stream_buffer_encoder.c File Reference

Single-call .xz Stream encoder. More...

#include "index.h"

Go to the source code of this file.

Macros
#define	INDEX_BOUND   ((1 + 1 + 2 * LZMA_VLI_BYTES_MAX + 4 + 3) & ~3)
#define	HEADERS_BOUND   (2 * LZMA_STREAM_HEADER_SIZE + INDEX_BOUND)
	Stream Header, Stream Footer, and Index. More...

Functions
	LZMA_API (size_t)
	Calculate maximum output size for single-call Block encoding. More...
	LZMA_API (lzma_ret)

Detailed Description

Single-call .xz Stream encoder.

Definition in file stream_buffer_encoder.c.

Macro Definition Documentation

HEADERS_BOUND

#define HEADERS_BOUND   (2 * LZMA_STREAM_HEADER_SIZE + INDEX_BOUND)

Stream Header, Stream Footer, and Index.

Definition at line 22 of file stream_buffer_encoder.c.

INDEX_BOUND

#define INDEX_BOUND   ((1 + 1 + 2 * LZMA_VLI_BYTES_MAX + 4 + 3) & ~3)

Maximum size of Index that has exactly one Record. Index Indicator + Number of Records + Record + CRC32 rounded up to the next multiple of four.

Definition at line 19 of file stream_buffer_encoder.c.

Function Documentation

LZMA_API() [1/2]

LZMA_API

(

lzma_ret

)

Definition at line 43 of file stream_buffer_encoder.c.

{
    // Sanity checks
    if (filters == NULL || (unsigned int)(check) > LZMA_CHECK_ID_MAX
            || (in == NULL && in_size != 0) || out == NULL
            || out_pos_ptr == NULL || *out_pos_ptr > out_size)
        return LZMA_PROG_ERROR;
 
    if (!lzma_check_is_supported(check))
        return LZMA_UNSUPPORTED_CHECK;
 
    // Note for the paranoids: Index encoder prevents the Stream from
    // getting too big and still being accepted with LZMA_OK, and Block
    // encoder catches if the input is too big. So we don't need to
    // separately check if the buffers are too big.
 
    // Use a local copy. We update *out_pos_ptr only if everything
    // succeeds.
    size_t out_pos = *out_pos_ptr;
 
    // Check that there's enough space for both Stream Header and
    // Stream Footer.
    if (out_size - out_pos <= 2 * LZMA_STREAM_HEADER_SIZE)
        return LZMA_BUF_ERROR;
 
    // Reserve space for Stream Footer so we don't need to check for
    // available space again before encoding Stream Footer.
    out_size -= LZMA_STREAM_HEADER_SIZE;
 
    // Encode the Stream Header.
    lzma_stream_flags stream_flags = {
        .version = 0,
        .check = check,
    };
 
    if (lzma_stream_header_encode(&stream_flags, out + out_pos)
            != LZMA_OK)
        return LZMA_PROG_ERROR;
 
    out_pos += LZMA_STREAM_HEADER_SIZE;
 
    // Encode a Block but only if there is at least one byte of input.
    lzma_block block = {
        .version = 0,
        .check = check,
        .filters = filters,
    };
 
    if (in_size > 0)
        return_if_error(lzma_block_buffer_encode(&block, allocator,
                in, in_size, out, &out_pos, out_size));
 
    // Index
    {
        // Create an Index. It will have one Record if there was
        // at least one byte of input to encode. Otherwise the
        // Index will be empty.
        lzma_index *i = lzma_index_init(allocator);
        if (i == NULL)
            return LZMA_MEM_ERROR;
 
        lzma_ret ret = LZMA_OK;
 
        if (in_size > 0)
            ret = lzma_index_append(i, allocator,
                    lzma_block_unpadded_size(&block),
                    block.uncompressed_size);
 
        // If adding the Record was successful, encode the Index
        // and get its size which will be stored into Stream Footer.
        if (ret == LZMA_OK) {
            ret = lzma_index_buffer_encode(
                    i, out, &out_pos, out_size);
 
            stream_flags.backward_size = lzma_index_size(i);
        }
 
        lzma_index_end(i, allocator);
 
        if (ret != LZMA_OK)
            return ret;
    }
 
    // Stream Footer. We have already reserved space for this.
    if (lzma_stream_footer_encode(&stream_flags, out + out_pos)
            != LZMA_OK)
        return LZMA_PROG_ERROR;
 
    out_pos += LZMA_STREAM_HEADER_SIZE;
 
    // Everything went fine, make the new output position available
    // to the application.
    *out_pos_ptr = out_pos;
    return LZMA_OK;
}

References allocator, lzma_stream_flags::backward_size, check, filters, i, in, in_size, LZMA_BUF_ERROR, LZMA_CHECK_ID_MAX, LZMA_MEM_ERROR, LZMA_OK, LZMA_PROG_ERROR, LZMA_STREAM_HEADER_SIZE, LZMA_UNSUPPORTED_CHECK, NULL, out, out_pos, return_if_error, lzma_block::uncompressed_size, lzma_block::version, and lzma_stream_flags::version.

LZMA_API() [2/2]

LZMA_API

(

size_t

)

Calculate maximum output size for single-call Block encoding.

Calculate output buffer size for single-call Stream encoder.

This is equivalent to lzma_stream_buffer_bound() but for .xz Blocks. See the documentation of lzma_stream_buffer_bound().

Definition at line 25 of file stream_buffer_encoder.c.

{
    // Get the maximum possible size of a Block.
    const size_t block_bound = lzma_block_buffer_bound(uncompressed_size);
    if (block_bound == 0)
        return 0;
 
    // Catch the possible integer overflow and also prevent the size of
    // the Stream exceeding LZMA_VLI_MAX (theoretically possible on
    // 64-bit systems).
    if (my_min(SIZE_MAX, LZMA_VLI_MAX) - block_bound < HEADERS_BOUND)
        return 0;
 
    return block_bound + HEADERS_BOUND;
}

References HEADERS_BOUND, lzma_block_buffer_bound64(), LZMA_VLI_MAX, my_min, SIZE_MAX, and uncompressed_size.