Implement ZipWriter for quickly writing ZipFiles.

The ZipWriter implementation exposes a stateful interface that allows
bytes of data to be streamed in as they arrive. ZipEntries can be
compressed and/or aligned on a 32-bit boundary for mmapping at runtime.

Change-Id: I43ac9e661aa5022f00d9e12b247c4314d61c441c

6 files changed, 738 insertions, 162 deletions

diff --git a/include/ziparchive/zip_writer.h b/include/ziparchive/zip_writer.h
new file mode 100644
index 0000000000..9ee4abec29
--- /dev/null
+++ b/include/ziparchive/zip_writer.h
@@ -0,0 +1,141 @@
+/*
+ * Copyright (C) 2015 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.
+ */
+
+#ifndef LIBZIPARCHIVE_ZIPWRITER_H_
+#define LIBZIPARCHIVE_ZIPWRITER_H_
+
+#include "base/macros.h"
+#include <utils/Compat.h>
+
+#include <cstdio>
+#include <string>
+#include <ctime>
+#include <vector>
+
+/**
+ * Writes a Zip file via a stateful interface.
+ *
+ * Example:
+ *
+ *   FILE* file = fopen("path/to/zip.zip", "wb");
+ *
+ *   ZipWriter writer(file);
+ *
+ *   writer.StartEntry("test.txt", ZipWriter::kCompress | ZipWriter::kAlign);
+ *   writer.WriteBytes(buffer, bufferLen);
+ *   writer.WriteBytes(buffer2, bufferLen2);
+ *   writer.FinishEntry();
+ *
+ *   writer.StartEntry("empty.txt", 0);
+ *   writer.FinishEntry();
+ *
+ *   writer.Finish();
+ *
+ *   fclose(file);
+ */
+class ZipWriter {
+public:
+  enum {
+    /**
+     * Flag to compress the zip entry using deflate.
+     */
+    kCompress = 0x01,
+
+    /**
+     * Flag to align the zip entry data on a 32bit boundary. Useful for
+     * mmapping the data at runtime.
+     */
+    kAlign32 = 0x02,
+  };
+
+  static const char* ErrorCodeString(int32_t error_code);
+
+  /**
+   * Create a ZipWriter that will write into a FILE stream. The file should be opened with
+   * open mode of "wb" or "w+b". ZipWriter does not take ownership of the file stream. The
+   * caller is responsible for closing the file.
+   */
+  explicit ZipWriter(FILE* f);
+
+  // Move constructor.
+  ZipWriter(ZipWriter&& zipWriter);
+
+  // Move assignment.
+  ZipWriter& operator=(ZipWriter&& zipWriter);
+
+  /**
+   * Starts a new zip entry with the given path and flags.
+   * Flags can be a bitwise OR of ZipWriter::kCompress and ZipWriter::kAlign.
+   * Subsequent calls to WriteBytes(const void*, size_t) will add data to this entry.
+   * Returns 0 on success, and an error value < 0 on failure.
+   */
+  int32_t StartEntry(const char* path, size_t flags);
+
+  /**
+   * Same as StartEntry(const char*, size_t), but sets a last modified time for the entry.
+   */
+  int32_t StartEntryWithTime(const char* path, size_t flags, time_t time);
+
+  /**
+   * Writes bytes to the zip file for the previously started zip entry.
+   * Returns 0 on success, and an error value < 0 on failure.
+   */
+  int32_t WriteBytes(const void* data, size_t len);
+
+  /**
+   * Finish a zip entry started with StartEntry(const char*, size_t) or
+   * StartEntryWithTime(const char*, size_t, time_t). This must be called before
+   * any new zip entries are started, or before Finish() is called.
+   * Returns 0 on success, and an error value < 0 on failure.
+   */
+  int32_t FinishEntry();
+
+  /**
+   * Writes the Central Directory Headers and flushes the zip file stream.
+   * Returns 0 on success, and an error value < 0 on failure.
+   */
+  int32_t Finish();
+
+private:
+  DISALLOW_COPY_AND_ASSIGN(ZipWriter);
+
+  int32_t HandleError(int32_t error_code);
+
+  struct FileInfo {
+    std::string path;
+    uint16_t compression_method;
+    uint32_t crc32;
+    uint32_t compressed_size;
+    uint32_t uncompressed_size;
+    uint16_t last_mod_time;
+    uint16_t last_mod_date;
+    uint32_t local_file_header_offset;
+  };
+
+  enum class State {
+    kWritingZip,
+    kWritingEntry,
+    kDone,
+    kError,
+  };
+
+  FILE* file_;
+  off64_t current_offset_;
+  State state_;
+  std::vector<FileInfo> files_;
+};
+
+#endif /* LIBZIPARCHIVE_ZIPWRITER_H_ */
diff --git a/libziparchive/Android.mk b/libziparchive/Android.mk
index 608ff1cc0c..8ff94d4122 100644
--- a/libziparchive/Android.mk
+++ b/libziparchive/Android.mk
@@ -15,7 +15,12 @@
 
 LOCAL_PATH := $(call my-dir)
 
-source_files := zip_archive.cc
+source_files := zip_archive.cc zip_writer.cc
+test_files := zip_archive_test.cc zip_writer_test.cc entry_name_utils_test.cc
+
+# Incorrectly warns when C++11 empty brace {} initializer is used.
+# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61489
+common_cpp_flags := -Wno-missing-field-initializers
 
 include $(CLEAR_VARS)
 LOCAL_CPP_EXTENSION := .cc
@@ -24,7 +29,7 @@ LOCAL_STATIC_LIBRARIES := libz
 LOCAL_SHARED_LIBRARIES := libutils libbase
 LOCAL_MODULE:= libziparchive
 LOCAL_CFLAGS := -Werror -Wall
-LOCAL_CPPFLAGS := -Wold-style-cast
+LOCAL_CPPFLAGS := -Wold-style-cast $(common_cpp_flags)
 include $(BUILD_STATIC_LIBRARY)
 
 include $(CLEAR_VARS)
@@ -34,6 +39,8 @@ LOCAL_STATIC_LIBRARIES := libz libutils libbase
 LOCAL_MODULE:= libziparchive-host
 LOCAL_CFLAGS := -Werror
 LOCAL_CFLAGS_windows := -mno-ms-bitfields
+LOCAL_CPPFLAGS := $(common_cpp_flags)
+
 LOCAL_MULTILIB := both
 LOCAL_MODULE_HOST_OS := darwin linux windows
 include $(BUILD_HOST_STATIC_LIBRARY)
@@ -45,6 +52,7 @@ LOCAL_STATIC_LIBRARIES := libutils
 LOCAL_SHARED_LIBRARIES := libz-host liblog libbase
 LOCAL_MODULE:= libziparchive-host
 LOCAL_CFLAGS := -Werror
+LOCAL_CPPFLAGS := $(common_cpp_flags)
 LOCAL_MULTILIB := both
 include $(BUILD_HOST_SHARED_LIBRARY)
 
@@ -53,7 +61,8 @@ include $(CLEAR_VARS)
 LOCAL_MODULE := ziparchive-tests
 LOCAL_CPP_EXTENSION := .cc
 LOCAL_CFLAGS := -Werror
-LOCAL_SRC_FILES := zip_archive_test.cc entry_name_utils_test.cc
+LOCAL_CPPFLAGS := $(common_cpp_flags)
+LOCAL_SRC_FILES := $(test_files)
 LOCAL_SHARED_LIBRARIES := liblog libbase
 LOCAL_STATIC_LIBRARIES := libziparchive libz libutils
 include $(BUILD_NATIVE_TEST)
@@ -61,10 +70,9 @@ include $(BUILD_NATIVE_TEST)
 include $(CLEAR_VARS)
 LOCAL_MODULE := ziparchive-tests-host
 LOCAL_CPP_EXTENSION := .cc
-LOCAL_CFLAGS += \
-    -Werror \
-    -Wno-unnamed-type-template-args
-LOCAL_SRC_FILES := zip_archive_test.cc entry_name_utils_test.cc
+LOCAL_CFLAGS := -Werror
+LOCAL_CPPFLAGS := -Wno-unnamed-type-template-args $(common_cpp_flags)
+LOCAL_SRC_FILES := $(test_files)
 LOCAL_SHARED_LIBRARIES := libziparchive-host liblog libbase
 LOCAL_STATIC_LIBRARIES := \
     libz \
diff --git a/libziparchive/zip_archive.cc b/libziparchive/zip_archive.cc
index 3716343aee..f1e13a7bc2 100644
--- a/libziparchive/zip_archive.cc
+++ b/libziparchive/zip_archive.cc
@@ -39,6 +39,7 @@
 #include "zlib.h"
 
 #include "entry_name_utils-inl.h"
+#include "zip_archive_common.h"
 #include "ziparchive/zip_archive.h"
 
 using android::base::get_unaligned;
@@ -49,161 +50,6 @@ using android::base::get_unaligned;
 #define O_BINARY 0
 #endif
 
-// The "end of central directory" (EOCD) record. Each archive
-// contains exactly once such record which appears at the end of
-// the archive. It contains archive wide information like the
-// number of entries in the archive and the offset to the central
-// directory of the offset.
-struct EocdRecord {
-  static const uint32_t kSignature = 0x06054b50;
-
-  // End of central directory signature, should always be
-  // |kSignature|.
-  uint32_t eocd_signature;
-  // The number of the current "disk", i.e, the "disk" that this
-  // central directory is on.
-  //
-  // This implementation assumes that each archive spans a single
-  // disk only. i.e, that disk_num == 1.
-  uint16_t disk_num;
-  // The disk where the central directory starts.
-  //
-  // This implementation assumes that each archive spans a single
-  // disk only. i.e, that cd_start_disk == 1.
-  uint16_t cd_start_disk;
-  // The number of central directory records on this disk.
-  //
-  // This implementation assumes that each archive spans a single
-  // disk only. i.e, that num_records_on_disk == num_records.
-  uint16_t num_records_on_disk;
-  // The total number of central directory records.
-  uint16_t num_records;
-  // The size of the central directory (in bytes).
-  uint32_t cd_size;
-  // The offset of the start of the central directory, relative
-  // to the start of the file.
-  uint32_t cd_start_offset;
-  // Length of the central directory comment.
-  uint16_t comment_length;
- private:
-  EocdRecord() = default;
-  DISALLOW_COPY_AND_ASSIGN(EocdRecord);
-} __attribute__((packed));
-
-// A structure representing the fixed length fields for a single
-// record in the central directory of the archive. In addition to
-// the fixed length fields listed here, each central directory
-// record contains a variable length "file_name" and "extra_field"
-// whose lengths are given by |file_name_length| and |extra_field_length|
-// respectively.
-struct CentralDirectoryRecord {
-  static const uint32_t kSignature = 0x02014b50;
-
-  // The start of record signature. Must be |kSignature|.
-  uint32_t record_signature;
-  // Tool version. Ignored by this implementation.
-  uint16_t version_made_by;
-  // Tool version. Ignored by this implementation.
-  uint16_t version_needed;
-  // The "general purpose bit flags" for this entry. The only
-  // flag value that we currently check for is the "data descriptor"
-  // flag.
-  uint16_t gpb_flags;
-  // The compression method for this entry, one of |kCompressStored|
-  // and |kCompressDeflated|.
-  uint16_t compression_method;
-  // The file modification time and date for this entry.
-  uint16_t last_mod_time;
-  uint16_t last_mod_date;
-  // The CRC-32 checksum for this entry.
-  uint32_t crc32;
-  // The compressed size (in bytes) of this entry.
-  uint32_t compressed_size;
-  // The uncompressed size (in bytes) of this entry.
-  uint32_t uncompressed_size;
-  // The length of the entry file name in bytes. The file name
-  // will appear immediately after this record.
-  uint16_t file_name_length;
-  // The length of the extra field info (in bytes). This data
-  // will appear immediately after the entry file name.
-  uint16_t extra_field_length;
-  // The length of the entry comment (in bytes). This data will
-  // appear immediately after the extra field.
-  uint16_t comment_length;
-  // The start disk for this entry. Ignored by this implementation).
-  uint16_t file_start_disk;
-  // File attributes. Ignored by this implementation.
-  uint16_t internal_file_attributes;
-  // File attributes. Ignored by this implementation.
-  uint32_t external_file_attributes;
-  // The offset to the local file header for this entry, from the
-  // beginning of this archive.
-  uint32_t local_file_header_offset;
- private:
-  CentralDirectoryRecord() = default;
-  DISALLOW_COPY_AND_ASSIGN(CentralDirectoryRecord);
-} __attribute__((packed));
-
-// The local file header for a given entry. This duplicates information
-// present in the central directory of the archive. It is an error for
-// the information here to be different from the central directory
-// information for a given entry.
-struct LocalFileHeader {
-  static const uint32_t kSignature = 0x04034b50;
-
-  // The local file header signature, must be |kSignature|.
-  uint32_t lfh_signature;
-  // Tool version. Ignored by this implementation.
-  uint16_t version_needed;
-  // The "general purpose bit flags" for this entry. The only
-  // flag value that we currently check for is the "data descriptor"
-  // flag.
-  uint16_t gpb_flags;
-  // The compression method for this entry, one of |kCompressStored|
-  // and |kCompressDeflated|.
-  uint16_t compression_method;
-  // The file modification time and date for this entry.
-  uint16_t last_mod_time;
-  uint16_t last_mod_date;
-  // The CRC-32 checksum for this entry.
-  uint32_t crc32;
-  // The compressed size (in bytes) of this entry.
-  uint32_t compressed_size;
-  // The uncompressed size (in bytes) of this entry.
-  uint32_t uncompressed_size;
-  // The length of the entry file name in bytes. The file name
-  // will appear immediately after this record.
-  uint16_t file_name_length;
-  // The length of the extra field info (in bytes). This data
-  // will appear immediately after the entry file name.
-  uint16_t extra_field_length;
- private:
-  LocalFileHeader() = default;
-  DISALLOW_COPY_AND_ASSIGN(LocalFileHeader);
-} __attribute__((packed));
-
-struct DataDescriptor {
-  // The *optional* data descriptor start signature.
-  static const uint32_t kOptSignature = 0x08074b50;
-
-  // CRC-32 checksum of the entry.
-  uint32_t crc32;
-  // Compressed size of the entry.
-  uint32_t compressed_size;
-  // Uncompressed size of the entry.
-  uint32_t uncompressed_size;
- private:
-  DataDescriptor() = default;
-  DISALLOW_COPY_AND_ASSIGN(DataDescriptor);
-} __attribute__((packed));
-
-
-static const uint32_t kGPBDDFlagMask = 0x0008;         // mask value that signifies that the entry has a DD
-
-// The maximum size of a central directory or a file
-// comment in bytes.
-static const uint32_t kMaxCommentLen = 65535;
-
 // The maximum number of bytes to scan backwards for the EOCD start.
 static const uint32_t kMaxEOCDSearch = kMaxCommentLen + sizeof(EocdRecord);
 
diff --git a/libziparchive/zip_archive_common.h b/libziparchive/zip_archive_common.h
new file mode 100644
index 0000000000..7f20d51c64
--- /dev/null
+++ b/libziparchive/zip_archive_common.h
@@ -0,0 +1,179 @@
+/*
+ * Copyright (C) 2015 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.
+ */
+
+#ifndef LIBZIPARCHIVE_ZIPARCHIVECOMMON_H_
+#define LIBZIPARCHIVE_ZIPARCHIVECOMMON_H_
+
+#include "base/macros.h"
+
+#include <inttypes.h>
+
+// The "end of central directory" (EOCD) record. Each archive
+// contains exactly once such record which appears at the end of
+// the archive. It contains archive wide information like the
+// number of entries in the archive and the offset to the central
+// directory of the offset.
+struct EocdRecord {
+  static const uint32_t kSignature = 0x06054b50;
+
+  // End of central directory signature, should always be
+  // |kSignature|.
+  uint32_t eocd_signature;
+  // The number of the current "disk", i.e, the "disk" that this
+  // central directory is on.
+  //
+  // This implementation assumes that each archive spans a single
+  // disk only. i.e, that disk_num == 1.
+  uint16_t disk_num;
+  // The disk where the central directory starts.
+  //
+  // This implementation assumes that each archive spans a single
+  // disk only. i.e, that cd_start_disk == 1.
+  uint16_t cd_start_disk;
+  // The number of central directory records on this disk.
+  //
+  // This implementation assumes that each archive spans a single
+  // disk only. i.e, that num_records_on_disk == num_records.
+  uint16_t num_records_on_disk;
+  // The total number of central directory records.
+  uint16_t num_records;
+  // The size of the central directory (in bytes).
+  uint32_t cd_size;
+  // The offset of the start of the central directory, relative
+  // to the start of the file.
+  uint32_t cd_start_offset;
+  // Length of the central directory comment.
+  uint16_t comment_length;
+ private:
+  EocdRecord() = default;
+  DISALLOW_COPY_AND_ASSIGN(EocdRecord);
+} __attribute__((packed));
+
+// A structure representing the fixed length fields for a single
+// record in the central directory of the archive. In addition to
+// the fixed length fields listed here, each central directory
+// record contains a variable length "file_name" and "extra_field"
+// whose lengths are given by |file_name_length| and |extra_field_length|
+// respectively.
+struct CentralDirectoryRecord {
+  static const uint32_t kSignature = 0x02014b50;
+
+  // The start of record signature. Must be |kSignature|.
+  uint32_t record_signature;
+  // Tool version. Ignored by this implementation.
+  uint16_t version_made_by;
+  // Tool version. Ignored by this implementation.
+  uint16_t version_needed;
+  // The "general purpose bit flags" for this entry. The only
+  // flag value that we currently check for is the "data descriptor"
+  // flag.
+  uint16_t gpb_flags;
+  // The compression method for this entry, one of |kCompressStored|
+  // and |kCompressDeflated|.
+  uint16_t compression_method;
+  // The file modification time and date for this entry.
+  uint16_t last_mod_time;
+  uint16_t last_mod_date;
+  // The CRC-32 checksum for this entry.
+  uint32_t crc32;
+  // The compressed size (in bytes) of this entry.
+  uint32_t compressed_size;
+  // The uncompressed size (in bytes) of this entry.
+  uint32_t uncompressed_size;
+  // The length of the entry file name in bytes. The file name
+  // will appear immediately after this record.
+  uint16_t file_name_length;
+  // The length of the extra field info (in bytes). This data
+  // will appear immediately after the entry file name.
+  uint16_t extra_field_length;
+  // The length of the entry comment (in bytes). This data will
+  // appear immediately after the extra field.
+  uint16_t comment_length;
+  // The start disk for this entry. Ignored by this implementation).
+  uint16_t file_start_disk;
+  // File attributes. Ignored by this implementation.
+  uint16_t internal_file_attributes;
+  // File attributes. Ignored by this implementation.
+  uint32_t external_file_attributes;
+  // The offset to the local file header for this entry, from the
+  // beginning of this archive.
+  uint32_t local_file_header_offset;
+ private:
+  CentralDirectoryRecord() = default;
+  DISALLOW_COPY_AND_ASSIGN(CentralDirectoryRecord);
+} __attribute__((packed));
+
+// The local file header for a given entry. This duplicates information
+// present in the central directory of the archive. It is an error for
+// the information here to be different from the central directory
+// information for a given entry.
+struct LocalFileHeader {
+  static const uint32_t kSignature = 0x04034b50;
+
+  // The local file header signature, must be |kSignature|.
+  uint32_t lfh_signature;
+  // Tool version. Ignored by this implementation.
+  uint16_t version_needed;
+  // The "general purpose bit flags" for this entry. The only
+  // flag value that we currently check for is the "data descriptor"
+  // flag.
+  uint16_t gpb_flags;
+  // The compression method for this entry, one of |kCompressStored|
+  // and |kCompressDeflated|.
+  uint16_t compression_method;
+  // The file modification time and date for this entry.
+  uint16_t last_mod_time;
+  uint16_t last_mod_date;
+  // The CRC-32 checksum for this entry.
+  uint32_t crc32;
+  // The compressed size (in bytes) of this entry.
+  uint32_t compressed_size;
+  // The uncompressed size (in bytes) of this entry.
+  uint32_t uncompressed_size;
+  // The length of the entry file name in bytes. The file name
+  // will appear immediately after this record.
+  uint16_t file_name_length;
+  // The length of the extra field info (in bytes). This data
+  // will appear immediately after the entry file name.
+  uint16_t extra_field_length;
+ private:
+  LocalFileHeader() = default;
+  DISALLOW_COPY_AND_ASSIGN(LocalFileHeader);
+} __attribute__((packed));
+
+struct DataDescriptor {
+  // The *optional* data descriptor start signature.
+  static const uint32_t kOptSignature = 0x08074b50;
+
+  // CRC-32 checksum of the entry.
+  uint32_t crc32;
+  // Compressed size of the entry.
+  uint32_t compressed_size;
+  // Uncompressed size of the entry.
+  uint32_t uncompressed_size;
+ private:
+  DataDescriptor() = default;
+  DISALLOW_COPY_AND_ASSIGN(DataDescriptor);
+} __attribute__((packed));
+
+// mask value that signifies that the entry has a DD
+static const uint32_t kGPBDDFlagMask = 0x0008;
+
+// The maximum size of a central directory or a file
+// comment in bytes.
+static const uint32_t kMaxCommentLen = 65535;
+
+#endif /* LIBZIPARCHIVE_ZIPARCHIVECOMMON_H_ */
diff --git a/libziparchive/zip_writer.cc b/libziparchive/zip_writer.cc
new file mode 100644
index 0000000000..de75d1edeb
--- /dev/null
+++ b/libziparchive/zip_writer.cc
@@ -0,0 +1,262 @@
+/*
+ * Copyright (C) 2015 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 "entry_name_utils-inl.h"
+#include "zip_archive_common.h"
+#include "ziparchive/zip_writer.h"
+
+#include <cassert>
+#include <cstdio>
+#include <memory>
+#include <zlib.h>
+
+/* Zip compression methods we support */
+enum {
+  kCompressStored     = 0,        // no compression
+  kCompressDeflated   = 8,        // standard deflate
+};
+
+// No error, operation completed successfully.
+static const int32_t kNoError = 0;
+
+// The ZipWriter is in a bad state.
+static const int32_t kInvalidState = -1;
+
+// There was an IO error while writing to disk.
+static const int32_t kIoError = -2;
+
+// The zip entry name was invalid.
+static const int32_t kInvalidEntryName = -3;
+
+static const char* sErrorCodes[] = {
+    "Invalid state",
+    "IO error",
+    "Invalid entry name",
+};
+
+const char* ZipWriter::ErrorCodeString(int32_t error_code) {
+  if (error_code < 0 && (-error_code) < static_cast<int32_t>(arraysize(sErrorCodes))) {
+    return sErrorCodes[-error_code];
+  }
+  return nullptr;
+}
+
+ZipWriter::ZipWriter(FILE* f) : file_(f), current_offset_(0), state_(State::kWritingZip) {
+}
+
+ZipWriter::ZipWriter(ZipWriter&& writer) : file_(writer.file_),
+                                           current_offset_(writer.current_offset_),
+                                           state_(writer.state_),
+                                           files_(std::move(writer.files_)) {
+  writer.file_ = nullptr;
+  writer.state_ = State::kError;
+}
+
+ZipWriter& ZipWriter::operator=(ZipWriter&& writer) {
+  file_ = writer.file_;
+  current_offset_ = writer.current_offset_;
+  state_ = writer.state_;
+  files_ = std::move(writer.files_);
+  writer.file_ = nullptr;
+  writer.state_ = State::kError;
+  return *this;
+}
+
+int32_t ZipWriter::HandleError(int32_t error_code) {
+  state_ = State::kError;
+  return error_code;
+}
+
+int32_t ZipWriter::StartEntry(const char* path, size_t flags) {
+  return StartEntryWithTime(path, flags, time_t());
+}
+
+static void ExtractTimeAndDate(time_t when, uint16_t* out_time, uint16_t* out_date) {
+  /* round up to an even number of seconds */
+  when = static_cast<time_t>((static_cast<unsigned long>(when) + 1) & (~1));
+
+  struct tm* ptm;
+#if !defined(_WIN32)
+    struct tm tm_result;
+    ptm = localtime_r(&when, &tm_result);
+#else
+    ptm = localtime(&when);
+#endif
+
+  int year = ptm->tm_year;
+  if (year < 80) {
+    year = 80;
+  }
+
+  *out_date = (year - 80) << 9 | (ptm->tm_mon + 1) << 5 | ptm->tm_mday;
+  *out_time = ptm->tm_hour << 11 | ptm->tm_min << 5 | ptm->tm_sec >> 1;
+}
+
+int32_t ZipWriter::StartEntryWithTime(const char* path, size_t flags, time_t time) {
+  if (state_ != State::kWritingZip) {
+    return kInvalidState;
+  }
+
+  FileInfo fileInfo = {};
+  fileInfo.path = std::string(path);
+  fileInfo.local_file_header_offset = current_offset_;
+
+  if (!IsValidEntryName(reinterpret_cast<const uint8_t*>(fileInfo.path.data()),
+                       fileInfo.path.size())) {
+    return kInvalidEntryName;
+  }
+
+  LocalFileHeader header = {};
+  header.lfh_signature = LocalFileHeader::kSignature;
+
+  // Set this flag to denote that a DataDescriptor struct will appear after the data,
+  // containing the crc and size fields.
+  header.gpb_flags |= kGPBDDFlagMask;
+
+  // For now, ignore the ZipWriter::kCompress flag.
+  fileInfo.compression_method = kCompressStored;
+  header.compression_method = fileInfo.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;
+
+  header.file_name_length = fileInfo.path.size();
+
+  off64_t offset = current_offset_ + sizeof(header) + fileInfo.path.size();
+  if ((flags & ZipWriter::kAlign32) && (offset & 0x03)) {
+    // Pad the extra field so the data will be aligned.
+    uint16_t padding = 4 - (offset % 4);
+    header.extra_field_length = padding;
+    offset += padding;
+  }
+
+  if (fwrite(&header, sizeof(header), 1, file_) != 1) {
+    return HandleError(kIoError);
+  }
+
+  if (fwrite(path, sizeof(*path), fileInfo.path.size(), file_) != fileInfo.path.size()) {
+    return HandleError(kIoError);
+  }
+
+  if (fwrite("\0\0\0", 1, header.extra_field_length, file_) != header.extra_field_length) {
+    return HandleError(kIoError);
+  }
+
+  files_.emplace_back(std::move(fileInfo));
+
+  current_offset_ = offset;
+  state_ = State::kWritingEntry;
+  return kNoError;
+}
+
+int32_t ZipWriter::WriteBytes(const void* data, size_t len) {
+  if (state_ != State::kWritingEntry) {
+    return HandleError(kInvalidState);
+  }
+
+  FileInfo& currentFile = files_.back();
+  if (currentFile.compression_method & kCompressDeflated) {
+    // TODO(adamlesinski): Implement compression using zlib deflate.
+    assert(false);
+  } else {
+    if (fwrite(data, 1, len, file_) != len) {
+      return HandleError(kIoError);
+    }
+    currentFile.crc32 = crc32(currentFile.crc32, reinterpret_cast<const Bytef*>(data), len);
+    currentFile.compressed_size += len;
+    current_offset_ += len;
+  }
+
+  currentFile.uncompressed_size += len;
+  return kNoError;
+}
+
+int32_t ZipWriter::FinishEntry() {
+  if (state_ != State::kWritingEntry) {
+    return kInvalidState;
+  }
+
+  const uint32_t sig = DataDescriptor::kOptSignature;
+  if (fwrite(&sig, sizeof(sig), 1, file_) != 1) {
+    state_ = State::kError;
+    return kIoError;
+  }
+
+  FileInfo& currentFile = files_.back();
+  DataDescriptor dd = {};
+  dd.crc32 = currentFile.crc32;
+  dd.compressed_size = currentFile.compressed_size;
+  dd.uncompressed_size = currentFile.uncompressed_size;
+  if (fwrite(&dd, sizeof(dd), 1, file_) != 1) {
+    return HandleError(kIoError);
+  }
+
+  current_offset_ += sizeof(DataDescriptor::kOptSignature) + sizeof(dd);
+  state_ = State::kWritingZip;
+  return kNoError;
+}
+
+int32_t ZipWriter::Finish() {
+  if (state_ != State::kWritingZip) {
+    return kInvalidState;
+  }
+
+  off64_t startOfCdr = current_offset_;
+  for (FileInfo& file : files_) {
+    CentralDirectoryRecord cdr = {};
+    cdr.record_signature = CentralDirectoryRecord::kSignature;
+    cdr.gpb_flags |= kGPBDDFlagMask;
+    cdr.compression_method = file.compression_method;
+    cdr.last_mod_time = file.last_mod_time;
+    cdr.last_mod_date = file.last_mod_date;
+    cdr.crc32 = file.crc32;
+    cdr.compressed_size = file.compressed_size;
+    cdr.uncompressed_size = file.uncompressed_size;
+    cdr.file_name_length = file.path.size();
+    cdr.local_file_header_offset = file.local_file_header_offset;
+    if (fwrite(&cdr, sizeof(cdr), 1, file_) != 1) {
+      return HandleError(kIoError);
+    }
+
+    if (fwrite(file.path.data(), 1, file.path.size(), file_) != file.path.size()) {
+      return HandleError(kIoError);
+    }
+
+    current_offset_ += sizeof(cdr) + file.path.size();
+  }
+
+  EocdRecord er = {};
+  er.eocd_signature = EocdRecord::kSignature;
+  er.disk_num = 1;
+  er.cd_start_disk = 1;
+  er.num_records_on_disk = files_.size();
+  er.num_records = files_.size();
+  er.cd_size = current_offset_ - startOfCdr;
+  er.cd_start_offset = startOfCdr;
+
+  if (fwrite(&er, sizeof(er), 1, file_) != 1) {
+    return HandleError(kIoError);
+  }
+
+  if (fflush(file_) != 0) {
+    return HandleError(kIoError);
+  }
+
+  current_offset_ += sizeof(er);
+  state_ = State::kDone;
+  return kNoError;
+}
diff --git a/libziparchive/zip_writer_test.cc b/libziparchive/zip_writer_test.cc
new file mode 100644
index 0000000000..5269730d77
--- /dev/null
+++ b/libziparchive/zip_writer_test.cc
@@ -0,0 +1,140 @@
+/*
+ * Copyright (C) 2015 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 "ziparchive/zip_archive.h"
+#include "ziparchive/zip_writer.h"
+
+#include <base/test_utils.h>
+#include <gtest/gtest.h>
+#include <memory>
+
+struct zipwriter : public ::testing::Test {
+  TemporaryFile* temp_file_;
+  int fd_;
+  FILE* file_;
+
+  void SetUp() override {
+    temp_file_ = new TemporaryFile();
+    fd_ = temp_file_->fd;
+    file_ = fdopen(fd_, "w");
+    ASSERT_NE(file_, nullptr);
+  }
+
+  void TearDown() override {
+    fclose(file_);
+    delete temp_file_;
+  }
+};
+
+TEST_F(zipwriter, WriteUncompressedZipWithOneFile) {
+  ZipWriter writer(file_);
+
+  const char* expected = "hello";
+
+  ASSERT_EQ(writer.StartEntry("file.txt", 0), 0);
+  ASSERT_EQ(writer.WriteBytes("he", 2), 0);
+  ASSERT_EQ(writer.WriteBytes("llo", 3), 0);
+  ASSERT_EQ(writer.FinishEntry(), 0);
+  ASSERT_EQ(writer.Finish(), 0);
+
+  ASSERT_GE(lseek(fd_, 0, SEEK_SET), 0);
+
+  ZipArchiveHandle handle;
+  ASSERT_EQ(OpenArchiveFd(fd_, "temp", &handle, false), 0);
+
+  ZipEntry data;
+  ASSERT_EQ(FindEntry(handle, ZipString("file.txt"), &data), 0);
+  EXPECT_EQ(data.compressed_length, strlen(expected));
+  EXPECT_EQ(data.uncompressed_length, strlen(expected));
+  EXPECT_EQ(data.method, kCompressStored);
+
+  char buffer[6];
+  EXPECT_EQ(ExtractToMemory(handle, &data, reinterpret_cast<uint8_t*>(&buffer), sizeof(buffer)),
+            0);
+  buffer[5] = 0;
+
+  EXPECT_STREQ(expected, buffer);
+
+  CloseArchive(handle);
+}
+
+TEST_F(zipwriter, WriteUncompressedZipWithMultipleFiles) {
+  ZipWriter writer(file_);
+
+  ASSERT_EQ(writer.StartEntry("file.txt", 0), 0);
+  ASSERT_EQ(writer.WriteBytes("he", 2), 0);
+  ASSERT_EQ(writer.FinishEntry(), 0);
+
+  ASSERT_EQ(writer.StartEntry("file/file.txt", 0), 0);
+  ASSERT_EQ(writer.WriteBytes("llo", 3), 0);
+  ASSERT_EQ(writer.FinishEntry(), 0);
+
+  ASSERT_EQ(writer.StartEntry("file/file2.txt", 0), 0);
+  ASSERT_EQ(writer.FinishEntry(), 0);
+
+  ASSERT_EQ(writer.Finish(), 0);
+
+  ASSERT_GE(lseek(fd_, 0, SEEK_SET), 0);
+
+  ZipArchiveHandle handle;
+  ASSERT_EQ(OpenArchiveFd(fd_, "temp", &handle, false), 0);
+
+  char buffer[4];
+  ZipEntry data;
+
+  ASSERT_EQ(FindEntry(handle, ZipString("file.txt"), &data), 0);
+  EXPECT_EQ(data.method, kCompressStored);
+  EXPECT_EQ(data.compressed_length, 2u);
+  EXPECT_EQ(data.uncompressed_length, 2u);
+  ASSERT_EQ(ExtractToMemory(handle, &data, reinterpret_cast<uint8_t*>(buffer), arraysize(buffer)),
+            0);
+  buffer[2] = 0;
+  EXPECT_STREQ("he", buffer);
+
+  ASSERT_EQ(FindEntry(handle, ZipString("file/file.txt"), &data), 0);
+  EXPECT_EQ(data.method, kCompressStored);
+  EXPECT_EQ(data.compressed_length, 3u);
+  EXPECT_EQ(data.uncompressed_length, 3u);
+  ASSERT_EQ(ExtractToMemory(handle, &data, reinterpret_cast<uint8_t*>(buffer), arraysize(buffer)),
+            0);
+  buffer[3] = 0;
+  EXPECT_STREQ("llo", buffer);
+
+  ASSERT_EQ(FindEntry(handle, ZipString("file/file2.txt"), &data), 0);
+  EXPECT_EQ(data.method, kCompressStored);
+  EXPECT_EQ(data.compressed_length, 0u);
+  EXPECT_EQ(data.uncompressed_length, 0u);
+
+  CloseArchive(handle);
+}
+
+TEST_F(zipwriter, WriteUncompressedZipWithAlignedFile) {
+  ZipWriter writer(file_);
+
+  ASSERT_EQ(writer.StartEntry("align.txt", ZipWriter::kAlign32), 0);
+  ASSERT_EQ(writer.WriteBytes("he", 2), 0);
+  ASSERT_EQ(writer.FinishEntry(), 0);
+  ASSERT_EQ(writer.Finish(), 0);
+
+  ASSERT_GE(lseek(fd_, 0, SEEK_SET), 0);
+
+  ZipArchiveHandle handle;
+  ASSERT_EQ(OpenArchiveFd(fd_, "temp", &handle, false), 0);
+
+  ZipEntry data;
+  ASSERT_EQ(FindEntry(handle, ZipString("align.txt"), &data), 0);
+  EXPECT_EQ(data.offset & 0x03, 0);
+}