1 use endian::{Endian, Parse, ToBytes};
2 use flate2::read::ZlibDecoder;
4 use num_derive::FromPrimitive;
7 io::{Error as IoError, Read, Seek, SeekFrom},
15 #[derive(Error, Debug)]
17 #[error("Not an SPSS system file")]
20 #[error("Invalid magic number {0:?}")]
23 #[error("I/O error ({0})")]
26 #[error("Invalid SAV compression code {0}")]
27 InvalidSavCompression(u32),
29 #[error("Invalid ZSAV compression code {0}")]
30 InvalidZsavCompression(u32),
32 #[error("Variable record at offset {offset:#x} specifies width {width} not in valid range [-1,255).")]
33 BadVariableWidth { offset: u64, width: i32 },
35 #[error("Misplaced type 4 record near offset {0:#x}.")]
36 MisplacedType4Record(u64),
38 #[error("Document record at offset {offset:#x} has document line count ({n}) greater than the maximum number {max}.")]
39 BadDocumentLength { offset: u64, n: u32, max: u32 },
41 #[error("At offset {offset:#x}, Unrecognized record type {rec_type}.")]
42 BadRecordType { offset: u64, rec_type: u32 },
44 #[error("At offset {offset:#x}, variable label code ({code}) is not 0 or 1.")]
45 BadVariableLabelCode { offset: u64, code: u32 },
48 "At offset {offset:#x}, numeric missing value code ({code}) is not -3, -2, 0, 1, 2, or 3."
50 BadNumericMissingValueCode { offset: u64, code: i32 },
52 #[error("At offset {offset:#x}, string missing value code ({code}) is not 0, 1, 2, or 3.")]
53 BadStringMissingValueCode { offset: u64, code: i32 },
55 #[error("At offset {offset:#x}, number of value labels ({n}) is greater than the maximum number {max}.")]
56 BadNumberOfValueLabels { offset: u64, n: u32, max: u32 },
58 #[error("At offset {offset:#x}, variable index record (type 4) does not immediately follow value label record (type 3) as it should.")]
59 MissingVariableIndexRecord { offset: u64 },
61 #[error("At offset {offset:#x}, number of variables indexes ({n}) is greater than the maximum number ({max}).")]
62 BadNumberOfVarIndexes { offset: u64, n: u32, max: u32 },
64 #[error("At offset {offset:#x}, record type 7 subtype {subtype} is too large with element size {size} and {count} elements.")]
65 ExtensionRecordTooLarge {
72 #[error("Wrong ZLIB data header offset {zheader_offset:#x} (expected {offset:#x}).")]
73 BadZlibHeaderOffset { offset: u64, zheader_offset: u64 },
75 #[error("At offset {offset:#x}, impossible ZLIB trailer offset {ztrailer_offset:#x}.")]
76 BadZlibTrailerOffset { offset: u64, ztrailer_offset: u64 },
78 #[error("At offset {offset:#x}, impossible ZLIB trailer length {ztrailer_len}.")]
79 BadZlibTrailerLen { offset: u64, ztrailer_len: u64 },
81 #[error("Unexpected end of file at offset {offset:#x}, {case_ofs} bytes into a {case_len}-byte case.")]
89 "Unexpected end of file at offset {offset:#x}, {case_ofs} bytes into a compressed case."
91 EofInCompressedCase { offset: u64, case_ofs: u64 },
93 #[error("Data ends at offset {offset:#x}, {case_ofs} bytes into a compressed case.")]
94 PartialCompressedCase { offset: u64, case_ofs: u64 },
96 #[error("At {case_ofs} bytes into compressed case starting at offset {offset:#x}, a string was found where a number was expected.")]
97 CompressedNumberExpected { offset: u64, case_ofs: u64 },
99 #[error("At {case_ofs} bytes into compressed case starting at offset {offset:#x}, a number was found where a string was expected.")]
100 CompressedStringExpected { offset: u64, case_ofs: u64 },
102 #[error("Block count {n_blocks} in ZLIB trailer at offset {offset:#x} differs from expected block count {expected_n_blocks} calculated from trailer length {ztrailer_len}.")]
103 BadZlibTrailerNBlocks {
106 expected_n_blocks: u64,
111 #[derive(Error, Debug)]
113 #[error("Unexpected floating-point bias {0} or unrecognized floating-point format.")]
116 #[error("Duplicate type 6 (document) record.")]
117 DuplicateDocumentRecord,
120 #[derive(Copy, Clone, Debug)]
121 pub enum Compression {
130 ValueLabel(ValueLabel),
131 VarIndexes(VarIndexes),
132 Extension(Extension),
143 /// Eye-catcher string, product name, in the file's encoding. Padded
144 /// on the right with spaces.
145 pub eye_catcher: [u8; 60],
147 /// Layout code, normally either 2 or 3.
148 pub layout_code: u32,
150 /// Number of variable positions, or `None` if the value in the file is
151 /// questionably trustworthy.
152 pub nominal_case_size: Option<u32>,
154 /// Compression type, if any,
155 pub compression: Option<Compression>,
157 /// 0-based variable index of the weight variable, or `None` if the file is
159 pub weight_index: Option<u32>,
161 /// Claimed number of cases, if known.
162 pub n_cases: Option<u32>,
164 /// Compression bias, usually 100.0.
167 /// `dd mmm yy` in the file's encoding.
168 pub creation_date: [u8; 9],
170 /// `HH:MM:SS` in the file's encoding.
171 pub creation_time: [u8; 8],
173 /// File label, in the file's encoding. Padded on the right with spaces.
174 pub file_label: [u8; 64],
176 /// Endianness of the data in the file header.
180 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
181 pub struct Magic([u8; 4]);
184 /// Magic number for a regular system file.
185 pub const SAV: Magic = Magic(*b"$FL2");
187 /// Magic number for a system file that contains zlib-compressed data.
188 pub const ZSAV: Magic = Magic(*b"$FL3");
190 /// Magic number for an EBDIC-encoded system file. This is `$FL2` encoded
192 pub const EBCDIC: Magic = Magic([0x5b, 0xc6, 0xd3, 0xf2]);
195 impl TryFrom<[u8; 4]> for Magic {
198 fn try_from(value: [u8; 4]) -> Result<Self, Self::Error> {
199 let magic = Magic(value);
201 Magic::SAV | Magic::ZSAV | Magic::EBCDIC => Ok(magic),
202 _ => Err(Error::BadMagic(value)),
207 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
214 fn from_width(width: i32) -> VarType {
216 0 => VarType::Number,
217 _ => VarType::String,
223 #[allow(clippy::type_complexity)]
224 fn read(self: Box<Self>) -> Result<Option<(Record, Box<dyn State>)>, Error>;
227 struct Start<R: Read + Seek> {
231 struct CommonState<R: Read + Seek> {
235 compression: Option<Compression>,
236 var_types: Vec<VarType>,
239 impl<R: Read + Seek + 'static> State for Start<R> {
240 fn read(mut self: Box<Self>) -> Result<Option<(Record, Box<dyn State>)>, Error> {
241 let header = read_header(&mut self.reader)?;
242 let next_state = Headers(CommonState {
244 endian: header.endian,
246 compression: header.compression,
247 var_types: Vec::new(),
249 Ok(Some((Record::Header(header), Box::new(next_state))))
253 struct Headers<R: Read + Seek>(CommonState<R>);
255 impl<R: Read + Seek + 'static> State for Headers<R> {
256 fn read(mut self: Box<Self>) -> Result<Option<(Record, Box<dyn State>)>, Error> {
257 let endian = self.0.endian;
258 let rec_type: u32 = endian.parse(read_bytes(&mut self.0.reader)?);
259 let record = match rec_type {
261 let variable = read_variable_record(&mut self.0.reader, endian)?;
262 self.0.var_types.push(VarType::from_width(variable.width));
263 Record::Variable(variable)
265 3 => Record::ValueLabel(read_value_label_record(&mut self.0.reader, endian)?),
266 4 => Record::VarIndexes(read_var_indexes_record(&mut self.0.reader, endian)?),
267 6 => Record::Document(read_document_record(&mut self.0.reader, endian)?),
268 7 => Record::Extension(read_extension_record(&mut self.0.reader, endian)?),
270 let _: [u8; 4] = read_bytes(&mut self.0.reader)?;
271 let next_state: Box<dyn State> = match self.0.compression {
272 None => Box::new(Data(self.0)),
273 Some(Compression::Simple) => Box::new(CompressedData::new(self.0)),
274 Some(Compression::ZLib) => Box::new(ZlibHeader(self.0)),
276 return Ok(Some((Record::EndOfHeaders, next_state)));
279 return Err(Error::BadRecordType {
280 offset: self.0.reader.stream_position()?,
285 Ok(Some((record, self)))
289 struct ZlibHeader<R: Read + Seek>(CommonState<R>);
291 impl<R: Read + Seek + 'static> State for ZlibHeader<R> {
292 fn read(mut self: Box<Self>) -> Result<Option<(Record, Box<dyn State>)>, Error> {
293 let zheader = read_zheader(&mut self.0.reader, self.0.endian)?;
294 Ok(Some((Record::ZHeader(zheader), self)))
298 struct ZlibTrailer<R: Read + Seek>(CommonState<R>, ZHeader);
300 impl<R: Read + Seek + 'static> State for ZlibTrailer<R> {
301 fn read(mut self: Box<Self>) -> Result<Option<(Record, Box<dyn State>)>, Error> {
302 let retval = read_ztrailer(&mut self.0.reader, self.0.endian, self.1.ztrailer_offset, self.1.ztrailer_len)?;
303 let next_state = Box::new(CompressedData::new(CommonState {
304 reader: ZlibDecodeMultiple::new(self.0.reader),
305 endian: self.0.endian,
307 compression: self.0.compression,
308 var_types: self.0.var_types
311 None => next_state.read(),
312 Some(ztrailer) => Ok(Some((Record::ZTrailer(ztrailer), next_state)))
317 struct Data<R: Read + Seek>(CommonState<R>);
319 impl<R: Read + Seek + 'static> State for Data<R> {
320 fn read(mut self: Box<Self>) -> Result<Option<(Record, Box<dyn State>)>, Error> {
321 let case_start = self.0.reader.stream_position()?;
322 let mut values = Vec::with_capacity(self.0.var_types.len());
323 for (i, &var_type) in self.0.var_types.iter().enumerate() {
324 let Some(raw) = try_read_bytes(&mut self.0.reader)? else {
328 let offset = self.0.reader.stream_position()?;
329 return Err(Error::EofInCase {
331 case_ofs: offset - case_start,
332 case_len: self.0.var_types.len() * 8,
336 values.push(Value::from_raw(var_type, raw, self.0.endian));
338 Ok(Some((Record::Case(values), self)))
342 struct CompressedData<R: Read + Seek> {
343 common: CommonState<R>,
347 impl<R: Read + Seek + 'static> CompressedData<R> {
348 fn new(common: CommonState<R>) -> CompressedData<R> {
349 CompressedData { common, codes: VecDeque::new() }
353 impl<R: Read + Seek + 'static> State for CompressedData<R> {
354 fn read(mut self: Box<Self>) -> Result<Option<(Record, Box<dyn State>)>, Error> {
355 let case_start = self.common.reader.stream_position()?;
356 let mut values = Vec::with_capacity(self.common.var_types.len());
357 for (i, &var_type) in self.common.var_types.iter().enumerate() {
359 let Some(code) = self.codes.pop_front() else {
360 let Some(new_codes): Option<[u8; 8]> = try_read_bytes(&mut self.common.reader)?
365 let offset = self.common.reader.stream_position()?;
366 return Err(Error::EofInCompressedCase {
368 case_ofs: offset - case_start,
372 self.codes.extend(new_codes.into_iter());
377 1..=251 => match var_type {
378 VarType::Number => break Value::Number(Some(code as f64 - self.common.bias)),
380 break Value::String(self.common.endian.to_bytes(code as f64 - self.common.bias))
387 let offset = self.common.reader.stream_position()?;
388 return Err(Error::PartialCompressedCase {
390 case_ofs: offset - case_start,
395 break Value::from_raw(
397 read_bytes(&mut self.common.reader)?,
401 254 => match var_type {
402 VarType::String => break Value::String(*b" "), // XXX EBCDIC
404 return Err(Error::CompressedStringExpected {
406 case_ofs: self.common.reader.stream_position()? - case_start,
410 255 => match var_type {
411 VarType::Number => break Value::Number(None),
413 return Err(Error::CompressedNumberExpected {
415 case_ofs: self.common.reader.stream_position()? - case_start,
423 Ok(Some((Record::Case(values), self)))
427 struct ZlibDecodeMultiple<R>
431 reader: Option<ZlibDecoder<R>>,
434 impl<R> ZlibDecodeMultiple<R>
438 fn new(reader: R) -> ZlibDecodeMultiple<R> {
440 reader: Some(ZlibDecoder::new(reader)),
445 impl<R> Read for ZlibDecodeMultiple<R>
449 fn read(&mut self, buf: &mut [u8]) -> Result<usize, IoError> {
451 match self.reader.as_mut().unwrap().read(buf)? {
453 let inner = self.reader.take().unwrap().into_inner();
454 self.reader = Some(ZlibDecoder::new(inner));
462 impl<R> Seek for ZlibDecodeMultiple<R>
466 fn seek(&mut self, pos: SeekFrom) -> Result<u64, IoError> {
467 self.reader.as_mut().unwrap().get_mut().seek(pos)
471 #[derive(Copy, Clone)]
478 pub fn from_raw(var_type: VarType, raw: [u8; 8], endian: Endian) -> Value {
480 VarType::String => Value::String(raw),
482 let number: f64 = endian.parse(raw);
483 Value::Number((number != -f64::MAX).then_some(number))
490 state: Option<Box<dyn State>>,
494 pub fn new<R: Read + Seek + 'static>(reader: R) -> Result<Reader, Error> {
496 state: Some(Box::new(Start { reader })),
501 impl Iterator for Reader {
502 type Item = Result<Record, Error>;
504 fn next(&mut self) -> Option<Self::Item> {
505 match self.state.take()?.read() {
506 Ok(Some((record, next_state))) => {
507 self.state = Some(next_state);
511 Err(error) => Some(Err(error)),
516 impl FusedIterator for Reader {}
518 fn read_header<R: Read>(r: &mut R) -> Result<Header, Error> {
519 let magic: [u8; 4] = read_bytes(r)?;
520 let magic: Magic = magic.try_into().map_err(|_| Error::NotASystemFile)?;
522 let eye_catcher: [u8; 60] = read_bytes(r)?;
523 let layout_code: [u8; 4] = read_bytes(r)?;
524 let endian = Endian::identify_u32(2, layout_code)
525 .or_else(|| Endian::identify_u32(2, layout_code))
526 .ok_or_else(|| Error::NotASystemFile)?;
527 let layout_code = endian.parse(layout_code);
529 let nominal_case_size: u32 = endian.parse(read_bytes(r)?);
530 let nominal_case_size =
531 (nominal_case_size <= i32::MAX as u32 / 16).then_some(nominal_case_size);
533 let compression_code: u32 = endian.parse(read_bytes(r)?);
534 let compression = match (magic, compression_code) {
535 (Magic::ZSAV, 2) => Some(Compression::ZLib),
536 (Magic::ZSAV, code) => return Err(Error::InvalidZsavCompression(code)),
538 (_, 1) => Some(Compression::Simple),
539 (_, code) => return Err(Error::InvalidSavCompression(code)),
542 let weight_index: u32 = endian.parse(read_bytes(r)?);
543 let weight_index = (weight_index > 0).then_some(weight_index - 1);
545 let n_cases: u32 = endian.parse(read_bytes(r)?);
546 let n_cases = (n_cases < i32::MAX as u32 / 2).then_some(n_cases);
548 let bias: f64 = endian.parse(read_bytes(r)?);
550 let creation_date: [u8; 9] = read_bytes(r)?;
551 let creation_time: [u8; 8] = read_bytes(r)?;
552 let file_label: [u8; 64] = read_bytes(r)?;
553 let _: [u8; 3] = read_bytes(r)?;
571 pub struct Variable {
572 /// Offset from the start of the file to the start of the record.
575 /// Variable width, in the range -1..=255.
578 /// Variable name, padded on the right with spaces.
582 pub print_format: u32,
585 pub write_format: u32,
587 /// Missing value code, one of -3, -2, 0, 1, 2, or 3.
588 pub missing_value_code: i32,
590 /// Raw missing values, up to 3 of them.
591 pub missing: Vec<[u8; 8]>,
593 /// Optional variable label.
594 pub label: Option<Vec<u8>>,
597 fn read_variable_record<R: Read + Seek>(r: &mut R, endian: Endian) -> Result<Variable, Error> {
598 let offset = r.stream_position()?;
599 let width: i32 = endian.parse(read_bytes(r)?);
600 let has_variable_label: u32 = endian.parse(read_bytes(r)?);
601 let missing_value_code: i32 = endian.parse(read_bytes(r)?);
602 let print_format: u32 = endian.parse(read_bytes(r)?);
603 let write_format: u32 = endian.parse(read_bytes(r)?);
604 let name: [u8; 8] = read_bytes(r)?;
606 let label = match has_variable_label {
609 let len: u32 = endian.parse(read_bytes(r)?);
610 let read_len = len.min(65535) as usize;
611 let label = Some(read_vec(r, read_len)?);
613 let padding_bytes = Integer::next_multiple_of(&len, &4) - len;
614 let _ = read_vec(r, padding_bytes as usize)?;
619 return Err(Error::BadVariableLabelCode {
621 code: has_variable_label,
626 let mut missing = Vec::new();
627 if missing_value_code != 0 {
628 match (width, missing_value_code) {
629 (0, -3 | -2 | 1 | 2 | 3) => (),
631 return Err(Error::BadNumericMissingValueCode {
633 code: missing_value_code,
638 return Err(Error::BadStringMissingValueCode {
640 code: missing_value_code,
645 for _ in 0..missing_value_code.abs() {
646 missing.push(read_bytes(r)?);
662 pub struct ValueLabel {
663 /// Offset from the start of the file to the start of the record.
667 pub labels: Vec<([u8; 8], Vec<u8>)>,
671 /// Maximum number of value labels in a record.
672 pub const MAX: u32 = u32::MAX / 8;
675 fn read_value_label_record<R: Read + Seek>(r: &mut R, endian: Endian) -> Result<ValueLabel, Error> {
676 let offset = r.stream_position()?;
677 let n: u32 = endian.parse(read_bytes(r)?);
678 if n > ValueLabel::MAX {
679 return Err(Error::BadNumberOfValueLabels {
682 max: ValueLabel::MAX,
686 let mut labels = Vec::new();
688 let value: [u8; 8] = read_bytes(r)?;
689 let label_len: u8 = endian.parse(read_bytes(r)?);
690 let label_len = label_len as usize;
691 let padded_len = Integer::next_multiple_of(&(label_len + 1), &8);
693 let mut label = read_vec(r, padded_len)?;
694 label.truncate(label_len);
695 labels.push((value, label));
697 Ok(ValueLabel { offset, labels })
700 pub struct VarIndexes {
701 /// Offset from the start of the file to the start of the record.
704 /// The 0-based indexes of the variable indexes.
705 pub var_indexes: Vec<u32>,
709 /// Maximum number of variable indexes in a record.
710 pub const MAX: u32 = u32::MAX / 8;
713 fn read_var_indexes_record<R: Read + Seek>(r: &mut R, endian: Endian) -> Result<VarIndexes, Error> {
714 let offset = r.stream_position()?;
715 let n: u32 = endian.parse(read_bytes(r)?);
716 if n > VarIndexes::MAX {
717 return Err(Error::BadNumberOfVarIndexes {
720 max: VarIndexes::MAX,
723 let mut var_indexes = Vec::with_capacity(n as usize);
725 var_indexes.push(endian.parse(read_bytes(r)?));
734 pub const DOC_LINE_LEN: u32 = 80;
735 pub const DOC_MAX_LINES: u32 = i32::MAX as u32 / DOC_LINE_LEN;
737 pub struct Document {
738 /// Offset from the start of the file to the start of the record.
741 /// The document, as an array of 80-byte lines.
742 pub lines: Vec<[u8; DOC_LINE_LEN as usize]>,
745 fn read_document_record<R: Read + Seek>(r: &mut R, endian: Endian) -> Result<Document, Error> {
746 let offset = r.stream_position()?;
747 let n: u32 = endian.parse(read_bytes(r)?);
749 0..=DOC_MAX_LINES => {
750 let pos = r.stream_position()?;
751 let mut lines = Vec::with_capacity(n as usize);
753 let line: [u8; 80] = read_bytes(r)?;
756 Ok(Document { pos, lines })
758 _ => Err(Error::BadDocumentLength {
766 #[derive(FromPrimitive)]
768 /// Machine integer info.
770 /// Machine floating-point info.
776 /// Multiple response sets.
780 /// Extra product info text.
782 /// Variable display parameters.
784 /// Long variable names.
788 /// Extended number of cases.
790 /// Data file attributes.
792 /// Variable attributes.
794 /// Multiple response sets (extended).
796 /// Character encoding.
798 /// Value labels for long strings.
800 /// Missing values for long strings.
802 /// "Format properties in dataview table".
806 pub struct Extension {
807 /// Offset from the start of the file to the start of the record.
813 /// Size of each data element.
816 /// Number of data elements.
819 /// `size * count` bytes of data.
823 fn extension_record_size_requirements(extension: ExtensionType) -> (u32, u32) {
825 /* Implemented record types. */
826 ExtensionType::Integer => (4, 8),
827 ExtensionType::Float => (8, 3),
828 ExtensionType::VarSets => (1, 0),
829 ExtensionType::Mrsets => (1, 0),
830 ExtensionType::ProductInfo => (1, 0),
831 ExtensionType::Display => (4, 0),
832 ExtensionType::LongNames => (1, 0),
833 ExtensionType::LongStrings => (1, 0),
834 ExtensionType::Ncases => (8, 2),
835 ExtensionType::FileAttrs => (1, 0),
836 ExtensionType::VarAttrs => (1, 0),
837 ExtensionType::Mrsets2 => (1, 0),
838 ExtensionType::Encoding => (1, 0),
839 ExtensionType::LongLabels => (1, 0),
840 ExtensionType::LongMissing => (1, 0),
842 /* Ignored record types. */
843 ExtensionType::Date => (0, 0),
844 ExtensionType::DataEntry => (0, 0),
845 ExtensionType::Dataview => (0, 0),
849 fn read_extension_record<R: Read + Seek>(r: &mut R, endian: Endian) -> Result<Extension, Error> {
850 let subtype = endian.parse(read_bytes(r)?);
851 let offset = r.stream_position()?;
852 let size: u32 = endian.parse(read_bytes(r)?);
853 let count = endian.parse(read_bytes(r)?);
854 let Some(product) = size.checked_mul(count) else {
855 return Err(Error::ExtensionRecordTooLarge {
862 let offset = r.stream_position()?;
863 let data = read_vec(r, product as usize)?;
874 /// File offset to the start of the record.
877 /// File offset to the ZLIB data header.
878 pub zheader_offset: u64,
880 /// File offset to the ZLIB trailer.
881 pub ztrailer_offset: u64,
883 /// Length of the ZLIB trailer in bytes.
884 pub ztrailer_len: u64,
887 fn read_zheader<R: Read + Seek>(r: &mut R, endian: Endian) -> Result<ZHeader, Error> {
888 let offset = r.stream_position()?;
889 let zheader_offset: u64 = endian.parse(read_bytes(r)?);
890 let ztrailer_offset: u64 = endian.parse(read_bytes(r)?);
891 let ztrailer_len: u64 = endian.parse(read_bytes(r)?);
901 pub struct ZTrailer {
902 /// File offset to the start of the record.
905 /// Compression bias as a negative integer, e.g. -100.
908 /// Always observed as zero.
911 /// Uncompressed size of each block, except possibly the last. Only
912 /// `0x3ff000` has been observed so far.
915 /// Block descriptors, always `(ztrailer_len - 24) / 24)` of them.
916 pub blocks: Vec<ZBlock>,
920 /// Offset of block of data if simple compression were used.
921 pub uncompressed_ofs: u64,
923 /// Actual offset within the file of the compressed data block.
924 pub compressed_ofs: u64,
926 /// The number of bytes in this data block after decompression. This is
927 /// `block_size` in every data block but the last, which may be smaller.
928 pub uncompressed_size: u32,
930 /// The number of bytes in this data block, as stored compressed in this
932 pub compressed_size: u32,
935 fn read_ztrailer<R: Read + Seek>(
940 ) -> Result<Option<ZTrailer>, Error> {
941 let start_offset = r.stream_position()?;
942 if r.seek(SeekFrom::Start(ztrailer_ofs)).is_err() {
945 let int_bias = endian.parse(read_bytes(r)?);
946 let zero = endian.parse(read_bytes(r)?);
947 let block_size = endian.parse(read_bytes(r)?);
948 let n_blocks: u32 = endian.parse(read_bytes(r)?);
949 let expected_n_blocks = (ztrailer_len - 24) / 24;
950 if n_blocks as u64 != expected_n_blocks {
951 return Err(Error::BadZlibTrailerNBlocks {
952 offset: ztrailer_ofs,
958 let mut blocks = Vec::with_capacity(n_blocks as usize);
959 for _ in 0..n_blocks {
960 let uncompressed_ofs = endian.parse(read_bytes(r)?);
961 let compressed_ofs = endian.parse(read_bytes(r)?);
962 let uncompressed_size = endian.parse(read_bytes(r)?);
963 let compressed_size = endian.parse(read_bytes(r)?);
971 r.seek(SeekFrom::Start(start_offset))?;
973 offset: ztrailer_ofs,
981 fn try_read_bytes<const N: usize, R: Read>(r: &mut R) -> Result<Option<[u8; N]>, IoError> {
982 let mut buf = [0; N];
983 let n = r.read(&mut buf)?;
986 r.read_exact(&mut buf[n..])?;
994 fn read_bytes<const N: usize, R: Read>(r: &mut R) -> Result<[u8; N], IoError> {
995 let mut buf = [0; N];
996 r.read_exact(&mut buf)?;
1000 fn read_vec<R: Read>(r: &mut R, n: usize) -> Result<Vec<u8>, IoError> {
1001 let mut vec = vec![0; n];
1002 r.read_exact(&mut vec)?;
1007 fn trim_end(mut s: Vec<u8>, c: u8) -> Vec<u8> {
1008 while s.last() == Some(&c) {
1014 fn skip_bytes<R: Read>(r: &mut R, mut n: u64) -> Result<(), IoError> {
1015 let mut buf = [0; 1024];
1017 let chunk = u64::min(n, buf.len() as u64);
1018 r.read_exact(&mut buf[0..chunk as usize])?;