.\" zip_file_extra_fields_count.mdoc -- count extra field for file in zip
.\" Copyright (C) 2012-2017 Dieter Baron and Thomas Klausner
.\"
.\" This file is part of libzip, a library to manipulate ZIP files.
.\" The authors can be contacted at <libzip@nih.at>
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.Dd December 18, 2017
.Dt ZIP_FILE_EXTRA_FIELDS_COUNT 3
.Os
.Sh NAME
.Nm zip_file_extra_fields_count ,
.Nm zip_file_extra_fields_count_by_id
.Nd count extra fields for file in zip
.Sh LIBRARY
libzip (-lzip)
.Sh SYNOPSIS
.In zip.h
.Ft zip_int16_t
.Fn zip_file_extra_fields_count "zip_t *archive" "zip_uint64_t index" "zip_flags_t flags"
.Ft zip_int16_t
.Fn zip_file_extra_fields_count_by_id "zip_t *archive" "zip_uint64_t index" "zip_uint16_t extra_field_id" "zip_flags_t flags"
.Sh DESCRIPTION
The
.Fn zip_file_extra_fields_count
function counts the extra fields for the file at position
.Ar index
in the zip archive.
.Pp
The following
.Ar flags
are supported:
.Bl -tag -width ZIP_FL_CENTRALXX -offset indent
.It Dv ZIP_FL_CENTRAL
Count extra fields from the archive's central directory.
.It Dv ZIP_FL_LOCAL
Count extra fields from the local file headers.
.It Dv ZIP_FL_UNCHANGED
Count the original unchanged extra fields, ignoring any changes made.
.El
.Pp
The
.Fn zip_file_extra_fields_count_by_id
function counts the extra fields with ID (two-byte signature)
.Ar extra_field_id .
The other arguments are the same as for
.Fn zip_file_extra_fields_count .
.Pp
Extra fields that are the same in the central directory and the local file
header are merged into one.
Therefore, the counts with
.Dv ZIP_FL_CENTRAL
and
.Dv ZIP_FL_LOCAL
do not need to add up to the same value as when given
.Dv ZIP_FL_CENTRAL|ZIP_FL_LOCAL
at the same time.
.Sh RETURN VALUES
Upon successful completion, the requested number of extra fields is returned.
Otherwise, \-1 is returned and the error code in
.Ar archive
is set to indicate the error.
.Sh ERRORS
.Fn zip_file_extra_fields_count
and
.Fn zip_file_extra_fields_count_by_id
fail if:
.Bl -tag -width Er
.It Bq Er ZIP_ER_NOENT
.Ar index
is not a valid file index in
.Ar archive .
.\" TODO: _zip_read_local_ef errors
.El
.Sh SEE ALSO
.Xr libzip 3 ,
.Xr zip_file_extra_field_delete 3 ,
.Xr zip_file_extra_field_get 3 ,
.Xr zip_file_extra_field_set 3
.Sh HISTORY
.Fn zip_file_extra_fields_count
and
.Fn zip_file_extra_fields_count_by_id
were added in libzip 0.11.
.Sh AUTHORS
.An -nosplit
.An Dieter Baron Aq Mt dillo@nih.at
and
.An Thomas Klausner Aq Mt tk@giga.or.at