.\" zip_source_function.mdoc \-- create data source from function
.\" Copyright (C) 2004-2011 Dieter Baron and Thomas Klausner
.\"
.\" This file is part of libzip, a library to manipulate ZIP archives.
.\" The authors can be contacted at <libzip@nih.at>
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.TH ZIP_SOURCE_FUNCTION 3 "March 22, 2011" NiH
.SH "NAME"
zip_source_function \- create data source from function
.SH "LIBRARY"
libzip (-lzip)
.SH "SYNOPSIS"
#include <zip.h>
.PP
struct zip_source *
zip_source_function(struct zip *archive, zip_source_callback fn, void *userdata);
.SH "DESCRIPTION"
The function
zip_source_function
creates a zip source from the user-provided function
\fBfn,\fR
which must be of the following type:
.Bd \-literal
typedef zip_int64_t (*zip_source_callback)(void *state,
    void *data, zip_uint64_t len, enum zip_source_cmd cmd);
.Ed
.PP
When called by the library, the first argument is the
\fBuserdata\fR
argument supplied to
zip_source_function.
The next two arguments are a buffer
\fBdata\fR
of size
\fBlen\fR
when data is expected to be returned, or else
\fBNULL\fR
and 0.
The last argument,
\fBcmd,\fR
specifies which action the function should perform:
.RS
.TP 21
\fBZIP_SOURCE_OPEN\fR
Prepare for reading.
Return 0 on success, \-1 on error.
.TP 21
\fBZIP_SOURCE_READ\fR
Read data into the buffer
\fBdata\fR
of size
\fBlen.\fR
Return the number of bytes placed into
\fBdata\fR
on success, \-1 on error.
.TP 21
\fBZIP_SOURCE_CLOSE\fR
Reading is done.
Return 0.
.TP 21
\fBZIP_SOURCE_STAT\fR
Get meta information for the input data.
\fBdata\fR
points to an initialized
.Vt struct zip_stat,
which should be filled in.
(See
zip_stat_init(3). )
Information only available after the source has been read (e.g. size)
can be omitted in an earlier call.
Return sizeof(struct zip_stat) on success, \-1 on error.
.I NOTE :
zip_source_function
may be called with this argument even after being called with
\fBZIP_SOURCE_CLOSE.\fR
.TP 21
\fBZIP_SOURCE_ERROR\fR
Get error information.
\fBdata\fR
points to an array of two ints, which should be filled with the libzip
error code and the corresponding system error code for the error that
occurred.
See
zip_errors(3)
for details on the error codes.
Return return(2 * sizeof(int)).
.TP 21
\fBZIP_SOURCE_FREE\fR
Clean up and free all resources.
Return 0.
.RE
.PP
The library will always issue
\fBZIP_SOURCE_OPEN\fR
before issuing
\fBZIP_SOURCE_READ.\fR
When it no longer wishes to read from this source, it will issue
\fBZIP_SOURCE_CLOSE.\fR
If the library wishes to read the data again, it will issue
\fBZIP_SOURCE_OPEN\fR
a second time.
If the function is unable to provide the data again, it should
return \-1.
.PP
\fBZIP_SOURCE_STAT\fR
can be issued at any time.
\fBZIP_SOURCE_ERROR\fR
will only be issued in response to the function
returning \-1.
\fBZIP_SOURCE_FREE\fR
will be the last command issued;
if
\fBZIP_SOURCE_OPEN\fR
was called and succeeded,
\fBZIP_SOURCE_CLOSE\fR
will be called before
\fBZIP_SOURCE_FREE.\fR
.SH "RETURN VALUES"
Upon successful completion, the created source is returned.
Otherwise,
\fBNULL\fR
is returned and the error code in
\fBarchive\fR
is set to indicate the error.
.SH "ERRORS"
zip_source_function
fails if:
.RS
.TP 4
[ZIP_ER_MEMORY]
Required memory could not be allocated.
.RE
.SH "SEE ALSO"
libzip(3),
zip_add(3),
zip_replace(3),
zip_source_buffer(3),
zip_source_file(3),
zip_source_filep(3),
zip_source_free(3),
zip_source_zip(3),
zip_stat_init(3)
.SH "AUTHORS"

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