, *domain == 0 ? "" : ": ",
+	       chomp_length(message), message);
+}
+
+static void
+log_init_syslog(void)
+{
+	assert(out_path.IsNull());
+
+	openlog(PACKAGE, 0, LOG_DAEMON);
+	g_log_set_default_handler(syslog_log_func, NULL);
+}
+
+#endif
+
+static inline GLogLevelFlags
+parse_log_level(const char *value, unsigned line)
+{
+	if (0 == strcmp(value, "default"))
+		return G_LOG_LEVEL_MESSAGE;
+	if (0 == strcmp(value, "secure"))
+		return LOG_LEVEL_SECURE;
+	else if (0 == strcmp(value, "verbose"))
+		return G_LOG_LEVEL_DEBUG;
+	else {
+		FormatFatalError("unknown log level \"%s\" at line %u",
+				 value, line);
+		return G_LOG_LEVEL_MESSAGE;
+	}
+}
+
+void
+log_early_init(bool verbose)
+{
+	if (verbose)
+		log_threshold = G_LOG_LEVEL_DEBUG;
+
+	log_init_stdout();
+}
+
+bool
+log_init(bool verbose, bool use_stdout, Error &error)
+{
+	const struct config_param *param;
+
+	g_get_charset(&log_charset);
+
+	if (verbose)
+		log_threshold = G_LOG_LEVEL_DEBUG;
+	else if ((param = config_get_param(CONF_LOG_LEVEL)) != NULL)
+		log_threshold = parse_log_level(param->value, param->line);
+
+	if (use_stdout) {
+		log_init_stdout();
+		return true;
+	} else {
+		param = config_get_param(CONF_LOG_FILE);
+		if (param == NULL) {
+#ifdef HAVE_SYSLOG
+			/* no configuration: default to syslog (if
+			   available) */
+			log_init_syslog();
+			return true;
+#else
+			error.Set(log_domain,
+				  "config parameter 'log_file' not found");
+			return false;
+#endif
+#ifdef HAVE_SYSLOG
+		} else if (strcmp(param->value, "syslog") == 0) {
+			log_init_syslog();
+			return true;
+#endif
+		} else {
+			out_path = config_get_path(CONF_LOG_FILE, error);
+			return !out_path.IsNull() &&
+				log_init_file(param->line, error);
+		}
+	}
+}
+
+static void
+close_log_files(void)
+{
+	if (stdout_mode)
+		return;
+
+#ifdef HAVE_SYSLOG
+	if (out_path.IsNull())
+		closelog();
+#endif
+}
+
+void
+log_deinit(void)
+{
+	close_log_files();
+	out_path = Path::Null();
+}
+
+
+void setup_log_output(bool use_stdout)
+{
+	fflush(NULL);
+	if (!use_stdout) {
+#ifndef WIN32
+		if (out_path.IsNull())
+			out_fd = open("/dev/null", O_WRONLY);
+#endif
+
+		if (out_fd >= 0) {
+			redirect_logs(out_fd);
+			close(out_fd);
+		}
+
+		stdout_mode = false;
+		log_charset = NULL;
+	}
+}
+
+int cycle_log_files(void)
+{
+	int fd;
+
+	if (stdout_mode || out_path.IsNull())
+		return 0;
+
+	assert(!out_path.IsNull());
+
+	FormatDebug(log_domain, "Cycling log files");
+	close_log_files();
+
+	fd = open_log_file();
+	if (fd < 0) {
+		const std::string out_path_utf8 = out_path.ToUTF8();
+		FormatError(log_domain,
+			    "error re-opening log file: %s",
+			    out_path_utf8.c_str());
+		return -1;
+	}
+
+	redirect_logs(fd);
+	FormatDebug(log_domain, "Done cycling log files");
+	return 0;
+}