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xdelta3-decode.h
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xdelta3-decode.h
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/* xdelta 3 - delta compression tools and library
* Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010,
* 2011, 2012, 2013, 2014, 2015. Joshua P. MacDonald
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifndef _XDELTA3_DECODE_H_
#define _XDELTA3_DECODE_H_
#include "xdelta3-internal.h"
#define SRCORTGT(x) ((((x) & VCD_SRCORTGT) == VCD_SOURCE) ? \
VCD_SOURCE : ((((x) & VCD_SRCORTGT) == \
VCD_TARGET) ? VCD_TARGET : 0))
static inline int
xd3_decode_byte (xd3_stream *stream, usize_t *val)
{
if (stream->avail_in == 0)
{
stream->msg = "further input required";
return XD3_INPUT;
}
(*val) = stream->next_in[0];
DECODE_INPUT (1);
return 0;
}
static inline int
xd3_decode_bytes (xd3_stream *stream, uint8_t *buf, usize_t *pos, usize_t size)
{
usize_t want;
usize_t take;
/* Note: The case where (*pos == size) happens when a zero-length
* appheader or code table is transmitted, but there is nothing in
* the standard against that. */
while (*pos < size)
{
if (stream->avail_in == 0)
{
stream->msg = "further input required";
return XD3_INPUT;
}
want = size - *pos;
take = xd3_min (want, stream->avail_in);
memcpy (buf + *pos, stream->next_in, (size_t) take);
DECODE_INPUT (take);
(*pos) += take;
}
return 0;
}
/* Initialize the decoder for a new window. The dec_tgtlen value is
* preserved across successive window decodings, and the update to
* dec_winstart is delayed until a new window actually starts. This
* is to avoid throwing an error due to overflow until the last
* possible moment. This makes it possible to encode exactly 4GB
* through a 32-bit encoder. */
static int
xd3_decode_init_window (xd3_stream *stream)
{
stream->dec_cpylen = 0;
stream->dec_cpyoff = 0;
stream->dec_cksumbytes = 0;
xd3_init_cache (& stream->acache);
return 0;
}
/* Allocates buffer space for the target window and possibly the
* VCD_TARGET copy-window. Also sets the base of the two copy
* segments. */
static int
xd3_decode_setup_buffers (xd3_stream *stream)
{
/* If VCD_TARGET is set then the previous buffer may be reused. */
if (stream->dec_win_ind & VCD_TARGET)
{
/* Note: this implementation is untested, since Xdelta3 itself
* does not implement an encoder for VCD_TARGET mode. Thus, mark
* unimplemented until needed. */
if (1)
{
stream->msg = "VCD_TARGET not implemented";
return XD3_UNIMPLEMENTED;
}
/* But this implementation only supports copying from the last
* target window. If the offset is outside that range, it can't
* be done. */
if (stream->dec_cpyoff < stream->dec_laststart)
{
stream->msg = "unsupported VCD_TARGET offset";
return XD3_INVALID_INPUT;
}
/* See if the two windows are the same. This indicates the
* first time VCD_TARGET is used. This causes a second buffer
* to be allocated, after that the two are swapped in the
* DEC_FINISH case. */
if (stream->dec_lastwin == stream->next_out)
{
stream->next_out = NULL;
stream->space_out = 0;
}
/* TODO: (See note above, this looks incorrect) */
stream->dec_cpyaddrbase = stream->dec_lastwin +
(usize_t) (stream->dec_cpyoff - stream->dec_laststart);
}
/* See if the current output window is large enough. */
if (stream->space_out < stream->dec_tgtlen)
{
xd3_free (stream, stream->dec_buffer);
stream->space_out =
xd3_round_blksize (stream->dec_tgtlen, XD3_ALLOCSIZE);
if ((stream->dec_buffer =
(uint8_t*) xd3_alloc (stream, stream->space_out, 1)) == NULL)
{
return ENOMEM;
}
stream->next_out = stream->dec_buffer;
}
/* dec_tgtaddrbase refers to an invalid base address, but it is
* always used with a sufficiently large instruction offset (i.e.,
* beyond the copy window). This condition is enforced by
* xd3_decode_output_halfinst. */
stream->dec_tgtaddrbase = stream->next_out - stream->dec_cpylen;
return 0;
}
static int
xd3_decode_allocate (xd3_stream *stream,
usize_t size,
uint8_t **buf_ptr,
usize_t *buf_alloc)
{
IF_DEBUG2 (DP(RINT "[xd3_decode_allocate] size %u alloc %u\n",
size, *buf_alloc));
if (*buf_ptr != NULL && *buf_alloc < size)
{
xd3_free (stream, *buf_ptr);
*buf_ptr = NULL;
}
if (*buf_ptr == NULL)
{
*buf_alloc = xd3_round_blksize (size, XD3_ALLOCSIZE);
if ((*buf_ptr = (uint8_t*) xd3_alloc (stream, *buf_alloc, 1)) == NULL)
{
return ENOMEM;
}
}
return 0;
}
static int
xd3_decode_section (xd3_stream *stream,
xd3_desect *section,
xd3_decode_state nstate,
int copy)
{
XD3_ASSERT (section->pos <= section->size);
XD3_ASSERT (stream->dec_state != nstate);
if (section->pos < section->size)
{
usize_t sect_take;
if (stream->avail_in == 0)
{
return XD3_INPUT;
}
if ((copy == 0) && (section->pos == 0))
{
/* No allocation/copy needed */
section->buf = stream->next_in;
sect_take = section->size;
IF_DEBUG1 (DP(RINT "[xd3_decode_section] zerocopy %u @ %u avail %u\n",
sect_take, section->pos, stream->avail_in));
}
else
{
usize_t sect_need = section->size - section->pos;
/* Allocate and copy */
sect_take = xd3_min (sect_need, stream->avail_in);
if (section->pos == 0)
{
int ret;
if ((ret = xd3_decode_allocate (stream,
section->size,
& section->copied1,
& section->alloc1)))
{
return ret;
}
section->buf = section->copied1;
}
IF_DEBUG2 (DP(RINT "[xd3_decode_section] take %u @ %u [need %u] avail %u\n",
sect_take, section->pos, sect_need, stream->avail_in));
XD3_ASSERT (section->pos + sect_take <= section->alloc1);
memcpy (section->copied1 + section->pos,
stream->next_in,
sect_take);
}
section->pos += sect_take;
stream->dec_winbytes += sect_take;
DECODE_INPUT (sect_take);
}
if (section->pos < section->size)
{
IF_DEBUG1 (DP(RINT "[xd3_decode_section] further input required %u\n", section->size - section->pos));
stream->msg = "further input required";
return XD3_INPUT;
}
XD3_ASSERT (section->pos == section->size);
stream->dec_state = nstate;
section->buf_max = section->buf + section->size;
section->pos = 0;
return 0;
}
/* Decode the size and address for half of an instruction (i.e., a
* single opcode). This updates the stream->dec_position, which are
* bytes already output prior to processing this instruction. Perform
* bounds checking for sizes and copy addresses, which uses the
* dec_position (which is why these checks are done here). */
static int
xd3_decode_parse_halfinst (xd3_stream *stream, xd3_hinst *inst)
{
int ret;
/* If the size from the instruction table is zero then read a size value. */
if ((inst->size == 0) &&
(ret = xd3_read_size (stream,
& stream->inst_sect.buf,
stream->inst_sect.buf_max,
& inst->size)))
{
return XD3_INVALID_INPUT;
}
/* For copy instructions, read address. */
if (inst->type >= XD3_CPY)
{
IF_DEBUG2 ({
static int cnt = 0;
XPR(NT "DECODE:%u: COPY at %"Q"u (winoffset %u) size %u winaddr %u\n",
cnt++,
stream->total_out + (stream->dec_position -
stream->dec_cpylen),
(stream->dec_position - stream->dec_cpylen),
inst->size,
inst->addr);
});
if ((ret = xd3_decode_address (stream,
stream->dec_position,
inst->type - XD3_CPY,
& stream->addr_sect.buf,
stream->addr_sect.buf_max,
& inst->addr)))
{
return ret;
}
/* Cannot copy an address before it is filled-in. */
if (inst->addr >= stream->dec_position)
{
stream->msg = "address too large";
return XD3_INVALID_INPUT;
}
/* Check: a VCD_TARGET or VCD_SOURCE copy cannot exceed the remaining
* buffer space in its own segment. */
if (inst->addr < stream->dec_cpylen &&
inst->addr + inst->size > stream->dec_cpylen)
{
stream->msg = "size too large";
return XD3_INVALID_INPUT;
}
}
else
{
IF_DEBUG2 ({
if (inst->type == XD3_ADD)
{
static int cnt;
XPR(NT "DECODE:%d: ADD at %"Q"u (winoffset %u) size %u\n",
cnt++,
(stream->total_out + stream->dec_position - stream->dec_cpylen),
stream->dec_position - stream->dec_cpylen,
inst->size);
}
else
{
static int cnt;
XD3_ASSERT (inst->type == XD3_RUN);
XPR(NT "DECODE:%d: RUN at %"Q"u (winoffset %u) size %u\n",
cnt++,
stream->total_out + stream->dec_position - stream->dec_cpylen,
stream->dec_position - stream->dec_cpylen,
inst->size);
}
});
}
/* Check: The instruction will not overflow the output buffer. */
if (stream->dec_position + inst->size > stream->dec_maxpos)
{
stream->msg = "size too large";
return XD3_INVALID_INPUT;
}
stream->dec_position += inst->size;
return 0;
}
/* Decode a single opcode and then decode the two half-instructions. */
static int
xd3_decode_instruction (xd3_stream *stream)
{
int ret;
const xd3_dinst *inst;
if (stream->inst_sect.buf == stream->inst_sect.buf_max)
{
stream->msg = "instruction underflow";
return XD3_INVALID_INPUT;
}
inst = &stream->code_table[*stream->inst_sect.buf++];
stream->dec_current1.type = inst->type1;
stream->dec_current2.type = inst->type2;
stream->dec_current1.size = inst->size1;
stream->dec_current2.size = inst->size2;
/* For each instruction with a real operation, decode the
* corresponding size and addresses if necessary. Assume a
* code-table may have NOOP in either position, although this is
* unlikely. */
if (inst->type1 != XD3_NOOP &&
(ret = xd3_decode_parse_halfinst (stream, & stream->dec_current1)))
{
return ret;
}
if (inst->type2 != XD3_NOOP &&
(ret = xd3_decode_parse_halfinst (stream, & stream->dec_current2)))
{
return ret;
}
return 0;
}
/* Output the result of a single half-instruction. OPT: This the
decoder hotspot. Modifies "hinst", see below. */
static int
xd3_decode_output_halfinst (xd3_stream *stream, xd3_hinst *inst)
{
/* This method is reentrant for copy instructions which may return
* XD3_GETSRCBLK to the caller. Each time through a copy takes the
* minimum of inst->size and the available space on whichever block
* supplies the data */
usize_t take = inst->size;
if (USIZE_T_OVERFLOW (stream->avail_out, take) ||
stream->avail_out + take > stream->space_out)
{
stream->msg = "overflow while decoding";
return XD3_INVALID_INPUT;
}
XD3_ASSERT (inst->type != XD3_NOOP);
switch (inst->type)
{
case XD3_RUN:
{
/* Only require a single data byte. */
if (stream->data_sect.buf == stream->data_sect.buf_max)
{
stream->msg = "data underflow";
return XD3_INVALID_INPUT;
}
memset (stream->next_out + stream->avail_out,
stream->data_sect.buf[0],
take);
stream->data_sect.buf += 1;
stream->avail_out += take;
inst->type = XD3_NOOP;
break;
}
case XD3_ADD:
{
/* Require at least TAKE data bytes. */
if (stream->data_sect.buf + take > stream->data_sect.buf_max)
{
stream->msg = "data underflow";
return XD3_INVALID_INPUT;
}
memcpy (stream->next_out + stream->avail_out,
stream->data_sect.buf,
take);
stream->data_sect.buf += take;
stream->avail_out += take;
inst->type = XD3_NOOP;
break;
}
default:
{
usize_t i;
const uint8_t *src;
uint8_t *dst;
int overlap;
/* See if it copies from the VCD_TARGET/VCD_SOURCE window or
* the target window. Out-of-bounds checks for the addresses
* and sizes are performed in xd3_decode_parse_halfinst. This
* if/else must set "overlap", "src", and "dst". */
if (inst->addr < stream->dec_cpylen)
{
/* In both branches we are copying from outside the
* current decoder window, the first (VCD_TARGET) is
* unimplemented. */
overlap = 0;
/* This branch sets "src". As a side-effect, we modify
* "inst" so that if we reenter this method after a
* XD3_GETSRCBLK response the state is correct. So if the
* instruction can be fulfilled by a contiguous block of
* memory then we will set:
*
* inst->type = XD3_NOOP;
* inst->size = 0;
*/
if (stream->dec_win_ind & VCD_TARGET)
{
/* TODO: Users have requested long-distance copies of
* similar material within a target (e.g., for dup
* supression in backups). This code path is probably
* dead due to XD3_UNIMPLEMENTED in xd3_decode_setup_buffers */
inst->size = 0;
inst->type = XD3_NOOP;
stream->msg = "VCD_TARGET not implemented";
return XD3_UNIMPLEMENTED;
}
else
{
/* In this case we have to read a source block, which
* could return control to the caller. We need to
* know the first block number needed for this
* copy. */
xd3_source *source = stream->src;
xoff_t block = source->cpyoff_blocks;
usize_t blkoff = source->cpyoff_blkoff;
const usize_t blksize = source->blksize;
int ret;
xd3_blksize_add (&block, &blkoff, source, inst->addr);
XD3_ASSERT (blkoff < blksize);
if ((ret = xd3_getblk (stream, block)))
{
/* could be a XD3_GETSRCBLK failure. */
if (ret == XD3_TOOFARBACK)
{
stream->msg = "non-seekable source in decode";
ret = XD3_INTERNAL;
}
return ret;
}
src = source->curblk + blkoff;
/* This block is either full, or a partial block that
* must contain enough bytes. */
if ((source->onblk != blksize) &&
(blkoff + take > source->onblk))
{
IF_DEBUG1 (XPR(NT "[srcfile] short at blkno %"Q"u onblk "
"%u blksize %u blkoff %u take %u\n",
block,
source->onblk,
blksize,
blkoff,
take));
stream->msg = "source file too short";
return XD3_INVALID_INPUT;
}
XD3_ASSERT (blkoff != blksize);
/* Check if we have enough data on this block to
* finish the instruction. */
if (blkoff + take <= blksize)
{
inst->type = XD3_NOOP;
inst->size = 0;
}
else
{
take = blksize - blkoff;
inst->size -= take;
inst->addr += take;
/* because (blkoff + take > blksize), above */
XD3_ASSERT (inst->size != 0);
}
}
}
else
{
/* TODO: the memcpy/overlap optimization, etc. Overlap
* here could be more specific, it's whether (inst->addr -
* srclen) + inst->size > input_pos ? And is the system
* memcpy really any good? */
overlap = 1;
/* For a target-window copy, we know the entire range is
* in-memory. The dec_tgtaddrbase is negatively offset by
* dec_cpylen because the addresses start beyond that
* point. */
src = stream->dec_tgtaddrbase + inst->addr;
inst->type = XD3_NOOP;
inst->size = 0;
}
dst = stream->next_out + stream->avail_out;
stream->avail_out += take;
if (overlap)
{
/* Can't just memcpy here due to possible overlap. */
for (i = take; i != 0; i -= 1)
{
*dst++ = *src++;
}
}
else
{
memcpy (dst, src, take);
}
}
}
return 0;
}
static int
xd3_decode_finish_window (xd3_stream *stream)
{
stream->dec_winbytes = 0;
stream->dec_state = DEC_FINISH;
stream->data_sect.pos = 0;
stream->inst_sect.pos = 0;
stream->addr_sect.pos = 0;
return XD3_OUTPUT;
}
static int
xd3_decode_secondary_sections (xd3_stream *secondary_stream)
{
#if SECONDARY_ANY
int ret;
#define DECODE_SECONDARY_SECTION(UPPER,LOWER) \
((secondary_stream->dec_del_ind & VCD_ ## UPPER ## COMP) && \
(ret = xd3_decode_secondary (secondary_stream, \
& secondary_stream-> LOWER ## _sect, \
& xd3_sec_ ## LOWER (secondary_stream))))
if (DECODE_SECONDARY_SECTION (DATA, data) ||
DECODE_SECONDARY_SECTION (INST, inst) ||
DECODE_SECONDARY_SECTION (ADDR, addr))
{
return ret;
}
#undef DECODE_SECONDARY_SECTION
#endif
return 0;
}
static int
xd3_decode_sections (xd3_stream *stream)
{
usize_t need, more, take;
int copy, ret;
if ((stream->flags & XD3_JUST_HDR) != 0)
{
/* Nothing left to do. */
return xd3_decode_finish_window (stream);
}
/* To avoid extra copying, allocate three sections at once (but
* check for overflow). */
need = stream->inst_sect.size;
if (USIZE_T_OVERFLOW (need, stream->addr_sect.size))
{
stream->msg = "decoder section size overflow";
return XD3_INTERNAL;
}
need += stream->addr_sect.size;
if (USIZE_T_OVERFLOW (need, stream->data_sect.size))
{
stream->msg = "decoder section size overflow";
return XD3_INTERNAL;
}
need += stream->data_sect.size;
/* The window may be entirely processed. */
XD3_ASSERT (stream->dec_winbytes <= need);
/* Compute how much more input is needed. */
more = (need - stream->dec_winbytes);
/* How much to consume. */
take = xd3_min (more, stream->avail_in);
/* See if the input is completely available, to avoid copy. */
copy = (take != more);
/* If the window is skipped... */
if ((stream->flags & XD3_SKIP_WINDOW) != 0)
{
/* Skip the available input. */
DECODE_INPUT (take);
stream->dec_winbytes += take;
if (copy)
{
stream->msg = "further input required";
return XD3_INPUT;
}
return xd3_decode_finish_window (stream);
}
/* Process all but the DATA section. */
switch (stream->dec_state)
{
default:
stream->msg = "internal error";
return XD3_INVALID_INPUT;
case DEC_DATA:
if ((ret = xd3_decode_section (stream, & stream->data_sect,
DEC_INST, copy))) { return ret; }
case DEC_INST:
if ((ret = xd3_decode_section (stream, & stream->inst_sect,
DEC_ADDR, copy))) { return ret; }
case DEC_ADDR:
if ((ret = xd3_decode_section (stream, & stream->addr_sect,
DEC_EMIT, copy))) { return ret; }
}
XD3_ASSERT (stream->dec_winbytes == need);
if ((ret = xd3_decode_secondary_sections (stream))) { return ret; }
if (stream->flags & XD3_SKIP_EMIT)
{
return xd3_decode_finish_window (stream);
}
/* OPT: A possible optimization is to avoid allocating memory in
* decode_setup_buffers and to avoid a large memcpy when the window
* consists of a single VCD_SOURCE copy instruction. */
if ((ret = xd3_decode_setup_buffers (stream))) { return ret; }
return 0;
}
static int
xd3_decode_emit (xd3_stream *stream)
{
int ret;
/* Produce output: originally structured to allow reentrant code
* that fills as much of the output buffer as possible, but VCDIFF
* semantics allows to copy from anywhere from the target window, so
* instead allocate a sufficiently sized buffer after the target
* window length is decoded.
*
* This code still needs to be reentrant to allow XD3_GETSRCBLK to
* return control. This is handled by setting the
* stream->dec_currentN instruction types to XD3_NOOP after they
* have been processed. */
XD3_ASSERT (! (stream->flags & XD3_SKIP_EMIT));
XD3_ASSERT (stream->dec_tgtlen <= stream->space_out);
while (stream->inst_sect.buf != stream->inst_sect.buf_max ||
stream->dec_current1.type != XD3_NOOP ||
stream->dec_current2.type != XD3_NOOP)
{
/* Decode next instruction pair. */
if ((stream->dec_current1.type == XD3_NOOP) &&
(stream->dec_current2.type == XD3_NOOP) &&
(ret = xd3_decode_instruction (stream))) { return ret; }
/* Output dec_current1 */
while ((stream->dec_current1.type != XD3_NOOP))
{
if ((ret = xd3_decode_output_halfinst (stream, & stream->dec_current1)))
{
return ret;
}
}
/* Output dec_current2 */
while (stream->dec_current2.type != XD3_NOOP)
{
if ((ret = xd3_decode_output_halfinst (stream, & stream->dec_current2)))
{
return ret;
}
}
}
if (stream->avail_out != stream->dec_tgtlen)
{
IF_DEBUG2 (DP(RINT "AVAIL_OUT(%d) != DEC_TGTLEN(%d)\n",
stream->avail_out, stream->dec_tgtlen));
stream->msg = "wrong window length";
return XD3_INVALID_INPUT;
}
if (stream->data_sect.buf != stream->data_sect.buf_max)
{
stream->msg = "extra data section";
return XD3_INVALID_INPUT;
}
if (stream->addr_sect.buf != stream->addr_sect.buf_max)
{
stream->msg = "extra address section";
return XD3_INVALID_INPUT;
}
/* OPT: Should cksum computation be combined with the above loop? */
if ((stream->dec_win_ind & VCD_ADLER32) != 0 &&
(stream->flags & XD3_ADLER32_NOVER) == 0)
{
uint32_t a32 = adler32 (1L, stream->next_out, stream->avail_out);
if (a32 != stream->dec_adler32)
{
stream->msg = "target window checksum mismatch";
return XD3_INVALID_INPUT;
}
}
/* Finished with a window. */
return xd3_decode_finish_window (stream);
}
int
xd3_decode_input (xd3_stream *stream)
{
int ret;
if (stream->enc_state != 0)
{
stream->msg = "encoder/decoder transition";
return XD3_INVALID_INPUT;
}
#define BYTE_CASE(expr,x,nstate) \
do { \
if ( (expr) && \
((ret = xd3_decode_byte (stream, & (x))) != 0) ) { return ret; } \
stream->dec_state = (nstate); \
} while (0)
#define OFFSET_CASE(expr,x,nstate) \
do { \
if ( (expr) && \
((ret = xd3_decode_offset (stream, & (x))) != 0) ) { return ret; } \
stream->dec_state = (nstate); \
} while (0)
#define SIZE_CASE(expr,x,nstate) \
do { \
if ( (expr) && \
((ret = xd3_decode_size (stream, & (x))) != 0) ) { return ret; } \
stream->dec_state = (nstate); \
} while (0)
switch (stream->dec_state)
{
case DEC_VCHEAD:
{
if ((ret = xd3_decode_bytes (stream, stream->dec_magic,
& stream->dec_magicbytes, 4)))
{
return ret;
}
if (stream->dec_magic[0] != VCDIFF_MAGIC1 ||
stream->dec_magic[1] != VCDIFF_MAGIC2 ||
stream->dec_magic[2] != VCDIFF_MAGIC3)
{
stream->msg = "not a VCDIFF input";
return XD3_INVALID_INPUT;
}
if (stream->dec_magic[3] != 0)
{
stream->msg = "VCDIFF input version > 0 is not supported";
return XD3_INVALID_INPUT;
}
stream->dec_state = DEC_HDRIND;
}
case DEC_HDRIND:
{
if ((ret = xd3_decode_byte (stream, & stream->dec_hdr_ind)))
{
return ret;
}
if ((stream->dec_hdr_ind & VCD_INVHDR) != 0)
{
stream->msg = "unrecognized header indicator bits set";
return XD3_INVALID_INPUT;
}
stream->dec_state = DEC_SECONDID;
}
case DEC_SECONDID:
/* Secondary compressor ID: only if VCD_SECONDARY is set */
if ((stream->dec_hdr_ind & VCD_SECONDARY) != 0)
{
BYTE_CASE (1, stream->dec_secondid, DEC_TABLEN);
switch (stream->dec_secondid)
{
case VCD_FGK_ID:
FGK_CASE (stream);
case VCD_DJW_ID:
DJW_CASE (stream);
case VCD_LZMA_ID:
LZMA_CASE (stream);
default:
stream->msg = "unknown secondary compressor ID";
return XD3_INVALID_INPUT;
}
}
case DEC_TABLEN:
/* Length of code table data: only if VCD_CODETABLE is set */
SIZE_CASE ((stream->dec_hdr_ind & VCD_CODETABLE) != 0,
stream->dec_codetblsz, DEC_NEAR);
/* The codetblsz counts the two NEAR/SAME bytes */
if ((stream->dec_hdr_ind & VCD_CODETABLE) != 0) {
if (stream->dec_codetblsz <= 2) {
stream->msg = "invalid code table size";
return ENOMEM;
}
stream->dec_codetblsz -= 2;
}
case DEC_NEAR:
/* Near modes: only if VCD_CODETABLE is set */
BYTE_CASE((stream->dec_hdr_ind & VCD_CODETABLE) != 0,
stream->acache.s_near, DEC_SAME);
case DEC_SAME:
/* Same modes: only if VCD_CODETABLE is set */
BYTE_CASE((stream->dec_hdr_ind & VCD_CODETABLE) != 0,
stream->acache.s_same, DEC_TABDAT);
case DEC_TABDAT:
/* Compressed code table data */
if ((stream->dec_hdr_ind & VCD_CODETABLE) != 0)
{
stream->msg = "VCD_CODETABLE support was removed";
return XD3_UNIMPLEMENTED;
}
else
{
/* Use the default table. */
stream->acache.s_near = __rfc3284_code_table_desc.near_modes;
stream->acache.s_same = __rfc3284_code_table_desc.same_modes;
stream->code_table = xd3_rfc3284_code_table ();
}
if ((ret = xd3_alloc_cache (stream))) { return ret; }
stream->dec_state = DEC_APPLEN;
case DEC_APPLEN:
/* Length of application data */
SIZE_CASE((stream->dec_hdr_ind & VCD_APPHEADER) != 0,
stream->dec_appheadsz, DEC_APPDAT);
case DEC_APPDAT:
/* Application data */
if (stream->dec_hdr_ind & VCD_APPHEADER)
{
/* Note: we add an additional byte for padding, to allow
0-termination. Check for overflow: */
if (USIZE_T_OVERFLOW(stream->dec_appheadsz, 1))
{
stream->msg = "exceptional appheader size";
return XD3_INVALID_INPUT;
}
if ((stream->dec_appheader == NULL) &&
(stream->dec_appheader =
(uint8_t*) xd3_alloc (stream,
stream->dec_appheadsz+1, 1)) == NULL)
{
return ENOMEM;
}
stream->dec_appheader[stream->dec_appheadsz] = 0;
if ((ret = xd3_decode_bytes (stream, stream->dec_appheader,
& stream->dec_appheadbytes,
stream->dec_appheadsz)))
{
return ret;
}
}
/* xoff_t -> usize_t is safe because this is the first block. */
stream->dec_hdrsize = (usize_t) stream->total_in;
stream->dec_state = DEC_WININD;
case DEC_WININD:
{
/* Start of a window: the window indicator */
if ((ret = xd3_decode_byte (stream, & stream->dec_win_ind)))
{
return ret;
}
stream->current_window = stream->dec_window_count;
if (XOFF_T_OVERFLOW (stream->dec_winstart, stream->dec_tgtlen))
{
stream->msg = "decoder file offset overflow";
return XD3_INVALID_INPUT;
}
stream->dec_winstart += stream->dec_tgtlen;