Initial vendor packages

Signed-off-by: Valentin Popov <valentin@popov.link>

1 files changed, 1270 insertions, 0 deletions

diff --git a/vendor/fdeflate/src/decompress.rs b/vendor/fdeflate/src/decompress.rs
new file mode 100644
index 0000000..d38f63b
--- /dev/null
+++ b/vendor/fdeflate/src/decompress.rs
@@ -0,0 +1,1270 @@
+use std::convert::TryInto;
+
+use simd_adler32::Adler32;
+
+use crate::tables::{
+    self, CLCL_ORDER, DIST_SYM_TO_DIST_BASE, DIST_SYM_TO_DIST_EXTRA, FDEFLATE_DIST_DECODE_TABLE,
+    FDEFLATE_LITLEN_DECODE_TABLE, FIXED_CODE_LENGTHS, LEN_SYM_TO_LEN_BASE, LEN_SYM_TO_LEN_EXTRA,
+};
+
+/// An error encountered while decompressing a deflate stream.
+#[derive(Debug, PartialEq)]
+pub enum DecompressionError {
+    /// The zlib header is corrupt.
+    BadZlibHeader,
+    /// All input was consumed, but the end of the stream hasn't been reached.
+    InsufficientInput,
+    /// A block header specifies an invalid block type.
+    InvalidBlockType,
+    /// An uncompressed block's NLEN value is invalid.
+    InvalidUncompressedBlockLength,
+    /// Too many literals were specified.
+    InvalidHlit,
+    /// Too many distance codes were specified.
+    InvalidHdist,
+    /// Attempted to repeat a previous code before reading any codes, or past the end of the code
+    /// lengths.
+    InvalidCodeLengthRepeat,
+    /// The stream doesn't specify a valid huffman tree.
+    BadCodeLengthHuffmanTree,
+    /// The stream doesn't specify a valid huffman tree.
+    BadLiteralLengthHuffmanTree,
+    /// The stream doesn't specify a valid huffman tree.
+    BadDistanceHuffmanTree,
+    /// The stream contains a literal/length code that was not allowed by the header.
+    InvalidLiteralLengthCode,
+    /// The stream contains a distance code that was not allowed by the header.
+    InvalidDistanceCode,
+    /// The stream contains contains back-reference as the first symbol.
+    InputStartsWithRun,
+    /// The stream contains a back-reference that is too far back.
+    DistanceTooFarBack,
+    /// The deflate stream checksum is incorrect.
+    WrongChecksum,
+    /// Extra input data.
+    ExtraInput,
+}
+
+struct BlockHeader {
+    hlit: usize,
+    hdist: usize,
+    hclen: usize,
+    num_lengths_read: usize,
+
+    /// Low 3-bits are code length code length, high 5-bits are code length code.
+    table: [u8; 128],
+    code_lengths: [u8; 320],
+}
+
+const LITERAL_ENTRY: u32 = 0x8000;
+const EXCEPTIONAL_ENTRY: u32 = 0x4000;
+const SECONDARY_TABLE_ENTRY: u32 = 0x2000;
+
+/// The Decompressor state for a compressed block.
+///
+/// The main litlen_table uses a 12-bit input to lookup the meaning of the symbol. The table is
+/// split into 4 sections:
+///
+///   aaaaaaaa_bbbbbbbb_1000yyyy_0000xxxx  x = input_advance_bits, y = output_advance_bytes (literal)
+///   0000000z_zzzzzzzz_00000yyy_0000xxxx  x = input_advance_bits, y = extra_bits, z = distance_base (length)
+///   00000000_00000000_01000000_0000xxxx  x = input_advance_bits (EOF)
+///   0000xxxx_xxxxxxxx_01100000_00000000  x = secondary_table_index
+///   00000000_00000000_01000000_00000000  invalid code
+///
+/// The distance table is a 512-entry table that maps 9 bits of distance symbols to their meaning.
+///
+///   00000000_00000000_00000000_00000000     symbol is more than 9 bits
+///   zzzzzzzz_zzzzzzzz_0000yyyy_0000xxxx     x = input_advance_bits, y = extra_bits, z = distance_base
+#[repr(align(64))]
+#[derive(Eq, PartialEq, Debug)]
+struct CompressedBlock {
+    litlen_table: [u32; 4096],
+    dist_table: [u32; 512],
+
+    dist_symbol_lengths: [u8; 30],
+    dist_symbol_masks: [u16; 30],
+    dist_symbol_codes: [u16; 30],
+
+    secondary_table: Vec<u16>,
+    eof_code: u16,
+    eof_mask: u16,
+    eof_bits: u8,
+}
+
+const FDEFLATE_COMPRESSED_BLOCK: CompressedBlock = CompressedBlock {
+    litlen_table: FDEFLATE_LITLEN_DECODE_TABLE,
+    dist_table: FDEFLATE_DIST_DECODE_TABLE,
+    dist_symbol_lengths: [
+        1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    ],
+    dist_symbol_masks: [
+        1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    ],
+    dist_symbol_codes: [
+        0, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff,
+        0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff,
+        0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff,
+    ],
+    secondary_table: Vec::new(),
+    eof_code: 0x8ff,
+    eof_mask: 0xfff,
+    eof_bits: 0xc,
+};
+
+#[derive(Debug, Copy, Clone, Eq, PartialEq)]
+enum State {
+    ZlibHeader,
+    BlockHeader,
+    CodeLengthCodes,
+    CodeLengths,
+    CompressedData,
+    UncompressedData,
+    Checksum,
+    Done,
+}
+
+/// Decompressor for arbitrary zlib streams.
+pub struct Decompressor {
+    /// State for decoding a compressed block.
+    compression: CompressedBlock,
+    // State for decoding a block header.
+    header: BlockHeader,
+    // Number of bytes left for uncompressed block.
+    uncompressed_bytes_left: u16,
+
+    buffer: u64,
+    nbits: u8,
+
+    queued_rle: Option<(u8, usize)>,
+    queued_backref: Option<(usize, usize)>,
+    last_block: bool,
+
+    state: State,
+    checksum: Adler32,
+    ignore_adler32: bool,
+}
+
+impl Default for Decompressor {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl Decompressor {
+    /// Create a new decompressor.
+    pub fn new() -> Self {
+        Self {
+            buffer: 0,
+            nbits: 0,
+            compression: CompressedBlock {
+                litlen_table: [0; 4096],
+                dist_table: [0; 512],
+                secondary_table: Vec::new(),
+                dist_symbol_lengths: [0; 30],
+                dist_symbol_masks: [0; 30],
+                dist_symbol_codes: [0xffff; 30],
+                eof_code: 0,
+                eof_mask: 0,
+                eof_bits: 0,
+            },
+            header: BlockHeader {
+                hlit: 0,
+                hdist: 0,
+                hclen: 0,
+                table: [0; 128],
+                num_lengths_read: 0,
+                code_lengths: [0; 320],
+            },
+            uncompressed_bytes_left: 0,
+            queued_rle: None,
+            queued_backref: None,
+            checksum: Adler32::new(),
+            state: State::ZlibHeader,
+            last_block: false,
+            ignore_adler32: false,
+        }
+    }
+
+    /// Ignore the checksum at the end of the stream.
+    pub fn ignore_adler32(&mut self) {
+        self.ignore_adler32 = true;
+    }
+
+    fn fill_buffer(&mut self, input: &mut &[u8]) {
+        if input.len() >= 8 {
+            self.buffer |= u64::from_le_bytes(input[..8].try_into().unwrap()) << self.nbits;
+            *input = &mut &input[(63 - self.nbits as usize) / 8..];
+            self.nbits |= 56;
+        } else {
+            let nbytes = input.len().min((63 - self.nbits as usize) / 8);
+            let mut input_data = [0; 8];
+            input_data[..nbytes].copy_from_slice(&input[..nbytes]);
+            self.buffer |= u64::from_le_bytes(input_data)
+                .checked_shl(self.nbits as u32)
+                .unwrap_or(0);
+            self.nbits += nbytes as u8 * 8;
+            *input = &mut &input[nbytes..];
+        }
+    }
+
+    fn peak_bits(&mut self, nbits: u8) -> u64 {
+        debug_assert!(nbits <= 56 && nbits <= self.nbits);
+        self.buffer & ((1u64 << nbits) - 1)
+    }
+    fn consume_bits(&mut self, nbits: u8) {
+        debug_assert!(self.nbits >= nbits);
+        self.buffer >>= nbits;
+        self.nbits -= nbits;
+    }
+
+    fn read_block_header(&mut self, remaining_input: &mut &[u8]) -> Result<(), DecompressionError> {
+        self.fill_buffer(remaining_input);
+        if self.nbits < 3 {
+            return Ok(());
+        }
+
+        let start = self.peak_bits(3);
+        self.last_block = start & 1 != 0;
+        match start >> 1 {
+            0b00 => {
+                let align_bits = (self.nbits - 3) % 8;
+                let header_bits = 3 + 32 + align_bits;
+                if self.nbits < header_bits {
+                    return Ok(());
+                }
+
+                let len = (self.peak_bits(align_bits + 19) >> (align_bits + 3)) as u16;
+                let nlen = (self.peak_bits(header_bits) >> (align_bits + 19)) as u16;
+                if nlen != !len {
+                    return Err(DecompressionError::InvalidUncompressedBlockLength);
+                }
+
+                self.state = State::UncompressedData;
+                self.uncompressed_bytes_left = len;
+                self.consume_bits(header_bits);
+                Ok(())
+            }
+            0b01 => {
+                self.consume_bits(3);
+                // TODO: Do this statically rather than every time.
+                Self::build_tables(288, &FIXED_CODE_LENGTHS, &mut self.compression, 6)?;
+                self.state = State::CompressedData;
+                Ok(())
+            }
+            0b10 => {
+                if self.nbits < 17 {
+                    return Ok(());
+                }
+
+                self.header.hlit = (self.peak_bits(8) >> 3) as usize + 257;
+                self.header.hdist = (self.peak_bits(13) >> 8) as usize + 1;
+                self.header.hclen = (self.peak_bits(17) >> 13) as usize + 4;
+                if self.header.hlit > 286 {
+                    return Err(DecompressionError::InvalidHlit);
+                }
+                if self.header.hdist > 30 {
+                    return Err(DecompressionError::InvalidHdist);
+                }
+
+                self.consume_bits(17);
+                self.state = State::CodeLengthCodes;
+                Ok(())
+            }
+            0b11 => Err(DecompressionError::InvalidBlockType),
+            _ => unreachable!(),
+        }
+    }
+
+    fn read_code_length_codes(
+        &mut self,
+        remaining_input: &mut &[u8],
+    ) -> Result<(), DecompressionError> {
+        self.fill_buffer(remaining_input);
+        if self.nbits as usize + remaining_input.len() * 8 < 3 * self.header.hclen {
+            return Ok(());
+        }
+
+        let mut code_length_lengths = [0; 19];
+        for i in 0..self.header.hclen {
+            code_length_lengths[CLCL_ORDER[i]] = self.peak_bits(3) as u8;
+            self.consume_bits(3);
+
+            // We need to refill the buffer after reading 3 * 18 = 54 bits since the buffer holds
+            // between 56 and 63 bits total.
+            if i == 17 {
+                self.fill_buffer(remaining_input);
+            }
+        }
+        let code_length_codes: [u16; 19] = crate::compute_codes(&code_length_lengths)
+            .ok_or(DecompressionError::BadCodeLengthHuffmanTree)?;
+
+        self.header.table = [255; 128];
+        for i in 0..19 {
+            let length = code_length_lengths[i];
+            if length > 0 {
+                let mut j = code_length_codes[i];
+                while j < 128 {
+                    self.header.table[j as usize] = ((i as u8) << 3) | length;
+                    j += 1 << length;
+                }
+            }
+        }
+
+        self.state = State::CodeLengths;
+        self.header.num_lengths_read = 0;
+        Ok(())
+    }
+
+    fn read_code_lengths(&mut self, remaining_input: &mut &[u8]) -> Result<(), DecompressionError> {
+        let total_lengths = self.header.hlit + self.header.hdist;
+        while self.header.num_lengths_read < total_lengths {
+            self.fill_buffer(remaining_input);
+            if self.nbits < 7 {
+                return Ok(());
+            }
+
+            let code = self.peak_bits(7);
+            let entry = self.header.table[code as usize];
+            let length = entry & 0x7;
+            let symbol = entry >> 3;
+
+            debug_assert!(length != 0);
+            match symbol {
+                0..=15 => {
+                    self.header.code_lengths[self.header.num_lengths_read] = symbol;
+                    self.header.num_lengths_read += 1;
+                    self.consume_bits(length);
+                }
+                16..=18 => {
+                    let (base_repeat, extra_bits) = match symbol {
+                        16 => (3, 2),
+                        17 => (3, 3),
+                        18 => (11, 7),
+                        _ => unreachable!(),
+                    };
+
+                    if self.nbits < length + extra_bits {
+                        return Ok(());
+                    }
+
+                    let value = match symbol {
+                        16 => {
+                            self.header.code_lengths[self
+                                .header
+                                .num_lengths_read
+                                .checked_sub(1)
+                                .ok_or(DecompressionError::InvalidCodeLengthRepeat)?]
+                            // TODO: is this right?
+                        }
+                        17 => 0,
+                        18 => 0,
+                        _ => unreachable!(),
+                    };
+
+                    let repeat =
+                        (self.peak_bits(length + extra_bits) >> length) as usize + base_repeat;
+                    if self.header.num_lengths_read + repeat > total_lengths {
+                        return Err(DecompressionError::InvalidCodeLengthRepeat);
+                    }
+
+                    for i in 0..repeat {
+                        self.header.code_lengths[self.header.num_lengths_read + i] = value;
+                    }
+                    self.header.num_lengths_read += repeat;
+                    self.consume_bits(length + extra_bits);
+                }
+                _ => unreachable!(),
+            }
+        }
+
+        self.header
+            .code_lengths
+            .copy_within(self.header.hlit..total_lengths, 288);
+        for i in self.header.hlit..288 {
+            self.header.code_lengths[i] = 0;
+        }
+        for i in 288 + self.header.hdist..320 {
+            self.header.code_lengths[i] = 0;
+        }
+
+        if self.header.hdist == 1
+            && self.header.code_lengths[..286] == tables::HUFFMAN_LENGTHS
+            && self.header.code_lengths[288] == 1
+        {
+            self.compression = FDEFLATE_COMPRESSED_BLOCK;
+        } else {
+            Self::build_tables(
+                self.header.hlit,
+                &self.header.code_lengths,
+                &mut self.compression,
+                6,
+            )?;
+        }
+        self.state = State::CompressedData;
+        Ok(())
+    }
+
+    fn build_tables(
+        hlit: usize,
+        code_lengths: &[u8],
+        compression: &mut CompressedBlock,
+        max_search_bits: u8,
+    ) -> Result<(), DecompressionError> {
+        // Build the literal/length code table.
+        let lengths = &code_lengths[..288];
+        let codes: [u16; 288] = crate::compute_codes(&lengths.try_into().unwrap())
+            .ok_or(DecompressionError::BadLiteralLengthHuffmanTree)?;
+
+        let table_bits = lengths.iter().cloned().max().unwrap().min(12).max(6);
+        let table_size = 1 << table_bits;
+
+        for i in 0..256 {
+            let code = codes[i];
+            let length = lengths[i];
+            let mut j = code;
+
+            while j < table_size && length != 0 && length <= 12 {
+                compression.litlen_table[j as usize] =
+                    ((i as u32) << 16) | LITERAL_ENTRY | (1 << 8) | length as u32;
+                j += 1 << length;
+            }
+
+            if length > 0 && length <= max_search_bits {
+                for ii in 0..256 {
+                    let code2 = codes[ii];
+                    let length2 = lengths[ii];
+                    if length2 != 0 && length + length2 <= table_bits {
+                        let mut j = code | (code2 << length);
+
+                        while j < table_size {
+                            compression.litlen_table[j as usize] = (ii as u32) << 24
+                                | (i as u32) << 16
+                                | LITERAL_ENTRY
+                                | (2 << 8)
+                                | ((length + length2) as u32);
+                            j += 1 << (length + length2);
+                        }
+                    }
+                }
+            }
+        }
+
+        if lengths[256] != 0 && lengths[256] <= 12 {
+            let mut j = codes[256];
+            while j < table_size {
+                compression.litlen_table[j as usize] = EXCEPTIONAL_ENTRY | lengths[256] as u32;
+                j += 1 << lengths[256];
+            }
+        }
+
+        let table_size = table_size as usize;
+        for i in (table_size..4096).step_by(table_size) {
+            compression.litlen_table.copy_within(0..table_size, i);
+        }
+
+        compression.eof_code = codes[256];
+        compression.eof_mask = (1 << lengths[256]) - 1;
+        compression.eof_bits = lengths[256];
+
+        for i in 257..hlit {
+            let code = codes[i];
+            let length = lengths[i];
+            if length != 0 && length <= 12 {
+                let mut j = code;
+                while j < 4096 {
+                    compression.litlen_table[j as usize] = if i < 286 {
+                        (LEN_SYM_TO_LEN_BASE[i - 257] as u32) << 16
+                            | (LEN_SYM_TO_LEN_EXTRA[i - 257] as u32) << 8
+                            | length as u32
+                    } else {
+                        EXCEPTIONAL_ENTRY
+                    };
+                    j += 1 << length;
+                }
+            }
+        }
+
+        for i in 0..hlit {
+            if lengths[i] > 12 {
+                compression.litlen_table[(codes[i] & 0xfff) as usize] = u32::MAX;
+            }
+        }
+
+        let mut secondary_table_len = 0;
+        for i in 0..hlit {
+            if lengths[i] > 12 {
+                let j = (codes[i] & 0xfff) as usize;
+                if compression.litlen_table[j] == u32::MAX {
+                    compression.litlen_table[j] =
+                        (secondary_table_len << 16) | EXCEPTIONAL_ENTRY | SECONDARY_TABLE_ENTRY;
+                    secondary_table_len += 8;
+                }
+            }
+        }
+        assert!(secondary_table_len <= 0x7ff);
+        compression.secondary_table = vec![0; secondary_table_len as usize];
+        for i in 0..hlit {
+            let code = codes[i];
+            let length = lengths[i];
+            if length > 12 {
+                let j = (codes[i] & 0xfff) as usize;
+                let k = (compression.litlen_table[j] >> 16) as usize;
+
+                let mut s = code >> 12;
+                while s < 8 {
+                    debug_assert_eq!(compression.secondary_table[k + s as usize], 0);
+                    compression.secondary_table[k + s as usize] =
+                        ((i as u16) << 4) | (length as u16);
+                    s += 1 << (length - 12);
+                }
+            }
+        }
+        debug_assert!(compression
+            .secondary_table
+            .iter()
+            .all(|&x| x != 0 && (x & 0xf) > 12));
+
+        // Build the distance code table.
+        let lengths = &code_lengths[288..320];
+        if lengths == [0; 32] {
+            compression.dist_symbol_masks = [0; 30];
+            compression.dist_symbol_codes = [0xffff; 30];
+            compression.dist_table.fill(0);
+        } else {
+            let codes: [u16; 32] = match crate::compute_codes(&lengths.try_into().unwrap()) {
+                Some(codes) => codes,
+                None => {
+                    if lengths.iter().filter(|&&l| l != 0).count() != 1 {
+                        return Err(DecompressionError::BadDistanceHuffmanTree);
+                    }
+                    [0; 32]
+                }
+            };
+
+            compression.dist_symbol_codes.copy_from_slice(&codes[..30]);
+            compression
+                .dist_symbol_lengths
+                .copy_from_slice(&lengths[..30]);
+            compression.dist_table.fill(0);
+            for i in 0..30 {
+                let length = lengths[i];
+                let code = codes[i];
+                if length == 0 {
+                    compression.dist_symbol_masks[i] = 0;
+                    compression.dist_symbol_codes[i] = 0xffff;
+                } else {
+                    compression.dist_symbol_masks[i] = (1 << lengths[i]) - 1;
+                    if lengths[i] <= 9 {
+                        let mut j = code;
+                        while j < 512 {
+                            compression.dist_table[j as usize] = (DIST_SYM_TO_DIST_BASE[i] as u32)
+                                << 16
+                                | (DIST_SYM_TO_DIST_EXTRA[i] as u32) << 8
+                                | length as u32;
+                            j += 1 << lengths[i];
+                        }
+                    }
+                }
+            }
+        }
+
+        Ok(())
+    }
+
+    fn read_compressed(
+        &mut self,
+        remaining_input: &mut &[u8],
+        output: &mut [u8],
+        mut output_index: usize,
+    ) -> Result<usize, DecompressionError> {
+        while let State::CompressedData = self.state {
+            self.fill_buffer(remaining_input);
+            if output_index == output.len() {
+                break;
+            }
+
+            let mut bits = self.buffer;
+            let litlen_entry = self.compression.litlen_table[(bits & 0xfff) as usize];
+            let litlen_code_bits = litlen_entry as u8;
+
+            if litlen_entry & LITERAL_ENTRY != 0 {
+                // Ultra-fast path: do 3 more consecutive table lookups and bail if any of them need the slow path.
+                if self.nbits >= 48 {
+                    let litlen_entry2 =
+                        self.compression.litlen_table[(bits >> litlen_code_bits & 0xfff) as usize];
+                    let litlen_code_bits2 = litlen_entry2 as u8;
+                    let litlen_entry3 = self.compression.litlen_table
+                        [(bits >> (litlen_code_bits + litlen_code_bits2) & 0xfff) as usize];
+                    let litlen_code_bits3 = litlen_entry3 as u8;
+                    let litlen_entry4 = self.compression.litlen_table[(bits
+                        >> (litlen_code_bits + litlen_code_bits2 + litlen_code_bits3)
+                        & 0xfff)
+                        as usize];
+                    let litlen_code_bits4 = litlen_entry4 as u8;
+                    if litlen_entry2 & litlen_entry3 & litlen_entry4 & LITERAL_ENTRY != 0 {
+                        let advance_output_bytes = ((litlen_entry & 0xf00) >> 8) as usize;
+                        let advance_output_bytes2 = ((litlen_entry2 & 0xf00) >> 8) as usize;
+                        let advance_output_bytes3 = ((litlen_entry3 & 0xf00) >> 8) as usize;
+                        let advance_output_bytes4 = ((litlen_entry4 & 0xf00) >> 8) as usize;
+                        if output_index
+                            + advance_output_bytes
+                            + advance_output_bytes2
+                            + advance_output_bytes3
+                            + advance_output_bytes4
+                            < output.len()
+                        {
+                            self.consume_bits(
+                                litlen_code_bits
+                                    + litlen_code_bits2
+                                    + litlen_code_bits3
+                                    + litlen_code_bits4,
+                            );
+
+                            output[output_index] = (litlen_entry >> 16) as u8;
+                            output[output_index + 1] = (litlen_entry >> 24) as u8;
+                            output_index += advance_output_bytes;
+                            output[output_index] = (litlen_entry2 >> 16) as u8;
+                            output[output_index + 1] = (litlen_entry2 >> 24) as u8;
+                            output_index += advance_output_bytes2;
+                            output[output_index] = (litlen_entry3 >> 16) as u8;
+                            output[output_index + 1] = (litlen_entry3 >> 24) as u8;
+                            output_index += advance_output_bytes3;
+                            output[output_index] = (litlen_entry4 >> 16) as u8;
+                            output[output_index + 1] = (litlen_entry4 >> 24) as u8;
+                            output_index += advance_output_bytes4;
+                            continue;
+                        }
+                    }
+                }
+
+                // Fast path: the next symbol is <= 12 bits and a literal, the table specifies the
+                // output bytes and we can directly write them to the output buffer.
+                let advance_output_bytes = ((litlen_entry & 0xf00) >> 8) as usize;
+
+                // match advance_output_bytes {
+                //     1 => println!("[{output_index}] LIT1 {}", litlen_entry >> 16),
+                //     2 => println!(
+                //         "[{output_index}] LIT2 {} {} {}",
+                //         (litlen_entry >> 16) as u8,
+                //         litlen_entry >> 24,
+                //         bits & 0xfff
+                //     ),
+                //     n => println!(
+                //         "[{output_index}] LIT{n} {} {}",
+                //         (litlen_entry >> 16) as u8,
+                //         litlen_entry >> 24,
+                //     ),
+                // }
+
+                if self.nbits < litlen_code_bits {
+                    break;
+                } else if output_index + 1 < output.len() {
+                    output[output_index] = (litlen_entry >> 16) as u8;
+                    output[output_index + 1] = (litlen_entry >> 24) as u8;
+                    output_index += advance_output_bytes;
+                    self.consume_bits(litlen_code_bits);
+                    continue;
+                } else if output_index + advance_output_bytes == output.len() {
+                    debug_assert_eq!(advance_output_bytes, 1);
+                    output[output_index] = (litlen_entry >> 16) as u8;
+                    output_index += 1;
+                    self.consume_bits(litlen_code_bits);
+                    break;
+                } else {
+                    debug_assert_eq!(advance_output_bytes, 2);
+                    output[output_index] = (litlen_entry >> 16) as u8;
+                    self.queued_rle = Some(((litlen_entry >> 24) as u8, 1));
+                    output_index += 1;
+                    self.consume_bits(litlen_code_bits);
+                    break;
+                }
+            }
+
+            let (length_base, length_extra_bits, litlen_code_bits) =
+                if litlen_entry & EXCEPTIONAL_ENTRY == 0 {
+                    (
+                        litlen_entry >> 16,
+                        (litlen_entry >> 8) as u8,
+                        litlen_code_bits,
+                    )
+                } else if litlen_entry & SECONDARY_TABLE_ENTRY != 0 {
+                    let secondary_index = litlen_entry >> 16;
+                    let secondary_entry = self.compression.secondary_table
+                        [secondary_index as usize + ((bits >> 12) & 0x7) as usize];
+                    let litlen_symbol = secondary_entry >> 4;
+                    let litlen_code_bits = (secondary_entry & 0xf) as u8;
+
+                    if self.nbits < litlen_code_bits {
+                        break;
+                    } else if litlen_symbol < 256 {
+                        // println!("[{output_index}] LIT1b {} (val={:04x})", litlen_symbol, self.peak_bits(15));
+
+                        self.consume_bits(litlen_code_bits);
+                        output[output_index] = litlen_symbol as u8;
+                        output_index += 1;
+                        continue;
+                    } else if litlen_symbol == 256 {
+                        // println!("[{output_index}] EOF");
+                        self.consume_bits(litlen_code_bits);
+                        self.state = match self.last_block {
+                            true => State::Checksum,
+                            false => State::BlockHeader,
+                        };
+                        break;
+                    }
+
+                    (
+                        LEN_SYM_TO_LEN_BASE[litlen_symbol as usize - 257] as u32,
+                        LEN_SYM_TO_LEN_EXTRA[litlen_symbol as usize - 257],
+                        litlen_code_bits,
+                    )
+                } else if litlen_code_bits == 0 {
+                    return Err(DecompressionError::InvalidLiteralLengthCode);
+                } else {
+                    if self.nbits < litlen_code_bits {
+                        break;
+                    }
+                    // println!("[{output_index}] EOF");
+                    self.consume_bits(litlen_code_bits);
+                    self.state = match self.last_block {
+                        true => State::Checksum,
+                        false => State::BlockHeader,
+                    };
+                    break;
+                };
+            bits >>= litlen_code_bits;
+
+            let length_extra_mask = (1 << length_extra_bits) - 1;
+            let length = length_base as usize + (bits & length_extra_mask) as usize;
+            bits >>= length_extra_bits;
+
+            let dist_entry = self.compression.dist_table[(bits & 0x1ff) as usize];
+            let (dist_base, dist_extra_bits, dist_code_bits) = if dist_entry != 0 {
+                (
+                    (dist_entry >> 16) as u16,
+                    (dist_entry >> 8) as u8,
+                    dist_entry as u8,
+                )
+            } else {
+                let mut dist_extra_bits = 0;
+                let mut dist_base = 0;
+                let mut dist_advance_bits = 0;
+                for i in 0..self.compression.dist_symbol_lengths.len() {
+                    if bits as u16 & self.compression.dist_symbol_masks[i]
+                        == self.compression.dist_symbol_codes[i]
+                    {
+                        dist_extra_bits = DIST_SYM_TO_DIST_EXTRA[i];
+                        dist_base = DIST_SYM_TO_DIST_BASE[i];
+                        dist_advance_bits = self.compression.dist_symbol_lengths[i];
+                        break;
+                    }
+                }
+                if dist_advance_bits == 0 {
+                    return Err(DecompressionError::InvalidDistanceCode);
+                }
+                (dist_base, dist_extra_bits, dist_advance_bits)
+            };
+            bits >>= dist_code_bits;
+
+            let dist = dist_base as usize + (bits & ((1 << dist_extra_bits) - 1)) as usize;
+            let total_bits =
+                litlen_code_bits + length_extra_bits + dist_code_bits + dist_extra_bits;
+
+            if self.nbits < total_bits {
+                break;
+            } else if dist > output_index {
+                return Err(DecompressionError::DistanceTooFarBack);
+            }
+
+            // println!("[{output_index}] BACKREF len={} dist={} {:x}", length, dist, dist_entry);
+            self.consume_bits(total_bits);
+
+            let copy_length = length.min(output.len() - output_index);
+            if dist == 1 {
+                let last = output[output_index - 1];
+                output[output_index..][..copy_length].fill(last);
+
+                if copy_length < length {
+                    self.queued_rle = Some((last, length - copy_length));
+                    output_index = output.len();
+                    break;
+                }
+            } else if output_index + length + 15 <= output.len() {
+                let start = output_index - dist;
+                output.copy_within(start..start + 16, output_index);
+
+                if length > 16 || dist < 16 {
+                    for i in (0..length).step_by(dist.min(16)).skip(1) {
+                        output.copy_within(start + i..start + i + 16, output_index + i);
+                    }
+                }
+            } else {
+                if dist < copy_length {
+                    for i in 0..copy_length {
+                        output[output_index + i] = output[output_index + i - dist];
+                    }
+                } else {
+                    output.copy_within(
+                        output_index - dist..output_index + copy_length - dist,
+                        output_index,
+                    )
+                }
+
+                if copy_length < length {
+                    self.queued_backref = Some((dist, length - copy_length));
+                    output_index = output.len();
+                    break;
+                }
+            }
+            output_index += copy_length;
+        }
+
+        if self.state == State::CompressedData
+            && self.queued_backref.is_none()
+            && self.queued_rle.is_none()
+            && self.nbits >= 15
+            && self.peak_bits(15) as u16 & self.compression.eof_mask == self.compression.eof_code
+        {
+            self.consume_bits(self.compression.eof_bits);
+            self.state = match self.last_block {
+                true => State::Checksum,
+                false => State::BlockHeader,
+            };
+        }
+
+        Ok(output_index)
+    }
+
+    /// Decompresses a chunk of data.
+    ///
+    /// Returns the number of bytes read from `input` and the number of bytes written to `output`,
+    /// or an error if the deflate stream is not valid. `input` is the compressed data. `output` is
+    /// the buffer to write the decompressed data to, starting at index `output_position`.
+    /// `end_of_input` indicates whether more data may be available in the future.
+    ///
+    /// The contents of `output` after `output_position` are ignored. However, this function may
+    /// write additional data to `output` past what is indicated by the return value.
+    ///
+    /// When this function returns `Ok`, at least one of the following is true:
+    /// - The input is fully consumed.
+    /// - The output is full but there are more bytes to output.
+    /// - The deflate stream is complete (and `is_done` will return true).
+    ///
+    /// # Panics
+    ///
+    /// This function will panic if `output_position` is out of bounds.
+    pub fn read(
+        &mut self,
+        input: &[u8],
+        output: &mut [u8],
+        output_position: usize,
+        end_of_input: bool,
+    ) -> Result<(usize, usize), DecompressionError> {
+        if let State::Done = self.state {
+            return Ok((0, 0));
+        }
+
+        assert!(output_position <= output.len());
+
+        let mut remaining_input = input;
+        let mut output_index = output_position;
+
+        if let Some((data, len)) = self.queued_rle.take() {
+            let n = len.min(output.len() - output_index);
+            output[output_index..][..n].fill(data);
+            output_index += n;
+            if n < len {
+                self.queued_rle = Some((data, len - n));
+                return Ok((0, n));
+            }
+        }
+        if let Some((dist, len)) = self.queued_backref.take() {
+            let n = len.min(output.len() - output_index);
+            for i in 0..n {
+                output[output_index + i] = output[output_index + i - dist];
+            }
+            output_index += n;
+            if n < len {
+                self.queued_backref = Some((dist, len - n));
+                return Ok((0, n));
+            }
+        }
+
+        // Main decoding state machine.
+        let mut last_state = None;
+        while last_state != Some(self.state) {
+            last_state = Some(self.state);
+            match self.state {
+                State::ZlibHeader => {
+                    self.fill_buffer(&mut remaining_input);
+                    if self.nbits < 16 {
+                        break;
+                    }
+
+                    let input0 = self.peak_bits(8);
+                    let input1 = self.peak_bits(16) >> 8 & 0xff;
+                    if input0 & 0x0f != 0x08
+                        || (input0 & 0xf0) > 0x70
+                        || input1 & 0x20 != 0
+                        || (input0 << 8 | input1) % 31 != 0
+                    {
+                        return Err(DecompressionError::BadZlibHeader);
+                    }
+
+                    self.consume_bits(16);
+                    self.state = State::BlockHeader;
+                }
+                State::BlockHeader => {
+                    self.read_block_header(&mut remaining_input)?;
+                }
+                State::CodeLengthCodes => {
+                    self.read_code_length_codes(&mut remaining_input)?;
+                }
+                State::CodeLengths => {
+                    self.read_code_lengths(&mut remaining_input)?;
+                }
+                State::CompressedData => {
+                    output_index =
+                        self.read_compressed(&mut remaining_input, output, output_index)?
+                }
+                State::UncompressedData => {
+                    // Drain any bytes from our buffer.
+                    debug_assert_eq!(self.nbits % 8, 0);
+                    while self.nbits > 0
+                        && self.uncompressed_bytes_left > 0
+                        && output_index < output.len()
+                    {
+                        output[output_index] = self.peak_bits(8) as u8;
+                        self.consume_bits(8);
+                        output_index += 1;
+                        self.uncompressed_bytes_left -= 1;
+                    }
+                    // Buffer may contain one additional byte. Clear it to avoid confusion.
+                    if self.nbits == 0 {
+                        self.buffer = 0;
+                    }
+
+                    // Copy subsequent bytes directly from the input.
+                    let copy_bytes = (self.uncompressed_bytes_left as usize)
+                        .min(remaining_input.len())
+                        .min(output.len() - output_index);
+                    output[output_index..][..copy_bytes]
+                        .copy_from_slice(&remaining_input[..copy_bytes]);
+                    remaining_input = &remaining_input[copy_bytes..];
+                    output_index += copy_bytes;
+                    self.uncompressed_bytes_left -= copy_bytes as u16;
+
+                    if self.uncompressed_bytes_left == 0 {
+                        self.state = if self.last_block {
+                            State::Checksum
+                        } else {
+                            State::BlockHeader
+                        };
+                    }
+                }
+                State::Checksum => {
+                    self.fill_buffer(&mut remaining_input);
+
+                    let align_bits = self.nbits % 8;
+                    if self.nbits >= 32 + align_bits {
+                        self.checksum.write(&output[output_position..output_index]);
+                        if align_bits != 0 {
+                            self.consume_bits(align_bits);
+                        }
+                        #[cfg(not(fuzzing))]
+                        if !self.ignore_adler32
+                            && (self.peak_bits(32) as u32).swap_bytes() != self.checksum.finish()
+                        {
+                            return Err(DecompressionError::WrongChecksum);
+                        }
+                        self.state = State::Done;
+                        self.consume_bits(32);
+                        break;
+                    }
+                }
+                State::Done => unreachable!(),
+            }
+        }
+
+        if !self.ignore_adler32 && self.state != State::Done {
+            self.checksum.write(&output[output_position..output_index]);
+        }
+
+        if self.state == State::Done || !end_of_input || output_index >= output.len() - 1 {
+            let input_left = remaining_input.len();
+            Ok((input.len() - input_left, output_index - output_position))
+        } else {
+            Err(DecompressionError::InsufficientInput)
+        }
+    }
+
+    /// Returns true if the decompressor has finished decompressing the input.
+    pub fn is_done(&self) -> bool {
+        self.state == State::Done
+    }
+}
+
+/// Decompress the given data.
+pub fn decompress_to_vec(input: &[u8]) -> Result<Vec<u8>, DecompressionError> {
+    match decompress_to_vec_bounded(input, usize::MAX) {
+        Ok(output) => Ok(output),
+        Err(BoundedDecompressionError::DecompressionError { inner }) => Err(inner),
+        Err(BoundedDecompressionError::OutputTooLarge { .. }) => {
+            unreachable!("Impossible to allocate more than isize::MAX bytes")
+        }
+    }
+}
+
+/// An error encountered while decompressing a deflate stream given a bounded maximum output.
+pub enum BoundedDecompressionError {
+    /// The input is not a valid deflate stream.
+    DecompressionError {
+        /// The underlying error.
+        inner: DecompressionError,
+    },
+
+    /// The output is too large.
+    OutputTooLarge {
+        /// The output decoded so far.
+        partial_output: Vec<u8>,
+    },
+}
+impl From<DecompressionError> for BoundedDecompressionError {
+    fn from(inner: DecompressionError) -> Self {
+        BoundedDecompressionError::DecompressionError { inner }
+    }
+}
+
+/// Decompress the given data, returning an error if the output is larger than
+/// `maxlen` bytes.
+pub fn decompress_to_vec_bounded(
+    input: &[u8],
+    maxlen: usize,
+) -> Result<Vec<u8>, BoundedDecompressionError> {
+    let mut decoder = Decompressor::new();
+    let mut output = vec![0; 1024.min(maxlen)];
+    let mut input_index = 0;
+    let mut output_index = 0;
+    loop {
+        let (consumed, produced) =
+            decoder.read(&input[input_index..], &mut output, output_index, true)?;
+        input_index += consumed;
+        output_index += produced;
+        if decoder.is_done() || output_index == maxlen {
+            break;
+        }
+        output.resize((output_index + 32 * 1024).min(maxlen), 0);
+    }
+    output.resize(output_index, 0);
+
+    if decoder.is_done() {
+        Ok(output)
+    } else {
+        Err(BoundedDecompressionError::OutputTooLarge {
+            partial_output: output,
+        })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::tables::{self, LENGTH_TO_LEN_EXTRA, LENGTH_TO_SYMBOL};
+
+    use super::*;
+    use rand::Rng;
+
+    fn roundtrip(data: &[u8]) {
+        let compressed = crate::compress_to_vec(data);
+        let decompressed = decompress_to_vec(&compressed).unwrap();
+        assert_eq!(&decompressed, data);
+    }
+
+    fn roundtrip_miniz_oxide(data: &[u8]) {
+        let compressed = miniz_oxide::deflate::compress_to_vec_zlib(data, 3);
+        let decompressed = decompress_to_vec(&compressed).unwrap();
+        assert_eq!(decompressed.len(), data.len());
+        for (i, (a, b)) in decompressed.chunks(1).zip(data.chunks(1)).enumerate() {
+            assert_eq!(a, b, "chunk {}..{}", i * 1, i * 1 + 1);
+        }
+        assert_eq!(&decompressed, data);
+    }
+
+    #[allow(unused)]
+    fn compare_decompression(data: &[u8]) {
+        // let decompressed0 = flate2::read::ZlibDecoder::new(std::io::Cursor::new(&data))
+        //     .bytes()
+        //     .collect::<Result<Vec<_>, _>>()
+        //     .unwrap();
+        let decompressed = decompress_to_vec(&data).unwrap();
+        let decompressed2 = miniz_oxide::inflate::decompress_to_vec_zlib(&data).unwrap();
+        for i in 0..decompressed.len().min(decompressed2.len()) {
+            if decompressed[i] != decompressed2[i] {
+                panic!(
+                    "mismatch at index {} {:?} {:?}",
+                    i,
+                    &decompressed[i.saturating_sub(1)..(i + 16).min(decompressed.len())],
+                    &decompressed2[i.saturating_sub(1)..(i + 16).min(decompressed2.len())]
+                );
+            }
+        }
+        if decompressed != decompressed2 {
+            panic!(
+                "length mismatch {} {} {:x?}",
+                decompressed.len(),
+                decompressed2.len(),
+                &decompressed2[decompressed.len()..][..16]
+            );
+        }
+        //assert_eq!(decompressed, decompressed2);
+    }
+
+    #[test]
+    fn tables() {
+        for (i, &bits) in LEN_SYM_TO_LEN_EXTRA.iter().enumerate() {
+            let len_base = LEN_SYM_TO_LEN_BASE[i];
+            for j in 0..(1 << bits) {
+                if i == 27 && j == 31 {
+                    continue;
+                }
+                assert_eq!(LENGTH_TO_LEN_EXTRA[len_base + j - 3], bits, "{} {}", i, j);
+                assert_eq!(
+                    LENGTH_TO_SYMBOL[len_base + j - 3],
+                    i as u16 + 257,
+                    "{} {}",
+                    i,
+                    j
+                );
+            }
+        }
+    }
+
+    #[test]
+    fn fdeflate_table() {
+        let mut compression = CompressedBlock {
+            litlen_table: [0; 4096],
+            dist_table: [0; 512],
+            dist_symbol_lengths: [0; 30],
+            dist_symbol_masks: [0; 30],
+            dist_symbol_codes: [0; 30],
+            secondary_table: Vec::new(),
+            eof_code: 0,
+            eof_mask: 0,
+            eof_bits: 0,
+        };
+        let mut lengths = tables::HUFFMAN_LENGTHS.to_vec();
+        lengths.resize(288, 0);
+        lengths.push(1);
+        lengths.resize(320, 0);
+        Decompressor::build_tables(286, &lengths, &mut compression, 11).unwrap();
+
+        assert_eq!(
+            compression, FDEFLATE_COMPRESSED_BLOCK,
+            "{:#x?}",
+            compression
+        );
+    }
+
+    #[test]
+    fn it_works() {
+        roundtrip(b"Hello world!");
+    }
+
+    #[test]
+    fn constant() {
+        roundtrip_miniz_oxide(&vec![0; 50]);
+        roundtrip_miniz_oxide(&vec![5; 2048]);
+        roundtrip_miniz_oxide(&vec![128; 2048]);
+        roundtrip_miniz_oxide(&vec![254; 2048]);
+    }
+
+    #[test]
+    fn random() {
+        let mut rng = rand::thread_rng();
+        let mut data = vec![0; 50000];
+        for _ in 0..10 {
+            for byte in &mut data {
+                *byte = rng.gen::<u8>() % 5;
+            }
+            println!("Random data: {:?}", data);
+            roundtrip_miniz_oxide(&data);
+        }
+    }
+
+    #[test]
+    fn ignore_adler32() {
+        let mut compressed = crate::compress_to_vec(b"Hello world!");
+        let last_byte = compressed.len() - 1;
+        compressed[last_byte] = compressed[last_byte].wrapping_add(1);
+
+        match decompress_to_vec(&compressed) {
+            Err(DecompressionError::WrongChecksum) => {}
+            r => panic!("expected WrongChecksum, got {:?}", r),
+        }
+
+        let mut decompressor = Decompressor::new();
+        decompressor.ignore_adler32();
+        let mut decompressed = vec![0; 1024];
+        let decompressed_len = decompressor
+            .read(&compressed, &mut decompressed, 0, true)
+            .unwrap()
+            .1;
+        assert_eq!(&decompressed[..decompressed_len], b"Hello world!");
+    }
+
+    #[test]
+    fn checksum_after_eof() {
+        let input = b"Hello world!";
+        let compressed = crate::compress_to_vec(input);
+
+        let mut decompressor = Decompressor::new();
+        let mut decompressed = vec![0; 1024];
+        let (input_consumed, output_written) = decompressor
+            .read(
+                &compressed[..compressed.len() - 1],
+                &mut decompressed,
+                0,
+                false,
+            )
+            .unwrap();
+        assert_eq!(output_written, input.len());
+        assert_eq!(input_consumed, compressed.len() - 1);
+
+        let (input_consumed, output_written) = decompressor
+            .read(
+                &compressed[input_consumed..],
+                &mut decompressed[..output_written],
+                output_written,
+                true,
+            )
+            .unwrap();
+        assert!(decompressor.is_done());
+        assert_eq!(input_consumed, 1);
+        assert_eq!(output_written, 0);
+
+        assert_eq!(&decompressed[..input.len()], input);
+    }
+
+    #[test]
+    fn zero_length() {
+        let mut compressed = crate::compress_to_vec(b"").to_vec();
+
+        // Splice in zero-length non-compressed blocks.
+        for _ in 0..10 {
+            println!("compressed len: {}", compressed.len());
+            compressed.splice(2..2, [0u8, 0, 0, 0xff, 0xff].into_iter());
+        }
+
+        // Ensure that the full input is decompressed, regardless of whether
+        // `end_of_input` is set.
+        for end_of_input in [true, false] {
+            let mut decompressor = Decompressor::new();
+            let (input_consumed, output_written) = decompressor
+                .read(&compressed, &mut [], 0, end_of_input)
+                .unwrap();
+
+            assert!(decompressor.is_done());
+            assert_eq!(input_consumed, compressed.len());
+            assert_eq!(output_written, 0);
+        }
+    }
+}