`bpak_transport` — BPAK Transport API¶

The BPAK transport layer handles encoding and decoding of packages for transport. This typically means that two versions of the same package is transport encoded using the bsdiff algorithm.

Source code: include/bpak/transport.h, lib/transport_decode.c, lib/transport_encode.c

BPAK - Bit Packer

SPDX-License-Identifier: BSD-3-Clause

Functions

int bpak_transport_decode_init(struct bpak_transport_decode *ctx, uint8_t *buffer, size_t buffer_length, struct bpak_header *patch_header, bpak_io_t write_output, bpak_io_t read_output, off_t output_offset, bpak_io_t write_output_header, void *user)¶

Initalizes the transport decode context for a BPAK package

NOTE: It’s expected that the user provied correct offsets for io callbacks. The transport decode layer assumes that reading/writing at offset zero means where the data starts.

Parameters:

ctx – [in] Pointer to a transport decode context
buffer – [in] Work buffer
buffer_length – [in] Length of work buffer
patch_header – [in] Input patch BPAK header
write_output – [in] Callback for writing output
read_output – [in] Callback for reading output
output_offset – [in] Offset where output data should be written
write_output_header – [in] Callback for writing the output header
user – [in] User pointer for io callbacks

Returns:

BPAK_OK on success or a negative number on failure

int bpak_transport_decode_set_origin(struct bpak_transport_decode *ctx, struct bpak_header *origin_header, bpak_io_t read_origin, off_t origin_offset)¶

Provide an origin stream for the decoder. The patch decoder needs an origin stream to produce the target binary. However, de-compressors merkle-tree generator does not need this.

Parameters:

ctx – [in] Pointer to a transport decode context
origin_header – [in] Origin BPAK header
read_origin – [in] Callback for reading origin data
origin_offset – [in] Offset where origin data block starts
origin_data_offset – [in] Origin data offset

Returns:

BPAK_OK on success or a negative number on failure

int bpak_transport_decode_start(struct bpak_transport_decode *ctx, struct bpak_part_header *part)¶

Starts the decoding process. Some parts are re-created, for example merkle hash tress, and therefore the input size is zero. In this case the start function will perform the actual decoding and no calls to ‘bpak_transport_decode_write_chunk’ are needed.

Note: This call can take a significant amount of time, for example if a large hash tree needs to be re-built.

Parameters:

ctx – [in] Pointer to a transport decode context
part – [in] Pointer to the BPAK part that should be processed

Returns:

BPAK_OK on success or a negative number on failure

int bpak_transport_decode_write_chunk(struct bpak_transport_decode *ctx, uint8_t *buffer, size_t length)¶

Write chunked input data to the decoder

Parameters:

ctx – [in] Pointer to a transport decode context
buffer – [in] Pointer to a buffer that holds input data
length – [in] Length of input buffer

Returns:

BPAK_OK on success or a negative number on failure

int bpak_transport_decode_finish(struct bpak_transport_decode *ctx)¶

Should be called when no more data should be written to the decoder

Parameters:: ctx – [in] Pointer to a transport decode context
Returns:: BPAK_OK on success or a negative number on failure

void bpak_transport_decode_free(struct bpak_transport_decode *ctx)¶

Free’s the decoder context

Parameters:: ctx – [in] Pointer to a transport decode context

int bpak_transport_encode(FILE *input_fp, struct bpak_header *input_header, FILE *output_fp, struct bpak_header *output_header, FILE *origin_fp, struct bpak_header *origin_header)¶

Transport encode package stream ‘input_fp’ according to metadata in package and use package stream ‘origin_fp’ as origin data. The output package is written to ‘output_fp’.

NOTE: The transport encode function only accepts input streams where the bpak header is at the start of the stream and the data at sizeof(struct bpak_header) offset from start.

Parameters:

input_fp – [in] Input file stream
input_header – [in] BPAK header from input stream
output_fp – [in] Output file stream
output_header – [in] BPAK header from output stream
origin_fp – [in] Origin file stream
origin_header – [in] BPAK header from origin stream

Returns:

BPAK_OK on success or a negative number on failure

struct bpak_transport_decode¶

Public Members

uint8_t *buffer¶

size_t buffer_length¶

struct bpak_header *patch_header¶

struct bpak_header *origin_header¶

struct bpak_part_header *part¶

bpak_io_t write_output¶

bpak_io_t read_output¶

bpak_io_t read_origin¶

bpak_io_t write_output_header¶

uint32_t decoder_id¶

off_t copy_offset¶

off_t output_offset¶

off_t origin_offset¶

struct bpak_bspatch_context bspatch¶

union bpak_transport_decode::[anonymous] decoders¶

void *user¶

bpak_transport — BPAK Transport API¶

`bpak_transport` — BPAK Transport API¶