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Handles ZIP64 extension in the ZIP reader
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@mmalecot
mmalecot committed Nov 24, 2023
1 parent 8bfbdb2 commit 42e82c3
Showing 1 changed file with 75 additions and 36 deletions.
111 changes: 75 additions & 36 deletions src/readers.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -819,59 +819,101 @@ impl crate::FileFormat {
/// Determines file format from a ZIP reader.
#[cfg(feature = "reader-zip")]
pub(crate) fn from_zip_reader<R: Read + Seek>(reader: R) -> Result<Self> {
// Maximum number of files that can be processed by the reader.
const FILE_LIMIT: usize = 1024;
// Maximum number of entries that can be processed by the reader.
const ENTRY_LIMIT: usize = 1024;

// Signature of the central directory file header.
const CENTRAL_DIRECTORY_FILE_HEADER_SIGNATURE: &[u8] = b"\x50\x4B\x01\x02";
// Signature of the ZIP64 end of central directory locator.
const EOCD64_LOCATOR_SIGNATURE: &[u8] = b"\x50\x4B\x06\x07";

// Signature of the end of central directory.
const END_OF_CENTRAL_DIRECTORY_SIGNATURE: &[u8] = b"\x50\x4B\x05\x06";
// Signature of the end of central directory record.
const EOCD_SIGNATURE: &[u8] = b"\x50\x4B\x05\x06";

// Maximum size of the end of central directory.
const END_OF_CENTRAL_DIRECTORY_MAX_SIZE: usize = 22 + u16::MAX as usize;
// Size of the ZIP64 end of central directory locator.
const EOCD64_LOCATOR_SIZE: usize = 20;

// Maximum size of the end of central directory record.
const EOCD_MAX_SIZE: usize = EOCD_MIN_SIZE + u16::MAX as usize;

// Minimum size of the end of central directory record.
const EOCD_MIN_SIZE: usize = 22;

// Creates a buffered reader.
let mut reader = BufReader::new(reader);

// Gets the stream length.
let length = reader.seek(SeekFrom::End(0))?;

// Searches for the end of central directory.
let offset = length.saturating_sub(END_OF_CENTRAL_DIRECTORY_MAX_SIZE as u64);
// Searches for the end of central directory record.
let offset = length.saturating_sub(EOCD_MAX_SIZE as u64);
reader.seek(SeekFrom::Start(offset))?;
let mut buffer = vec![0; std::cmp::min(END_OF_CENTRAL_DIRECTORY_MAX_SIZE, length as usize)];
let mut buffer = vec![0; (length as usize).clamp(EOCD_MIN_SIZE, EOCD_MAX_SIZE)];
reader.read_exact(&mut buffer)?;
let buffer_index = find(&buffer, END_OF_CENTRAL_DIRECTORY_SIGNATURE)
.ok_or_else(|| Error::new(ErrorKind::InvalidData, "cannot find the EOCD"))?;
let buffer_index = find(&buffer, EOCD_SIGNATURE)
.ok_or_else(|| Error::new(ErrorKind::InvalidData, "cannot find the EOCD record"))?;
let eocd_offset = offset + buffer_index as u64;

// Checks if the end of central directory record is at the beginning of the file, which
// corresponds to an empty ZIP.
if eocd_offset == 0 {
return Ok(Self::Zip);
}

// Seeks to the end of central directory.
reader.seek(SeekFrom::Start(offset + buffer_index as u64))?;
// Seeks to the potential ZIP64 end of central directory locator.
reader.seek(SeekFrom::Start(eocd_offset - EOCD64_LOCATOR_SIZE as u64))?;

// Reads the start of central directory offset.
reader.seek(SeekFrom::Current(16))?;
let mut offset = [0; 4];
reader.read_exact(&mut offset)?;
let offset = u32::from_le_bytes(offset);
// Reads the signature.
let mut signature = [0; 4];
reader.read_exact(&mut signature)?;

// Reads the number of entries and the start of central directory offset.
let (number_of_entries, socd_offset) = if signature == EOCD64_LOCATOR_SIGNATURE {
// Reads the offset of the ZIP64 end of central directory record.
reader.seek(SeekFrom::Current(4))?;
let mut eocd64_offset = [0; 8];
reader.read_exact(&mut eocd64_offset)?;
let eocd64_offset = u64::from_le_bytes(eocd64_offset);

// Reads the number of entries.
reader.seek(SeekFrom::Start(eocd64_offset + 32))?;
let mut number_of_entries = [0; 8];
reader.read_exact(&mut number_of_entries)?;
let number_of_entries = u64::from_le_bytes(number_of_entries) as usize;

// Reads the start of central directory offset.
reader.seek(SeekFrom::Current(8))?;
let mut socd_offset = [0; 8];
reader.read_exact(&mut socd_offset)?;
let socd_offset = u64::from_le_bytes(socd_offset);

// Returns the result.
(number_of_entries, socd_offset)
} else {
// Reads the number of entries.
reader.seek(SeekFrom::Start(eocd_offset + 10))?;
let mut number_of_entries = [0; 2];
reader.read_exact(&mut number_of_entries)?;
let number_of_entries = u16::from_le_bytes(number_of_entries);

// Reads the start of central directory offset.
reader.seek(SeekFrom::Current(4))?;
let mut socd_offset = [0; 4];
reader.read_exact(&mut socd_offset)?;
let socd_offset = u32::from_le_bytes(socd_offset);

// Returns the result.
(number_of_entries as usize, socd_offset as u64)
};

// Seeks to the start of central directory.
reader.seek(SeekFrom::Start(offset as u64))?;
reader.seek(SeekFrom::Start(socd_offset))?;

// Sets the default value.
let mut format = Self::Zip;

// Browses central directory file headers.
let mut file_count = 0;
while file_count < FILE_LIMIT && reader.stream_position()? < length {
// Reads and checks the signature.
let mut signature = [0; 4];
reader.read_exact(&mut signature)?;
if signature != CENTRAL_DIRECTORY_FILE_HEADER_SIGNATURE {
break;
}

// Browses central directory headers.
for _ in 0..std::cmp::min(ENTRY_LIMIT, number_of_entries) {
// Reads the compressed size.
reader.seek(SeekFrom::Current(16))?;
reader.seek(SeekFrom::Current(20))?;
let mut compressed_size = [0; 4];
reader.read_exact(&mut compressed_size)?;
let compressed_size = u32::from_le_bytes(compressed_size);
Expand Down Expand Up @@ -1033,13 +1075,10 @@ impl crate::FileFormat {
}
}

// Seeks to the next central directory file header.
// Seeks to the next central directory entry.
reader.seek(SeekFrom::Current(
extra_field_length as i64 + file_comment_length as i64,
))?;

// Increments the file count.
file_count += 1;
}
Ok(format)
}
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