This library provides access to ZIP files. ZIP files are used to store SWI-Prolog resources. Ths library provides more high level access and documentation in addition to the low level access provided as built in as it is needed to bootstrap SWI-Prolog.

Access to a zip file is provided by means of a zipper object. This is a blob that is subject to atom garbage collection. Collecting a zipper closes the underlying OS access.

A zipper is a stateful object. We recognise the following states: idle, scan, read_entry, write_entry and close. The interface raise a permission_error when trying to make an illegal state transition.

Being stateful, a zipper cannot be used simultaneously from multiple threads. The zipper becomes owned by a thread when moving to scan using zipper_goto/2. It is released after zipper_open_current/3 followed by closing the stream.

 zip_open(+File, +Mode, -Zipper, +Options) is det

Create a Zipper, providing access to File. Mode is one of read or write. The Options list is currently ignored.

 zip_close(+Zipper) is det

 zip_close(+Zipper, +Options) is det

Close a zipper. Options processed:

comment(+Comment)

If the zipper is open for writing, set the global comment for the zip file.

 zipper_goto(+Zipper, +Where) is semidet

Seek Zipper to a specified entry. Where is one of

first

Go to the first entry. Fails if the zip is empty.

next

Go to the next entry. Fails if there is no next entry.

file(Name)

Go to the entry with the specified name.

 zipper_open_current(+Zipper, -Stream, +Options) is det

Open the current entry as an input stream. Before this call the caller must use zipper_goto/2 to position to archive. Options:

type(+Type)

encoding(+Encoding)

bom(+Boolean)

Determine type and encoding of the stream. The semantics is the same as for open/4.

release(+Boolean)

If true (default), release te archive for access by other threads after the entry is closed.

It is allowed to call zip_close/1 immediately after this call, in which case the archive is closed when the entry is closed.

 with_zipper(+Zipper, :Goal)

Run Goal while holding ownership over Zipper.

 zipper_members(+Zipper, -Members:list(atom)) is det

True when Members is the list of file names in the Zipper.

 zipper_file_info(+Zipper, -Name, -Attrs) is det

Obtain information about the current zip entry. Name is an atom representing the name of the entry. Attrs is a dict holding:

compressed_size:Bytes

Size in the archive

uncompressed_size:Bytes

Bytes after decompression

time:Stamp

Numeric time stamp in Prolog native format (float expressing seconds since Jan 1, 1970). Note that the resolution of time in zip archives is one second.

extra:Extra

comment:Extra

Optional additional fields.

offset:Offset

Direct pointer to this entry. May be used with zip_goto/2.

 zipper_open_new_file_in_zip(+Zipper, +Name, -Stream, +Options) is det

Create a new file in a zip archive. Options provided are:

extra(+Text)

Additional meta-data

comment(+Text)

Comment for the entry.

time(+Stamp)

Last modified time claimed for the entry.

method(+Method)

One of deflated (default) or store (store uncompressed)

level(+Compression)

Compression level (0..9, default 6).

zip64(+Boolean)

When true (default false), allow the entry to grow above 4Gb.