dm: ima: avoid extra calls to strlen()

Since 'scnprintf()' returns the number of characters emitted (not
including the trailing '\0'), use that return value instead of the
subsequent calls to 'strlen()' where appropriate. Compile tested only.

Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>

Author: dmantipov

drivers/md/dm-ima.c

@@ -241,10 +241,11 @@ void dm_ima_measure_on_table_load(struct dm_table *table, unsigned int status_fl
 		/*
 		 * First retrieve the target metadata.
 		 */
-		scnprintf(target_metadata_buf, DM_IMA_TARGET_METADATA_BUF_LEN,
-			  "target_index=%d,target_begin=%llu,target_len=%llu,",
-			  i, ti->begin, ti->len);
-		target_metadata_buf_len = strlen(target_metadata_buf);
+		target_metadata_buf_len =
+			scnprintf(target_metadata_buf,
+				  DM_IMA_TARGET_METADATA_BUF_LEN,
+				  "target_index=%d,target_begin=%llu,target_len=%llu,",
+				  i, ti->begin, ti->len);
 
 		/*
 		 * Then retrieve the actual target data.
@@ -448,11 +449,9 @@ void dm_ima_measure_on_device_resume(struct mapped_device *md, bool swap)
 		if (r)
 			goto error;
 
-		scnprintf(device_table_data, DM_IMA_DEVICE_BUF_LEN,
-			  "%sname=%s,uuid=%s;device_resume=no_data;",
-			  DM_IMA_VERSION_STR, dev_name, dev_uuid);
-		l = strlen(device_table_data);
-
+		l = scnprintf(device_table_data, DM_IMA_DEVICE_BUF_LEN,
+			      "%sname=%s,uuid=%s;device_resume=no_data;",
+			      DM_IMA_VERSION_STR, dev_name, dev_uuid);
 	}
 
 	capacity_len = strlen(capacity_str);
@@ -561,10 +560,9 @@ void dm_ima_measure_on_device_remove(struct mapped_device *md, bool remove_all)
 		if (dm_ima_alloc_and_copy_name_uuid(md, &dev_name, &dev_uuid, noio))
 			goto error;
 
-		scnprintf(device_table_data, DM_IMA_DEVICE_BUF_LEN,
-			  "%sname=%s,uuid=%s;device_remove=no_data;",
-			  DM_IMA_VERSION_STR, dev_name, dev_uuid);
-		l = strlen(device_table_data);
+		l = scnprintf(device_table_data, DM_IMA_DEVICE_BUF_LEN,
+			      "%sname=%s,uuid=%s;device_remove=no_data;",
+			      DM_IMA_VERSION_STR, dev_name, dev_uuid);
 	}
 
 	memcpy(device_table_data + l, remove_all_str, remove_all_len);
@@ -647,10 +645,9 @@ void dm_ima_measure_on_table_clear(struct mapped_device *md, bool new_map)
 		if (dm_ima_alloc_and_copy_name_uuid(md, &dev_name, &dev_uuid, noio))
 			goto error2;
 
-		scnprintf(device_table_data, DM_IMA_DEVICE_BUF_LEN,
-			  "%sname=%s,uuid=%s;table_clear=no_data;",
-			   DM_IMA_VERSION_STR, dev_name, dev_uuid);
-		l = strlen(device_table_data);
+		l = scnprintf(device_table_data, DM_IMA_DEVICE_BUF_LEN,
+			      "%sname=%s,uuid=%s;table_clear=no_data;",
+			      DM_IMA_VERSION_STR, dev_name, dev_uuid);
 	}
 
 	capacity_len = strlen(capacity_str);
@@ -706,7 +703,7 @@ void dm_ima_measure_on_device_rename(struct mapped_device *md)
 	char *old_device_data = NULL, *new_device_data = NULL, *combined_device_data = NULL;
 	char *new_dev_name = NULL, *new_dev_uuid = NULL, *capacity_str = NULL;
 	bool noio = true;
-	int r;
+	int r, len;
 
 	if (dm_ima_alloc_and_copy_device_data(md, &new_device_data,
 					      md->ima.active_table.num_targets, noio))
@@ -728,12 +725,11 @@ void dm_ima_measure_on_device_rename(struct mapped_device *md)
 	md->ima.active_table.device_metadata = new_device_data;
 	md->ima.active_table.device_metadata_len = strlen(new_device_data);
 
-	scnprintf(combined_device_data, DM_IMA_DEVICE_BUF_LEN * 2,
-		  "%s%snew_name=%s,new_uuid=%s;%s", DM_IMA_VERSION_STR, old_device_data,
-		  new_dev_name, new_dev_uuid, capacity_str);
+	len = scnprintf(combined_device_data, DM_IMA_DEVICE_BUF_LEN * 2,
+			"%s%snew_name=%s,new_uuid=%s;%s", DM_IMA_VERSION_STR, old_device_data,
+			new_dev_name, new_dev_uuid, capacity_str);
 
-	dm_ima_measure_data("dm_device_rename", combined_device_data, strlen(combined_device_data),
-			    noio);
+	dm_ima_measure_data("dm_device_rename", combined_device_data, len, noio);
 
 	goto exit;