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VLI encoder and decoder cleanups. Made encoder return

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LZMA_PROG_ERROR in single-call mode if there's no output
space.
This commit is contained in:
Lasse Collin 2008-11-23 15:09:03 +02:00
parent 4249c8c15a
commit 69472ee5f0
2 changed files with 33 additions and 13 deletions
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15
src/liblzma/common/vli_decoder.c
View file

@ -53,24 +53,27 @@ lzma_vli_decode(lzma_vli *restrict vli, size_t *restrict vli_pos,
}
do {
// Read the next byte.
*vli |= (lzma_vli)(in[*in_pos] & 0x7F) << (*vli_pos * 7);
// Read the next byte. Use a temporary variable so that we
// can update *in_pos immediatelly.
const uint8_t byte = in[*in_pos];
++*in_pos;
// Add the newly read byte to *vli.
*vli += (lzma_vli)(byte & 0x7F) << (*vli_pos * 7);
++*vli_pos;
// Check if this is the last byte of a multibyte integer.
if (!(in[*in_pos] & 0x80)) {
if ((byte & 0x80) == 0) {
// We don't allow using variable-length integers as
// padding i.e. the encoding must use the most the
// compact form.
if (in[(*in_pos)++] == 0x00 && *vli_pos > 1)
if (byte == 0x00 && *vli_pos > 1)
return LZMA_DATA_ERROR;
return vli_pos == &vli_pos_internal
? LZMA_OK : LZMA_STREAM_END;
}
++*in_pos;
// There is at least one more byte coming. If we have already
// read maximum number of bytes, the integer is considered
// corrupt.

31
src/liblzma/common/vli_encoder.c
View file

@ -27,30 +27,47 @@ lzma_vli_encode(lzma_vli vli, size_t *restrict vli_pos,
{
// If we haven't been given vli_pos, work in single-call mode.
size_t vli_pos_internal = 0;
if (vli_pos == NULL)
if (vli_pos == NULL) {
vli_pos = &vli_pos_internal;
// In single-call mode, we expect that the caller has
// reserved enough output space.
if (*out_pos >= out_size)
return LZMA_PROG_ERROR;
} else {
// This never happens when we are called by liblzma, but
// may happen if called directly from an application.
if (*out_pos >= out_size)
return LZMA_BUF_ERROR;
}
// Validate the arguments.
if (*vli_pos >= LZMA_VLI_BYTES_MAX || vli > LZMA_VLI_MAX)
return LZMA_PROG_ERROR;
if (*out_pos >= out_size)
return LZMA_BUF_ERROR;
// Shift vli so that the next bits to encode are the lowest. In
// single-call mode this never changes vli since *vli_pos is zero.
vli >>= *vli_pos * 7;
// Write the non-last bytes in a loop.
while ((vli >> (*vli_pos * 7)) >= 0x80) {
out[*out_pos] = (uint8_t)(vli >> (*vli_pos * 7)) | 0x80;
while (vli >= 0x80) {
// We don't need *vli_pos during this function call anymore,
// but update it here so that it is ready if we need to
// return before the whole integer has been decoded.
++*vli_pos;
assert(*vli_pos < LZMA_VLI_BYTES_MAX);
// Write the next byte.
out[*out_pos] = (uint8_t)(vli) | 0x80;
vli >>= 7;
if (++*out_pos == out_size)
return vli_pos == &vli_pos_internal
? LZMA_PROG_ERROR : LZMA_OK;
}
// Write the last byte.
out[*out_pos] = (uint8_t)(vli >> (*vli_pos * 7));
out[*out_pos] = (uint8_t)(vli);
++*out_pos;
++*vli_pos;