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      1 /*
      2  * Copyright (C) 2015 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #ifndef LIBZIPARCHIVE_ZIPARCHIVECOMMON_H_
     18 #define LIBZIPARCHIVE_ZIPARCHIVECOMMON_H_
     19 
     20 #include "android-base/macros.h"
     21 
     22 #include <inttypes.h>
     23 
     24 // The "end of central directory" (EOCD) record. Each archive
     25 // contains exactly once such record which appears at the end of
     26 // the archive. It contains archive wide information like the
     27 // number of entries in the archive and the offset to the central
     28 // directory of the offset.
     29 struct EocdRecord {
     30   static const uint32_t kSignature = 0x06054b50;
     31 
     32   // End of central directory signature, should always be
     33   // |kSignature|.
     34   uint32_t eocd_signature;
     35   // The number of the current "disk", i.e, the "disk" that this
     36   // central directory is on.
     37   //
     38   // This implementation assumes that each archive spans a single
     39   // disk only. i.e, that disk_num == 1.
     40   uint16_t disk_num;
     41   // The disk where the central directory starts.
     42   //
     43   // This implementation assumes that each archive spans a single
     44   // disk only. i.e, that cd_start_disk == 1.
     45   uint16_t cd_start_disk;
     46   // The number of central directory records on this disk.
     47   //
     48   // This implementation assumes that each archive spans a single
     49   // disk only. i.e, that num_records_on_disk == num_records.
     50   uint16_t num_records_on_disk;
     51   // The total number of central directory records.
     52   uint16_t num_records;
     53   // The size of the central directory (in bytes).
     54   uint32_t cd_size;
     55   // The offset of the start of the central directory, relative
     56   // to the start of the file.
     57   uint32_t cd_start_offset;
     58   // Length of the central directory comment.
     59   uint16_t comment_length;
     60  private:
     61   EocdRecord() = default;
     62   DISALLOW_COPY_AND_ASSIGN(EocdRecord);
     63 } __attribute__((packed));
     64 
     65 // A structure representing the fixed length fields for a single
     66 // record in the central directory of the archive. In addition to
     67 // the fixed length fields listed here, each central directory
     68 // record contains a variable length "file_name" and "extra_field"
     69 // whose lengths are given by |file_name_length| and |extra_field_length|
     70 // respectively.
     71 struct CentralDirectoryRecord {
     72   static const uint32_t kSignature = 0x02014b50;
     73 
     74   // The start of record signature. Must be |kSignature|.
     75   uint32_t record_signature;
     76   // Tool version. Ignored by this implementation.
     77   uint16_t version_made_by;
     78   // Tool version. Ignored by this implementation.
     79   uint16_t version_needed;
     80   // The "general purpose bit flags" for this entry. The only
     81   // flag value that we currently check for is the "data descriptor"
     82   // flag.
     83   uint16_t gpb_flags;
     84   // The compression method for this entry, one of |kCompressStored|
     85   // and |kCompressDeflated|.
     86   uint16_t compression_method;
     87   // The file modification time and date for this entry.
     88   uint16_t last_mod_time;
     89   uint16_t last_mod_date;
     90   // The CRC-32 checksum for this entry.
     91   uint32_t crc32;
     92   // The compressed size (in bytes) of this entry.
     93   uint32_t compressed_size;
     94   // The uncompressed size (in bytes) of this entry.
     95   uint32_t uncompressed_size;
     96   // The length of the entry file name in bytes. The file name
     97   // will appear immediately after this record.
     98   uint16_t file_name_length;
     99   // The length of the extra field info (in bytes). This data
    100   // will appear immediately after the entry file name.
    101   uint16_t extra_field_length;
    102   // The length of the entry comment (in bytes). This data will
    103   // appear immediately after the extra field.
    104   uint16_t comment_length;
    105   // The start disk for this entry. Ignored by this implementation).
    106   uint16_t file_start_disk;
    107   // File attributes. Ignored by this implementation.
    108   uint16_t internal_file_attributes;
    109   // File attributes. Ignored by this implementation.
    110   uint32_t external_file_attributes;
    111   // The offset to the local file header for this entry, from the
    112   // beginning of this archive.
    113   uint32_t local_file_header_offset;
    114  private:
    115   CentralDirectoryRecord() = default;
    116   DISALLOW_COPY_AND_ASSIGN(CentralDirectoryRecord);
    117 } __attribute__((packed));
    118 
    119 // The local file header for a given entry. This duplicates information
    120 // present in the central directory of the archive. It is an error for
    121 // the information here to be different from the central directory
    122 // information for a given entry.
    123 struct LocalFileHeader {
    124   static const uint32_t kSignature = 0x04034b50;
    125 
    126   // The local file header signature, must be |kSignature|.
    127   uint32_t lfh_signature;
    128   // Tool version. Ignored by this implementation.
    129   uint16_t version_needed;
    130   // The "general purpose bit flags" for this entry. The only
    131   // flag value that we currently check for is the "data descriptor"
    132   // flag.
    133   uint16_t gpb_flags;
    134   // The compression method for this entry, one of |kCompressStored|
    135   // and |kCompressDeflated|.
    136   uint16_t compression_method;
    137   // The file modification time and date for this entry.
    138   uint16_t last_mod_time;
    139   uint16_t last_mod_date;
    140   // The CRC-32 checksum for this entry.
    141   uint32_t crc32;
    142   // The compressed size (in bytes) of this entry.
    143   uint32_t compressed_size;
    144   // The uncompressed size (in bytes) of this entry.
    145   uint32_t uncompressed_size;
    146   // The length of the entry file name in bytes. The file name
    147   // will appear immediately after this record.
    148   uint16_t file_name_length;
    149   // The length of the extra field info (in bytes). This data
    150   // will appear immediately after the entry file name.
    151   uint16_t extra_field_length;
    152  private:
    153   LocalFileHeader() = default;
    154   DISALLOW_COPY_AND_ASSIGN(LocalFileHeader);
    155 } __attribute__((packed));
    156 
    157 struct DataDescriptor {
    158   // The *optional* data descriptor start signature.
    159   static const uint32_t kOptSignature = 0x08074b50;
    160 
    161   // CRC-32 checksum of the entry.
    162   uint32_t crc32;
    163   // Compressed size of the entry.
    164   uint32_t compressed_size;
    165   // Uncompressed size of the entry.
    166   uint32_t uncompressed_size;
    167  private:
    168   DataDescriptor() = default;
    169   DISALLOW_COPY_AND_ASSIGN(DataDescriptor);
    170 } __attribute__((packed));
    171 
    172 // mask value that signifies that the entry has a DD
    173 static const uint32_t kGPBDDFlagMask = 0x0008;
    174 
    175 // The maximum size of a central directory or a file
    176 // comment in bytes.
    177 static const uint32_t kMaxCommentLen = 65535;
    178 
    179 #endif /* LIBZIPARCHIVE_ZIPARCHIVECOMMON_H_ */
    180