s3-xattr_tdb: Be nice to xattr_tdb_getxattr callers, return the full blob

In this case, the blob is already in memory, so it is easier to return the full
blob to the caller, and let the caller decide if some interface restriction
stops the full blob from being passed all the way up the stack.

This allows us to quickly write a python wrapper for this xattr storage
mechanism.

Andrew Bartlett

3 files changed, 47 insertions, 11 deletions

diff --git a/source3/lib/xattr_tdb.c b/source3/lib/xattr_tdb.c
index 21223f04b8..6f33163ed6 100644
--- a/source3/lib/xattr_tdb.c
+++ b/source3/lib/xattr_tdb.c
@@ -169,8 +169,9 @@ static NTSTATUS xattr_tdb_save_attrs(struct db_record *rec,
  */
 
 ssize_t xattr_tdb_getattr(struct db_context *db_ctx,
+			  TALLOC_CTX *mem_ctx,
 			  const struct file_id *id,
-			  const char *name, void *value, size_t size)
+			  const char *name, DATA_BLOB *blob)
 {
 	struct tdb_xattrs *attribs;
 	uint32_t i;
@@ -200,13 +201,8 @@ ssize_t xattr_tdb_getattr(struct db_context *db_ctx,
 		goto fail;
 	}
 
-	if (attribs->eas[i].value.length > size) {
-		errno = ERANGE;
-		goto fail;
-	}
-
-	memcpy(value, attribs->eas[i].value.data,
-	       attribs->eas[i].value.length);
+	*blob = attribs->eas[i].value;
+	talloc_steal(mem_ctx, blob->data);
 	result = attribs->eas[i].value.length;
 
  fail:
diff --git a/source3/lib/xattr_tdb.h b/source3/lib/xattr_tdb.h
index 0a54833f51..03bc43a38c 100644
--- a/source3/lib/xattr_tdb.h
+++ b/source3/lib/xattr_tdb.h
@@ -26,8 +26,9 @@
 /* The following definitions come from lib/util/xattr_tdb.c  */
 
 ssize_t xattr_tdb_getattr(struct db_context *db_ctx,
+			  TALLOC_CTX *mem_ctx,
 			  const struct file_id *id,
-			  const char *name, void *value, size_t size);
+			  const char *name, DATA_BLOB *blob);
 int xattr_tdb_setattr(struct db_context *db_ctx,
 		      const struct file_id *id, const char *name,
 		      const void *value, size_t size, int flags);
diff --git a/source3/modules/vfs_xattr_tdb.c b/source3/modules/vfs_xattr_tdb.c
index f5e5440e16..5c105b5194 100644
--- a/source3/modules/vfs_xattr_tdb.c
+++ b/source3/modules/vfs_xattr_tdb.c
@@ -34,16 +34,35 @@ static ssize_t xattr_tdb_getxattr(struct vfs_handle_struct *handle,
 	SMB_STRUCT_STAT sbuf;
 	struct file_id id;
 	struct db_context *db;
+	ssize_t xattr_size;
+	DATA_BLOB blob;
+	TALLOC_CTX *frame = talloc_stackframe();
+	if (!frame) {
+		errno = ENOMEM;
+		return -1;
+	}
 
 	SMB_VFS_HANDLE_GET_DATA(handle, db, struct db_context, return -1);
 
 	if (vfs_stat_smb_fname(handle->conn, path, &sbuf) == -1) {
+		TALLOC_FREE(frame);
 		return -1;
 	}
 
 	id = SMB_VFS_FILE_ID_CREATE(handle->conn, &sbuf);
 
-	return xattr_tdb_getattr(db, &id, name, value, size);
+	xattr_size = xattr_tdb_getattr(db, frame, &id, name, &blob);
+	if (xattr_size < 0) {
+		TALLOC_FREE(frame);
+		return -1;
+	}
+	if (blob.length > size) {
+		TALLOC_FREE(frame);
+		errno = ERANGE;
+		return -1;
+	}
+	memcpy(value, blob.data, size);
+	return xattr_size;
 }
 
 static ssize_t xattr_tdb_fgetxattr(struct vfs_handle_struct *handle,
@@ -53,16 +72,36 @@ static ssize_t xattr_tdb_fgetxattr(struct vfs_handle_struct *handle,
 	SMB_STRUCT_STAT sbuf;
 	struct file_id id;
 	struct db_context *db;
+	ssize_t xattr_size;
+	DATA_BLOB blob;
+	TALLOC_CTX *frame = talloc_stackframe();
+	if (!frame) {
+		errno = ENOMEM;
+		return -1;
+	}
 
 	SMB_VFS_HANDLE_GET_DATA(handle, db, struct db_context, return -1);
 
 	if (SMB_VFS_FSTAT(fsp, &sbuf) == -1) {
+		TALLOC_FREE(frame);
 		return -1;
 	}
 
 	id = SMB_VFS_FILE_ID_CREATE(handle->conn, &sbuf);
 
-	return xattr_tdb_getattr(db, &id, name, value, size);
+	xattr_size = xattr_tdb_getattr(db, frame, &id, name, &blob);
+	if (xattr_size < 0) {
+		TALLOC_FREE(frame);
+		return -1;
+	}
+	if (blob.length > size) {
+		TALLOC_FREE(frame);
+		errno = ERANGE;
+		return -1;
+	}
+	memcpy(value, blob.data, size);
+	TALLOC_FREE(frame);
+	return xattr_size;
 }
 
 static int xattr_tdb_setxattr(struct vfs_handle_struct *handle,