//! Streaming decompression functionality.
use super::*;
use crate::shared::{update_adler32, HUFFMAN_LENGTH_ORDER};
use ::core::convert::TryInto;
use ::core::{cmp, slice};
use self::output_buffer::OutputBuffer;
pub const TINFL_LZ_DICT_SIZE: usize = 32_768;
/// A struct containing huffman code lengths and the huffman code tree used by the decompressor.
struct HuffmanTable {
/// Length of the code at each index.
pub code_size: [u8; MAX_HUFF_SYMBOLS_0],
/// Fast lookup table for shorter huffman codes.
///
/// See `HuffmanTable::fast_lookup`.
pub look_up: [i16; FAST_LOOKUP_SIZE as usize],
/// Full huffman tree.
///
/// Positive values are edge nodes/symbols, negative values are
/// parent nodes/references to other nodes.
pub tree: [i16; MAX_HUFF_TREE_SIZE],
}
impl HuffmanTable {
const fn new() -> HuffmanTable {
HuffmanTable {
code_size: [0; MAX_HUFF_SYMBOLS_0],
look_up: [0; FAST_LOOKUP_SIZE as usize],
tree: [0; MAX_HUFF_TREE_SIZE],
}
}
/// Look for a symbol in the fast lookup table.
/// The symbol is stored in the lower 9 bits, the length in the next 6.
/// If the returned value is negative, the code wasn't found in the
/// fast lookup table and the full tree has to be traversed to find the code.
#[inline]
fn fast_lookup(&self, bit_buf: BitBuffer) -> i16 {
self.look_up[(bit_buf & BitBuffer::from(FAST_LOOKUP_SIZE - 1)) as usize]
}
/// Get the symbol and the code length from the huffman tree.
#[inline]
fn tree_lookup(&self, fast_symbol: i32, bit_buf: BitBuffer, mut code_len: u32) -> (i32, u32) {
let mut symbol = fast_symbol;
// We step through the tree until we encounter a positive value, which indicates a
// symbol.
loop {
// symbol here indicates the position of the left (0) node, if the next bit is 1
// we add 1 to the lookup position to get the right node.
symbol = i32::from(self.tree[(!symbol + ((bit_buf >> code_len) & 1) as i32) as usize]);
code_len += 1;
if symbol >= 0 {
break;
}
}
(symbol, code_len)
}
#[inline]
/// Look up a symbol and code length from the bits in the provided bit buffer.
///
/// Returns Some(symbol, length) on success,
/// None if the length is 0.
///
/// It's possible we could avoid checking for 0 if we can guarantee a sane table.
/// TODO: Check if a smaller type for code_len helps performance.
fn lookup(&self, bit_buf: BitBuffer) -> Option<(i32, u32)> {
let symbol = self.fast_lookup(bit_buf).into();
if symbol >= 0 {
if (symbol >> 9) as u32 != 0 {
Some((symbol, (symbol >> 9) as u32))
} else {
// Zero-length code.
None
}
} else {
// We didn't get a symbol from the fast lookup table, so check the tree instead.
Some(self.tree_lookup(symbol, bit_buf, FAST_LOOKUP_BITS.into()))
}
}
}
/// The number of huffman tables used.
const MAX_HUFF_TABLES: usize = 3;
/// The length of the first (literal/length) huffman table.
const MAX_HUFF_SYMBOLS_0: usize = 288;
/// The length of the second (distance) huffman table.
const MAX_HUFF_SYMBOLS_1: usize = 32;
/// The length of the last (huffman code length) huffman table.
const _MAX_HUFF_SYMBOLS_2: usize = 19;
/// The maximum length of a code that can be looked up in the fast lookup table.
const FAST_LOOKUP_BITS: u8 = 10;
/// The size of the fast lookup table.
const FAST_LOOKUP_SIZE: u32 = 1 << FAST_LOOKUP_BITS;
const MAX_HUFF_TREE_SIZE: usize = MAX_HUFF_SYMBOLS_0 * 2;
const LITLEN_TABLE: usize = 0;
const DIST_TABLE: usize = 1;
const HUFFLEN_TABLE: usize = 2;
/// Flags to [`decompress()`] to control how inflation works.
///
/// These define bits for a bitmask argument.
pub mod inflate_flags {
/// Should we try to parse a zlib header?
///
/// If unset, [`decompress()`] will expect an RFC1951 deflate stream. If set, it will expect an
/// RFC1950 zlib wrapper around the deflate stream.
pub const TINFL_FLAG_PARSE_ZLIB_HEADER: u32 = 1;
/// There will be more input that hasn't been given to the decompressor yet.
///
/// This is useful when you want to decompress what you have so far,
/// even if you know there is probably more input that hasn't gotten here yet (_e.g._, over a
/// network connection). When [`decompress()`][super::decompress] reaches the end of the input
/// without finding the end of the compressed stream, it will return
/// [`TINFLStatus::NeedsMoreInput`][super::TINFLStatus::NeedsMoreInput] if this is set,
/// indicating that you should get more data before calling again. If not set, it will return
/// [`TINFLStatus::FailedCannotMakeProgress`][super::TINFLStatus::FailedCannotMakeProgress]
/// suggesting the stream is corrupt, since you claimed it was all there.
pub const TINFL_FLAG_HAS_MORE_INPUT: u32 = 2;
/// The output buffer should not wrap around.
pub const TINFL_FLAG_USING_NON_WRAPPING_OUTPUT_BUF: u32 = 4;
/// Calculate the adler32 checksum of the output data even if we're not inflating a zlib stream.
///
/// If [`TINFL_FLAG_IGNORE_ADLER32`] is specified, it will override this.
///
/// NOTE: Enabling/disabling this between calls to decompress will result in an incorect
/// checksum.
pub const TINFL_FLAG_COMPUTE_ADLER32: u32 = 8;
/// Ignore adler32 checksum even if we are inflating a zlib stream.
///
/// Overrides [`TINFL_FLAG_COMPUTE_ADLER32`] if both are enabled.
///
/// NOTE: This flag does not exist in miniz as it does not support this and is a
/// custom addition for miniz_oxide.
///
/// NOTE: Should not be changed from enabled to disabled after decompression has started,
/// this will result in checksum failure (outside the unlikely event where the checksum happens
/// to match anyway).
pub const TINFL_FLAG_IGNORE_ADLER32: u32 = 64;
}
use self::inflate_flags::*;
const MIN_TABLE_SIZES: [u16; 3] = [257, 1, 4];
#[cfg(target_pointer_width = "64")]
type BitBuffer = u64;
#[cfg(not(target_pointer_width = "64"))]
type BitBuffer = u32;
/// Main decompression struct.
///
pub struct DecompressorOxide {
/// Current state of the decompressor.
state: core::State,
/// Number of bits in the bit buffer.
num_bits: u32,
/// Zlib CMF
z_header0: u32,
/// Zlib FLG
z_header1: u32,
/// Adler32 checksum from the zlib header.
z_adler32: u32,
/// 1 if the current block is the last block, 0 otherwise.
finish: u32,
/// The type of the current block.
block_type: u32,
/// 1 if the adler32 value should be checked.
check_adler32: u32,
/// Last match distance.
dist: u32,
/// Variable used for match length, symbols, and a number of other things.
counter: u32,
/// Number of extra bits for the last length or distance code.
num_extra: u32,
/// Number of entries in each huffman table.
table_sizes: [u32; MAX_HUFF_TABLES],
/// Buffer of input data.
bit_buf: BitBuffer,
/// Huffman tables.
tables: [HuffmanTable; MAX_HUFF_TABLES],
/// Raw block header.
raw_header: [u8; 4],
/// Huffman length codes.
len_codes: [u8; MAX_HUFF_SYMBOLS_0 + MAX_HUFF_SYMBOLS_1 + 137],
}
impl DecompressorOxide {
/// Create a new tinfl_decompressor with all fields set to 0.
pub fn new() -> DecompressorOxide {
DecompressorOxide::default()
}
/// Set the current state to `Start`.
#[inline]
pub fn init(&mut self) {
// The rest of the data is reset or overwritten when used.
self.state = core::State::Start;
}
/// Returns the adler32 checksum of the currently decompressed data.
/// Note: Will return Some(1) if decompressing zlib but ignoring adler32.
#[inline]
pub fn adler32(&self) -> Option<u32> {
if self.state != State::Start && !self.state.is_failure() && self.z_header0 != 0 {
Some(self.check_adler32)
} else {
None
}
}
/// Returns the adler32 that was read from the zlib header if it exists.
#[inline]
pub fn adler32_header(&self) -> Option<u32> {
if self.state != State::Start && self.state != State::BadZlibHeader && self.z_header0 != 0 {
Some(self.z_adler32)
} else {
None
}
}
}
impl Default for DecompressorOxide {
/// Create a new tinfl_decompressor with all fields set to 0.
#[inline(always)]
fn default() -> Self {
DecompressorOxide {
state: core::State::Start,
num_bits: 0,
z_header0: 0,
z_header1: 0,
z_adler32: 0,
finish: 0,
block_type: 0,
check_adler32: 0,
dist: 0,
counter: 0,
num_extra: 0,
table_sizes: [0; MAX_HUFF_TABLES],
bit_buf: 0,
// TODO:(oyvindln) Check that copies here are optimized out in release mode.
tables: [
HuffmanTable::new(),
HuffmanTable::new(),
HuffmanTable::new(),
],
raw_header: [0; 4],
len_codes: [0; MAX_HUFF_SYMBOLS_0 + MAX_HUFF_SYMBOLS_1 + 137],
}
}
}
#[derive(Copy, Clone, PartialEq, Eq, Debug)]
enum State {
Start = 0,
ReadZlibCmf,
ReadZlibFlg,
ReadBlockHeader,
BlockTypeNoCompression,
RawHeader,
RawMemcpy1,
RawMemcpy2,
ReadTableSizes,
ReadHufflenTableCodeSize,
ReadLitlenDistTablesCodeSize,
ReadExtraBitsCodeSize,
DecodeLitlen,
WriteSymbol,
ReadExtraBitsLitlen,
DecodeDistance,
ReadExtraBitsDistance,
RawReadFirstByte,
RawStoreFirstByte,
WriteLenBytesToEnd,
BlockDone,
HuffDecodeOuterLoop1,
HuffDecodeOuterLoop2,
ReadAdler32,
DoneForever,
// Failure states.
BlockTypeUnexpected,
BadCodeSizeSum,
BadTotalSymbols,
BadZlibHeader,
DistanceOutOfBounds,
BadRawLength,
BadCodeSizeDistPrevLookup,
InvalidLitlen,
InvalidDist,
InvalidCodeLen,
}
impl State {
fn is_failure(self) -> bool {
match self {
BlockTypeUnexpected => true,
BadCodeSizeSum => true,
BadTotalSymbols => true,
BadZlibHeader => true,
DistanceOutOfBounds => true,
BadRawLength => true,
BadCodeSizeDistPrevLookup => true,
InvalidLitlen => true,
InvalidDist => true,
_ => false,
}
}
#[inline]
fn begin(&mut self, new_state: State) {
*self = new_state;
}
}
use self::State::*;
// Not sure why miniz uses 32-bit values for these, maybe alignment/cache again?
// # Optimization
// We add a extra value at the end and make the tables 32 elements long
// so we can use a mask to avoid bounds checks.
// The invalid values are set to something high enough to avoid underflowing
// the match length.
/// Base length for each length code.
///
/// The base is used together with the value of the extra bits to decode the actual
/// length/distance values in a match.
#[rustfmt::skip]
const LENGTH_BASE: [u16; 32] = [
3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31,
35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 512, 512, 512
];
/// Number of extra bits for each length code.
#[rustfmt::skip]
const LENGTH_EXTRA: [u8; 32] = [
0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2,
3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0, 0, 0, 0
];
/// Base length for each distance code.
#[rustfmt::skip]
const DIST_BASE: [u16; 32] = [
1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33,
49, 65, 97, 129, 193, 257, 385, 513, 769, 1025, 1537,
2049, 3073, 4097, 6145, 8193, 12_289, 16_385, 24_577, 32_768, 32_768
];
/// Number of extra bits for each distance code.
#[rustfmt::skip]
const DIST_EXTRA: [u8; 32] = [
0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6,
7, 7, 8, 8, 9, 9, 10, 10, 11, 11, 12, 12, 13, 13, 13, 13
];
/// The mask used when indexing the base/extra arrays.
const BASE_EXTRA_MASK: usize = 32 - 1;
/// Sets the value of all the elements of the slice to `val`.
#[inline]
fn memset<T: Copy>(slice: &mut [T], val: T) {
for x in slice {
*x = val
}
}
/// Read an le u16 value from the slice iterator.
///
/// # Panics
/// Panics if there are less than two bytes left.
#[inline]
fn read_u16_le(iter: &mut slice::Iter<u8>) -> u16 {
let ret = {
let two_bytes = iter.as_ref()[..2].try_into().unwrap();
u16::from_le_bytes(two_bytes)
};
iter.nth(1);
ret
}
/// Read an le u32 value from the slice iterator.
///
/// # Panics
/// Panics if there are less than four bytes left.
#[inline(always)]
#[cfg(target_pointer_width = "64")]
fn read_u32_le(iter: &mut slice::Iter<u8>) -> u32 {
let ret = {
let four_bytes: [u8; 4] = iter.as_ref()[..4].try_into().unwrap();
u32::from_le_bytes(four_bytes)
};
iter.nth(3);
ret
}
/// Ensure that there is data in the bit buffer.
///
/// On 64-bit platform, we use a 64-bit value so this will
/// result in there being at least 32 bits in the bit buffer.
/// This function assumes that there is at least 4 bytes left in the input buffer.
#[inline(always)]
#[cfg(target_pointer_width = "64")]
fn fill_bit_buffer(l: &mut LocalVars, in_iter: &mut slice::Iter<u8>) {
// Read four bytes into the buffer at once.
if l.num_bits < 30 {
l.bit_buf |= BitBuffer::from(read_u32_le(in_iter)) << l.num_bits;
l.num_bits += 32;
}
}
/// Same as previous, but for non-64-bit platforms.
/// Ensures at least 16 bits are present, requires at least 2 bytes in the in buffer.
#[inline(always)]
#[cfg(not(target_pointer_width = "64"))]
fn fill_bit_buffer(l: &mut LocalVars, in_iter: &mut slice::Iter<u8>) {
// If the buffer is 32-bit wide, read 2 bytes instead.
if l.num_bits < 15 {
l.bit_buf |= BitBuffer::from(read_u16_le(in_iter)) << l.num_bits;
l.num_bits += 16;
}
}
/// Check that the zlib header is correct and that there is enough space in the buffer
/// for the window size specified in the header.
///
/// See https://tools.ietf.org/html/rfc1950
#[inline]
fn validate_zlib_header(cmf: u32, flg: u32, flags: u32, mask: usize) -> Action {
let mut failed =
// cmf + flg should be divisible by 31.
(((cmf * 256) + flg) % 31 != 0) ||
// If this flag is set, a dictionary was used for this zlib compressed data.
// This is currently not supported by miniz or miniz-oxide
((flg & 0b0010_0000) != 0) ||
// Compression method. Only 8(DEFLATE) is defined by the standard.
((cmf & 15) != 8);
let window_size = 1 << ((cmf >> 4) + 8);
if (flags & TINFL_FLAG_USING_NON_WRAPPING_OUTPUT_BUF) == 0 {
// Bail if the buffer is wrapping and the window size is larger than the buffer.
failed |= (mask + 1) < window_size;
}
// Zlib doesn't allow window sizes above 32 * 1024.
failed |= window_size > 32_768;
if failed {
Action::Jump(BadZlibHeader)
} else {
Action::Jump(ReadBlockHeader)
}
}
enum Action {
None,
Jump(State),
End(TINFLStatus),
}
/// Try to decode the next huffman code, and puts it in the counter field of the decompressor
/// if successful.
///
/// # Returns
/// The specified action returned from `f` on success,
/// `Action::End` if there are not enough data left to decode a symbol.
fn decode_huffman_code<F>(
r: &mut DecompressorOxide,
l: &mut LocalVars,
table: usize,
flags: u32,
in_iter: &mut slice::Iter<u8>,
f: F,
) -> Action
where
F: FnOnce(&mut DecompressorOxide, &mut LocalVars, i32) -> Action,
{
// As the huffman codes can be up to 15 bits long we need at least 15 bits
// ready in the bit buffer to start decoding the next huffman code.
if l.num_bits < 15 {
// First, make sure there is enough data in the bit buffer to decode a huffman code.
if in_iter.len() < 2 {
// If there is less than 2 bytes left in the input buffer, we try to look up
// the huffman code with what's available, and return if that doesn't succeed.
// Original explanation in miniz:
// /* TINFL_HUFF_BITBUF_FILL() is only used rarely, when the number of bytes
// * remaining in the input buffer falls below 2. */
// /* It reads just enough bytes from the input stream that are needed to decode
// * the next Huffman code (and absolutely no more). It works by trying to fully
// * decode a */
// /* Huffman code by using whatever bits are currently present in the bit buffer.
// * If this fails, it reads another byte, and tries again until it succeeds or
// * until the */
// /* bit buffer contains >=15 bits (deflate's max. Huffman code size). */
loop {
let mut temp = i32::from(r.tables[table].fast_lookup(l.bit_buf));
if temp >= 0 {
let code_len = (temp >> 9) as u32;
if (code_len != 0) && (l.num_bits >= code_len) {
break;
}
} else if l.num_bits > FAST_LOOKUP_BITS.into() {
let mut code_len = u32::from(FAST_LOOKUP_BITS);
loop {
temp = i32::from(
r.tables[table].tree
[(!temp + ((l.bit_buf >> code_len) & 1) as i32) as usize],
);
code_len += 1;
if temp >= 0 || l.num_bits < code_len + 1 {
break;
}
}
if temp >= 0 {
break;
}
}
// TODO: miniz jumps straight to here after getting here again after failing to read
// a byte.
// Doing that lets miniz avoid re-doing the lookup that that was done in the
// previous call.
let mut byte = 0;
if let a @ Action::End(_) = read_byte(in_iter, flags, |b| {
byte = b;
Action::None
}) {
return a;
};
// Do this outside closure for now to avoid borrowing r.
l.bit_buf |= BitBuffer::from(byte) << l.num_bits;
l.num_bits += 8;
if l.num_bits >= 15 {
break;
}
}
} else {
// There is enough data in the input buffer, so read the next two bytes
// and add them to the bit buffer.
// Unwrapping here is fine since we just checked that there are at least two
// bytes left.
l.bit_buf |= BitBuffer::from(read_u16_le(in_iter)) << l.num_bits;
l.num_bits += 16;
}
}
// We now have at least 15 bits in the input buffer.
let mut symbol = i32::from(r.tables[table].fast_lookup(l.bit_buf));
let code_len;
// If the symbol was found in the fast lookup table.
if symbol >= 0 {
// Get the length value from the top bits.
// As we shift down the sign bit, converting to an unsigned value
// shouldn't overflow.
code_len = (symbol >> 9) as u32;
// Mask out the length value.
symbol &= 511;
} else {
let res = r.tables[table].tree_lookup(symbol, l.bit_buf, u32::from(FAST_LOOKUP_BITS));
symbol = res.0;
code_len = res.1 as u32;
};
if code_len == 0 {
return Action::Jump(InvalidCodeLen);
}
l.bit_buf >>= code_len as u32;
l.num_bits -= code_len;
f(r, l, symbol)
}
/// Try to read one byte from `in_iter` and call `f` with the read byte as an argument,
/// returning the result.
/// If reading fails, `Action::End is returned`
#[inline]
fn read_byte<F>(in_iter: &mut slice::Iter<u8>, flags: u32, f: F) -> Action
where
F: FnOnce(u8) -> Action,
{
match in_iter.next() {
None => end_of_input(flags),
Some(&byte) => f(byte),
}
}
// TODO: `l: &mut LocalVars` may be slow similar to decompress_fast (even with inline(always))
/// Try to read `amount` number of bits from `in_iter` and call the function `f` with the bits as an
/// an argument after reading, returning the result of that function, or `Action::End` if there are
/// not enough bytes left.
#[inline]
#[allow(clippy::while_immutable_condition)]
fn read_bits<F>(
l: &mut LocalVars,
amount: u32,
in_iter: &mut slice::Iter<u8>,
flags: u32,
f: F,
) -> Action
where
F: FnOnce(&mut LocalVars, BitBuffer) -> Action,
{
// Clippy gives a false positive warning here due to the closure.
// Read enough bytes from the input iterator to cover the number of bits we want.
while l.num_bits < amount {
match read_byte(in_iter, flags, |byte| {
l.bit_buf |= BitBuffer::from(byte) << l.num_bits;
l.num_bits += 8;
Action::None
}) {
Action::None => (),
// If there are not enough bytes in the input iterator, return and signal that we need
// more.
action => return action,
}
}
let bits = l.bit_buf & ((1 << amount) - 1);
l.bit_buf >>= amount;
l.num_bits -= amount;
f(l, bits)
}
#[inline]
fn pad_to_bytes<F>(l: &mut LocalVars, in_iter: &mut slice::Iter<u8>, flags: u32, f: F) -> Action
where
F: FnOnce(&mut LocalVars) -> Action,
{
let num_bits = l.num_bits & 7;
read_bits(l, num_bits, in_iter, flags, |l, _| f(l))
}
#[inline]
fn end_of_input(flags: u32) -> Action {
Action::End(if flags & TINFL_FLAG_HAS_MORE_INPUT != 0 {
TINFLStatus::NeedsMoreInput
} else {
TINFLStatus::FailedCannotMakeProgress
})
}
#[inline]
fn undo_bytes(l: &mut LocalVars, max: u32) -> u32 {
let res = cmp::min(l.num_bits >> 3, max);
l.num_bits -= res << 3;
res
}
fn start_static_table(r: &mut DecompressorOxide) {
r.table_sizes[LITLEN_TABLE] = 288;
r.table_sizes[DIST_TABLE] = 32;
memset(&mut r.tables[LITLEN_TABLE].code_size[0..144], 8);
memset(&mut r.tables[LITLEN_TABLE].code_size[144..256], 9);
memset(&mut r.tables[LITLEN_TABLE].code_size[256..280], 7);
memset(&mut r.tables[LITLEN_TABLE].code_size[280..288], 8);
memset(&mut r.tables[DIST_TABLE].code_size[0..32], 5);
}
fn init_tree(r: &mut DecompressorOxide, l: &mut LocalVars) -> Action {
loop {
let table = &mut r.tables[r.block_type as usize];
let table_size = r.table_sizes[r.block_type as usize] as usize;
let mut total_symbols = [0u32; 16];
let mut next_code = [0u32; 17];
memset(&mut table.look_up[..], 0);
memset(&mut table.tree[..], 0);
for &code_size in &table.code_size[..table_size] {
total_symbols[code_size as usize] += 1;
}
let mut used_symbols = 0;
let mut total = 0;
for i in 1..16 {
used_symbols += total_symbols[i];
total += total_symbols[i];
total <<= 1;
next_code[i + 1] = total;
}
if total != 65_536 && used_symbols > 1 {
return Action::Jump(BadTotalSymbols);
}
let mut tree_next = -1;
for symbol_index in 0..table_size {
let mut rev_code = 0;
let code_size = table.code_size[symbol_index];
if code_size == 0 {
continue;
}
let mut cur_code = next_code[code_size as usize];
next_code[code_size as usize] += 1;
for _ in 0..code_size {
rev_code = (rev_code << 1) | (cur_code & 1);
cur_code >>= 1;
}
if code_size <= FAST_LOOKUP_BITS {
let k = (i16::from(code_size) << 9) | symbol_index as i16;
while rev_code < FAST_LOOKUP_SIZE {
table.look_up[rev_code as usize] = k;
rev_code += 1 << code_size;
}
continue;
}
let mut tree_cur = table.look_up[(rev_code & (FAST_LOOKUP_SIZE - 1)) as usize];
if tree_cur == 0 {
table.look_up[(rev_code & (FAST_LOOKUP_SIZE - 1)) as usize] = tree_next as i16;
tree_cur = tree_next;
tree_next -= 2;
}
rev_code >>= FAST_LOOKUP_BITS - 1;
for _ in FAST_LOOKUP_BITS + 1..code_size {
rev_code >>= 1;
tree_cur -= (rev_code & 1) as i16;
if table.tree[(-tree_cur - 1) as usize] == 0 {
table.tree[(-tree_cur - 1) as usize] = tree_next as i16;
tree_cur = tree_next;
tree_next -= 2;
} else {
tree_cur = table.tree[(-tree_cur - 1) as usize];
}
}
rev_code >>= 1;
tree_cur -= (rev_code & 1) as i16;
table.tree[(-tree_cur - 1) as usize] = symbol_index as i16;
}
if r.block_type == 2 {
l.counter = 0;
return Action::Jump(ReadLitlenDistTablesCodeSize);
}
if r.block_type == 0 {
break;
}
r.block_type -= 1;
}
l.counter = 0;
Action::Jump(DecodeLitlen)
}
// A helper macro for generating the state machine.
//
// As Rust doesn't have fallthrough on matches, we have to return to the match statement
// and jump for each state change. (Which would ideally be optimized away, but often isn't.)
macro_rules! generate_state {
($state: ident, $state_machine: tt, $f: expr) => {
loop {
match $f {
Action::None => continue,
Action::Jump(new_state) => {
$state = new_state;
continue $state_machine;
},
Action::End(result) => break $state_machine result,
}
}
};
}
#[derive(Copy, Clone)]
struct LocalVars {
pub bit_buf: BitBuffer,
pub num_bits: u32,
pub dist: u32,
pub counter: u32,
pub num_extra: u32,
}
#[inline]
fn transfer(
out_slice: &mut [u8],
mut source_pos: usize,
mut out_pos: usize,
match_len: usize,
out_buf_size_mask: usize,
) {
for _ in 0..match_len >> 2 {
out_slice[out_pos] = out_slice[source_pos & out_buf_size_mask];
out_slice[out_pos + 1] = out_slice[(source_pos + 1) & out_buf_size_mask];
out_slice[out_pos + 2] = out_slice[(source_pos + 2) & out_buf_size_mask];
out_slice[out_pos + 3] = out_slice[(source_pos + 3) & out_buf_size_mask];
source_pos += 4;
out_pos += 4;
}
match match_len & 3 {
0 => (),
1 => out_slice[out_pos] = out_slice[source_pos & out_buf_size_mask],
2 => {
out_slice[out_pos] = out_slice[source_pos & out_buf_size_mask];
out_slice[out_pos + 1] = out_slice[(source_pos + 1) & out_buf_size_mask];
}
3 => {
out_slice[out_pos] = out_slice[source_pos & out_buf_size_mask];
out_slice[out_pos + 1] = out_slice[(source_pos + 1) & out_buf_size_mask];
out_slice[out_pos + 2] = out_slice[(source_pos + 2) & out_buf_size_mask];
}
_ => unreachable!(),
}
}
/// Presumes that there is at least match_len bytes in output left.
#[inline]
fn apply_match(
out_slice: &mut [u8],
out_pos: usize,
dist: usize,
match_len: usize,
out_buf_size_mask: usize,
) {
debug_assert!(out_pos + match_len <= out_slice.len());
let source_pos = out_pos.wrapping_sub(dist) & out_buf_size_mask;
if match_len == 3 {
// Fast path for match len 3.
out_slice[out_pos] = out_slice[source_pos];
out_slice[out_pos + 1] = out_slice[(source_pos + 1) & out_buf_size_mask];
out_slice[out_pos + 2] = out_slice[(source_pos + 2) & out_buf_size_mask];
return;
}
if cfg!(not(any(target_arch = "x86", target_arch = "x86_64"))) {
// We are not on x86 so copy manually.
transfer(out_slice, source_pos, out_pos, match_len, out_buf_size_mask);
return;
}
if source_pos >= out_pos && (source_pos - out_pos) < match_len {
transfer(out_slice, source_pos, out_pos, match_len, out_buf_size_mask);
} else if match_len <= dist && source_pos + match_len < out_slice.len() {
// Destination and source segments does not intersect and source does not wrap.
if source_pos < out_pos {
let (from_slice, to_slice) = out_slice.split_at_mut(out_pos);
to_slice[..match_len].copy_from_slice(&from_slice[source_pos..source_pos + match_len]);
} else {
let (to_slice, from_slice) = out_slice.split_at_mut(source_pos);
to_slice[out_pos..out_pos + match_len].copy_from_slice(&from_slice[..match_len]);
}
} else {
transfer(out_slice, source_pos, out_pos, match_len, out_buf_size_mask);
}
}
/// Fast inner decompression loop which is run while there is at least
/// 259 bytes left in the output buffer, and at least 6 bytes left in the input buffer
/// (The maximum one match would need + 1).
///
/// This was inspired by a similar optimization in zlib, which uses this info to do
/// faster unchecked copies of multiple bytes at a time.
/// Currently we don't do this here, but this function does avoid having to jump through the
/// big match loop on each state change(as rust does not have fallthrough or gotos at the moment),
/// and already improves decompression speed a fair bit.
fn decompress_fast(
r: &mut DecompressorOxide,
in_iter: &mut slice::Iter<u8>,
out_buf: &mut OutputBuffer,
flags: u32,
local_vars: &mut LocalVars,
out_buf_size_mask: usize,
) -> (TINFLStatus, State) {
// Make a local copy of the most used variables, to avoid having to update and read from values
// in a random memory location and to encourage more register use.
let mut l = *local_vars;
let mut state;
let status: TINFLStatus = 'o: loop {
state = State::DecodeLitlen;
loop {
// This function assumes that there is at least 259 bytes left in the output buffer,
// and that there is at least 14 bytes left in the input buffer. 14 input bytes:
// 15 (prev lit) + 15 (length) + 5 (length extra) + 15 (dist)
// + 29 + 32 (left in bit buf, including last 13 dist extra) = 111 bits < 14 bytes
// We need the one extra byte as we may write one length and one full match
// before checking again.
if out_buf.bytes_left() < 259 || in_iter.len() < 14 {
state = State::DecodeLitlen;
break 'o TINFLStatus::Done;
}
fill_bit_buffer(&mut l, in_iter);
if let Some((symbol, code_len)) = r.tables[LITLEN_TABLE].lookup(l.bit_buf) {
l.counter = symbol as u32;
l.bit_buf >>= code_len;
l.num_bits -= code_len;
if (l.counter & 256) != 0 {
// The symbol is not a literal.
break;
} else {
// If we have a 32-bit buffer we need to read another two bytes now
// to have enough bits to keep going.
if cfg!(not(target_pointer_width = "64")) {
fill_bit_buffer(&mut l, in_iter);
}
if let Some((symbol, code_len)) = r.tables[LITLEN_TABLE].lookup(l.bit_buf) {
l.bit_buf >>= code_len;
l.num_bits -= code_len;
// The previous symbol was a literal, so write it directly and check
// the next one.
out_buf.write_byte(l.counter as u8);
if (symbol & 256) != 0 {
l.counter = symbol as u32;
// The symbol is a length value.
break;
} else {
// The symbol is a literal, so write it directly and continue.
out_buf.write_byte(symbol as u8);
}
} else {
state.begin(InvalidCodeLen);
break 'o TINFLStatus::Failed;
}
}
} else {
state.begin(InvalidCodeLen);
break 'o TINFLStatus::Failed;
}
}
// Mask the top bits since they may contain length info.
l.counter &= 511;
if l.counter == 256 {
// We hit the end of block symbol.
state.begin(BlockDone);
break 'o TINFLStatus::Done;
} else if l.counter > 285 {
// Invalid code.
// We already verified earlier that the code is > 256.
state.begin(InvalidLitlen);
break 'o TINFLStatus::Failed;
} else {
// The symbol was a length code.
// # Optimization
// Mask the value to avoid bounds checks
// We could use get_unchecked later if can statically verify that
// this will never go out of bounds.
l.num_extra = u32::from(LENGTH_EXTRA[(l.counter - 257) as usize & BASE_EXTRA_MASK]);
l.counter = u32::from(LENGTH_BASE[(l.counter - 257) as usize & BASE_EXTRA_MASK]);
// Length and distance codes have a number of extra bits depending on
// the base, which together with the base gives us the exact value.
fill_bit_buffer(&mut l, in_iter);
if l.num_extra != 0 {
let extra_bits = l.bit_buf & ((1 << l.num_extra) - 1);
l.bit_buf >>= l.num_extra;
l.num_bits -= l.num_extra;
l.counter += extra_bits as u32;
}
// We found a length code, so a distance code should follow.
if cfg!(not(target_pointer_width = "64")) {
fill_bit_buffer(&mut l, in_iter);
}
if let Some((mut symbol, code_len)) = r.tables[DIST_TABLE].lookup(l.bit_buf) {
symbol &= 511;
l.bit_buf >>= code_len;
l.num_bits -= code_len;
if symbol > 29 {
state.begin(InvalidDist);
break 'o TINFLStatus::Failed;
}
l.num_extra = u32::from(DIST_EXTRA[symbol as usize]);
l.dist = u32::from(DIST_BASE[symbol as usize]);
} else {
state.begin(InvalidCodeLen);
break 'o TINFLStatus::Failed;
}
if l.num_extra != 0 {
fill_bit_buffer(&mut l, in_iter);
let extra_bits = l.bit_buf & ((1 << l.num_extra) - 1);
l.bit_buf >>= l.num_extra;
l.num_bits -= l.num_extra;
l.dist += extra_bits as u32;
}
let position = out_buf.position();
if l.dist as usize > out_buf.position()
&& (flags & TINFL_FLAG_USING_NON_WRAPPING_OUTPUT_BUF != 0)
{
// We encountered a distance that refers a position before
// the start of the decoded data, so we can't continue.
state.begin(DistanceOutOfBounds);
break TINFLStatus::Failed;
}
apply_match(
out_buf.get_mut(),
position,
l.dist as usize,
l.counter as usize,
out_buf_size_mask,
);
out_buf.set_position(position + l.counter as usize);
}
};
*local_vars = l;
(status, state)
}
/// Main decompression function. Keeps decompressing data from `in_buf` until the `in_buf` is
/// empty, `out` is full, the end of the deflate stream is hit, or there is an error in the
/// deflate stream.
///
/// # Arguments
///
/// `r` is a [`DecompressorOxide`] struct with the state of this stream.
///
/// `in_buf` is a reference to the compressed data that is to be decompressed. The decompressor will
/// start at the first byte of this buffer.
///
/// `out` is a reference to the buffer that will store the decompressed data, and that
/// stores previously decompressed data if any.
///
/// * The offset given by `out_pos` indicates where in the output buffer slice writing should start.
/// * If [`TINFL_FLAG_USING_NON_WRAPPING_OUTPUT_BUF`] is not set, the output buffer is used in a
/// wrapping manner, and it's size is required to be a power of 2.
/// * The decompression function normally needs access to 32KiB of the previously decompressed data
///(or to the beginning of the decompressed data if less than 32KiB has been decompressed.)
/// - If this data is not available, decompression may fail.
/// - Some deflate compressors allow specifying a window size which limits match distances to
/// less than this, or alternatively an RLE mode where matches will only refer to the previous byte
/// and thus allows a smaller output buffer. The window size can be specified in the zlib
/// header structure, however, the header data should not be relied on to be correct.
///
/// `flags` indicates settings and status to the decompression function.
/// * The [`TINFL_FLAG_HAS_MORE_INPUT`] has to be specified if more compressed data is to be provided
/// in a subsequent call to this function.
/// * See the the [`inflate_flags`] module for details on other flags.
///
/// # Returns
///
/// Returns a tuple containing the status of the compressor, the number of input bytes read, and the
/// number of bytes output to `out`.
///
/// This function shouldn't panic pending any bugs.
pub fn decompress(
r: &mut DecompressorOxide,
in_buf: &[u8],
out: &mut [u8],
out_pos: usize,
flags: u32,
) -> (TINFLStatus, usize, usize) {
let out_buf_size_mask = if flags & TINFL_FLAG_USING_NON_WRAPPING_OUTPUT_BUF != 0 {
usize::max_value()
} else {
// In the case of zero len, any attempt to write would produce HasMoreOutput,
// so to gracefully process the case of there really being no output,
// set the mask to all zeros.
out.len().saturating_sub(1)
};
// Ensure the output buffer's size is a power of 2, unless the output buffer
// is large enough to hold the entire output file (in which case it doesn't
// matter).
// Also make sure that the output buffer position is not past the end of the output buffer.
if (out_buf_size_mask.wrapping_add(1) & out_buf_size_mask) != 0 || out_pos > out.len() {
return (TINFLStatus::BadParam, 0, 0);
}
let mut in_iter = in_buf.iter();
let mut state = r.state;
let mut out_buf = OutputBuffer::from_slice_and_pos(out, out_pos);
// Make a local copy of the important variables here so we can work with them on the stack.
let mut l = LocalVars {
bit_buf: r.bit_buf,
num_bits: r.num_bits,
dist: r.dist,
counter: r.counter,
num_extra: r.num_extra,
};
let mut status = 'state_machine: loop {
match state {
Start => generate_state!(state, 'state_machine, {
l.bit_buf = 0;
l.num_bits = 0;
l.dist = 0;
l.counter = 0;
l.num_extra = 0;
r.z_header0 = 0;
r.z_header1 = 0;
r.z_adler32 = 1;
r.check_adler32 = 1;
if flags & TINFL_FLAG_PARSE_ZLIB_HEADER != 0 {
Action::Jump(State::ReadZlibCmf)
} else {
Action::Jump(State::ReadBlockHeader)
}
}),
ReadZlibCmf => generate_state!(state, 'state_machine, {
read_byte(&mut in_iter, flags, |cmf| {
r.z_header0 = u32::from(cmf);
Action::Jump(State::ReadZlibFlg)
})
}),
ReadZlibFlg => generate_state!(state, 'state_machine, {
read_byte(&mut in_iter, flags, |flg| {
r.z_header1 = u32::from(flg);
validate_zlib_header(r.z_header0, r.z_header1, flags, out_buf_size_mask)
})
}),
// Read the block header and jump to the relevant section depending on the block type.
ReadBlockHeader => generate_state!(state, 'state_machine, {
read_bits(&mut l, 3, &mut in_iter, flags, |l, bits| {
r.finish = (bits & 1) as u32;
r.block_type = (bits >> 1) as u32 & 3;
match r.block_type {
0 => Action::Jump(BlockTypeNoCompression),
1 => {
start_static_table(r);
init_tree(r, l)
},
2 => {
l.counter = 0;
Action::Jump(ReadTableSizes)
},
3 => Action::Jump(BlockTypeUnexpected),
_ => unreachable!()
}
})
}),
// Raw/Stored/uncompressed block.
BlockTypeNoCompression => generate_state!(state, 'state_machine, {
pad_to_bytes(&mut l, &mut in_iter, flags, |l| {
l.counter = 0;
Action::Jump(RawHeader)
})
}),
// Check that the raw block header is correct.
RawHeader => generate_state!(state, 'state_machine, {
if l.counter < 4 {
// Read block length and block length check.
if l.num_bits != 0 {
read_bits(&mut l, 8, &mut in_iter, flags, |l, bits| {
r.raw_header[l.counter as usize] = bits as u8;
l.counter += 1;
Action::None
})
} else {
read_byte(&mut in_iter, flags, |byte| {
r.raw_header[l.counter as usize] = byte;
l.counter += 1;
Action::None
})
}
} else {
// Check if the length value of a raw block is correct.
// The 2 first (2-byte) words in a raw header are the length and the
// ones complement of the length.
let length = u16::from(r.raw_header[0]) | (u16::from(r.raw_header[1]) << 8);
let check = u16::from(r.raw_header[2]) | (u16::from(r.raw_header[3]) << 8);
let valid = length == !check;
l.counter = length.into();
if !valid {
Action::Jump(BadRawLength)
} else if l.counter == 0 {
// Empty raw block. Sometimes used for synchronization.
Action::Jump(BlockDone)
} else if l.num_bits != 0 {
// There is some data in the bit buffer, so we need to write that first.
Action::Jump(RawReadFirstByte)
} else {
// The bit buffer is empty, so memcpy the rest of the uncompressed data from
// the block.
Action::Jump(RawMemcpy1)
}
}
}),
// Read the byte from the bit buffer.
RawReadFirstByte => generate_state!(state, 'state_machine, {
read_bits(&mut l, 8, &mut in_iter, flags, |l, bits| {
l.dist = bits as u32;
Action::Jump(RawStoreFirstByte)
})
}),
// Write the byte we just read to the output buffer.
RawStoreFirstByte => generate_state!(state, 'state_machine, {
if out_buf.bytes_left() == 0 {
Action::End(TINFLStatus::HasMoreOutput)
} else {
out_buf.write_byte(l.dist as u8);
l.counter -= 1;
if l.counter == 0 || l.num_bits == 0 {
Action::Jump(RawMemcpy1)
} else {
// There is still some data left in the bit buffer that needs to be output.
// TODO: Changed this to jump to `RawReadfirstbyte` rather than
// `RawStoreFirstByte` as that seemed to be the correct path, but this
// needs testing.
Action::Jump(RawReadFirstByte)
}
}
}),
RawMemcpy1 => generate_state!(state, 'state_machine, {
if l.counter == 0 {
Action::Jump(BlockDone)
} else if out_buf.bytes_left() == 0 {
Action::End(TINFLStatus::HasMoreOutput)
} else {
Action::Jump(RawMemcpy2)
}
}),
RawMemcpy2 => generate_state!(state, 'state_machine, {
if in_iter.len() > 0 {
// Copy as many raw bytes as possible from the input to the output using memcpy.
// Raw block lengths are limited to 64 * 1024, so casting through usize and u32
// is not an issue.
let space_left = out_buf.bytes_left();
let bytes_to_copy = cmp::min(cmp::min(
space_left,
in_iter.len()),
l.counter as usize
);
out_buf.write_slice(&in_iter.as_slice()[..bytes_to_copy]);
(&mut in_iter).nth(bytes_to_copy - 1);
l.counter -= bytes_to_copy as u32;
Action::Jump(RawMemcpy1)
} else {
end_of_input(flags)
}
}),
// Read how many huffman codes/symbols are used for each table.
ReadTableSizes => generate_state!(state, 'state_machine, {
if l.counter < 3 {
let num_bits = [5, 5, 4][l.counter as usize];
read_bits(&mut l, num_bits, &mut in_iter, flags, |l, bits| {
r.table_sizes[l.counter as usize] =
bits as u32 + u32::from(MIN_TABLE_SIZES[l.counter as usize]);
l.counter += 1;
Action::None
})
} else {
memset(&mut r.tables[HUFFLEN_TABLE].code_size[..], 0);
l.counter = 0;
Action::Jump(ReadHufflenTableCodeSize)
}
}),
// Read the 3-bit lengths of the huffman codes describing the huffman code lengths used
// to decode the lengths of the main tables.
ReadHufflenTableCodeSize => generate_state!(state, 'state_machine, {
if l.counter < r.table_sizes[HUFFLEN_TABLE] {
read_bits(&mut l, 3, &mut in_iter, flags, |l, bits| {
// These lengths are not stored in a normal ascending order, but rather one
// specified by the deflate specification intended to put the most used
// values at the front as trailing zero lengths do not have to be stored.
r.tables[HUFFLEN_TABLE]
.code_size[HUFFMAN_LENGTH_ORDER[l.counter as usize] as usize] =
bits as u8;
l.counter += 1;
Action::None
})
} else {
r.table_sizes[HUFFLEN_TABLE] = 19;
init_tree(r, &mut l)
}
}),
ReadLitlenDistTablesCodeSize => generate_state!(state, 'state_machine, {
if l.counter < r.table_sizes[LITLEN_TABLE] + r.table_sizes[DIST_TABLE] {
decode_huffman_code(
r, &mut l, HUFFLEN_TABLE,
flags, &mut in_iter, |r, l, symbol| {
l.dist = symbol as u32;
if l.dist < 16 {
r.len_codes[l.counter as usize] = l.dist as u8;
l.counter += 1;
Action::None
} else if l.dist == 16 && l.counter == 0 {
Action::Jump(BadCodeSizeDistPrevLookup)
} else {
l.num_extra = [2, 3, 7][l.dist as usize - 16];
Action::Jump(ReadExtraBitsCodeSize)
}
}
)
} else if l.counter != r.table_sizes[LITLEN_TABLE] + r.table_sizes[DIST_TABLE] {
Action::Jump(BadCodeSizeSum)
} else {
r.tables[LITLEN_TABLE].code_size[..r.table_sizes[LITLEN_TABLE] as usize]
.copy_from_slice(&r.len_codes[..r.table_sizes[LITLEN_TABLE] as usize]);
let dist_table_start = r.table_sizes[LITLEN_TABLE] as usize;
let dist_table_end = (r.table_sizes[LITLEN_TABLE] +
r.table_sizes[DIST_TABLE]) as usize;
r.tables[DIST_TABLE].code_size[..r.table_sizes[DIST_TABLE] as usize]
.copy_from_slice(&r.len_codes[dist_table_start..dist_table_end]);
r.block_type -= 1;
init_tree(r, &mut l)
}
}),
ReadExtraBitsCodeSize => generate_state!(state, 'state_machine, {
let num_extra = l.num_extra;
read_bits(&mut l, num_extra, &mut in_iter, flags, |l, mut extra_bits| {
// Mask to avoid a bounds check.
extra_bits += [3, 3, 11][(l.dist as usize - 16) & 3];
let val = if l.dist == 16 {
r.len_codes[l.counter as usize - 1]
} else {
0
};
memset(
&mut r.len_codes[
l.counter as usize..l.counter as usize + extra_bits as usize
],
val,
);
l.counter += extra_bits as u32;
Action::Jump(ReadLitlenDistTablesCodeSize)
})
}),
DecodeLitlen => generate_state!(state, 'state_machine, {
if in_iter.len() < 4 || out_buf.bytes_left() < 2 {
// See if we can decode a literal with the data we have left.
// Jumps to next state (WriteSymbol) if successful.
decode_huffman_code(
r,
&mut l,
LITLEN_TABLE,
flags,
&mut in_iter,
|_r, l, symbol| {
l.counter = symbol as u32;
Action::Jump(WriteSymbol)
},
)
} else if
// If there is enough space, use the fast inner decompression
// function.
out_buf.bytes_left() >= 259 &&
in_iter.len() >= 14
{
let (status, new_state) = decompress_fast(
r,
&mut in_iter,
&mut out_buf,
flags,
&mut l,
out_buf_size_mask,
);
state = new_state;
if status == TINFLStatus::Done {
Action::Jump(new_state)
} else {
Action::End(status)
}
} else {
fill_bit_buffer(&mut l, &mut in_iter);
if let Some((symbol, code_len)) = r.tables[LITLEN_TABLE].lookup(l.bit_buf) {
l.counter = symbol as u32;
l.bit_buf >>= code_len;
l.num_bits -= code_len;
if (l.counter & 256) != 0 {
// The symbol is not a literal.
Action::Jump(HuffDecodeOuterLoop1)
} else {
// If we have a 32-bit buffer we need to read another two bytes now
// to have enough bits to keep going.
if cfg!(not(target_pointer_width = "64")) {
fill_bit_buffer(&mut l, &mut in_iter);
}
if let Some((symbol, code_len)) = r.tables[LITLEN_TABLE].lookup(l.bit_buf) {
l.bit_buf >>= code_len;
l.num_bits -= code_len;
// The previous symbol was a literal, so write it directly and check
// the next one.
out_buf.write_byte(l.counter as u8);
if (symbol & 256) != 0 {
l.counter = symbol as u32;
// The symbol is a length value.
Action::Jump(HuffDecodeOuterLoop1)
} else {
// The symbol is a literal, so write it directly and continue.
out_buf.write_byte(symbol as u8);
Action::None
}
} else {
Action::Jump(InvalidCodeLen)
}
}
} else {
Action::Jump(InvalidCodeLen)
}
}
}),
WriteSymbol => generate_state!(state, 'state_machine, {
if l.counter >= 256 {
Action::Jump(HuffDecodeOuterLoop1)
} else if out_buf.bytes_left() > 0 {
out_buf.write_byte(l.counter as u8);
Action::Jump(DecodeLitlen)
} else {
Action::End(TINFLStatus::HasMoreOutput)
}
}),
HuffDecodeOuterLoop1 => generate_state!(state, 'state_machine, {
// Mask the top bits since they may contain length info.
l.counter &= 511;
if l.counter == 256 {
// We hit the end of block symbol.
Action::Jump(BlockDone)
} else if l.counter > 285 {
// Invalid code.
// We already verified earlier that the code is > 256.
Action::Jump(InvalidLitlen)
} else {
// # Optimization
// Mask the value to avoid bounds checks
// We could use get_unchecked later if can statically verify that
// this will never go out of bounds.
l.num_extra =
u32::from(LENGTH_EXTRA[(l.counter - 257) as usize & BASE_EXTRA_MASK]);
l.counter = u32::from(LENGTH_BASE[(l.counter - 257) as usize & BASE_EXTRA_MASK]);
// Length and distance codes have a number of extra bits depending on
// the base, which together with the base gives us the exact value.
if l.num_extra != 0 {
Action::Jump(ReadExtraBitsLitlen)
} else {
Action::Jump(DecodeDistance)
}
}
}),
ReadExtraBitsLitlen => generate_state!(state, 'state_machine, {
let num_extra = l.num_extra;
read_bits(&mut l, num_extra, &mut in_iter, flags, |l, extra_bits| {
l.counter += extra_bits as u32;
Action::Jump(DecodeDistance)
})
}),
DecodeDistance => generate_state!(state, 'state_machine, {
// Try to read a huffman code from the input buffer and look up what
// length code the decoded symbol refers to.
decode_huffman_code(r, &mut l, DIST_TABLE, flags, &mut in_iter, |_r, l, symbol| {
if symbol > 29 {
// Invalid distance code.
return Action::Jump(InvalidDist)
}
// # Optimization
// Mask the value to avoid bounds checks
// We could use get_unchecked later if can statically verify that
// this will never go out of bounds.
l.num_extra = u32::from(DIST_EXTRA[symbol as usize & BASE_EXTRA_MASK]);
l.dist = u32::from(DIST_BASE[symbol as usize & BASE_EXTRA_MASK]);
if l.num_extra != 0 {
// ReadEXTRA_BITS_DISTACNE
Action::Jump(ReadExtraBitsDistance)
} else {
Action::Jump(HuffDecodeOuterLoop2)
}
})
}),
ReadExtraBitsDistance => generate_state!(state, 'state_machine, {
let num_extra = l.num_extra;
read_bits(&mut l, num_extra, &mut in_iter, flags, |l, extra_bits| {
l.dist += extra_bits as u32;
Action::Jump(HuffDecodeOuterLoop2)
})
}),
HuffDecodeOuterLoop2 => generate_state!(state, 'state_machine, {
if l.dist as usize > out_buf.position() &&
(flags & TINFL_FLAG_USING_NON_WRAPPING_OUTPUT_BUF != 0)
{
// We encountered a distance that refers a position before
// the start of the decoded data, so we can't continue.
Action::Jump(DistanceOutOfBounds)
} else {
let out_pos = out_buf.position();
let source_pos = out_buf.position()
.wrapping_sub(l.dist as usize) & out_buf_size_mask;
let out_len = out_buf.get_ref().len() as usize;
let match_end_pos = out_buf.position() + l.counter as usize;
if match_end_pos > out_len ||
// miniz doesn't do this check here. Not sure how it makes sure
// that this case doesn't happen.
(source_pos >= out_pos && (source_pos - out_pos) < l.counter as usize)
{
// Not enough space for all of the data in the output buffer,
// so copy what we have space for.
if l.counter == 0 {
Action::Jump(DecodeLitlen)
} else {
Action::Jump(WriteLenBytesToEnd)
}
} else {
apply_match(
out_buf.get_mut(),
out_pos,
l.dist as usize,
l.counter as usize,
out_buf_size_mask
);
out_buf.set_position(out_pos + l.counter as usize);
Action::Jump(DecodeLitlen)
}
}
}),
WriteLenBytesToEnd => generate_state!(state, 'state_machine, {
if out_buf.bytes_left() > 0 {
let out_pos = out_buf.position();
let source_pos = out_buf.position()
.wrapping_sub(l.dist as usize) & out_buf_size_mask;
let len = cmp::min(out_buf.bytes_left(), l.counter as usize);
transfer(out_buf.get_mut(), source_pos, out_pos, len, out_buf_size_mask);
out_buf.set_position(out_pos + len);
l.counter -= len as u32;
if l.counter == 0 {
Action::Jump(DecodeLitlen)
} else {
Action::None
}
} else {
Action::End(TINFLStatus::HasMoreOutput)
}
}),
BlockDone => generate_state!(state, 'state_machine, {
// End once we've read the last block.
if r.finish != 0 {
pad_to_bytes(&mut l, &mut in_iter, flags, |_| Action::None);
let in_consumed = in_buf.len() - in_iter.len();
let undo = undo_bytes(&mut l, in_consumed as u32) as usize;
in_iter = in_buf[in_consumed - undo..].iter();
l.bit_buf &= ((1 as BitBuffer) << l.num_bits) - 1;
debug_assert_eq!(l.num_bits, 0);
if flags & TINFL_FLAG_PARSE_ZLIB_HEADER != 0 {
l.counter = 0;
Action::Jump(ReadAdler32)
} else {
Action::Jump(DoneForever)
}
} else {
Action::Jump(ReadBlockHeader)
}
}),
ReadAdler32 => generate_state!(state, 'state_machine, {
if l.counter < 4 {
if l.num_bits != 0 {
read_bits(&mut l, 8, &mut in_iter, flags, |l, bits| {
r.z_adler32 <<= 8;
r.z_adler32 |= bits as u32;
l.counter += 1;
Action::None
})
} else {
read_byte(&mut in_iter, flags, |byte| {
r.z_adler32 <<= 8;
r.z_adler32 |= u32::from(byte);
l.counter += 1;
Action::None
})
}
} else {
Action::Jump(DoneForever)
}
}),
// We are done.
DoneForever => break TINFLStatus::Done,
// Anything else indicates failure.
// BadZlibHeader | BadRawLength | BlockTypeUnexpected | DistanceOutOfBounds |
// BadTotalSymbols | BadCodeSizeDistPrevLookup | BadCodeSizeSum | InvalidLitlen |
// InvalidDist | InvalidCodeLen
_ => break TINFLStatus::Failed,
};
};
let in_undo = if status != TINFLStatus::NeedsMoreInput
&& status != TINFLStatus::FailedCannotMakeProgress
{
undo_bytes(&mut l, (in_buf.len() - in_iter.len()) as u32) as usize
} else {
0
};
// Make sure HasMoreOutput overrides NeedsMoreInput if the output buffer is full.
// (Unless the missing input is the adler32 value in which case we don't need to write anything.)
// TODO: May want to see if we can do this in a better way.
if status == TINFLStatus::NeedsMoreInput
&& out_buf.bytes_left() == 0
&& state != State::ReadAdler32
{
status = TINFLStatus::HasMoreOutput
}
r.state = state;
r.bit_buf = l.bit_buf;
r.num_bits = l.num_bits;
r.dist = l.dist;
r.counter = l.counter;
r.num_extra = l.num_extra;
r.bit_buf &= ((1 as BitBuffer) << r.num_bits) - 1;
// If this is a zlib stream, and update the adler32 checksum with the decompressed bytes if
// requested.
let need_adler = if (flags & TINFL_FLAG_IGNORE_ADLER32) == 0 {
flags & (TINFL_FLAG_PARSE_ZLIB_HEADER | TINFL_FLAG_COMPUTE_ADLER32) != 0
} else {
// If TINFL_FLAG_IGNORE_ADLER32 is enabled, ignore the checksum.
false
};
if need_adler && status as i32 >= 0 {
let out_buf_pos = out_buf.position();
r.check_adler32 = update_adler32(r.check_adler32, &out_buf.get_ref()[out_pos..out_buf_pos]);
// disabled so that random input from fuzzer would not be rejected early,
// before it has a chance to reach interesting parts of code
if !cfg!(fuzzing) {
// Once we are done, check if the checksum matches with the one provided in the zlib header.
if status == TINFLStatus::Done
&& flags & TINFL_FLAG_PARSE_ZLIB_HEADER != 0
&& r.check_adler32 != r.z_adler32
{
status = TINFLStatus::Adler32Mismatch;
}
}
}
(
status,
in_buf.len() - in_iter.len() - in_undo,
out_buf.position() - out_pos,
)
}