zip_file_extra_field_set - Man Page

set extra field for file in zip


libzip (-lzip)


#include <zip.h>

zip_file_extra_field_set(zip_t *archive, zip_uint64_t index, zip_uint16_t extra_field_id, zip_uint16_t extra_field_index, const zip_uint8_t *extra_field_data, zip_uint16_t len, zip_flags_t flags);


The zip_file_extra_field_set() function sets the extra field with ID (two-byte signature) extra_field_id and index extra_field_index for the file at position index in the zip archive. The extra field's data will be set to extra_field_data and length len. If a new entry shall be appended, set extra_field_index to ZIP_EXTRA_FIELD_NEW.

At least one of the following flags must be set:


Set extra field in the archive's central directory.


Set extra field in the local file headers.

Please note that the extra field IDs 0x0001 (ZIP64 extension), 0x6375 (Infozip UTF-8 comment), and 0x7075 (Infozip UTF-8 file name) can not be set using zip_file_extra_field_set() since they are set by libzip(3) automatically when needed.

Return Values

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


zip_file_extra_field_set() fails if:


The extra field size is too large (ID and length need 4 bytes; the maximum length of all extra fields for one file combined is 65536 bytes). This error also occurs if extra_field_index is too large.


Required memory could not be allocated.


index is not a valid file index in archive.

See Also

libzip(3), zip_file_extra_field_delete(3), zip_file_extra_field_get(3), zip_file_extra_fields_count(3)


zip_file_extra_field_set() was added in libzip 0.11.


Dieter Baron <> and Thomas Klausner <>

Referenced By

libzip(3), zip_file_extra_field_delete(3), zip_file_extra_field_get(3), zip_file_extra_fields_count(3).

December 18, 2017