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std.compress.zstandard: also check block size when sequence count is 0

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This commit is contained in:
dweiller
2023-02-13 17:19:33 +11:00
parent a53cf299a6
commit 12aa478db0
2 changed files with 59 additions and 48 deletions
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104
lib/std/compress/zstandard/decode/block.zig
View File

@@ -654,29 +654,32 @@ pub fn decodeBlock(
bytes_read += fbs.pos;
var bytes_written: usize = 0;
if (sequences_header.sequence_count > 0) {
{
const bit_stream_bytes = src[bytes_read..block_size];
var bit_stream: readers.ReverseBitReader = undefined;
bit_stream.init(bit_stream_bytes) catch return error.MalformedCompressedBlock;
decode_state.readInitialFseState(&bit_stream) catch return error.MalformedCompressedBlock;
if (sequences_header.sequence_count > 0) {
decode_state.readInitialFseState(&bit_stream) catch
return error.MalformedCompressedBlock;
var sequence_size_limit = block_size_max;
var i: usize = 0;
while (i < sequences_header.sequence_count) : (i += 1) {
const write_pos = written_count + bytes_written;
const decompressed_size = decode_state.decodeSequenceSlice(
dest,
write_pos,
&bit_stream,
sequence_size_limit,
i == sequences_header.sequence_count - 1,
) catch |err| switch (err) {
error.DestTooSmall => return error.DestTooSmall,
else => return error.MalformedCompressedBlock,
};
bytes_written += decompressed_size;
sequence_size_limit -= decompressed_size;
var sequence_size_limit = block_size_max;
var i: usize = 0;
while (i < sequences_header.sequence_count) : (i += 1) {
const write_pos = written_count + bytes_written;
const decompressed_size = decode_state.decodeSequenceSlice(
dest,
write_pos,
&bit_stream,
sequence_size_limit,
i == sequences_header.sequence_count - 1,
) catch |err| switch (err) {
error.DestTooSmall => return error.DestTooSmall,
else => return error.MalformedCompressedBlock,
};
bytes_written += decompressed_size;
sequence_size_limit -= decompressed_size;
}
}
if (!bit_stream.isEmpty()) {
@@ -755,24 +758,27 @@ pub fn decodeBlockRingBuffer(
bytes_read += fbs.pos;
var bytes_written: usize = 0;
if (sequences_header.sequence_count > 0) {
{
const bit_stream_bytes = src[bytes_read..block_size];
var bit_stream: readers.ReverseBitReader = undefined;
bit_stream.init(bit_stream_bytes) catch return error.MalformedCompressedBlock;
decode_state.readInitialFseState(&bit_stream) catch return error.MalformedCompressedBlock;
if (sequences_header.sequence_count > 0) {
decode_state.readInitialFseState(&bit_stream) catch
return error.MalformedCompressedBlock;
var sequence_size_limit = block_size_max;
var i: usize = 0;
while (i < sequences_header.sequence_count) : (i += 1) {
const decompressed_size = decode_state.decodeSequenceRingBuffer(
dest,
&bit_stream,
sequence_size_limit,
i == sequences_header.sequence_count - 1,
) catch return error.MalformedCompressedBlock;
bytes_written += decompressed_size;
sequence_size_limit -= decompressed_size;
var sequence_size_limit = block_size_max;
var i: usize = 0;
while (i < sequences_header.sequence_count) : (i += 1) {
const decompressed_size = decode_state.decodeSequenceRingBuffer(
dest,
&bit_stream,
sequence_size_limit,
i == sequences_header.sequence_count - 1,
) catch return error.MalformedCompressedBlock;
bytes_written += decompressed_size;
sequence_size_limit -= decompressed_size;
}
}
if (!bit_stream.isEmpty()) {
@@ -847,28 +853,32 @@ pub fn decodeBlockReader(
try decode_state.prepare(block_reader, literals, sequences_header);
var bytes_written: usize = 0;
if (sequences_header.sequence_count > 0) {
if (sequence_buffer.len < block_reader_limited.bytes_left)
return error.SequenceBufferTooSmall;
{
const size = try block_reader.readAll(sequence_buffer);
var bit_stream: readers.ReverseBitReader = undefined;
try bit_stream.init(sequence_buffer[0..size]);
decode_state.readInitialFseState(&bit_stream) catch return error.MalformedCompressedBlock;
if (sequences_header.sequence_count > 0) {
if (sequence_buffer.len < block_reader_limited.bytes_left)
return error.SequenceBufferTooSmall;
var sequence_size_limit = block_size_max;
var i: usize = 0;
while (i < sequences_header.sequence_count) : (i += 1) {
const decompressed_size = decode_state.decodeSequenceRingBuffer(
dest,
&bit_stream,
sequence_size_limit,
i == sequences_header.sequence_count - 1,
) catch return error.MalformedCompressedBlock;
sequence_size_limit -= decompressed_size;
bytes_written += decompressed_size;
decode_state.readInitialFseState(&bit_stream) catch
return error.MalformedCompressedBlock;
var sequence_size_limit = block_size_max;
var i: usize = 0;
while (i < sequences_header.sequence_count) : (i += 1) {
const decompressed_size = decode_state.decodeSequenceRingBuffer(
dest,
&bit_stream,
sequence_size_limit,
i == sequences_header.sequence_count - 1,
) catch return error.MalformedCompressedBlock;
sequence_size_limit -= decompressed_size;
bytes_written += decompressed_size;
}
}
if (!bit_stream.isEmpty()) {
return error.MalformedCompressedBlock;
}

3
lib/std/compress/zstandard/readers.zig
View File

@@ -36,8 +36,9 @@ pub const ReverseBitReader = struct {
pub fn init(self: *ReverseBitReader, bytes: []const u8) error{BitStreamHasNoStartBit}!void {
self.byte_reader = ReversedByteReader.init(bytes);
self.bit_reader = std.io.bitReader(.Big, self.byte_reader.reader());
if (bytes.len == 0) return;
var i: usize = 0;
while (i < 8 and 0 == self.readBitsNoEof(u1, 1) catch return error.BitStreamHasNoStartBit) : (i += 1) {}
while (i < 8 and 0 == self.readBitsNoEof(u1, 1) catch unreachable) : (i += 1) {}
if (i == 8) return error.BitStreamHasNoStartBit;
}