www.LinuxHowtos.org

ZIP_SOURCE_LAYERED

Section: C Library Functions (3)
Index Return to Main Contents

BSD mandoc

NAME

zip_source_layered zip_source_layered_create - create layered data source from function

LIBRARY

libzip -lzip)

SYNOPSIS

In zip.h Ft zip_source_t * Fn zip_source_layered zip_t *archive zip_source_t *source zip_source_layered_callback fn void *userdata Ft zip_source_t * Fn zip_source_layered_create zip_source_t *source zip_source_layered_callback fn void *userdata zip_error_t *error

DESCRIPTION

The functions Fn zip_source_layered and Fn zip_source_layered_create create a layered zip source from the use-provided function fn which must be of the following type:

Ft typedef zip_int64_t Fo (*p_source_layered_callback) Fa zip_source_t *source void *userdata void *data zip_uint64_t length zip_source_cmd_t cmd Fc

archive or error are used for reporting errors and can be NULL

When called by the library, the first argument is the source of the lower layer, the second argument is the userdata argument supplied to the function. The next two arguments are a buffer data of size length when data is passed in or expected to be returned, or else NULL and 0. The last argument, cmd specifies which action the function should perform.

See zip_source_function3 for a description of the commands.

A layered source transforms the data or metadata of the source below in some way. Layered sources can't support writing and are not sufficient to cleanly add support for additional compression or encryption methods. This may be revised in a later release of libzip.

On success, the layered source takes ownership of source The caller should not free it.

The interaction with the lower layer depends on the command:

ZIP_SOURCE_ACCEPT_EMPTY

If the layered source supports this command, the lower layer is not called automatically. Otherwise, the return value of the lower source is used.

ZIP_SOURCE_CLOSE

The lower layer is closed after the callback returns.

ZIP_SOURCE_ERROR

The lower layer is not called automatically. If you need to retrieve error information from the lower layer, use zip_error_set_from_source3 or zip_source_pass_to_lower_layer3.

ZIP_SOURCE_FREE

The lower layer is freed after the callback returns.

ZIP_SOURCE_GET_FILE_ATTRIBUTES

The attributes of the lower layer are merged with the attributes returned by the callback: information set by the callback wins over the lower layer, with the following exceptions: the higher version_needed is used, and general_purpose_bit_flags are only overwritten if the corresponding bit is set in general_purpose_bit_mask

ZIP_SOURCE_OPEN

The lower layer is opened before the callback is called.

ZIP_SOURCE_READ

The lower layer is not called automatically.

ZIP_SOURCE_SEEK

The lower layer is not called automatically.

ZIP_SOURCE_STAT

data contains the stat information from the lower layer when the callback is called.

ZIP_SOURCE_SUPPORTS

data contains the bitmap of commands supported by the lower layer when the callback is called. Since layered sources can't support writing, all commands related to writing are stripped from the returned support bitmap.

ZIP_SOURCE_TELL

The lower layer is not called automatically.

RETURN VALUES

Upon successful completion, the created source is returned. Otherwise, NULL is returned and the error code in archive or error is set to indicate the error (unless it is NULL )

ERRORS

Fn zip_source_layered fails if:

Bq Er ZIP_ER_MEMORY: Required memory could not be allocated.

HISTORY

Fn zip_source_layered and Fn zip_source_layered_create were added in libzip 1.10.

AUTHORS

An -nosplit An Dieter Baron Aq Mt dillo@nih.at and An Thomas Klausner Aq Mt wiz@gatalith.at