.\" Automatically generated from an mdoc input file.  Do not edit.
.\" zip_file_extra_field_get.mdoc -- get 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.
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.TH "ZIP_FILE_EXTRA_FIELD_GET" "3" "December 18, 2017" "NiH" "Library Functions Manual"
.nh
.if n .ad l
.SH "NAME"
\fBzip_file_extra_field_get\fR,
\fBzip_file_extra_field_get_by_id\fR
\- get extra field for file in zip
.SH "LIBRARY"
libzip (-lzip)
.SH "SYNOPSIS"
\fB#include <zip.h>\fR
.sp
\fIconst zip_uint8_t *\fR
.br
.PD 0
.HP 4n
\fBzip_file_extra_field_get\fR(\fIzip_t\ *archive\fR, \fIzip_uint64_t\ index\fR, \fIzip_uint16_t\ extra_field_index\fR, \fIzip_uint16_t\ *idp\fR, \fIzip_uint16_t\ *lenp\fR, \fIzip_flags_t\ flags\fR);
.PD
.PP
\fIconst zip_uint8_t *\fR
.br
.PD 0
.HP 4n
\fBzip_file_extra_field_get_by_id\fR(\fIzip_t\ *archive\fR, \fIzip_uint64_t\ index\fR, \fIzip_uint16_t\ extra_field_id\fR, \fIzip_uint16_t\ extra_field_index\fR, \fIzip_uint16_t\ *lenp\fR, \fIzip_flags_t\ flags\fR);
.PD
.SH "DESCRIPTION"
The
\fBzip_file_extra_field_get\fR()
function returns the extra field with index
\fIextra_field_index\fR
for the file at position
\fIindex\fR
in the zip archive.
This pointer should not be modified or
free(3)'d,
and becomes invalid when
\fIarchive\fR
is closed.
If
\fIidp\fR
is not
\fRNULL\fR,
the integer to which it points will be set to the ID (two-byte
signature) of the selected extra field.
If
\fIlenp\fR
is not
\fRNULL\fR,
the integer to which it points will be set to the length of the
extra field.
Generally speaking,
\fIlenp\fR
and
\fIidp\fR
should be passed since only the extra field data is returned (i.e.,
neither the ID nor the length, if the
\fIidp\fR
and
\fIlenp\fR
arguments are not provided).
.PP
The following
\fIflags\fR
are supported:
.RS 6n
.TP 20n
\fRZIP_FL_CENTRAL\fR
Return extra fields from the archive's central directory.
.TP 20n
\fRZIP_FL_LOCAL\fR
Return extra fields from the local file headers.
.TP 20n
\fRZIP_FL_UNCHANGED\fR
Return the original unchanged extra fields, ignoring any changes made.
.RE
.PP
The
\fBzip_file_extra_field_get_by_id\fR()
function returns the extra field with ID (two-byte signature)
\fIextra_field_id\fR
and index
\fIextra_field_index\fR
(in other words, the
\fIextra_field_index\fR'th
extra field with ID
\fIextra_field_id\fR)
The other arguments are the same as for
\fBzip_file_extra_field_get\fR().
.SH "RETURN VALUES"
Upon successful completion, a pointer to an extra field is returned,
or
\fRNULL\fR
if there is no extra field with that
\fIextra_field_index\fR
for the file with index
\fIindex\fR.
In case of an error,
\fRNULL\fR
is returned and the error code in
\fIarchive\fR
is set to indicate the error.
.SH "ERRORS"
\fBzip_file_extra_field_get\fR()
and
\fBzip_file_extra_field_get_by_id\fR()
fail if:
.TP 19n
[\fRZIP_ER_NOENT\fR]
\fIindex\fR
is not a valid file index in
\fIarchive\fR,
or
\fIextra_field_index\fR
is not a valid extra file index (for ID
\fIextra_field_id\fR).
.SH "SEE ALSO"
libzip(3),
zip_file_extra_field_delete(3),
zip_file_extra_field_set(3),
zip_file_extra_fields_count(3)
.SH "HISTORY"
\fBzip_file_extra_field_get\fR()
and
\fBzip_file_extra_field_get_by_id\fR()
were added in libzip 0.11.
.SH "AUTHORS"
Dieter Baron <\fIdillo@nih.at\fR>
and
Thomas Klausner <\fItk@giga.or.at\fR>
.SH "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
\fBzip_file_extra_field_get\fR()
since they are used by
libzip(3)
internally.