NAME

       zip_file_extra_field_get, zip_file_extra_field_get_by_id - get extra field for file in zip

LIBRARY

       libzip (-lzip)

SYNOPSIS

       #include <zip.h>

       const zip_uint8_t *
       zip_file_extra_field_get(zip_t *archive, zip_uint64_t index,
           zip_uint16_t extra_field_index, zip_uint16_t *idp, zip_uint16_t *lenp,
           zip_flags_t flags);

       const zip_uint8_t *
       zip_file_extra_field_get_by_id(zip_t *archive, zip_uint64_t index,
           zip_uint16_t extra_field_id, zip_uint16_t extra_field_index, zip_uint16_t *lenp,
           zip_flags_t flags);

DESCRIPTION

       The zip_file_extra_field_get() function returns the extra field with index
       extra_field_index for the file at position index in the zip archive.  This pointer should
       not be modified or free(3)'d, and becomes invalid when archive is closed.  If idp is not
       NULL, the integer to which it points will be set to the ID (two-byte signature) of the
       selected extra field.  If lenp is not NULL, the integer to which it points will be set to
       the length of the extra field.  Generally speaking, lenp and idp should be passed since
       only the extra field data is returned (i.e., neither the ID nor the length, if the idp and
       lenp arguments are not provided).

       The following flags are supported:

             ZIP_FL_CENTRAL      Return extra fields from the archive's central directory.

             ZIP_FL_LOCAL        Return extra fields from the local file headers.

             ZIP_FL_UNCHANGED    Return the original unchanged extra fields, ignoring any changes
                                 made.

       The zip_file_extra_field_get_by_id() function returns the extra field with ID (two-byte
       signature) extra_field_id and index extra_field_index (in other words, the
       extra_field_index'th extra field with ID extra_field_id) The other arguments are the same
       as for zip_file_extra_field_get().

RETURN VALUES

       Upon successful completion, a pointer to an extra field is returned, or NULL if there is
       no extra field with that extra_field_index for the file with index index.  In case of an
       error, NULL is returned and the error code in archive is set to indicate the error.

ERRORS

       zip_file_extra_field_get() and zip_file_extra_field_get_by_id() fail if:

       [ZIP_ER_NOENT]     index is not a valid file index in archive, or extra_field_index is not
                          a valid extra file index (for ID extra_field_id).

SEE ALSO

       libzip(3), zip_file_extra_field_delete(3), zip_file_extra_field_set(3),
       zip_file_extra_fields_count(3)

AUTHORS

       Dieter Baron <dillo@nih.at> and Thomas Klausner <tk@giga.or.at>

CAVEATS

       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 read using
       zip_file_extra_field_get() since they are used by libzip(3) internally.