From 69472ee5f055a2bb6f28106f0923e1461fd1d080 Mon Sep 17 00:00:00 2001 From: Lasse Collin Date: Sun, 23 Nov 2008 15:09:03 +0200 Subject: VLI encoder and decoder cleanups. Made encoder return LZMA_PROG_ERROR in single-call mode if there's no output space. --- src/liblzma/common/vli_decoder.c | 15 +++++++++------ src/liblzma/common/vli_encoder.c | 31 ++++++++++++++++++++++++------- 2 files changed, 33 insertions(+), 13 deletions(-) (limited to 'src') diff --git a/src/liblzma/common/vli_decoder.c b/src/liblzma/common/vli_decoder.c index 60874baa..78ef539a 100644 --- a/src/liblzma/common/vli_decoder.c +++ b/src/liblzma/common/vli_decoder.c @@ -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. diff --git a/src/liblzma/common/vli_encoder.c b/src/liblzma/common/vli_encoder.c index 4bb4d351..0d8e7f1a 100644 --- a/src/liblzma/common/vli_encoder.c +++ b/src/liblzma/common/vli_encoder.c @@ -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; -- cgit v1.2.3