| Index: src/platform/update_engine/update_metadata.proto
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| diff --git a/src/platform/update_engine/update_metadata.proto b/src/platform/update_engine/update_metadata.proto
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| new file mode 100644
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| index 0000000000000000000000000000000000000000..48935d8a6b2b3f5f1ed2569f8047ec3e4689f38c
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| --- /dev/null
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| +++ b/src/platform/update_engine/update_metadata.proto
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| @@ -0,0 +1,127 @@
|
| +// Copyright (c) 2009 The Chromium Authors. All rights reserved.
|
| +// Use of this source code is governed by a BSD-style license that can be
|
| +// found in the LICENSE file.
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| +
|
| +// Update file format: A delta update file contains all the deltas needed
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| +// to update a system from one specific version to another specific
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| +// version. The update format is represented by this struct pseudocode:
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| +// struct delta_update_file {
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| +// char magic[4] = "CrAU";
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| +// uint64 bom_offset; // Offset of protobuf DeltaArchiveManifest
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| +// uint64 bom_size; // Sise of protobuf DeltaArchiveManifest
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| +//
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| +// // Data blobs for files, no specific format. The specific offset
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| +// // and length of each data blob is recorded in the DeltaArchiveManifest.
|
| +// struct {
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| +// char data[];
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| +// } blobs[];
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| +//
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| +// // The Gzip compressed DeltaArchiveManifest
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| +// char bom[];
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| +// };
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| +
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| +// The DeltaArchiveManifest protobuf is an ordered list of File objects.
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| +// These File objects are stored in a linear array in the
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| +// DeltaArchiveManifest, each with a specific index. Each File object
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| +// can contain children in its children list. Each child in the list
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| +// has a name and an index. The index refers to the index within
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| +// DeltaArchiveManifest.files. Thus, the DeltaArchiveManifest.files
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| +// can be seen as a tree structure that mimicks the filesystem.
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| +// The root object (the object an index 0) has no name, since names
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| +// for children are stored in the parent.
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| +
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| +// The DeltaArchiveManifest will contain one File entry for each
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| +// file that will be on the resultant filesystem. Because we have
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| +// a tree structure, and children are ordered alphabetically within
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| +// a parent, we can do log-time˜path lookup on a DeltaArchiveManifest
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| +// object. We can also iterate through a DeltaArchiveManifest object
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| +// using a preorder tree traversal to see each file in the
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| +// DeltaArchiveManifest, seeing each directory before any of its children;
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| +// this takes linear time.
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| +
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| +// Here's an example from Dan Erat showing DeltaArchiveManifest
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| +// for a filesystem with files /bin/cat and /bin/ls.:
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| +
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| +// files[0] { // "/" directory
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| +// children[0] {
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| +// name "bin"
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| +// index 1
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| +// }
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| +// }
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| +// files[1] { // "/bin" directory
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| +// children[0] {
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| +// name "cat"
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| +// index 2
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| +// }
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| +// children[1] {
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| +// name "ls"
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| +// index 3
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| +// }
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| +// }
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| +// files[2] { // "/bin/cat"
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| +// }
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| +// files[3] { // "/bin/ls"
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| +// }
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| +
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| +// If a file has a data_format set, it should also have data_offset and
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| +// data_length set. data_offset and data_length refer to a range of bytes
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| +// in the delta update file itself which have the format specified by
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| +// data_format. FULL and FULL_GZ mean the entire file is present (FULL_GZ,
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| +// gzip compressed). BSDIFF means the old file with the same path should be
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| +// patched with 'bspatch' to produce the desired output file. COURGETTE
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| +// is not yet used, but it will be another binary diff format.
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| +
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| +// Directories should not have any data.
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| +
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| +// There are other types of files, too: symlinks, block and character devices,
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| +// fifos, and sockets. Fifos and sockets contain no data. Block and
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| +// character devices have data. It must be the format FULL or FULL_GZ, and
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| +// the contents are a serialized LinuxDevice protobuf. Symlinks must either
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| +// be FULL, FULL_GZ, or have no data. A symlink with no data is unchanged,
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| +// and with data it's set to that data.
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| +
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| +// TODO(adlr): Add support for hard links; CL is prepared already.
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| +// Extended attributes are unsupported at this time.
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| +
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| +package chromeos_update_engine;
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| +
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| +message DeltaArchiveManifest {
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| + message File {
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| + // This is st_mode from struct stat. It includes file type and permission
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| + // bits.
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| + optional uint32 mode = 1;
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| + optional uint32 uid = 2;
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| + optional uint32 gid = 3;
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| +
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| + // File Data, not for directories
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| + enum DataFormat {
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| + FULL = 0; // The data is the complete file
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| + FULL_GZ = 1; // The data is the complete file gzipped
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| + BSDIFF = 2; // The data is a bsdiff binary diff
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| + COURGETTE = 3; // The data is a courgette binary diff
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| + }
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| + // If present, there is data associated with this File object and
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| + // data_offset and data_size must be set.
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| + optional DataFormat data_format = 4;
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| + // The offset into the delta file where the data (if any) is stored
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| + optional uint32 data_offset = 5;
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| + // The length of the data in the delta file
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| + optional uint32 data_length = 6;
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| +
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| + message Child {
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| + // A File that's a directory (and only those types of File objects)
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| + // will have exactly one Child submessage per child.
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| + required string name = 1; // File name of child
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| +
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| + // Index into DeltaArchiveManifest.files for the File object of the child.
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| + required uint32 index = 2;
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| + }
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| + repeated Child children = 7;
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| + }
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| + repeated File files = 1;
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| +}
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| +
|
| +message LinuxDevice {
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| + required int32 major = 1;
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| + required int32 minor = 2;
|
| +}
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|
|