Add a save API to lttng-ctl

[lttng-tools.git] / src / common / config / config.c

/*
 * Copyright (C) 2013 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License, version 2 only, as
 * published by the Free Software Foundation.
 *
 * 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.
 */

#define _GNU_SOURCE
#include <assert.h>
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <inttypes.h>

#include <common/defaults.h>
#include <common/error.h>
#include <common/macros.h>
#include <common/utils.h>

#include "config.h"
#include "config-internal.h"

struct handler_filter_args {
	const char* section;
	config_entry_handler_cb handler;
	void *user_data;
};

const char * const config_str_yes = "yes";
const char * const config_str_true = "true";
const char * const config_str_on = "on";
const char * const config_str_no = "no";
const char * const config_str_false = "false";
const char * const config_str_off = "off";
const char * const config_xml_encoding = "UTF-8";
/* Size of the encoding's largest character */
const size_t config_xml_encoding_bytes_per_char = 2;
const char * const config_xml_indent_string = "\t";
const char * const config_xml_true = "true";
const char * const config_xml_false = "false";

static int config_entry_handler_filter(struct handler_filter_args *args,
		const char *section, const char *name, const char *value)
{
	int ret = 0;
	struct config_entry entry = { section, name, value };

	assert(args);

	if (!section || !name || !value) {
		ret = -EIO;
		goto end;
	}

	if (args->section) {
		if (strcmp(args->section, section)) {
			goto end;
		}
	}

	ret = args->handler(&entry, args->user_data);
end:
	return ret;
}

LTTNG_HIDDEN
int config_get_section_entries(const char *override_path, const char *section,
		config_entry_handler_cb handler, void *user_data)
{
	int ret = 0;
	FILE *config_file = NULL;
	struct handler_filter_args filter = { section, handler, user_data };

	if (override_path) {
		config_file = fopen(override_path, "r");
		if (config_file) {
			DBG("Loaded daemon configuration file at %s",
				override_path);
		} else {
			ERR("Failed to open daemon configuration file at %s",
				override_path);
			ret = -ENOENT;
			goto end;
		}
	} else {
		char *path = utils_get_home_dir();

		/* Try to open the user's daemon configuration file */
		if (path) {
			ret = asprintf(&path, DEFAULT_DAEMON_HOME_CONFIGPATH, path);
			if (ret < 0) {
				goto end;
			}

			ret = 0;
			config_file = fopen(path, "r");
			if (config_file) {
				DBG("Loaded daemon configuration file at %s", path);
			}

			free(path);
		}

		/* Try to open the system daemon configuration file */
		if (!config_file) {
			config_file = fopen(DEFAULT_DAEMON_HOME_CONFIGPATH, "r");
		}
	}

	if (!config_file) {
		DBG("No daemon configuration file found.");
		goto end;
	}

	ret = ini_parse_file(config_file,
			(ini_entry_handler) config_entry_handler_filter, (void *) &filter);

end:
	return ret;
}

LTTNG_HIDDEN
int config_parse_value(const char *value)
{
	int i, ret = 0;
	char *endptr, *lower_str;
	size_t len;
	unsigned long v;

	len = strlen(value);
	if (!len) {
		ret = -1;
		goto end;
	}

	v = strtoul(value, &endptr, 10);
	if (endptr != value) {
		ret = v;
		goto end;
	}

	lower_str = zmalloc(len + 1);
	if (!lower_str) {
		PERROR("zmalloc");
		ret = -errno;
		goto end;
	}

	for (i = 0; i < len; i++) {
		lower_str[i] = tolower(value[i]);
	}

	if (!strcmp(lower_str, config_str_yes) ||
		!strcmp(lower_str, config_str_true) ||
		!strcmp(lower_str, config_str_on)) {
		ret = 1;
	} else if (!strcmp(lower_str, config_str_no) ||
		!strcmp(lower_str, config_str_false) ||
		!strcmp(lower_str, config_str_off)) {
		ret = 0;
	} else {
		ret = -1;
	}

	free(lower_str);
end:
	return ret;
}

/*
 * Returns a xmlChar string which must be released using xmlFree().
 */
static xmlChar *encode_string(const char *in_str)
{
	xmlChar *out_str = NULL;
	xmlCharEncodingHandlerPtr handler;
	int out_len, ret, in_len;

	assert(in_str);

	handler = xmlFindCharEncodingHandler(config_xml_encoding);
	if (!handler) {
		ERR("xmlFindCharEncodingHandler return NULL!. Configure issue!");
		goto end;
	}

	in_len = strlen(in_str);
	/*
	 * Add 1 byte for the NULL terminted character. The factor 2 here is
	 * because UTF-8 can be on two bytes so this fits the worst case for each
	 * bytes.
	 */
	out_len = (in_len * 2) + 1;
	out_str = xmlMalloc(out_len);
	if (!out_str) {
		goto end;
	}

	ret = handler->input(out_str, &out_len, (const xmlChar *) in_str, &in_len);
	if (ret < 0) {
		xmlFree(out_str);
		out_str = NULL;
		goto end;
	}

	/* out_len is now the size of out_str */
	out_str[out_len] = '\0';
end:
	return out_str;
}

LTTNG_HIDDEN
struct config_writer *config_writer_create(int fd_output)
{
	int ret;
	struct config_writer *writer;
	xmlOutputBufferPtr buffer;

	writer = zmalloc(sizeof(struct config_writer));
	if (!writer) {
		PERROR("zmalloc config_writer_create");
		goto end;
	}

	buffer = xmlOutputBufferCreateFd(fd_output, NULL);
	if (!buffer) {
		goto error_destroy;
	}

	writer->writer = xmlNewTextWriter(buffer);
	ret = xmlTextWriterStartDocument(writer->writer, NULL,
		config_xml_encoding, NULL);
	if (ret < 0) {
		goto error_destroy;
	}

	ret = xmlTextWriterSetIndentString(writer->writer,
		BAD_CAST config_xml_indent_string);
	if (ret)  {
		goto error_destroy;
	}

	ret = xmlTextWriterSetIndent(writer->writer, 1);
	if (ret)  {
		goto error_destroy;
	}

end:
	return writer;
error_destroy:
	config_writer_destroy(writer);
	return NULL;
}

LTTNG_HIDDEN
int config_writer_destroy(struct config_writer *writer)
{
	int ret = 0;

	if (!writer) {
		ret = -EINVAL;
		goto end;
	}

	if (xmlTextWriterEndDocument(writer->writer) < 0) {
		WARN("Could not close XML document");
		ret = -EIO;
	}

	if (writer->writer) {
		xmlFreeTextWriter(writer->writer);
	}

	free(writer);
end:
	return ret;
}

LTTNG_HIDDEN
int config_writer_open_element(struct config_writer *writer,
	const char *element_name)
{
	int ret;
	xmlChar *encoded_element_name;

	if (!writer || !writer->writer || !element_name || !element_name[0]) {
		ret = -1;
		goto end;
	}

	encoded_element_name = encode_string(element_name);
	if (!encoded_element_name) {
		ret = -1;
		goto end;
	}

	ret = xmlTextWriterStartElement(writer->writer, encoded_element_name);
	xmlFree(encoded_element_name);
end:
	return ret > 0 ? 0 : ret;
}

LTTNG_HIDDEN
int config_writer_close_element(struct config_writer *writer)
{
	int ret;

	if (!writer || !writer->writer) {
		ret = -1;
		goto end;
	}

	ret = xmlTextWriterEndElement(writer->writer);
end:
	return ret > 0 ? 0 : ret;
}

LTTNG_HIDDEN
int config_writer_write_element_unsigned_int(struct config_writer *writer,
		const char *element_name, uint64_t value)
{
	int ret;
	xmlChar *encoded_element_name;

	if (!writer || !writer->writer || !element_name || !element_name[0]) {
		ret = -1;
		goto end;
	}

	encoded_element_name = encode_string(element_name);
	if (!encoded_element_name) {
		ret = -1;
		goto end;
	}

	ret = xmlTextWriterWriteFormatElement(writer->writer,
		encoded_element_name, "%" PRIu64, value);
	xmlFree(encoded_element_name);
end:
	return ret > 0 ? 0 : ret;
}

LTTNG_HIDDEN
int config_writer_write_element_signed_int(struct config_writer *writer,
		const char *element_name, int64_t value)
{
	int ret;
	xmlChar *encoded_element_name;

	if (!writer || !writer->writer || !element_name || !element_name[0]) {
		ret = -1;
		goto end;
	}

	encoded_element_name = encode_string(element_name);
	if (!encoded_element_name) {
		ret = -1;
		goto end;
	}

	ret = xmlTextWriterWriteFormatElement(writer->writer,
		encoded_element_name, "%" PRIi64, value);
	xmlFree(encoded_element_name);
end:
	return ret > 0 ? 0 : ret;
}

LTTNG_HIDDEN
int config_writer_write_element_bool(struct config_writer *writer,
		const char *element_name, int value)
{
	return config_writer_write_element_string(writer, element_name,
		value ? config_xml_true : config_xml_false);
}

LTTNG_HIDDEN
int config_writer_write_element_string(struct config_writer *writer,
		const char *element_name, const char *value)
{
	int ret;
	xmlChar *encoded_element_name = NULL;
	xmlChar *encoded_value = NULL;

	if (!writer || !writer->writer || !element_name || !element_name[0] ||
		!value) {
		ret = -1;
		goto end;
	}

	encoded_element_name = encode_string(element_name);
	if (!encoded_element_name) {
		ret = -1;
		goto end;
	}

	encoded_value = encode_string(value);
	if (!encoded_value) {
		ret = -1;
		goto end;
	}

	ret = xmlTextWriterWriteElement(writer->writer, encoded_element_name,
		encoded_value);
end:
	xmlFree(encoded_element_name);
	xmlFree(encoded_value);
	return ret > 0 ? 0 : ret;
}