Tribblix: manual page: zip_set_file

ZIP_SET_FILE_COMPRESSION(3) Introduction to Library Functions

NAME

zip_set_file_compression - set compression method for file in zip

LIBRARY

libzip (-lzip)

SYNOPSIS

#include <zip.h>

int
zip_set_file_compression(zip_t *archive, zip_uint64_t index,
zip_int32_t comp, zip_uint32_t comp_flags);

DESCRIPTION

The zip_set_file_compression() function sets the compression method for
the file at position index in the zip archive to comp with the
compression method specific comp_flags. The comp is the same as
returned by zip_stat(3). For the comp argument, currently only the
following values are supported:

ZIP_CM_DEFAULT default compression; currently the same as
ZIP_CM_DEFLATE, but flags are ignored.

ZIP_CM_STORE Store the file uncompressed.

ZIP_CM_BZIP2 Compress the file using the bzip2(1) algorithm.

ZIP_CM_DEFLATE Deflate the file with the zlib(3) algorithm and
default options.

ZIP_CM_XZ Use the xz(1) algorithm for compression

ZIP_CM_ZSTD Use the zstd(1) algorithm for compression

NOTE: Only the deflate and store methods can be assumed to be
universally supported.

The comp_flags argument defines the compression level. This value is
dependent on the compression algorithm. In general, lower numbers mean
faster de/compression and higher numbers mean slower de/compression.
For ZIP_CM_BZIP, ZIP_CM_DEFLATE, and ZIP_CM_XZ 1 is the fastest
compression and 9 the best, 0 chooses the default. For ZIP_CM_ZSTD
possible values are ZSTD_minCLevel(3) to ZSTD_maxCLevel(3); negative
values must be cast to zip_uint32_t.

Further compression method specific flags might be added over time.

The current compression method for a file in a zip archive can be
determined using zip_stat(3).

RETURN VALUES

Upon successful completion 0 is returned. Otherwise, -1 is returned
and the error information in archive is set to indicate the error.

ERRORS

zip_set_file_compression() fails if:

[ZIP_ER_COMPNOTSUPP]
Unsupported compression method requested.

[ZIP_ER_INVAL] index is not a valid file index in archive, or the
argument combination is invalid.

[ZIP_ER_RDONLY] Read-only zip file, no changes allowed.

HISTORY

zip_set_file_compression() was added in libzip 0.11.

AUTHORS

Dieter Baron <dillo@nih.at> and Thomas Klausner <wiz@gatalith.at>

illumos February 2, 2023 illumos