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ZIP_SET_FILE_COMPRESSION

Section: C Library Functions (3)
Index Return to Main Contents

BSD mandoc

NAME

zip_set_file_compression - set compression method for file in zip

LIBRARY

libzip -lzip)

SYNOPSIS

In zip.h Ft int Fn zip_set_file_compression zip_t *archive zip_uint64_t index zip_int32_t comp zip_uint32_t comp_flags

DESCRIPTION

The Fn 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_stat3. 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_minCLevel3 to ZSTD_maxCLevel3;negativevaluesmustbecastto Ft 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_stat3.

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

Fn zip_set_file_compression fails if:

Bq Er ZIP_ER_COMPNOTSUPP: Unsupported compression method requested.
Bq Er ZIP_ER_INVAL: index is not a valid file index in archive or the argument combination is invalid.
Bq Er ZIP_ER_RDONLY: Rea-only zip file, no changes allowed.