Merge pull request #486 from PX4/param_save_fix

Parameter saving fixed

src/modules/commander/commander.cpp

@@ -687,7 +687,7 @@ int commander_thread_main(int argc, char *argv[])
 
 	bool updated = false;
 
-	bool rc_calibration_ok = (OK == rc_calibration_check());
+	bool rc_calibration_ok = (OK == rc_calibration_check(mavlink_fd));
 
 	/* Subscribe to safety topic */
 	int safety_sub = orb_subscribe(ORB_ID(safety));
@@ -802,7 +802,7 @@ int commander_thread_main(int argc, char *argv[])
 				status_changed = true;
 
 				/* re-check RC calibration */
-				rc_calibration_ok = (OK == rc_calibration_check());
+				rc_calibration_ok = (OK == rc_calibration_check(mavlink_fd));
 
 				/* navigation parameters */
 				param_get(_param_takeoff_alt, &takeoff_alt);

src/modules/systemlib/param/param.c

@@ -508,64 +508,63 @@ param_get_default_file(void)
 int
 param_save_default(void)
 {
-	int result;
-	unsigned retries = 0;
-
-	/* delete the file in case it exists */
-	struct stat buffer;
-	if (stat(param_get_default_file(), &buffer) == 0) {
-
-		do {
-			result = unlink(param_get_default_file());
-			if (result != 0) {
-				retries++;
-				usleep(1000 * retries);
-			}
-		} while (result != OK && retries < 10);
-
-		if (result != OK)
-			warnx("unlinking file %s failed.", param_get_default_file());
-	}
-
-	/* create the file */
+	int res;
 	int fd;
 
-	do {
-		/* do another attempt in case the unlink call is not synced yet */
-		fd = open(param_get_default_file(), O_WRONLY | O_CREAT | O_EXCL);
+	const char *filename = param_get_default_file();
+	const char *filename_tmp = malloc(strlen(filename) + 5);
+	sprintf(filename_tmp, "%s.tmp", filename);
+
+	/* delete temp file if exist */
+	res = unlink(filename_tmp);
+
+	if (res != OK && errno == ENOENT)
+		res = OK;
+
+	if (res != OK)
+		warn("failed to delete temp file: %s", filename_tmp);
+
+	if (res == OK) {
+		/* write parameters to temp file */
+		fd = open(filename_tmp, O_WRONLY | O_CREAT | O_EXCL);
+
 		if (fd < 0) {
-			retries++;
-			usleep(1000 * retries);
+			warn("failed to open temp file: %s", filename_tmp);
+			res = ERROR;
 		}
 
-	} while (fd < 0 && retries < 10);
+		if (res == OK) {
+			res = param_export(fd, false);
 
-	if (fd < 0) {
-		
-		warn("opening '%s' for writing failed", param_get_default_file());
-		return fd;
-	}
-
-	do {
-		result = param_export(fd, false);
-
-		if (result != OK) {
-			retries++;
-			usleep(1000 * retries);
+			if (res != OK)
+				warnx("failed to write parameters to file: %s", filename_tmp);
 		}
 
-	} while (result != 0 && retries < 10);
-
-
-	close(fd);
-
-	if (result != OK) {
-		warn("error exporting parameters to '%s'", param_get_default_file());
-		(void)unlink(param_get_default_file());
-		return result;
+		close(fd);
 	}
 
-	return 0;
+	if (res == OK) {
+		/* delete parameters file */
+		res = unlink(filename);
+
+		if (res != OK && errno == ENOENT)
+			res = OK;
+
+		if (res != OK)
+			warn("failed to delete parameters file: %s", filename);
+	}
+
+	if (res == OK) {
+		/* rename temp file to parameters */
+		res = rename(filename_tmp, filename);
+
+		if (res != OK)
+			warn("failed to rename %s to %s", filename_tmp, filename);
+	}
+
+	free(filename_tmp);
+
+	return res;
 }
 
 /**

src/modules/systemlib/rc_check.c

@@ -47,14 +47,12 @@
 #include <mavlink/mavlink_log.h>
 #include <uORB/topics/rc_channels.h>
 
-int rc_calibration_check(void) {
+int rc_calibration_check(int mavlink_fd) {
 
 	char nbuf[20];
 	param_t _parameter_handles_min, _parameter_handles_trim, _parameter_handles_max,
 	_parameter_handles_rev, _parameter_handles_dz;
 
-	int mavlink_fd = open(MAVLINK_LOG_DEVICE, 0);
-
 	float param_min, param_max, param_trim, param_rev, param_dz;
 
 	/* first check channel mappings */

src/modules/systemlib/rc_check.h

@@ -47,6 +47,6 @@
  * @return			0 / OK if RC calibration is ok, index + 1 of the first
  *				channel that failed else (so 1 == first channel failed)
  */
-__EXPORT int	rc_calibration_check(void);
+__EXPORT int	rc_calibration_check(int mavlink_fd);
 
 __END_DECLS

src/systemcmds/preflight_check/preflight_check.c

@@ -140,7 +140,7 @@ int preflight_check_main(int argc, char *argv[])
 
 	/* ---- RC CALIBRATION ---- */
 
-	bool rc_ok = (OK == rc_calibration_check());
+	bool rc_ok = (OK == rc_calibration_check(mavlink_fd));
 
 	/* warn */
 	if (!rc_ok)
@@ -227,4 +227,4 @@ static int led_off(int leds, int led)
 static int led_on(int leds, int led)
 {
 	return ioctl(leds, LED_ON, led);
-}
+}