include/androidfw/ZipUtils.h

/*
 * Copyright (C) 2007 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.
 */

//
// Miscellaneous zip/gzip utility functions.
//
#ifndef __LIBS_ZIPUTILS_H
#define __LIBS_ZIPUTILS_H

#include <stdint.h>
#include <string.h>
#include <stdio.h>
#include <time.h>

namespace android {

/*
 * Container class for utility functions, primarily for namespace reasons.
 */
class ZipUtils {
public:
    /*
     * General utility function for uncompressing "deflate" data from a file
     * to a buffer.
     */
    static bool inflateToBuffer(FILE* fp, void* buf, long uncompressedLen,
        long compressedLen);
    static bool inflateToBuffer(int fd, void* buf, long uncompressedLen,
        long compressedLen);
    static bool inflateToBuffer(void *in, void* buf, long uncompressedLen,
        long compressedLen);

    /*
     * Someday we might want to make this generic and handle bzip2 ".bz2"
     * files too.
     *
     * We could declare gzip to be a sub-class of zip that has exactly
     * one always-compressed entry, but we currently want to treat Zip
     * and gzip as distinct, so there's no value.
     *
     * The zlib library has some gzip utilities, but it has no interface
     * for extracting the uncompressed length of the file (you do *not*
     * want to gzseek to the end).
     *
     * Pass in a seeked file pointer for the gzip file.  If this is a gzip
     * file, we set our return values appropriately and return "true" with
     * the file seeked to the start of the compressed data.
     */
    static bool examineGzip(FILE* fp, int* pCompressionMethod,
        long* pUncompressedLen, long* pCompressedLen, unsigned long* pCRC32);

    /*
     * Utility function to convert ZIP's time format to a timespec struct.
     *
     * NOTE: this method will clear all existing state from |timespec|.
     */
    static inline void zipTimeToTimespec(uint32_t when, struct tm* timespec) {
        const uint32_t date = when >> 16;

        memset(timespec, 0, sizeof(struct tm));
        timespec->tm_year = ((date >> 9) & 0x7F) + 80; // Zip is years since 1980
        timespec->tm_mon = ((date >> 5) & 0x0F) - 1;
        timespec->tm_mday = date & 0x1F;

        timespec->tm_hour = (when >> 11) & 0x1F;
        timespec->tm_min = (when >> 5) & 0x3F;
        timespec->tm_sec = (when & 0x1F) << 1;
        timespec->tm_isdst = -1;
    }
private:
    ZipUtils() {}
    ~ZipUtils() {}
};

}; // namespace android

#endif /*__LIBS_ZIPUTILS_H*/