Enabling random access within objects in zip archives

A method of fulfilling a request to stream an object, the method performed on a device having a processor and comprising:

• executing, on the processor, instructions that cause the device to:
• access an archive comprising the object compressed with a compression technique, the archive comprising:
• a set of blocks comprising the object, wherein respective sections of the object having a section size have been compressed using the compression technique into a block having a block size, wherein the blocks of the object include a first block having a first block size and a second block having a second block size that is different from the first block size;
• and
• a block table specifying, for the respective blocks of the respective objects compressed with the compression technique, the block size of the block corresponding to the section of the object of the section size;
• and
• responsive to a streaming access request to stream the object from an uncompressed start location that is beyond a beginning of the object;
• using the block map:
• identify a selected block of the object that corresponds to the section of the object that includes the uncompressed start location;
• and
• identify a compressed start location of the selected block within the archive;
• seek within the archive to the compressed start location of the selected block as a current block;
• and
• incrementally stream the object by:
• reading the current block of the block size as indicated by the block map;
• uncompressing the block with the compression technique to produce the section of the object;
• inserting the section into the stream;
• and
• advancing within the archive by the block size of the current block as indicated by the block map.

A device that provides streaming access within an archive compressing at least one object comprising sections of a section size on a device having a processor and a compression technique, the device comprising:

• a processor;
• and
• a memory storing instructions that, when executed by the processor, cause the device to:
• for respective objects, using the compression technique, compress the object from the sections of the section size into blocks respectively having a block size, the blocks including a first block having a first block size and a second block having a second block size that is different from the first block size;
• and
• generate an archive comprising:
• the blocks of the respective objects;
• and
• a block table specifying, for the respective blocks of the respective objects compressed with the compression technique, the block size of the block corresponding to the section of the object of the section size;
• and
• respond to a streaming access request to stream a selected object of the object set from an uncompressed start location that is beyond a beginning of the selected object by:
• identifying a selected block of the object that corresponds to the section of the object that includes the uncompressed start location;
• using the block map, identifying a compressed start location of the selected block within the archive;
• seeking within the archive to the compressed start location of the selected block as a current block;
• and
• incrementally streaming the object by:
• reading the current block of the block size as indicated by the block map;
• uncompressing the block with the compression technique to produce the section of the object;
• inserting the section into the stream;
• and
• advancing within the archive by the block size of the current block as indicated by the block map.

The device of 22, wherein executing the instructions further causes the device to fulfill a request to read at least one selected section of a selected object by:

• using the central directory of the archive, identify a start address of the selected object within the archive;
• for respective selected sections of the selected object:
• using the block table stored in the extension of the central directory of the archive, identifying, relative to the start address, a block offset of the block of the archive that corresponds to the selected section;
• identifying a block address of the block within the archive according to the start address of the object and the block offset;
• reading the block of the selected object at the block address;
• and
• using the compression technique, expanding the block to generate the selected section;
• and
• providing the at least one selected section to fulfill the request.