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Merge pull request #307 from image-rs/public-byte-order

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Provide a `tags::ByteOrder` public API
This commit is contained in:
Aurelia Molzer authored and GitHub committed 2025-11-05 03:40:13 +00:00
2 parents bec6558aa8 6cdf3d8d22
commit 34e35fb27e
4 files changed
+348 -164
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src/decoder/ifd.rs
+218 -120
View File
@@ -376,7 +376,10 @@ impl Entry {
}
/// Returns a mem_reader for the offset/value field
fn r(&self, byte_order: ByteOrder) -> EndianReader<io::Cursor<Vec<u8>>> {
pub(crate) fn offset_field_reader(
&self,
byte_order: ByteOrder,
) -> EndianReader<io::Cursor<Vec<u8>>> {
EndianReader::new(io::Cursor::new(self.offset.to_vec()), byte_order)
}
@@ -392,43 +395,25 @@ impl Entry {
}
let bo = reader.byte_order;
let tag_size = match self.type_ {
Type::BYTE | Type::SBYTE | Type::ASCII | Type::UNDEFINED => 1,
Type::SHORT | Type::SSHORT => 2,
Type::LONG | Type::SLONG | Type::FLOAT | Type::IFD => 4,
Type::LONG8
| Type::SLONG8
| Type::DOUBLE
| Type::RATIONAL
| Type::SRATIONAL
| Type::IFD8 => 8,
};
let value_bytes = match self.count.checked_mul(tag_size) {
Some(n) => n,
None => {
return Err(TiffError::LimitsExceeded);
}
};
let value_bytes = self.type_.value_bytes(self.count)?;
// Case 2: there is one value.
if self.count == 1 {
// 2a: the value is 5-8 bytes and we're in BigTiff mode.
if bigtiff && value_bytes > 4 && value_bytes <= 8 {
return Ok(match self.type_ {
Type::LONG8 => UnsignedBig(self.r(bo).read_u64()?),
Type::SLONG8 => SignedBig(self.r(bo).read_i64()?),
Type::DOUBLE => Double(self.r(bo).read_f64()?),
Type::LONG8 => UnsignedBig(self.offset_field_reader(bo).read_u64()?),
Type::SLONG8 => SignedBig(self.offset_field_reader(bo).read_i64()?),
Type::DOUBLE => Double(self.offset_field_reader(bo).read_f64()?),
Type::RATIONAL => {
let mut r = self.r(bo);
let mut r = self.offset_field_reader(bo);
Rational(r.read_u32()?, r.read_u32()?)
}
Type::SRATIONAL => {
let mut r = self.r(bo);
let mut r = self.offset_field_reader(bo);
SRational(r.read_i32()?, r.read_i32()?)
}
Type::IFD8 => IfdBig(self.r(bo).read_u64()?),
Type::IFD8 => IfdBig(self.offset_field_reader(bo).read_u64()?),
Type::BYTE
| Type::SBYTE
| Type::ASCII
@@ -447,11 +432,11 @@ impl Entry {
Type::BYTE => Byte(self.offset[0]),
Type::SBYTE => SignedByte(self.offset[0] as i8),
Type::UNDEFINED => Byte(self.offset[0]),
Type::SHORT => Short(self.r(bo).read_u16()?),
Type::SSHORT => SignedShort(self.r(bo).read_i16()?),
Type::LONG => Unsigned(self.r(bo).read_u32()?),
Type::SLONG => Signed(self.r(bo).read_i32()?),
Type::FLOAT => Float(self.r(bo).read_f32()?),
Type::SHORT => Short(self.offset_field_reader(bo).read_u16()?),
Type::SSHORT => SignedShort(self.offset_field_reader(bo).read_i16()?),
Type::LONG => Unsigned(self.offset_field_reader(bo).read_u32()?),
Type::SLONG => Signed(self.offset_field_reader(bo).read_i32()?),
Type::FLOAT => Float(self.offset_field_reader(bo).read_f32()?),
Type::ASCII => {
if self.offset[0] == 0 {
Ascii("".to_string())
@@ -460,28 +445,28 @@ impl Entry {
}
}
Type::LONG8 => {
reader.goto_offset(self.r(bo).read_u32()?.into())?;
reader.goto_offset(self.offset_field_reader(bo).read_u32()?.into())?;
UnsignedBig(reader.read_u64()?)
}
Type::SLONG8 => {
reader.goto_offset(self.r(bo).read_u32()?.into())?;
reader.goto_offset(self.offset_field_reader(bo).read_u32()?.into())?;
SignedBig(reader.read_i64()?)
}
Type::DOUBLE => {
reader.goto_offset(self.r(bo).read_u32()?.into())?;
reader.goto_offset(self.offset_field_reader(bo).read_u32()?.into())?;
Double(reader.read_f64()?)
}
Type::RATIONAL => {
reader.goto_offset(self.r(bo).read_u32()?.into())?;
reader.goto_offset(self.offset_field_reader(bo).read_u32()?.into())?;
Rational(reader.read_u32()?, reader.read_u32()?)
}
Type::SRATIONAL => {
reader.goto_offset(self.r(bo).read_u32()?.into())?;
reader.goto_offset(self.offset_field_reader(bo).read_u32()?.into())?;
SRational(reader.read_i32()?, reader.read_i32()?)
}
Type::IFD => Ifd(self.r(bo).read_u32()?),
Type::IFD => Ifd(self.offset_field_reader(bo).read_u32()?),
Type::IFD8 => {
reader.goto_offset(self.r(bo).read_u32()?.into())?;
reader.goto_offset(self.offset_field_reader(bo).read_u32()?.into())?;
IfdBig(reader.read_u64()?)
}
});
@@ -512,7 +497,7 @@ impl Entry {
));
}
Type::SHORT => {
let mut r = self.r(bo);
let mut r = self.offset_field_reader(bo);
let mut v = Vec::new();
for _ in 0..self.count {
v.push(Short(r.read_u16()?));
@@ -520,7 +505,7 @@ impl Entry {
return Ok(List(v));
}
Type::SSHORT => {
let mut r = self.r(bo);
let mut r = self.offset_field_reader(bo);
let mut v = Vec::new();
for _ in 0..self.count {
v.push(SignedShort(r.read_i16()?));
@@ -528,7 +513,7 @@ impl Entry {
return Ok(List(v));
}
Type::LONG => {
let mut r = self.r(bo);
let mut r = self.offset_field_reader(bo);
let mut v = Vec::new();
for _ in 0..self.count {
v.push(Unsigned(r.read_u32()?));
@@ -536,7 +521,7 @@ impl Entry {
return Ok(List(v));
}
Type::SLONG => {
let mut r = self.r(bo);
let mut r = self.offset_field_reader(bo);
let mut v = Vec::new();
for _ in 0..self.count {
v.push(Signed(r.read_i32()?));
@@ -544,7 +529,7 @@ impl Entry {
return Ok(List(v));
}
Type::FLOAT => {
let mut r = self.r(bo);
let mut r = self.offset_field_reader(bo);
let mut v = Vec::new();
for _ in 0..self.count {
v.push(Float(r.read_f32()?));
@@ -552,7 +537,7 @@ impl Entry {
return Ok(List(v));
}
Type::IFD => {
let mut r = self.r(bo);
let mut r = self.offset_field_reader(bo);
let mut v = Vec::new();
for _ in 0..self.count {
v.push(Ifd(r.read_u32()?));
@@ -571,74 +556,149 @@ impl Entry {
}
// Case 4: there is more than one value, and it doesn't fit in the offset field.
let mut v;
self.set_reader_offset(bo, bigtiff, reader)?;
match self.type_ {
// TODO check if this could give wrong results
// at a different endianess of file/computer.
Type::BYTE => self.decode_offset(self.count, bo, bigtiff, limits, reader, |reader| {
let mut buf = [0; 1];
reader.inner().read_exact(&mut buf)?;
Ok(Byte(buf[0]))
}),
Type::SBYTE => self.decode_offset(self.count, bo, bigtiff, limits, reader, |reader| {
Ok(SignedByte(reader.read_i8()?))
}),
Type::SHORT => self.decode_offset(self.count, bo, bigtiff, limits, reader, |reader| {
Ok(Short(reader.read_u16()?))
}),
Type::SSHORT => self.decode_offset(self.count, bo, bigtiff, limits, reader, |reader| {
Ok(SignedShort(reader.read_i16()?))
}),
Type::LONG => self.decode_offset(self.count, bo, bigtiff, limits, reader, |reader| {
Ok(Unsigned(reader.read_u32()?))
}),
Type::SLONG => self.decode_offset(self.count, bo, bigtiff, limits, reader, |reader| {
Ok(Signed(reader.read_i32()?))
}),
Type::FLOAT => self.decode_offset(self.count, bo, bigtiff, limits, reader, |reader| {
Ok(Float(reader.read_f32()?))
}),
Type::DOUBLE => self.decode_offset(self.count, bo, bigtiff, limits, reader, |reader| {
Ok(Double(reader.read_f64()?))
}),
Type::BYTE | Type::UNDEFINED => {
v = Self::vec_with_capacity(self.count, limits)?;
self.decode_values(self.count, self.type_, reader, |bytes| {
v.extend(bytes.iter().copied().map(Byte))
})
}
Type::SBYTE => {
v = Self::vec_with_capacity(self.count, limits)?;
self.decode_values(self.count, self.type_, reader, |bytes| {
v.extend(bytes.iter().copied().map(|v| SignedByte(v as i8)))
})
}
Type::SHORT => {
v = Self::vec_with_capacity(self.count, limits)?;
self.decode_values(self.count, self.type_, reader, |bytes| {
v.extend(
bytes
.chunks_exact(2)
.map(|ch| Short(u16::from_ne_bytes(ch.try_into().unwrap()))),
)
})
}
Type::SSHORT => {
v = Self::vec_with_capacity(self.count, limits)?;
self.decode_values(self.count, self.type_, reader, |bytes| {
v.extend(
bytes
.chunks_exact(2)
.map(|ch| SignedShort(i16::from_ne_bytes(ch.try_into().unwrap()))),
)
})
}
Type::LONG => {
v = Self::vec_with_capacity(self.count, limits)?;
self.decode_values(self.count, self.type_, reader, |bytes| {
v.extend(
bytes
.chunks_exact(4)
.map(|ch| Unsigned(u32::from_ne_bytes(ch.try_into().unwrap()))),
)
})
}
Type::SLONG => {
v = Self::vec_with_capacity(self.count, limits)?;
self.decode_values(self.count, self.type_, reader, |bytes| {
v.extend(
bytes
.chunks_exact(4)
.map(|ch| Signed(i32::from_ne_bytes(ch.try_into().unwrap()))),
)
})
}
Type::FLOAT => {
v = Self::vec_with_capacity(self.count, limits)?;
self.decode_values(self.count, self.type_, reader, |bytes| {
v.extend(
bytes
.chunks_exact(4)
.map(|ch| Float(f32::from_ne_bytes(ch.try_into().unwrap()))),
)
})
}
Type::DOUBLE => {
v = Self::vec_with_capacity(self.count, limits)?;
self.decode_values(self.count, self.type_, reader, |bytes| {
v.extend(
bytes
.chunks_exact(8)
.map(|ch| Double(f64::from_ne_bytes(ch.try_into().unwrap()))),
)
})
}
Type::RATIONAL => {
self.decode_offset(self.count, bo, bigtiff, limits, reader, |reader| {
Ok(Rational(reader.read_u32()?, reader.read_u32()?))
v = Self::vec_with_capacity(self.count, limits)?;
self.decode_values(self.count, self.type_, reader, |bytes| {
v.extend(bytes.chunks_exact(8).map(|ch| {
Rational(
u32::from_ne_bytes(ch[..4].try_into().unwrap()),
u32::from_ne_bytes(ch[4..].try_into().unwrap()),
)
}))
})
}
Type::SRATIONAL => {
self.decode_offset(self.count, bo, bigtiff, limits, reader, |reader| {
Ok(SRational(reader.read_i32()?, reader.read_i32()?))
v = Self::vec_with_capacity(self.count, limits)?;
self.decode_values(self.count, self.type_, reader, |bytes| {
v.extend(bytes.chunks_exact(8).map(|ch| {
SRational(
i32::from_ne_bytes(ch[..4].try_into().unwrap()),
i32::from_ne_bytes(ch[4..].try_into().unwrap()),
)
}))
})
}
Type::LONG8 => self.decode_offset(self.count, bo, bigtiff, limits, reader, |reader| {
Ok(UnsignedBig(reader.read_u64()?))
}),
Type::SLONG8 => self.decode_offset(self.count, bo, bigtiff, limits, reader, |reader| {
Ok(SignedBig(reader.read_i64()?))
}),
Type::IFD => self.decode_offset(self.count, bo, bigtiff, limits, reader, |reader| {
Ok(Ifd(reader.read_u32()?))
}),
Type::IFD8 => self.decode_offset(self.count, bo, bigtiff, limits, reader, |reader| {
Ok(IfdBig(reader.read_u64()?))
}),
Type::UNDEFINED => {
self.decode_offset(self.count, bo, bigtiff, limits, reader, |reader| {
let mut buf = [0; 1];
reader.inner().read_exact(&mut buf)?;
Ok(Byte(buf[0]))
Type::LONG8 => {
v = Self::vec_with_capacity(self.count, limits)?;
self.decode_values(self.count, self.type_, reader, |bytes| {
v.extend(
bytes
.chunks_exact(8)
.map(|ch| UnsignedBig(u64::from_ne_bytes(ch.try_into().unwrap()))),
)
})
}
Type::SLONG8 => {
v = Self::vec_with_capacity(self.count, limits)?;
self.decode_values(self.count, self.type_, reader, |bytes| {
v.extend(
bytes
.chunks_exact(8)
.map(|ch| SignedBig(i64::from_ne_bytes(ch.try_into().unwrap()))),
)
})
}
Type::IFD => {
v = Self::vec_with_capacity(self.count, limits)?;
self.decode_values(self.count, self.type_, reader, |bytes| {
v.extend(
bytes
.chunks_exact(4)
.map(|ch| Ifd(u32::from_ne_bytes(ch.try_into().unwrap()))),
)
})
}
Type::IFD8 => {
v = Self::vec_with_capacity(self.count, limits)?;
self.decode_values(self.count, self.type_, reader, |bytes| {
v.extend(
bytes
.chunks_exact(8)
.map(|ch| IfdBig(u64::from_ne_bytes(ch.try_into().unwrap()))),
)
})
}
Type::ASCII => {
let n = usize::try_from(self.count)?;
if n > limits.decoding_buffer_size {
return Err(TiffError::LimitsExceeded);
}
if bigtiff {
reader.goto_offset(self.r(bo).read_u64()?)?
} else {
reader.goto_offset(self.r(bo).read_u32()?.into())?
if n > limits.decoding_buffer_size {
return Err(dbg!(TiffError::LimitsExceeded));
}
let mut out = vec![0; n];
@@ -647,43 +707,81 @@ impl Entry {
if let Some(first) = out.iter().position(|&b| b == 0) {
out.truncate(first);
}
Ok(Ascii(String::from_utf8(out)?))
return Ok(Ascii(String::from_utf8(out)?));
}
}
}?;
Ok(List(v))
}
#[inline]
fn decode_offset<R, F>(
&self,
fn vec_with_capacity(
value_count: u64,
bo: ByteOrder,
bigtiff: bool,
limits: &super::Limits,
reader: &mut EndianReader<R>,
decode_fn: F,
) -> TiffResult<Value>
where
R: Read + Seek,
F: Fn(&mut EndianReader<R>) -> TiffResult<Value>,
{
) -> Result<Vec<Value>, TiffError> {
let value_count = usize::try_from(value_count)?;
if value_count > limits.decoding_buffer_size / mem::size_of::<Value>() {
return Err(TiffError::LimitsExceeded);
}
let mut v = Vec::with_capacity(value_count);
Ok(Vec::with_capacity(value_count))
}
fn set_reader_offset<R>(
&self,
bo: ByteOrder,
bigtiff: bool,
reader: &mut EndianReader<R>,
) -> TiffResult<()>
where
R: Read + Seek,
{
let offset = if bigtiff {
self.r(bo).read_u64()?
self.offset_field_reader(bo).read_u64()?
} else {
self.r(bo).read_u32()?.into()
self.offset_field_reader(bo).read_u32()?.into()
};
reader.goto_offset(offset)?;
for _ in 0..value_count {
v.push(decode_fn(reader)?)
Ok(())
}
#[inline]
fn decode_values<R, F>(
&self,
value_count: u64,
type_: Type,
reader: &mut EndianReader<R>,
mut collect: F,
) -> TiffResult<()>
where
R: Read + Seek,
F: FnMut(&[u8]),
{
let mut total_bytes = type_.value_bytes(value_count)?;
let mut buffer = [0u8; 512];
let buf_unit = usize::from(type_.byte_len());
let mul_of_ty = buffer.len() / buf_unit * buf_unit;
let cls = type_.endian_bytes();
let native = ByteOrder::native();
while total_bytes > 0 {
// `now <= mul_of_ty < 512` so casting is mathematical
let now = total_bytes.min(mul_of_ty as u64);
total_bytes -= now;
let buffer = &mut buffer[..now as usize];
reader.inner().read_exact(buffer)?;
reader.byte_order.convert_endian_bytes(cls, buffer, native);
collect(buffer);
}
Ok(List(v))
Ok(())
}
}
src/decoder/mod.rs
+14 -25
View File
@@ -590,32 +590,16 @@ fn invert_colors(
/// Fix endianness. If `byte_order` matches the host, then conversion is a no-op.
fn fix_endianness(buf: &mut [u8], byte_order: ByteOrder, bit_depth: u8) {
match byte_order {
ByteOrder::LittleEndian => match bit_depth {
0..=8 => {}
9..=16 => buf.chunks_exact_mut(2).for_each(|v| {
v.copy_from_slice(&u16::from_le_bytes((*v).try_into().unwrap()).to_ne_bytes())
}),
17..=32 => buf.chunks_exact_mut(4).for_each(|v| {
v.copy_from_slice(&u32::from_le_bytes((*v).try_into().unwrap()).to_ne_bytes())
}),
_ => buf.chunks_exact_mut(8).for_each(|v| {
v.copy_from_slice(&u64::from_le_bytes((*v).try_into().unwrap()).to_ne_bytes())
}),
},
ByteOrder::BigEndian => match bit_depth {
0..=8 => {}
9..=16 => buf.chunks_exact_mut(2).for_each(|v| {
v.copy_from_slice(&u16::from_be_bytes((*v).try_into().unwrap()).to_ne_bytes())
}),
17..=32 => buf.chunks_exact_mut(4).for_each(|v| {
v.copy_from_slice(&u32::from_be_bytes((*v).try_into().unwrap()).to_ne_bytes())
}),
_ => buf.chunks_exact_mut(8).for_each(|v| {
v.copy_from_slice(&u64::from_be_bytes((*v).try_into().unwrap()).to_ne_bytes())
}),
},
let host = ByteOrder::native();
let class = match bit_depth {
0..=8 => crate::tags::EndianBytes::One,
9..=16 => crate::tags::EndianBytes::Two,
17..=32 => crate::tags::EndianBytes::Four,
_ => crate::tags::EndianBytes::Eight,
};
host.convert_endian_bytes(class, buf, byte_order);
}
impl<R: Read + Seek> Decoder<R> {
@@ -802,6 +786,11 @@ impl<R: Read + Seek> Decoder<R> {
}
/// Returns the byte_order of the file.
///
/// # Usage
///
/// This is only relevant to interpreting raw bytes read from tags. The image decoding methods
/// will correct to the host byte order automatically.
pub fn byte_order(&self) -> ByteOrder {
self.value_reader.reader.byte_order
}
src/decoder/stream.rs
+1 -19
View File
@@ -1,14 +1,7 @@
//! All IO functionality needed for TIFF decoding
use std::io::{self, BufRead, BufReader, Read, Seek, Take};
/// Byte order of the TIFF file.
#[derive(Clone, Copy, Debug)]
pub enum ByteOrder {
/// little endian byte order
LittleEndian,
/// big endian byte order
BigEndian,
}
pub use crate::tags::ByteOrder;
/// Reader that is aware of the byte order.
#[derive(Debug)]
@@ -45,17 +38,6 @@ impl<R: Read> EndianReader<R> {
})
}
/// Reads an i8
#[inline(always)]
pub fn read_i8(&mut self) -> Result<i8, io::Error> {
let mut n = [0u8; 1];
self.reader.read_exact(&mut n)?;
Ok(match self.byte_order {
ByteOrder::LittleEndian => i8::from_le_bytes(n),
ByteOrder::BigEndian => i8::from_be_bytes(n),
})
}
/// Reads an i16
#[inline(always)]
pub fn read_i16(&mut self) -> Result<i16, io::Error> {