libziparchive: Add ability to backup in ZipWriter
Based on the compressed size of a file entry,
the decision needs to be made to instead store the file
uncompressed. This adds support to ZipWriter to backup
its last file entry.
The file is now always truncated when the EOCD is written out,
to account for the case where a file entry is backed-up and the
resulting file written is much smaller, leaving garbage data at
the end of the file.
This change also includes a rename of FileInfo -> FileEntry.
This struct was private (now public), so it shouldn't affect any
clients.
Bug: 35461578
Test: make ziparchive-tests
Change-Id: I23dc584406274ab7b8ce62b3fbc3562ca4c2603e
diff --git a/libziparchive/zip_writer.cc b/libziparchive/zip_writer.cc
index b72ed7f..ddd4dd5 100644
--- a/libziparchive/zip_writer.cc
+++ b/libziparchive/zip_writer.cc
@@ -14,21 +14,22 @@
* limitations under the License.
*/
-#include "entry_name_utils-inl.h"
-#include "zip_archive_common.h"
#include "ziparchive/zip_writer.h"
-#include <utils/Log.h>
-
-#include <sys/param.h>
-
-#include <cassert>
#include <cstdio>
-#include <memory>
-#include <vector>
+#include <sys/param.h>
#include <zlib.h>
#define DEF_MEM_LEVEL 8 // normally in zutil.h?
+#include <memory>
+#include <vector>
+
+#include "android-base/logging.h"
+#include "utils/Log.h"
+
+#include "entry_name_utils-inl.h"
+#include "zip_archive_common.h"
+
#if !defined(powerof2)
#define powerof2(x) ((((x)-1)&(x))==0)
#endif
@@ -171,12 +172,12 @@
return kInvalidAlignment;
}
- FileInfo fileInfo = {};
- fileInfo.path = std::string(path);
- fileInfo.local_file_header_offset = current_offset_;
+ current_file_entry_ = {};
+ current_file_entry_.path = path;
+ current_file_entry_.local_file_header_offset = current_offset_;
- if (!IsValidEntryName(reinterpret_cast<const uint8_t*>(fileInfo.path.data()),
- fileInfo.path.size())) {
+ if (!IsValidEntryName(reinterpret_cast<const uint8_t*>(current_file_entry_.path.data()),
+ current_file_entry_.path.size())) {
return kInvalidEntryName;
}
@@ -188,24 +189,24 @@
header.gpb_flags |= kGPBDDFlagMask;
if (flags & ZipWriter::kCompress) {
- fileInfo.compression_method = kCompressDeflated;
+ current_file_entry_.compression_method = kCompressDeflated;
int32_t result = PrepareDeflate();
if (result != kNoError) {
return result;
}
} else {
- fileInfo.compression_method = kCompressStored;
+ current_file_entry_.compression_method = kCompressStored;
}
- header.compression_method = fileInfo.compression_method;
+ header.compression_method = current_file_entry_.compression_method;
- ExtractTimeAndDate(time, &fileInfo.last_mod_time, &fileInfo.last_mod_date);
- header.last_mod_time = fileInfo.last_mod_time;
- header.last_mod_date = fileInfo.last_mod_date;
+ ExtractTimeAndDate(time, ¤t_file_entry_.last_mod_time, ¤t_file_entry_.last_mod_date);
+ header.last_mod_time = current_file_entry_.last_mod_time;
+ header.last_mod_date = current_file_entry_.last_mod_date;
- header.file_name_length = fileInfo.path.size();
+ header.file_name_length = current_file_entry_.path.size();
- off64_t offset = current_offset_ + sizeof(header) + fileInfo.path.size();
+ off64_t offset = current_offset_ + sizeof(header) + current_file_entry_.path.size();
std::vector<char> zero_padding;
if (alignment != 0 && (offset & (alignment - 1))) {
// Pad the extra field so the data will be aligned.
@@ -220,7 +221,8 @@
return HandleError(kIoError);
}
- if (fwrite(path, sizeof(*path), fileInfo.path.size(), file_) != fileInfo.path.size()) {
+ if (fwrite(path, sizeof(*path), current_file_entry_.path.size(), file_)
+ != current_file_entry_.path.size()) {
return HandleError(kIoError);
}
@@ -230,15 +232,37 @@
return HandleError(kIoError);
}
- files_.emplace_back(std::move(fileInfo));
-
current_offset_ = offset;
state_ = State::kWritingEntry;
return kNoError;
}
+int32_t ZipWriter::DiscardLastEntry() {
+ if (state_ != State::kWritingZip || files_.empty()) {
+ return kInvalidState;
+ }
+
+ FileEntry& last_entry = files_.back();
+ current_offset_ = last_entry.local_file_header_offset;
+ if (fseeko(file_, current_offset_, SEEK_SET) != 0) {
+ return HandleError(kIoError);
+ }
+ files_.pop_back();
+ return kNoError;
+}
+
+int32_t ZipWriter::GetLastEntry(FileEntry* out_entry) {
+ CHECK(out_entry != nullptr);
+
+ if (files_.empty()) {
+ return kInvalidState;
+ }
+ *out_entry = files_.back();
+ return kNoError;
+}
+
int32_t ZipWriter::PrepareDeflate() {
- assert(state_ == State::kWritingZip);
+ CHECK(state_ == State::kWritingZip);
// Initialize the z_stream for compression.
z_stream_ = std::unique_ptr<z_stream, void(*)(z_stream*)>(new z_stream(), DeleteZStream);
@@ -269,25 +293,25 @@
return HandleError(kInvalidState);
}
- FileInfo& currentFile = files_.back();
int32_t result = kNoError;
- if (currentFile.compression_method & kCompressDeflated) {
- result = CompressBytes(¤tFile, data, len);
+ if (current_file_entry_.compression_method & kCompressDeflated) {
+ result = CompressBytes(¤t_file_entry_, data, len);
} else {
- result = StoreBytes(¤tFile, data, len);
+ result = StoreBytes(¤t_file_entry_, data, len);
}
if (result != kNoError) {
return result;
}
- currentFile.crc32 = crc32(currentFile.crc32, reinterpret_cast<const Bytef*>(data), len);
- currentFile.uncompressed_size += len;
+ current_file_entry_.crc32 = crc32(current_file_entry_.crc32,
+ reinterpret_cast<const Bytef*>(data), len);
+ current_file_entry_.uncompressed_size += len;
return kNoError;
}
-int32_t ZipWriter::StoreBytes(FileInfo* file, const void* data, size_t len) {
- assert(state_ == State::kWritingEntry);
+int32_t ZipWriter::StoreBytes(FileEntry* file, const void* data, size_t len) {
+ CHECK(state_ == State::kWritingEntry);
if (fwrite(data, 1, len, file_) != len) {
return HandleError(kIoError);
@@ -297,11 +321,11 @@
return kNoError;
}
-int32_t ZipWriter::CompressBytes(FileInfo* file, const void* data, size_t len) {
- assert(state_ == State::kWritingEntry);
- assert(z_stream_);
- assert(z_stream_->next_out != nullptr);
- assert(z_stream_->avail_out != 0);
+int32_t ZipWriter::CompressBytes(FileEntry* file, const void* data, size_t len) {
+ CHECK(state_ == State::kWritingEntry);
+ CHECK(z_stream_);
+ CHECK(z_stream_->next_out != nullptr);
+ CHECK(z_stream_->avail_out != 0);
// Prepare the input.
z_stream_->next_in = reinterpret_cast<const uint8_t*>(data);
@@ -331,17 +355,17 @@
return kNoError;
}
-int32_t ZipWriter::FlushCompressedBytes(FileInfo* file) {
- assert(state_ == State::kWritingEntry);
- assert(z_stream_);
- assert(z_stream_->next_out != nullptr);
- assert(z_stream_->avail_out != 0);
+int32_t ZipWriter::FlushCompressedBytes(FileEntry* file) {
+ CHECK(state_ == State::kWritingEntry);
+ CHECK(z_stream_);
+ CHECK(z_stream_->next_out != nullptr);
+ CHECK(z_stream_->avail_out != 0);
// Keep deflating while there isn't enough space in the buffer to
// to complete the compress.
int zerr;
while ((zerr = deflate(z_stream_.get(), Z_FINISH)) == Z_OK) {
- assert(z_stream_->avail_out == 0);
+ CHECK(z_stream_->avail_out == 0);
size_t write_bytes = z_stream_->next_out - buffer_.data();
if (fwrite(buffer_.data(), 1, write_bytes, file_) != write_bytes) {
return HandleError(kIoError);
@@ -373,9 +397,8 @@
return kInvalidState;
}
- FileInfo& currentFile = files_.back();
- if (currentFile.compression_method & kCompressDeflated) {
- int32_t result = FlushCompressedBytes(¤tFile);
+ if (current_file_entry_.compression_method & kCompressDeflated) {
+ int32_t result = FlushCompressedBytes(¤t_file_entry_);
if (result != kNoError) {
return result;
}
@@ -388,13 +411,15 @@
}
DataDescriptor dd = {};
- dd.crc32 = currentFile.crc32;
- dd.compressed_size = currentFile.compressed_size;
- dd.uncompressed_size = currentFile.uncompressed_size;
+ dd.crc32 = current_file_entry_.crc32;
+ dd.compressed_size = current_file_entry_.compressed_size;
+ dd.uncompressed_size = current_file_entry_.uncompressed_size;
if (fwrite(&dd, sizeof(dd), 1, file_) != 1) {
return HandleError(kIoError);
}
+ files_.emplace_back(std::move(current_file_entry_));
+
current_offset_ += sizeof(DataDescriptor::kOptSignature) + sizeof(dd);
state_ = State::kWritingZip;
return kNoError;
@@ -406,7 +431,7 @@
}
off64_t startOfCdr = current_offset_;
- for (FileInfo& file : files_) {
+ for (FileEntry& file : files_) {
CentralDirectoryRecord cdr = {};
cdr.record_signature = CentralDirectoryRecord::kSignature;
cdr.gpb_flags |= kGPBDDFlagMask;
@@ -442,11 +467,19 @@
return HandleError(kIoError);
}
+ current_offset_ += sizeof(er);
+
+ // Since we can BackUp() and potentially finish writing at an offset less than one we had
+ // already written at, we must truncate the file.
+
+ if (ftruncate64(fileno(file_), current_offset_) != 0) {
+ return HandleError(kIoError);
+ }
+
if (fflush(file_) != 0) {
return HandleError(kIoError);
}
- current_offset_ += sizeof(er);
state_ = State::kDone;
return kNoError;
}