stream-unzip 0.0.67

Python function to stream unzip all the files in a ZIP archive, without loading the entire ZIP file into memory or any of its uncompressed files

stream-unzip

Python function to stream unzip all the files in a ZIP archive, without loading the entire ZIP file into memory or any of its uncompressed files. Deflate and Deflate64/Enhanced Deflate ZIPs are supported, as well as AES and legacy (ZipCrypto/Zip 2.0) encrypted/password-protected ZIPs.

While the ZIP format does have its main directory at the end, each compressed file in the archive is prefixed with a header that contains its name. Also, the Deflate algorithm that most ZIP files use indicates when it has reached the end of the stream of a member file. These facts make the streaming decompression of ZIP archives possible.

Installation

pip install stream-unzip

Usage

A single function is exposed, stream_unzip, that takes a single argument: an iterable that should yield the bytes of a ZIP file [with no zero-length chunks]. It returns an iterable, where each yielded item is a tuple of the file name, file size [None if this is not known], and another iterable itself yielding the unzipped bytes of that file.

from stream_unzip import stream_unzip
import httpx

def zipped_chunks():
    # Iterable that yields the bytes of a zip file
    with httpx.stream('GET', 'https://www.example.com/my.zip') as r:
        yield from r.iter_bytes(chunk_size=65536)

for file_name, file_size, unzipped_chunks in stream_unzip(zipped_chunks(), password=b'my-password'):
    # unzipped_chunks must be iterated to completion or UnfinishedIterationError will be raised
    for chunk in unzipped_chunks:
        print(chunk)

The file name and file size are extracted as reported from the file. If you don't trust the creator of the ZIP file, these should be treated as untrusted input.

Exceptions

Exceptions raised by the source iterable are passed through stream_unzip unchanged. Other exceptions are in the stream_unzip module, and derive from its UnzipError.

Exception hierarchy

• UnzipError

  Base class for all explicitly-thrown exceptions

  • InvalidOperationError

    • UnfinishedIterationError

      The unzipped chunks iterator of a member file has not been iterated to completion.

  • UnzipValueError (also inherits from the ValueError built-in)

    Base class for errors relating to invalid arguments

    • PasswordError

      • MissingPasswordError

        A file requires a password, but it was not supplied.

        • MissingZipCryptoPasswordError

          A file is legacy (ZipCrypto/Zip 2.0) encrypted, but a password was not supplied.

        • MissingAESPasswordError

          A file is AES encrypted, but a password was not supplied.

        • IncorrectPasswordError

          An incorrect password was supplied. Note that due to nature of the ZIP file format, some incorrect passwords would not raise this exception, and instead raise a DataError, or even in pathalogical cases, not raise any exception.

          • IncorrectZipCryptoPasswordError

            An incorrect password was supplied for a legacy (ZipCrypto/Zip 2.0) encrypted file.

          • IncorrectAESPasswordError

            An incorrect password was supplied for an AES encrypted file.

    • DataError

      An issue with the ZIP bytes themselves was encountered.

      • UnsupportedFeatureError

        A file in the ZIP uses features that are unsupported.

        • UnsupportedFlagsError

        • UnsupportedCompressionTypeError

      • UncompressError

        • DeflateError

          An error in the deflate-compressed data meant it could not be decompressed.

      • IntegrityError

        • HMACIntegrityError

          The HMAC integrity check on AES encrypted bytes failed

        • CRC32IntegrityError

          The CRC32 integrity check on decrypted and decompressed bytes failed.

      • TruncatedDataError

        The stream of bytes ended unexpectedly.

      • UnexpectedSignatureError

        Each section of a ZIP file starts with a signature, and an unexpected one was encountered.

      • MissingExtraError

        Metadata known as extra that some ZIP files require is missing.

        • MissingZip64ExtraError

        • MissingAESExtraError

      • TruncatedExtraError

        Metadata known as extra that some ZIP files require is present, but too short.

        • TruncatedZip64ExtraError

        • TruncatedAESExtraError

      • InvalidExtraError

        Metadata known as extra that some ZIP files require is present, long enough, but holds an invalid value.

        • InvalidAESKeyLengthError

          AES key length specified in the ZIP is not any of 1, 2, or 3 (which correspond to 128, 192, and 256 bits respectively).