ZIP_SOURCE_FUNCTION(3)

NAME
zip_source_function - create data source from function

LIBRARY
libzip (-lzip)

SYNOPSIS
#include <zip.h>

struct zip_source *
zip_source_function(struct zip *archive, zip_source_callback fn, void *userdata);

DESCRIPTION
The function zip_source_function() creates a zip source from the user-provided function fn, which must be of the following type:

    typedef zip_int64_t (*zip_source_callback)(void *state,
        void *data, zip_uint64_t len, enum zip_source_cmd cmd);

When called by the library, the first argument is the userdata argument supplied to zip_source_function(). The next two arguments are a buffer data of size len when data is expected to be returned, or else NULL and 0. The last argument, cmd, specifies which action the function should perform:

    ZIP_SOURCE_OPEN
        Prepare for reading. Return 0 on success, -1 on error.

    ZIP_SOURCE_READ
        Read data into the buffer data of size len. Return the number of bytes placed into data on success, -1 on error.

    ZIP_SOURCE_CLOSE
        Reading is done. Return 0.

    ZIP_SOURCE_STAT
        Get meta information for the input data. data points to an allocated struct zip_stat, which should be initialized using zip_stat_init(3) and then filled in. 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. NOTE: zip_source_function() may be called with this argument even after being called with ZIP_SOURCE_CLOSE.

    ZIP_SOURCE_ERROR
        Get error information. data 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)).

    ZIP_SOURCE_FREE
        Clean up and free all resources. Return 0.

The library will always issue ZIP_SOURCE_OPEN before issuing ZIP_SOURCE_READ. When it no longer wishes to read from this source, it will issue ZIP_SOURCE_CLOSE. If the library wishes to read the data again, it will issue ZIP_SOURCE_OPEN a second time. If the function is unable to provide the data again, it should return -1.

ZIP_SOURCE_STAT can be issued at any time. ZIP_SOURCE_ERROR will only be issued in response to the function returning -1. ZIP_SOURCE_FREE will be the last command issued; if ZIP_SOURCE_OPEN was called and succeeded, ZIP_SOURCE_CLOSE will be called before ZIP_SOURCE_FREE.

RETURN VALUES
Upon successful completion, the created source is returned. Otherwise, NULL is returned and the error code in archive is set to indicate the error.

ERRORS
zip_source_function() fails if:

[ZIP_ER_MEMORY]
    Required memory could not be allocated.

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)

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