fix bugs in lseek in dfs_posix.c and dfs_jffs2.c

git-svn-id: https://rt-thread.googlecode.com/svn/trunk@1946 bbd45198-f89e-11dd-88c7-29a3b14d5316

components/dfs/filesystems/jffs2/dfs_jffs2.c

@@ -438,10 +438,12 @@ static int dfs_jffs2_lseek(struct dfs_fd* file,
 	jffs2_file = (cyg_file *)(file->data);		
 	
 	/* set offset as current offset */
-	jffs2_file_lseek(jffs2_file, &offset, SEEK_SET);
+	result = jffs2_file_lseek(jffs2_file, &offset, SEEK_SET);
 	if (result)
 		return jffs2_result_to_dfs(result);
-	return 0;
+	/* update file position */
+	file->pos = offset;
+	return offset;
 }
 
 /* return the size of  struct dirent*/

components/dfs/src/dfs_posix.c

@@ -199,11 +199,16 @@ off_t lseek(int fd, off_t offset, int whence)
 	case DFS_SEEK_END:
 		offset += d->size;
 		break;
+
+	default:
+		rt_set_errno(-DFS_STATUS_EINVAL);
+		return -1;
+
 	}
 
 	if (offset < 0)
 	{
-		rt_set_errno(DFS_STATUS_EINVAL);
+		rt_set_errno(-DFS_STATUS_EINVAL);
 		return -1;
 	}
 	result = dfs_file_lseek(d, offset);