Tools: acrnlog: fix confusing message "bad file descriptor" when start acrnlog

ACRNLog tries to open acrn_hvlog_last_* without check the presence of the device nodes at startup, which results a confusing message reporting "bad file descriptor" when there is no last device nodes exist. This commit fix the issue by checking the number of last devices before trying to open them.

Tracked-On: #2787
Signed-off-by: Jiang Mao <maox.jiang@intel.com>
Acked-by: Yan, Like <like.yan@intel.com>

Author: JiangMaox

tools/acrnlog/acrnlog.c

@@ -24,7 +24,7 @@
 				"Try reducing polling interval"
 
 /* Count of /dev/acrn_hvlog_cur_xxx */
-static unsigned int dev_cnt;
+static int cur_cnt,last_cnt;
 static unsigned long interval = DEFAULT_POLL_INTERVAL;
 
 /* this is for log file */
@@ -83,9 +83,8 @@ struct hvlog_dev {
 
 size_t write_log_file(struct hvlog_file * log, const char *buf, size_t len);
 
-static int get_dev_cnt(void)
+static int get_dev_cnt(char *prefix)
 {
-	char prefix[32] = "acrn_hvlog_cur_"; /* acrnlog dev prefix */
 	struct dirent *pdir;
 	int cnt = 0;
 	char *ret;
@@ -354,8 +353,8 @@ static void *cur_read_func(void *arg)
 	char warn_msg[LOG_MSG_SIZE] = {0};
 
 	while (1) {
-		hvlog_dev_read_msg(cur, dev_cnt);
-		msg = get_min_seq_msg(cur, dev_cnt);
+		hvlog_dev_read_msg(cur, cur_cnt);
+		msg = get_min_seq_msg(cur, cur_cnt);
 		if (!msg) {
 			usleep(interval);
 			continue;
@@ -502,27 +501,32 @@ int main(int argc, char *argv[])
 		return ret;
 	}
 
-	dev_cnt = get_dev_cnt();
-	if (dev_cnt == 0) {
+	cur_cnt = get_dev_cnt("acrn_hvlog_cur_");
+	last_cnt = get_dev_cnt("acrn_hvlog_last_");
+
+	if (cur_cnt == 0) {
 		printf("Failed to find acrn hvlog devices, please check whether module acrn_hvlog is inserted\n");
 		return -1;
-	}
+	} else if (cur_cnt == -1)
+		return -1;
 
-	cur = calloc(dev_cnt, sizeof(struct hvlog_data));
+	cur = calloc(cur_cnt, sizeof(struct hvlog_data));
 	if (!cur) {
 		printf("Failed to allocate buf for cur log buf\n");
 		return -1;
 	}
 
-	last = calloc(dev_cnt, sizeof(struct hvlog_data));
-	if (!last) {
-		printf("Failed to allocate buf for last log buf\n");
-		free(cur);
-		return -1;
+	if (last_cnt) {
+		last = calloc(cur_cnt, sizeof(struct hvlog_data));
+		if (!last) {
+			printf("Failed to allocate buf for last log buf\n");
+			free(cur);
+			return -1;
+		}
 	}
 
 	num_cur = 0;
-	for (i = 0; i < dev_cnt; i++) {
+	for (i = 0; i < cur_cnt; i++) {
 		if (snprintf(name, sizeof(name), "/dev/acrn_hvlog_cur_%d", i) >= sizeof(name)) {
 			printf("ERROR: cur hvlog path is truncated\n");
 			return -1;
@@ -536,17 +540,19 @@ int main(int argc, char *argv[])
 	}
 
 	num_last = 0;
-	for (i = 0; i < dev_cnt; i++) {
-		if (snprintf(name, sizeof(name), "/dev/acrn_hvlog_last_%d", i) >= sizeof(name)) {
-			printf("ERROR: last hvlog path is truncated\n");
-			return -1;
+	if (last_cnt) {
+		for (i = 0; i < cur_cnt; i++) {
+			if (snprintf(name, sizeof(name), "/dev/acrn_hvlog_last_%d", i) >= sizeof(name)) {
+				printf("ERROR: last hvlog path is truncated\n");
+				return -1;
+			}
+			last[i].dev = hvlog_open_dev(name);
+			if (!last[i].dev)
+				perror(name);
+			else
+				num_last++;
+			last[i].msg = NULL;
 		}
-		last[i].dev = hvlog_open_dev(name);
-		if (!last[i].dev)
-			perror(name);
-		else
-			num_last++;
-		last[i].msg = NULL;
 	}
 
 	printf("open cur:%d last:%d\n", num_cur, num_last);
@@ -562,8 +568,8 @@ int main(int argc, char *argv[])
 
 	if (num_last) {
 		while (1) {
-			hvlog_dev_read_msg(last, dev_cnt);
-			msg = get_min_seq_msg(last, dev_cnt);
+			hvlog_dev_read_msg(last, cur_cnt);
+			msg = get_min_seq_msg(last, cur_cnt);
 			if (!msg)
 				break;
 			write_log_file(&last_log, msg->raw, msg->len);
@@ -573,13 +579,17 @@ int main(int argc, char *argv[])
 	if (cur_thread)
 		pthread_join(cur_thread, NULL);
 
-	for (i = 0; i < dev_cnt; i++) {
+	for (i = 0; i < cur_cnt; i++) {
 		hvlog_close_dev(cur[i].dev);
+	}
+
+	for (i = 0; i < last_cnt; i++) {
 		hvlog_close_dev(last[i].dev);
 	}
 
 	free(cur);
-	free(last);
+	if (last_cnt)
+		free(last);
 
 	return 0;
 }