1 #![allow(unused_variables)]
2 use endian::{Endian, Parse, ToBytes};
3 use flate2::read::ZlibDecoder;
5 use num_derive::FromPrimitive;
8 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.
177 pub endianness: Endian,
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 fn read(self: Box<Self>) -> Result<Option<(Record, Box<dyn State>)>, Error>;
226 struct Start<R: Read + Seek> {
230 impl<R: Read + Seek + 'static> State for Start<R> {
231 fn read(mut self: Box<Self>) -> Result<Option<(Record, Box<dyn State>)>, Error> {
232 let header = read_header(&mut self.reader)?;
233 Ok(Some((Record::Header(header), self)))
237 struct Headers<R: Read + Seek> {
240 compression: Option<Compression>,
241 var_types: Vec<VarType>,
244 impl<R: Read + Seek + 'static> State for Headers<R> {
245 fn read(mut self: Box<Self>) -> Result<Option<(Record, Box<dyn State>)>, Error> {
246 let rec_type: u32 = self.endian.parse(read_bytes(&mut self.reader)?);
247 let record = match rec_type {
249 let variable = read_variable_record(&mut self.reader, self.endian)?;
250 self.var_types.push(VarType::from_width(variable.width));
251 Record::Variable(variable)
253 3 => Record::ValueLabel(read_value_label_record(&mut self.reader, self.endian)?),
254 4 => Record::VarIndexes(read_var_indexes_record(&mut self.reader, self.endian)?),
255 6 => Record::Document(read_document_record(&mut self.reader, self.endian)?),
256 7 => Record::Extension(read_extension_record(&mut self.reader, self.endian)?),
258 let _: [u8; 4] = read_bytes(&mut self.reader)?;
259 let next_state: Box<dyn State> = match self.compression {
260 None => Box::new(Data {
263 var_types: self.var_types,
265 Some(Compression::Simple) => Box::new(CompressedData {
268 var_types: self.var_types,
269 codes: VecDeque::new(),
271 Some(Compression::ZLib) => Box::new(CompressedData {
272 reader: ZlibDecodeMultiple::new(self.reader),
274 var_types: self.var_types,
275 codes: VecDeque::new(),
278 return Ok(Some((Record::EndOfHeaders, next_state)));
281 return Err(Error::BadRecordType {
282 offset: self.reader.stream_position()?,
287 Ok(Some((record, self)))
291 struct Data<R: Read + Seek> {
294 var_types: Vec<VarType>,
297 impl<R: Read + Seek + 'static> State for Data<R> {
298 fn read(mut self: Box<Self>) -> Result<Option<(Record, Box<dyn State>)>, Error> {
299 let case_start = self.reader.stream_position()?;
300 let mut values = Vec::with_capacity(self.var_types.len());
301 for (i, &var_type) in self.var_types.iter().enumerate() {
302 let Some(raw) = try_read_bytes(&mut self.reader)? else {
306 let offset = self.reader.stream_position()?;
307 return Err(Error::EofInCase {
309 case_ofs: offset - case_start,
310 case_len: self.var_types.len() * 8,
314 values.push(Value::from_raw(var_type, raw, self.endian));
316 Ok(Some((Record::Case(values), self)))
320 struct CompressedData<R: Read + Seek> {
323 var_types: Vec<VarType>,
327 impl<R: Read + Seek + 'static> State for CompressedData<R> {
328 fn read(mut self: Box<Self>) -> Result<Option<(Record, Box<dyn State>)>, Error> {
329 let case_start = self.reader.stream_position()?;
330 let mut values = Vec::with_capacity(self.var_types.len());
331 let bias = 100.0; // XXX
332 for (i, &var_type) in self.var_types.iter().enumerate() {
334 let Some(code) = self.codes.pop_front() else {
335 let Some(new_codes): Option<[u8; 8]> = try_read_bytes(&mut self.reader)? else {
339 let offset = self.reader.stream_position()?;
340 return Err(Error::EofInCompressedCase {
342 case_ofs: offset - case_start,
346 self.codes.extend(new_codes.into_iter());
351 1..=251 => match var_type {
352 VarType::Number => break Value::Number(Some(code as f64 - bias)),
354 break Value::String(self.endian.to_bytes(code as f64 - bias))
361 let offset = self.reader.stream_position()?;
362 return Err(Error::PartialCompressedCase {
364 case_ofs: offset - case_start,
369 break Value::from_raw(var_type, read_bytes(&mut self.reader)?, self.endian)
371 254 => match var_type {
372 VarType::String => break Value::String(*b" "), // XXX EBCDIC
374 return Err(Error::CompressedStringExpected {
376 case_ofs: self.reader.stream_position()? - case_start,
380 255 => match var_type {
381 VarType::Number => break Value::Number(None),
383 return Err(Error::CompressedNumberExpected {
385 case_ofs: self.reader.stream_position()? - case_start,
393 Ok(Some((Record::Case(values), self)))
397 struct ZlibDecodeMultiple<R>
401 reader: Option<ZlibDecoder<R>>,
404 impl<R> ZlibDecodeMultiple<R>
408 fn new(reader: R) -> ZlibDecodeMultiple<R> {
410 reader: Some(ZlibDecoder::new(reader)),
415 impl<R> Read for ZlibDecodeMultiple<R>
419 fn read(&mut self, buf: &mut [u8]) -> Result<usize, IoError> {
421 match self.reader.as_mut().unwrap().read(buf)? {
423 let inner = self.reader.take().unwrap().into_inner();
424 self.reader = Some(ZlibDecoder::new(inner));
432 impl<R> Seek for ZlibDecodeMultiple<R>
436 fn seek(&mut self, pos: SeekFrom) -> Result<u64, IoError> {
441 #[derive(Copy, Clone)]
448 pub fn from_raw(var_type: VarType, raw: [u8; 8], endian: Endian) -> Value {
450 VarType::String => Value::String(raw),
452 let number: f64 = endian.parse(raw);
453 Value::Number((number != -f64::MAX).then_some(number))
460 state: Option<Box<dyn State>>,
464 pub fn new<R: Read + Seek + 'static>(reader: R) -> Result<Reader, Error> {
466 state: Some(Box::new(Start { reader })),
471 impl Iterator for Reader {
472 type Item = Result<Record, Error>;
474 fn next(&mut self) -> Option<Self::Item> {
475 match self.state.take()?.read() {
476 Ok(Some((record, next_state))) => {
477 self.state = Some(next_state);
478 return Some(Ok(record));
480 Ok(None) => return None,
481 Err(error) => return Some(Err(error)),
486 impl FusedIterator for Reader {}
488 fn read_header<R: Read>(r: &mut R) -> Result<Header, Error> {
489 let magic: [u8; 4] = read_bytes(r)?;
490 let magic: Magic = magic.try_into().map_err(|_| Error::NotASystemFile)?;
492 let eye_catcher: [u8; 60] = read_bytes(r)?;
493 let layout_code: [u8; 4] = read_bytes(r)?;
494 let endianness = Endian::identify_u32(2, layout_code)
495 .or_else(|| Endian::identify_u32(2, layout_code))
496 .ok_or_else(|| Error::NotASystemFile)?;
497 let layout_code = endianness.parse(layout_code);
499 let nominal_case_size: u32 = endianness.parse(read_bytes(r)?);
500 let nominal_case_size =
501 (nominal_case_size <= i32::MAX as u32 / 16).then_some(nominal_case_size);
503 let compression_code: u32 = endianness.parse(read_bytes(r)?);
504 let compression = match (magic, compression_code) {
505 (Magic::ZSAV, 2) => Some(Compression::ZLib),
506 (Magic::ZSAV, code) => return Err(Error::InvalidZsavCompression(code)),
508 (_, 1) => Some(Compression::Simple),
509 (_, code) => return Err(Error::InvalidSavCompression(code)),
512 let weight_index: u32 = endianness.parse(read_bytes(r)?);
513 let weight_index = (weight_index > 0).then_some(weight_index - 1);
515 let n_cases: u32 = endianness.parse(read_bytes(r)?);
516 let n_cases = (n_cases < i32::MAX as u32 / 2).then_some(n_cases);
518 let bias: f64 = endianness.parse(read_bytes(r)?);
520 let creation_date: [u8; 9] = read_bytes(r)?;
521 let creation_time: [u8; 8] = read_bytes(r)?;
522 let file_label: [u8; 64] = read_bytes(r)?;
523 let _: [u8; 3] = read_bytes(r)?;
541 pub struct Variable {
542 /// Offset from the start of the file to the start of the record.
545 /// Variable width, in the range -1..=255.
548 /// Variable name, padded on the right with spaces.
552 pub print_format: u32,
555 pub write_format: u32,
557 /// Missing value code, one of -3, -2, 0, 1, 2, or 3.
558 pub missing_value_code: i32,
560 /// Raw missing values, up to 3 of them.
561 pub missing: Vec<[u8; 8]>,
563 /// Optional variable label.
564 pub label: Option<Vec<u8>>,
567 fn read_variable_record<R: Read + Seek>(r: &mut R, endian: Endian) -> Result<Variable, Error> {
568 let offset = r.stream_position()?;
569 let width: i32 = endian.parse(read_bytes(r)?);
570 let has_variable_label: u32 = endian.parse(read_bytes(r)?);
571 let missing_value_code: i32 = endian.parse(read_bytes(r)?);
572 let print_format: u32 = endian.parse(read_bytes(r)?);
573 let write_format: u32 = endian.parse(read_bytes(r)?);
574 let name: [u8; 8] = read_bytes(r)?;
576 let label = match has_variable_label {
579 let len: u32 = endian.parse(read_bytes(r)?);
580 let read_len = len.min(65535) as usize;
581 let label = Some(read_vec(r, read_len)?);
583 let padding_bytes = Integer::next_multiple_of(&len, &4) - len;
584 let _ = read_vec(r, padding_bytes as usize)?;
589 return Err(Error::BadVariableLabelCode {
591 code: has_variable_label,
596 let mut missing = Vec::new();
597 if missing_value_code != 0 {
598 match (width, missing_value_code) {
599 (0, -3 | -2 | 1 | 2 | 3) => (),
601 return Err(Error::BadNumericMissingValueCode {
603 code: missing_value_code,
608 return Err(Error::BadStringMissingValueCode {
610 code: missing_value_code,
615 for _ in 0..missing_value_code.abs() {
616 missing.push(read_bytes(r)?);
632 pub struct ValueLabel {
633 /// Offset from the start of the file to the start of the record.
637 pub labels: Vec<([u8; 8], Vec<u8>)>,
641 /// Maximum number of value labels in a record.
642 pub const MAX: u32 = u32::MAX / 8;
645 fn read_value_label_record<R: Read + Seek>(r: &mut R, endian: Endian) -> Result<ValueLabel, Error> {
646 let offset = r.stream_position()?;
647 let n: u32 = endian.parse(read_bytes(r)?);
648 if n > ValueLabel::MAX {
649 return Err(Error::BadNumberOfValueLabels {
652 max: ValueLabel::MAX,
656 let mut labels = Vec::new();
658 let value: [u8; 8] = read_bytes(r)?;
659 let label_len: u8 = endian.parse(read_bytes(r)?);
660 let label_len = label_len as usize;
661 let padded_len = Integer::next_multiple_of(&(label_len + 1), &8);
663 let mut label = read_vec(r, padded_len)?;
664 label.truncate(label_len);
665 labels.push((value, label));
667 Ok(ValueLabel { offset, labels })
670 pub struct VarIndexes {
671 /// Offset from the start of the file to the start of the record.
674 /// The 0-based indexes of the variable indexes.
675 pub var_indexes: Vec<u32>,
679 /// Maximum number of variable indexes in a record.
680 pub const MAX: u32 = u32::MAX / 8;
683 fn read_var_indexes_record<R: Read + Seek>(r: &mut R, endian: Endian) -> Result<VarIndexes, Error> {
684 let offset = r.stream_position()?;
685 let n: u32 = endian.parse(read_bytes(r)?);
686 if n > VarIndexes::MAX {
687 return Err(Error::BadNumberOfVarIndexes {
690 max: VarIndexes::MAX,
693 let mut var_indexes = Vec::with_capacity(n as usize);
695 var_indexes.push(endian.parse(read_bytes(r)?));
704 pub const DOC_LINE_LEN: u32 = 80;
705 pub const DOC_MAX_LINES: u32 = i32::MAX as u32 / DOC_LINE_LEN;
707 pub struct Document {
708 /// Offset from the start of the file to the start of the record.
711 /// The document, as an array of 80-byte lines.
712 pub lines: Vec<[u8; DOC_LINE_LEN as usize]>,
715 fn read_document_record<R: Read + Seek>(r: &mut R, endian: Endian) -> Result<Document, Error> {
716 let offset = r.stream_position()?;
717 let n: u32 = endian.parse(read_bytes(r)?);
719 0..=DOC_MAX_LINES => {
720 let pos = r.stream_position()?;
721 let mut lines = Vec::with_capacity(n as usize);
723 let line: [u8; 80] = read_bytes(r)?;
726 Ok(Document { pos, lines })
728 _ => Err(Error::BadDocumentLength {
736 #[derive(FromPrimitive)]
738 /// Machine integer info.
740 /// Machine floating-point info.
746 /// Multiple response sets.
750 /// Extra product info text.
752 /// Variable display parameters.
754 /// Long variable names.
758 /// Extended number of cases.
760 /// Data file attributes.
762 /// Variable attributes.
764 /// Multiple response sets (extended).
766 /// Character encoding.
768 /// Value labels for long strings.
770 /// Missing values for long strings.
772 /// "Format properties in dataview table".
776 pub struct Extension {
777 /// Offset from the start of the file to the start of the record.
783 /// Size of each data element.
786 /// Number of data elements.
789 /// `size * count` bytes of data.
793 fn extension_record_size_requirements(extension: ExtensionType) -> (u32, u32) {
795 /* Implemented record types. */
796 ExtensionType::Integer => (4, 8),
797 ExtensionType::Float => (8, 3),
798 ExtensionType::VarSets => (1, 0),
799 ExtensionType::Mrsets => (1, 0),
800 ExtensionType::ProductInfo => (1, 0),
801 ExtensionType::Display => (4, 0),
802 ExtensionType::LongNames => (1, 0),
803 ExtensionType::LongStrings => (1, 0),
804 ExtensionType::Ncases => (8, 2),
805 ExtensionType::FileAttrs => (1, 0),
806 ExtensionType::VarAttrs => (1, 0),
807 ExtensionType::Mrsets2 => (1, 0),
808 ExtensionType::Encoding => (1, 0),
809 ExtensionType::LongLabels => (1, 0),
810 ExtensionType::LongMissing => (1, 0),
812 /* Ignored record types. */
813 ExtensionType::Date => (0, 0),
814 ExtensionType::DataEntry => (0, 0),
815 ExtensionType::Dataview => (0, 0),
819 fn read_extension_record<R: Read + Seek>(r: &mut R, endian: Endian) -> Result<Extension, Error> {
820 let subtype = endian.parse(read_bytes(r)?);
821 let offset = r.stream_position()?;
822 let size: u32 = endian.parse(read_bytes(r)?);
823 let count = endian.parse(read_bytes(r)?);
824 let Some(product) = size.checked_mul(count) else {
825 return Err(Error::ExtensionRecordTooLarge {
832 let offset = r.stream_position()?;
833 let data = read_vec(r, product as usize)?;
844 /// File offset to the start of the record.
847 /// File offset to the ZLIB data header.
848 pub zheader_offset: u64,
850 /// File offset to the ZLIB trailer.
851 pub ztrailer_offset: u64,
853 /// Length of the ZLIB trailer in bytes.
854 pub ztrailer_len: u64,
857 fn read_zheader<R: Read + Seek>(r: &mut R, endian: Endian) -> Result<ZHeader, Error> {
858 let offset = r.stream_position()?;
859 let zheader_offset: u64 = endian.parse(read_bytes(r)?);
860 let ztrailer_offset: u64 = endian.parse(read_bytes(r)?);
861 let ztrailer_len: u64 = endian.parse(read_bytes(r)?);
871 pub struct ZTrailer {
872 /// File offset to the start of the record.
875 /// Compression bias as a negative integer, e.g. -100.
878 /// Always observed as zero.
881 /// Uncompressed size of each block, except possibly the last. Only
882 /// `0x3ff000` has been observed so far.
885 /// Block descriptors, always `(ztrailer_len - 24) / 24)` of them.
886 pub blocks: Vec<ZBlock>,
890 /// Offset of block of data if simple compression were used.
891 pub uncompressed_ofs: u64,
893 /// Actual offset within the file of the compressed data block.
894 pub compressed_ofs: u64,
896 /// The number of bytes in this data block after decompression. This is
897 /// `block_size` in every data block but the last, which may be smaller.
898 pub uncompressed_size: u32,
900 /// The number of bytes in this data block, as stored compressed in this
902 pub compressed_size: u32,
905 fn read_ztrailer<R: Read + Seek>(
910 ) -> Result<Option<ZTrailer>, Error> {
911 let start_offset = r.stream_position()?;
912 if r.seek(SeekFrom::Start(ztrailer_ofs)).is_err() {
915 let int_bias = endian.parse(read_bytes(r)?);
916 let zero = endian.parse(read_bytes(r)?);
917 let block_size = endian.parse(read_bytes(r)?);
918 let n_blocks: u32 = endian.parse(read_bytes(r)?);
919 let expected_n_blocks = (ztrailer_len - 24) / 24;
920 if n_blocks as u64 != expected_n_blocks {
921 return Err(Error::BadZlibTrailerNBlocks {
922 offset: ztrailer_ofs,
928 let mut blocks = Vec::with_capacity(n_blocks as usize);
929 for _ in 0..n_blocks {
930 let uncompressed_ofs = endian.parse(read_bytes(r)?);
931 let compressed_ofs = endian.parse(read_bytes(r)?);
932 let uncompressed_size = endian.parse(read_bytes(r)?);
933 let compressed_size = endian.parse(read_bytes(r)?);
941 r.seek(SeekFrom::Start(start_offset))?;
943 offset: ztrailer_ofs,
951 fn try_read_bytes<const N: usize, R: Read>(r: &mut R) -> Result<Option<[u8; N]>, IoError> {
952 let mut buf = [0; N];
953 let n = r.read(&mut buf)?;
956 r.read_exact(&mut buf[n..])?;
964 fn read_bytes<const N: usize, R: Read>(r: &mut R) -> Result<[u8; N], IoError> {
965 let mut buf = [0; N];
966 r.read_exact(&mut buf)?;
970 fn read_vec<R: Read>(r: &mut R, n: usize) -> Result<Vec<u8>, IoError> {
971 let mut vec = vec![0; n];
972 r.read_exact(&mut vec)?;
977 fn trim_end(mut s: Vec<u8>, c: u8) -> Vec<u8> {
978 while s.last() == Some(&c) {
984 fn skip_bytes<R: Read>(r: &mut R, mut n: u64) -> Result<(), IoError> {
985 let mut buf = [0; 1024];
987 let chunk = u64::min(n, buf.len() as u64);
988 r.read_exact(&mut buf[0..chunk as usize])?;