Improve config file sync during configuration save. (dae3180f) · Commits · e / os / android_packages_modules_Bluetooth

system/btif/src/btif_config.c

+0 −2

Original line number	Diff line number	Diff line
		@@ -489,12 +489,10 @@ static void btif_config_write(UNUSED_ATTR UINT16 event, UNUSED_ATTR char *p_para

		pthread_mutex_lock(&lock);
		rename(CONFIG_FILE_PATH, CONFIG_BACKUP_PATH);
		sync();
		config_t *config_paired = config_new_clone(config);
		btif_config_remove_unpaired(config_paired);
		config_save(config_paired, CONFIG_FILE_PATH);
		config_free(config_paired);
		sync();
		pthread_mutex_unlock(&lock);
		}

system/osi/src/config.c

+57 −8

Original line number	Diff line number	Diff line
		@@ -23,6 +23,8 @@
		#include <assert.h>
		#include <ctype.h>
		#include <errno.h>
		#include <fcntl.h>
		#include <libgen.h>
		#include <stdio.h>
		#include <stdlib.h>
		#include <string.h>
		@@ -278,12 +280,39 @@ bool config_save(const config_t config, const char filename) {
		assert(filename != NULL);
		assert(*filename != '\0');

		char *temp_filename = osi_calloc(strlen(filename) + 5);
		// Steps to ensure content of config file gets to disk:
		//
		// 1) Open and write to temp file (e.g. bt_config.conf.new).
		// 2) Sync the temp file to disk with fsync().
		// 3) Rename temp file to actual config file (e.g. bt_config.conf).
		// This ensures atomic update.
		// 4) Sync directory that has the conf file with fsync().
		// This ensures directory entries are up-to-date.
		int dir_fd = -1;
		FILE *fp = NULL;

		// Build temp config file based on config file (e.g. bt_config.conf.new).
		static const char *temp_file_ext = ".new";
		const int filename_len = strlen(filename);
		const int temp_filename_len = filename_len + strlen(temp_file_ext) + 1;
		char *temp_filename = osi_calloc(temp_filename_len);
		snprintf(temp_filename, temp_filename_len, "%s%s", filename, temp_file_ext);

		// Extract directory from file path (e.g. /data/misc/bluedroid).
		char *temp_dirname = osi_strdup(filename);
		const char *directoryname = dirname(temp_dirname);
		if (!directoryname) {
		LOG_ERROR(LOG_TAG, "%s error extracting directory from '%s': %s", __func__, filename, strerror(errno));
		goto error;
		}

		strcpy(temp_filename, filename);
		strcat(temp_filename, ".new");
		dir_fd = open(directoryname, O_RDONLY);
		if (dir_fd < 0) {
		LOG_ERROR(LOG_TAG, "%s unable to open dir '%s': %s", __func__, directoryname, strerror(errno));
		goto error;
		}

		FILE *fp = fopen(temp_filename, "wt");
		fp = fopen(temp_filename, "wt");
		if (!fp) {
		LOG_ERROR(LOG_TAG, "%s unable to write file '%s': %s", __func__, temp_filename, strerror(errno));
		goto error;
		@@ -313,9 +342,13 @@ bool config_save(const config_t config, const char filename) {
		}
		}

		// Sync written temp file out to disk. fsync() is blocking until data makes it to disk.
		if (fsync(fileno(fp)) < 0) {
		LOG_WARN(LOG_TAG, "%s unable to fsync file '%s': %s", __func__, temp_filename, strerror(errno));
		}

		if (fclose(fp) == EOF) {
		LOG_ERROR(LOG_TAG, "%s unable to close file '%s': %s", __func__, temp_filename, strerror(errno));
		fp = NULL;
		goto error;
		}
		fp = NULL;
		@@ -326,19 +359,35 @@ bool config_save(const config_t config, const char filename) {
		goto error;
		}

		// Rename written temp file to the actual config file.
		if (rename(temp_filename, filename) == -1) {
		LOG_ERROR(LOG_TAG, "%s unable to commit file '%s': %s", __func__, filename, strerror(errno));
		goto error;
		}

		// This should ensure the directory is updated as well.
		if (fsync(dir_fd) < 0) {
		LOG_WARN(LOG_TAG, "%s unable to fsync dir '%s': %s", __func__, directoryname, strerror(errno));
		}

		if (close(dir_fd) < 0) {
		LOG_ERROR(LOG_TAG, "%s unable to close dir '%s': %s", __func__, directoryname, strerror(errno));
		goto error;
		}

		osi_free(temp_filename);
		osi_free(temp_dirname);
		return true;

		error:;
		if (fp != NULL)
		fclose(fp);
		error:
		// This indicates there is a write issue. Unlink as partial data is not acceptable.
		unlink(temp_filename);
		if (fp)
		fclose(fp);
		if (dir_fd != -1)
		close(dir_fd);
		osi_free(temp_filename);
		osi_free(temp_dirname);
		return false;
		}