btrfs: Return more than a single dirent at a time in btrfs_read_dir().

* similar to what mmlr did in hrev45575 for bfs.

src/add-ons/kernel/file_systems/btrfs/DirectoryIterator.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011, Jérôme Duval, [email protected].
+ * Copyright 2011-2013, Jérôme Duval, [email protected].
  * This file may be used under the terms of the MIT License.
  */
 
@@ -52,14 +52,18 @@ status_t
 DirectoryIterator::GetNext(char* name, size_t* _nameLength, ino_t* _id)
 {
 	if (fOffset == 0) {
-		*_nameLength = 3;
+		if (*_nameLength < 3)
-		strlcpy(name, "..", *_nameLength);
+			return B_BUFFER_OVERFLOW;
+		*_nameLength = 2;
+		strlcpy(name, "..", *_nameLength + 1);
 		*_id = fInode->ID();
 		fOffset = 1;
 		return B_OK;
 	} else if (fOffset == 1) {
-		*_nameLength = 2;
+		if (*_nameLength < 2)
-		strlcpy(name, ".", *_nameLength);
+			return B_BUFFER_OVERFLOW;
+		*_nameLength = 1;
+		strlcpy(name, ".", *_nameLength + 1);
 		fOffset = 2;
 		if (fInode->ID() == BTRFS_OBJECT_ID_CHUNK_TREE) {
 			*_id = fInode->ID();
@@ -85,12 +89,19 @@ DirectoryIterator::GetNext(char* name, size_t* _nameLength, ino_t* _id)
 		entry = (btrfs_dir_entry *)((uint8*)entry + entry->Length());
 	}
 
+	size_t length = entry->NameLength();
+
 	TRACE("DirectoryIterator::GetNext() entries_length %ld name_length %d\n",
 		entries_length, entry->NameLength());
 
-	memcpy(name, entry + 1, entry->NameLength());
+	if (length + 1 > *_nameLength) {
-	name[entry->NameLength()] = '\0';
+		free(entries);
-	*_nameLength = entry->NameLength();
+		return B_BUFFER_OVERFLOW;
+	}
+
+	memcpy(name, entry + 1, length);
+	name[length] = '\0';
+	*_nameLength = length;
 	*_id = entry->InodeID();
 	free(entries);
 

src/add-ons/kernel/file_systems/btrfs/kernel_interface.cpp

@@ -520,22 +520,41 @@ btrfs_read_dir(fs_volume *_volume, fs_vnode *_node, void *_cookie,
 	struct dirent *dirent, size_t bufferSize, uint32 *_num)
 {
 	DirectoryIterator* iterator = (DirectoryIterator*)_cookie;
-
-	size_t length = bufferSize;
-	ino_t id;
-	status_t status = iterator->GetNext(dirent->d_name, &length, &id);
-	if (status == B_ENTRY_NOT_FOUND) {
-		*_num = 0;
-		return B_OK;
-	} else if (status != B_OK)
-		return status;
-
 	Volume* volume = (Volume*)_volume->private_volume;
-	dirent->d_dev = volume->ID();
-	dirent->d_ino = id;
-	dirent->d_reclen = sizeof(struct dirent) + length;
-	*_num = 1;
 
+	uint32 maxCount = *_num;
+	uint32 count = 0;
+
+	while (count < maxCount && bufferSize > sizeof(struct dirent)) {
+		ino_t id;
+		size_t length = bufferSize - sizeof(struct dirent) + 1;
+
+		status_t status = iterator->GetNext(dirent->d_name, &length,
+			&id);
+
+		if (status == B_ENTRY_NOT_FOUND)
+			break;
+
+		if (status == B_BUFFER_OVERFLOW) {
+			// the remaining name buffer length was too small
+			if (count == 0)
+				return B_BUFFER_OVERFLOW;
+			break;
+		}
+
+		if (status != B_OK)
+			return status;
+
+		dirent->d_dev = volume->ID();
+		dirent->d_ino = id;
+		dirent->d_reclen = sizeof(struct dirent) + length;
+
+		bufferSize -= dirent->d_reclen;
+		dirent = (struct dirent*)((uint8*)dirent + dirent->d_reclen);
+		count++;
+	}
+
+	*_num = count;
 	return B_OK;
 }