libsnapshot: Split CowReader into CowParserV2.
Remove format-specific logic from CowReader and split it out into a new
class called CowParserV2. To make reading the header easier, the
version and size bits are now in a separate CowHeaderPrefix struct.
Bug: 280529365
Test: apply OTA on CF
inspect_cow
Change-Id: I29b5617ec094d4fb0c284485883d2e921a5bdbf8
diff --git a/fs_mgr/libsnapshot/Android.bp b/fs_mgr/libsnapshot/Android.bp
index d3bd904..cba6844 100644
--- a/fs_mgr/libsnapshot/Android.bp
+++ b/fs_mgr/libsnapshot/Android.bp
@@ -179,6 +179,7 @@
"libsnapshot_cow/cow_writer.cpp",
"libsnapshot_cow/cow_format.cpp",
"libsnapshot_cow/cow_compress.cpp",
+ "libsnapshot_cow/parser_v2.cpp",
],
host_supported: true,
recovery_available: true,
diff --git a/fs_mgr/libsnapshot/include/libsnapshot/cow_format.h b/fs_mgr/libsnapshot/include/libsnapshot/cow_format.h
index c3ca00a..9f94699 100644
--- a/fs_mgr/libsnapshot/include/libsnapshot/cow_format.h
+++ b/fs_mgr/libsnapshot/include/libsnapshot/cow_format.h
@@ -52,13 +52,15 @@
// between writing the last operation/data pair, or the footer itself. In this
// case, the safest way to proceed is to assume the last operation is faulty.
-struct CowHeader {
+struct CowHeaderPrefix {
uint64_t magic;
uint16_t major_version;
uint16_t minor_version;
+ uint16_t header_size; // size of CowHeader.
+} __attribute__((packed));
- // Size of this struct.
- uint16_t header_size;
+struct CowHeader {
+ CowHeaderPrefix prefix;
// Size of footer struct
uint16_t footer_size;
@@ -88,7 +90,7 @@
// the compression type of that data (see constants below).
uint8_t compression;
- // Length of Footer Data. Currently 64 for both checksums
+ // Length of Footer Data. Currently 64.
uint16_t data_length;
// The amount of file space used by Cow operations
@@ -98,14 +100,6 @@
uint64_t num_ops;
} __attribute__((packed));
-struct CowFooterData {
- // SHA256 checksums of Footer op
- uint8_t footer_checksum[32];
-
- // SHA256 of the operation sequence.
- uint8_t ops_checksum[32];
-} __attribute__((packed));
-
// Cow operations are currently fixed-size entries, but this may change if
// needed.
struct CowOperation {
@@ -167,7 +161,7 @@
struct CowFooter {
CowFooterOperation op;
- CowFooterData data;
+ uint8_t unused[64];
} __attribute__((packed));
struct ScratchMetadata {
diff --git a/fs_mgr/libsnapshot/include/libsnapshot/cow_writer.h b/fs_mgr/libsnapshot/include/libsnapshot/cow_writer.h
index c7b83a8..4151b01 100644
--- a/fs_mgr/libsnapshot/include/libsnapshot/cow_writer.h
+++ b/fs_mgr/libsnapshot/include/libsnapshot/cow_writer.h
@@ -171,7 +171,7 @@
uint64_t GetCowSize() override;
- uint32_t GetCowVersion() { return header_.major_version; }
+ uint32_t GetCowVersion() { return header_.prefix.major_version; }
protected:
virtual bool EmitCopy(uint64_t new_block, uint64_t old_block, uint64_t num_blocks = 1) override;
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/cow_api_test.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/cow_api_test.cpp
index edc9d65..8f80bb3 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/cow_api_test.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/cow_api_test.cpp
@@ -65,9 +65,9 @@
ASSERT_TRUE(reader.Parse(cow_->fd));
const auto& header = reader.GetHeader();
- ASSERT_EQ(header.magic, kCowMagicNumber);
- ASSERT_EQ(header.major_version, kCowVersionMajor);
- ASSERT_EQ(header.minor_version, kCowVersionMinor);
+ ASSERT_EQ(header.prefix.magic, kCowMagicNumber);
+ ASSERT_EQ(header.prefix.major_version, kCowVersionMajor);
+ ASSERT_EQ(header.prefix.minor_version, kCowVersionMinor);
ASSERT_EQ(header.block_size, options.block_size);
CowFooter footer;
@@ -114,9 +114,9 @@
ASSERT_TRUE(reader.Parse(cow_->fd));
const auto& header = reader.GetHeader();
- ASSERT_EQ(header.magic, kCowMagicNumber);
- ASSERT_EQ(header.major_version, kCowVersionMajor);
- ASSERT_EQ(header.minor_version, kCowVersionMinor);
+ ASSERT_EQ(header.prefix.magic, kCowMagicNumber);
+ ASSERT_EQ(header.prefix.major_version, kCowVersionMajor);
+ ASSERT_EQ(header.prefix.minor_version, kCowVersionMinor);
ASSERT_EQ(header.block_size, options.block_size);
CowFooter footer;
@@ -193,9 +193,9 @@
ASSERT_TRUE(reader.Parse(cow_->fd));
const auto& header = reader.GetHeader();
- ASSERT_EQ(header.magic, kCowMagicNumber);
- ASSERT_EQ(header.major_version, kCowVersionMajor);
- ASSERT_EQ(header.minor_version, kCowVersionMinor);
+ ASSERT_EQ(header.prefix.magic, kCowMagicNumber);
+ ASSERT_EQ(header.prefix.major_version, kCowVersionMajor);
+ ASSERT_EQ(header.prefix.minor_version, kCowVersionMinor);
ASSERT_EQ(header.block_size, options.block_size);
CowFooter footer;
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/cow_reader.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/cow_reader.cpp
index 6749cf1..c2a7fdb 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/cow_reader.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/cow_reader.cpp
@@ -30,7 +30,7 @@
#include <zlib.h>
#include "cow_decompress.h"
-#include "libsnapshot/cow_format.h"
+#include "parser_v2.h"
namespace android {
namespace snapshot {
@@ -43,15 +43,6 @@
reader_flag_(reader_flag),
is_merge_(is_merge) {}
-static void SHA256(const void*, size_t, uint8_t[]) {
-#if 0
- SHA256_CTX c;
- SHA256_Init(&c);
- SHA256_Update(&c, data, length);
- SHA256_Final(out, &c);
-#endif
-}
-
std::unique_ptr<CowReader> CowReader::CloneCowReader() {
auto cow = std::make_unique<CowReader>();
cow->owned_fd_.reset();
@@ -63,7 +54,6 @@
cow->merge_op_start_ = merge_op_start_;
cow->num_total_data_ops_ = num_total_data_ops_;
cow->num_ordered_ops_to_merge_ = num_ordered_ops_to_merge_;
- cow->has_seq_ops_ = has_seq_ops_;
cow->data_loc_ = data_loc_;
cow->block_pos_index_ = block_pos_index_;
cow->is_merge_ = is_merge_;
@@ -101,217 +91,26 @@
bool CowReader::Parse(android::base::borrowed_fd fd, std::optional<uint64_t> label) {
fd_ = fd;
- auto pos = lseek(fd_.get(), 0, SEEK_END);
- if (pos < 0) {
- PLOG(ERROR) << "lseek end failed";
- return false;
- }
- fd_size_ = pos;
-
- if (lseek(fd_.get(), 0, SEEK_SET) < 0) {
- PLOG(ERROR) << "lseek header failed";
- return false;
- }
- if (!android::base::ReadFully(fd_, &header_, sizeof(header_))) {
- PLOG(ERROR) << "read header failed";
+ if (!ReadCowHeader(fd, &header_)) {
return false;
}
- if (header_.magic != kCowMagicNumber) {
- LOG(ERROR) << "Header Magic corrupted. Magic: " << header_.magic
- << "Expected: " << kCowMagicNumber;
- return false;
- }
- if (header_.footer_size != sizeof(CowFooter)) {
- LOG(ERROR) << "Footer size unknown, read " << header_.footer_size << ", expected "
- << sizeof(CowFooter);
- return false;
- }
- if (header_.op_size != sizeof(CowOperation)) {
- LOG(ERROR) << "Operation size unknown, read " << header_.op_size << ", expected "
- << sizeof(CowOperation);
- return false;
- }
- if (header_.cluster_ops == 1) {
- LOG(ERROR) << "Clusters must contain at least two operations to function.";
- return false;
- }
- if (header_.op_size != sizeof(CowOperation)) {
- LOG(ERROR) << "Operation size unknown, read " << header_.op_size << ", expected "
- << sizeof(CowOperation);
- return false;
- }
- if (header_.cluster_ops == 1) {
- LOG(ERROR) << "Clusters must contain at least two operations to function.";
+ CowParserV2 parser;
+ if (!parser.Parse(fd, header_, label)) {
return false;
}
- if ((header_.major_version > kCowVersionMajor) || (header_.minor_version != kCowVersionMinor)) {
- LOG(ERROR) << "Header version mismatch";
- LOG(ERROR) << "Major version: " << header_.major_version
- << "Expected: " << kCowVersionMajor;
- LOG(ERROR) << "Minor version: " << header_.minor_version
- << "Expected: " << kCowVersionMinor;
- return false;
- }
+ footer_ = parser.footer();
+ fd_size_ = parser.fd_size();
+ last_label_ = parser.last_label();
+ ops_ = std::move(parser.ops());
+ data_loc_ = parser.data_loc();
- if (!ParseOps(label)) {
- return false;
- }
// If we're resuming a write, we're not ready to merge
if (label.has_value()) return true;
return PrepMergeOps();
}
-bool CowReader::ParseOps(std::optional<uint64_t> label) {
- uint64_t pos;
- auto data_loc = std::make_shared<std::unordered_map<uint64_t, uint64_t>>();
-
- // Skip the scratch space
- if (header_.major_version >= 2 && (header_.buffer_size > 0)) {
- LOG(DEBUG) << " Scratch space found of size: " << header_.buffer_size;
- size_t init_offset = header_.header_size + header_.buffer_size;
- pos = lseek(fd_.get(), init_offset, SEEK_SET);
- if (pos != init_offset) {
- PLOG(ERROR) << "lseek ops failed";
- return false;
- }
- } else {
- pos = lseek(fd_.get(), header_.header_size, SEEK_SET);
- if (pos != header_.header_size) {
- PLOG(ERROR) << "lseek ops failed";
- return false;
- }
- // Reading a v1 version of COW which doesn't have buffer_size.
- header_.buffer_size = 0;
- }
- uint64_t data_pos = 0;
-
- if (header_.cluster_ops) {
- data_pos = pos + header_.cluster_ops * sizeof(CowOperation);
- } else {
- data_pos = pos + sizeof(CowOperation);
- }
-
- auto ops_buffer = std::make_shared<std::vector<CowOperation>>();
- uint64_t current_op_num = 0;
- uint64_t cluster_ops = header_.cluster_ops ?: 1;
- bool done = false;
-
- // Alternating op clusters and data
- while (!done) {
- uint64_t to_add = std::min(cluster_ops, (fd_size_ - pos) / sizeof(CowOperation));
- if (to_add == 0) break;
- ops_buffer->resize(current_op_num + to_add);
- if (!android::base::ReadFully(fd_, &ops_buffer->data()[current_op_num],
- to_add * sizeof(CowOperation))) {
- PLOG(ERROR) << "read op failed";
- return false;
- }
- // Parse current cluster to find start of next cluster
- while (current_op_num < ops_buffer->size()) {
- auto& current_op = ops_buffer->data()[current_op_num];
- current_op_num++;
- if (current_op.type == kCowXorOp) {
- data_loc->insert({current_op.new_block, data_pos});
- }
- pos += sizeof(CowOperation) + GetNextOpOffset(current_op, header_.cluster_ops);
- data_pos += current_op.data_length + GetNextDataOffset(current_op, header_.cluster_ops);
-
- if (current_op.type == kCowClusterOp) {
- break;
- } else if (current_op.type == kCowLabelOp) {
- last_label_ = {current_op.source};
-
- // If we reach the requested label, stop reading.
- if (label && label.value() == current_op.source) {
- done = true;
- break;
- }
- } else if (current_op.type == kCowFooterOp) {
- footer_.emplace();
- CowFooter* footer = &footer_.value();
- memcpy(&footer_->op, ¤t_op, sizeof(footer->op));
- off_t offs = lseek(fd_.get(), pos, SEEK_SET);
- if (offs < 0 || pos != static_cast<uint64_t>(offs)) {
- PLOG(ERROR) << "lseek next op failed " << offs;
- return false;
- }
- if (!android::base::ReadFully(fd_, &footer->data, sizeof(footer->data))) {
- LOG(ERROR) << "Could not read COW footer";
- return false;
- }
-
- // Drop the footer from the op stream.
- current_op_num--;
- done = true;
- break;
- } else if (current_op.type == kCowSequenceOp) {
- has_seq_ops_ = true;
- }
- }
-
- // Position for next cluster read
- off_t offs = lseek(fd_.get(), pos, SEEK_SET);
- if (offs < 0 || pos != static_cast<uint64_t>(offs)) {
- PLOG(ERROR) << "lseek next op failed " << offs;
- return false;
- }
- ops_buffer->resize(current_op_num);
- }
-
- LOG(DEBUG) << "COW file read complete. Total ops: " << ops_buffer->size();
- // To successfully parse a COW file, we need either:
- // (1) a label to read up to, and for that label to be found, or
- // (2) a valid footer.
- if (label) {
- if (!last_label_) {
- LOG(ERROR) << "Did not find label " << label.value()
- << " while reading COW (no labels found)";
- return false;
- }
- if (last_label_.value() != label.value()) {
- LOG(ERROR) << "Did not find label " << label.value()
- << ", last label=" << last_label_.value();
- return false;
- }
- } else if (!footer_) {
- LOG(ERROR) << "No COW footer found";
- return false;
- }
-
- uint8_t csum[32];
- memset(csum, 0, sizeof(uint8_t) * 32);
-
- if (footer_) {
- if (ops_buffer->size() != footer_->op.num_ops) {
- LOG(ERROR) << "num ops does not match, expected " << footer_->op.num_ops << ", found "
- << ops_buffer->size();
- return false;
- }
- if (ops_buffer->size() * sizeof(CowOperation) != footer_->op.ops_size) {
- LOG(ERROR) << "ops size does not match ";
- return false;
- }
- SHA256(&footer_->op, sizeof(footer_->op), footer_->data.footer_checksum);
- if (memcmp(csum, footer_->data.ops_checksum, sizeof(csum)) != 0) {
- LOG(ERROR) << "ops checksum does not match";
- return false;
- }
- SHA256(ops_buffer->data(), footer_->op.ops_size, csum);
- if (memcmp(csum, footer_->data.ops_checksum, sizeof(csum)) != 0) {
- LOG(ERROR) << "ops checksum does not match";
- return false;
- }
- }
-
- ops_ = ops_buffer;
- ops_->shrink_to_fit();
- data_loc_ = data_loc;
-
- return true;
-}
-
//
// This sets up the data needed for MergeOpIter. MergeOpIter presents
// data in the order we intend to merge in.
@@ -446,7 +245,8 @@
continue;
}
- if (!has_seq_ops_ && IsOrderedOp(current_op)) {
+ // Sequence ops must be the first ops in the stream.
+ if (seq_ops_set.empty() && IsOrderedOp(current_op)) {
merge_op_blocks->emplace_back(current_op.new_block);
} else if (seq_ops_set.count(current_op.new_block) == 0) {
other_ops.push_back(current_op.new_block);
@@ -718,8 +518,8 @@
bool CowReader::GetRawBytes(uint64_t offset, void* buffer, size_t len, size_t* read) {
// Validate the offset, taking care to acknowledge possible overflow of offset+len.
- if (offset < header_.header_size || offset >= fd_size_ - sizeof(CowFooter) || len >= fd_size_ ||
- offset + len > fd_size_ - sizeof(CowFooter)) {
+ if (offset < header_.prefix.header_size || offset >= fd_size_ - sizeof(CowFooter) ||
+ len >= fd_size_ || offset + len > fd_size_ - sizeof(CowFooter)) {
LOG(ERROR) << "invalid data offset: " << offset << ", " << len << " bytes";
return false;
}
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/cow_writer.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/cow_writer.cpp
index 0e18979..1eaa038 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/cow_writer.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/cow_writer.cpp
@@ -186,10 +186,10 @@
void CowWriter::SetupHeaders() {
header_ = {};
- header_.magic = kCowMagicNumber;
- header_.major_version = kCowVersionMajor;
- header_.minor_version = kCowVersionMinor;
- header_.header_size = sizeof(CowHeader);
+ header_.prefix.magic = kCowMagicNumber;
+ header_.prefix.major_version = kCowVersionMajor;
+ header_.prefix.minor_version = kCowVersionMinor;
+ header_.prefix.header_size = sizeof(CowHeader);
header_.footer_size = sizeof(CowFooter);
header_.op_size = sizeof(CowOperation);
header_.block_size = options_.block_size;
@@ -614,17 +614,6 @@
return true;
}
-// TODO: Fix compilation issues when linking libcrypto library
-// when snapuserd is compiled as part of ramdisk.
-static void SHA256(const void*, size_t, uint8_t[]) {
-#if 0
- SHA256_CTX c;
- SHA256_Init(&c);
- SHA256_Update(&c, data, length);
- SHA256_Final(out, &c);
-#endif
-}
-
bool CowWriter::Finalize() {
if (!FlushCluster()) {
LOG(ERROR) << "Finalize: FlushCluster() failed";
@@ -665,10 +654,8 @@
PLOG(ERROR) << "Failed to seek to footer position.";
return false;
}
- memset(&footer_.data.ops_checksum, 0, sizeof(uint8_t) * 32);
- memset(&footer_.data.footer_checksum, 0, sizeof(uint8_t) * 32);
+ memset(&footer_.unused, 0, sizeof(footer_.unused));
- SHA256(&footer_.op, sizeof(footer_.op), footer_.data.footer_checksum);
// Write out footer at end of file
if (!android::base::WriteFully(fd_, reinterpret_cast<const uint8_t*>(&footer_),
sizeof(footer_))) {
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/inspect_cow.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/inspect_cow.cpp
index 917cec4..c2c86ee 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/inspect_cow.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/inspect_cow.cpp
@@ -104,8 +104,9 @@
if (reader.GetFooter(&footer)) has_footer = true;
if (!opt.silent) {
- std::cout << "Version: " << header.major_version << "." << header.minor_version << "\n";
- std::cout << "Header size: " << header.header_size << "\n";
+ std::cout << "Version: " << header.prefix.major_version << "."
+ << header.prefix.minor_version << "\n";
+ std::cout << "Header size: " << header.prefix.header_size << "\n";
std::cout << "Footer size: " << header.footer_size << "\n";
std::cout << "Block size: " << header.block_size << "\n";
std::cout << "Merge ops: " << header.num_merge_ops << "\n";
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/parser_v2.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/parser_v2.cpp
new file mode 100644
index 0000000..fdb5c59
--- /dev/null
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/parser_v2.cpp
@@ -0,0 +1,238 @@
+// Copyright (C) 2023 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+#include "parser_v2.h"
+
+#include <unistd.h>
+
+#include <android-base/file.h>
+#include <android-base/logging.h>
+
+namespace android {
+namespace snapshot {
+
+using android::base::borrowed_fd;
+
+bool ReadCowHeader(android::base::borrowed_fd fd, CowHeader* header) {
+ if (lseek(fd.get(), 0, SEEK_SET) < 0) {
+ PLOG(ERROR) << "lseek header failed";
+ return false;
+ }
+
+ memset(header, 0, sizeof(*header));
+
+ if (!android::base::ReadFully(fd, &header->prefix, sizeof(header->prefix))) {
+ return false;
+ }
+ if (header->prefix.magic != kCowMagicNumber) {
+ LOG(ERROR) << "Header Magic corrupted. Magic: " << header->prefix.magic
+ << "Expected: " << kCowMagicNumber;
+ return false;
+ }
+ if (header->prefix.header_size > sizeof(CowHeader)) {
+ LOG(ERROR) << "Unknown CowHeader size (got " << header->prefix.header_size
+ << " bytes, expected at most " << sizeof(CowHeader) << " bytes)";
+ return false;
+ }
+
+ if (lseek(fd.get(), 0, SEEK_SET) < 0) {
+ PLOG(ERROR) << "lseek header failed";
+ return false;
+ }
+ return android::base::ReadFully(fd, header, header->prefix.header_size);
+}
+
+bool CowParserV2::Parse(borrowed_fd fd, const CowHeader& header, std::optional<uint64_t> label) {
+ auto pos = lseek(fd.get(), 0, SEEK_END);
+ if (pos < 0) {
+ PLOG(ERROR) << "lseek end failed";
+ return false;
+ }
+ fd_size_ = pos;
+ header_ = header;
+
+ if (header_.footer_size != sizeof(CowFooter)) {
+ LOG(ERROR) << "Footer size unknown, read " << header_.footer_size << ", expected "
+ << sizeof(CowFooter);
+ return false;
+ }
+ if (header_.op_size != sizeof(CowOperation)) {
+ LOG(ERROR) << "Operation size unknown, read " << header_.op_size << ", expected "
+ << sizeof(CowOperation);
+ return false;
+ }
+ if (header_.cluster_ops == 1) {
+ LOG(ERROR) << "Clusters must contain at least two operations to function.";
+ return false;
+ }
+ if (header_.op_size != sizeof(CowOperation)) {
+ LOG(ERROR) << "Operation size unknown, read " << header_.op_size << ", expected "
+ << sizeof(CowOperation);
+ return false;
+ }
+ if (header_.cluster_ops == 1) {
+ LOG(ERROR) << "Clusters must contain at least two operations to function.";
+ return false;
+ }
+
+ if ((header_.prefix.major_version > kCowVersionMajor) ||
+ (header_.prefix.minor_version != kCowVersionMinor)) {
+ LOG(ERROR) << "Header version mismatch, "
+ << "major version: " << header_.prefix.major_version
+ << ", expected: " << kCowVersionMajor
+ << ", minor version: " << header_.prefix.minor_version
+ << ", expected: " << kCowVersionMinor;
+ return false;
+ }
+
+ return ParseOps(fd, label);
+}
+
+bool CowParserV2::ParseOps(borrowed_fd fd, std::optional<uint64_t> label) {
+ uint64_t pos;
+ auto data_loc = std::make_shared<std::unordered_map<uint64_t, uint64_t>>();
+
+ // Skip the scratch space
+ if (header_.prefix.major_version >= 2 && (header_.buffer_size > 0)) {
+ LOG(DEBUG) << " Scratch space found of size: " << header_.buffer_size;
+ size_t init_offset = header_.prefix.header_size + header_.buffer_size;
+ pos = lseek(fd.get(), init_offset, SEEK_SET);
+ if (pos != init_offset) {
+ PLOG(ERROR) << "lseek ops failed";
+ return false;
+ }
+ } else {
+ pos = lseek(fd.get(), header_.prefix.header_size, SEEK_SET);
+ if (pos != header_.prefix.header_size) {
+ PLOG(ERROR) << "lseek ops failed";
+ return false;
+ }
+ // Reading a v1 version of COW which doesn't have buffer_size.
+ header_.buffer_size = 0;
+ }
+ uint64_t data_pos = 0;
+
+ if (header_.cluster_ops) {
+ data_pos = pos + header_.cluster_ops * sizeof(CowOperation);
+ } else {
+ data_pos = pos + sizeof(CowOperation);
+ }
+
+ auto ops_buffer = std::make_shared<std::vector<CowOperation>>();
+ uint64_t current_op_num = 0;
+ uint64_t cluster_ops = header_.cluster_ops ?: 1;
+ bool done = false;
+
+ // Alternating op clusters and data
+ while (!done) {
+ uint64_t to_add = std::min(cluster_ops, (fd_size_ - pos) / sizeof(CowOperation));
+ if (to_add == 0) break;
+ ops_buffer->resize(current_op_num + to_add);
+ if (!android::base::ReadFully(fd, &ops_buffer->data()[current_op_num],
+ to_add * sizeof(CowOperation))) {
+ PLOG(ERROR) << "read op failed";
+ return false;
+ }
+ // Parse current cluster to find start of next cluster
+ while (current_op_num < ops_buffer->size()) {
+ auto& current_op = ops_buffer->data()[current_op_num];
+ current_op_num++;
+ if (current_op.type == kCowXorOp) {
+ data_loc->insert({current_op.new_block, data_pos});
+ }
+ pos += sizeof(CowOperation) + GetNextOpOffset(current_op, header_.cluster_ops);
+ data_pos += current_op.data_length + GetNextDataOffset(current_op, header_.cluster_ops);
+
+ if (current_op.type == kCowClusterOp) {
+ break;
+ } else if (current_op.type == kCowLabelOp) {
+ last_label_ = {current_op.source};
+
+ // If we reach the requested label, stop reading.
+ if (label && label.value() == current_op.source) {
+ done = true;
+ break;
+ }
+ } else if (current_op.type == kCowFooterOp) {
+ footer_.emplace();
+ CowFooter* footer = &footer_.value();
+ memcpy(&footer_->op, ¤t_op, sizeof(footer->op));
+ off_t offs = lseek(fd.get(), pos, SEEK_SET);
+ if (offs < 0 || pos != static_cast<uint64_t>(offs)) {
+ PLOG(ERROR) << "lseek next op failed " << offs;
+ return false;
+ }
+ if (!android::base::ReadFully(fd, &footer->unused, sizeof(footer->unused))) {
+ LOG(ERROR) << "Could not read COW footer";
+ return false;
+ }
+
+ // Drop the footer from the op stream.
+ current_op_num--;
+ done = true;
+ break;
+ }
+ }
+
+ // Position for next cluster read
+ off_t offs = lseek(fd.get(), pos, SEEK_SET);
+ if (offs < 0 || pos != static_cast<uint64_t>(offs)) {
+ PLOG(ERROR) << "lseek next op failed " << offs;
+ return false;
+ }
+ ops_buffer->resize(current_op_num);
+ }
+
+ LOG(DEBUG) << "COW file read complete. Total ops: " << ops_buffer->size();
+ // To successfully parse a COW file, we need either:
+ // (1) a label to read up to, and for that label to be found, or
+ // (2) a valid footer.
+ if (label) {
+ if (!last_label_) {
+ LOG(ERROR) << "Did not find label " << label.value()
+ << " while reading COW (no labels found)";
+ return false;
+ }
+ if (last_label_.value() != label.value()) {
+ LOG(ERROR) << "Did not find label " << label.value()
+ << ", last label=" << last_label_.value();
+ return false;
+ }
+ } else if (!footer_) {
+ LOG(ERROR) << "No COW footer found";
+ return false;
+ }
+
+ uint8_t csum[32];
+ memset(csum, 0, sizeof(uint8_t) * 32);
+
+ if (footer_) {
+ if (ops_buffer->size() != footer_->op.num_ops) {
+ LOG(ERROR) << "num ops does not match, expected " << footer_->op.num_ops << ", found "
+ << ops_buffer->size();
+ return false;
+ }
+ if (ops_buffer->size() * sizeof(CowOperation) != footer_->op.ops_size) {
+ LOG(ERROR) << "ops size does not match ";
+ return false;
+ }
+ }
+
+ ops_ = ops_buffer;
+ ops_->shrink_to_fit();
+ data_loc_ = data_loc;
+ return true;
+}
+
+} // namespace snapshot
+} // namespace android
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/parser_v2.h b/fs_mgr/libsnapshot/libsnapshot_cow/parser_v2.h
new file mode 100644
index 0000000..afcf687
--- /dev/null
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/parser_v2.h
@@ -0,0 +1,55 @@
+// Copyright (C) 2023 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+#pragma once
+
+#include <stdint.h>
+
+#include <memory>
+#include <optional>
+#include <unordered_map>
+#include <vector>
+
+#include <android-base/unique_fd.h>
+#include <libsnapshot/cow_format.h>
+
+namespace android {
+namespace snapshot {
+
+class CowParserV2 {
+ public:
+ bool Parse(android::base::borrowed_fd fd, const CowHeader& header,
+ std::optional<uint64_t> label = {});
+
+ const CowHeader& header() const { return header_; }
+ const std::optional<CowFooter>& footer() const { return footer_; }
+ std::shared_ptr<std::vector<CowOperation>> ops() { return ops_; }
+ std::shared_ptr<std::unordered_map<uint64_t, uint64_t>> data_loc() const { return data_loc_; }
+ uint64_t fd_size() const { return fd_size_; }
+ const std::optional<uint64_t>& last_label() const { return last_label_; }
+
+ private:
+ bool ParseOps(android::base::borrowed_fd fd, std::optional<uint64_t> label);
+
+ CowHeader header_ = {};
+ std::optional<CowFooter> footer_;
+ std::shared_ptr<std::vector<CowOperation>> ops_;
+ std::shared_ptr<std::unordered_map<uint64_t, uint64_t>> data_loc_;
+ uint64_t fd_size_;
+ std::optional<uint64_t> last_label_;
+};
+
+bool ReadCowHeader(android::base::borrowed_fd fd, CowHeader* header);
+
+} // namespace snapshot
+} // namespace android
diff --git a/fs_mgr/libsnapshot/snapuserd/dm-snapshot-merge/snapuserd.cpp b/fs_mgr/libsnapshot/snapuserd/dm-snapshot-merge/snapuserd.cpp
index efa43b7..da9bd11 100644
--- a/fs_mgr/libsnapshot/snapuserd/dm-snapshot-merge/snapuserd.cpp
+++ b/fs_mgr/libsnapshot/snapuserd/dm-snapshot-merge/snapuserd.cpp
@@ -628,8 +628,8 @@
bool Snapuserd::MmapMetadata() {
const auto& header = reader_->GetHeader();
- if (header.major_version >= 2 && header.buffer_size > 0) {
- total_mapped_addr_length_ = header.header_size + BUFFER_REGION_DEFAULT_SIZE;
+ if (header.prefix.major_version >= 2 && header.buffer_size > 0) {
+ total_mapped_addr_length_ = header.prefix.header_size + BUFFER_REGION_DEFAULT_SIZE;
read_ahead_feature_ = true;
} else {
// mmap the first 4k page - older COW format
@@ -823,7 +823,7 @@
uint64_t Snapuserd::GetBufferMetadataOffset() {
const auto& header = reader_->GetHeader();
- size_t size = header.header_size + sizeof(BufferState);
+ size_t size = header.prefix.header_size + sizeof(BufferState);
return size;
}
@@ -845,7 +845,7 @@
size_t Snapuserd::GetBufferDataOffset() {
const auto& header = reader_->GetHeader();
- return (header.header_size + GetBufferMetadataSize());
+ return (header.prefix.header_size + GetBufferMetadataSize());
}
/*
@@ -862,7 +862,7 @@
const auto& header = reader_->GetHeader();
struct BufferState* ra_state =
- reinterpret_cast<struct BufferState*>((char*)mapped_addr_ + header.header_size);
+ reinterpret_cast<struct BufferState*>((char*)mapped_addr_ + header.prefix.header_size);
return ra_state;
}
diff --git a/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_core.cpp b/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_core.cpp
index a519639..c3343b8 100644
--- a/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_core.cpp
+++ b/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_core.cpp
@@ -240,9 +240,9 @@
bool SnapshotHandler::MmapMetadata() {
const auto& header = reader_->GetHeader();
- total_mapped_addr_length_ = header.header_size + BUFFER_REGION_DEFAULT_SIZE;
+ total_mapped_addr_length_ = header.prefix.header_size + BUFFER_REGION_DEFAULT_SIZE;
- if (header.major_version >= 2 && header.buffer_size > 0) {
+ if (header.prefix.major_version >= 2 && header.buffer_size > 0) {
scratch_space_ = true;
}
@@ -362,7 +362,7 @@
uint64_t SnapshotHandler::GetBufferMetadataOffset() {
const auto& header = reader_->GetHeader();
- return (header.header_size + sizeof(BufferState));
+ return (header.prefix.header_size + sizeof(BufferState));
}
/*
@@ -390,7 +390,7 @@
size_t SnapshotHandler::GetBufferDataOffset() {
const auto& header = reader_->GetHeader();
- return (header.header_size + GetBufferMetadataSize());
+ return (header.prefix.header_size + GetBufferMetadataSize());
}
/*
@@ -413,7 +413,7 @@
const auto& header = reader_->GetHeader();
struct BufferState* ra_state =
- reinterpret_cast<struct BufferState*>((char*)mapped_addr_ + header.header_size);
+ reinterpret_cast<struct BufferState*>((char*)mapped_addr_ + header.prefix.header_size);
return ra_state;
}