Wrap TIFF parser functions into a struct.

src/lib.rs

@@ -94,7 +94,7 @@ pub use jpeg::get_exif_attr as get_exif_attr_from_jpeg;
 pub use reader::{Exif, Reader};
 pub use tag::{Context, Tag};
 pub use tiff::{DateTime, Field, In};
-pub use tiff::parse_exif_compat03 as parse_exif;
+pub use tiff::parse_exif;
 pub use value::Value;
 pub use value::{Rational, SRational};
 

src/reader.rs

@@ -71,16 +71,15 @@ impl Reader {
     /// Parses the Exif attributes from raw Exif data.
     /// If an error occurred, `exif::Error` is returned.
     pub fn read_raw(&self, data: Vec<u8>) -> Result<Exif, Error> {
-        let buf = data;
+        let mut parser = tiff::Parser::new();
-        let (entries, le) = tiff::parse_exif(&buf)?;
+        parser.parse(&data)?;
-        let entry_map = entries.iter().enumerate()
+        let entry_map = parser.entries.iter().enumerate()
             .map(|(i, e)| (e.ifd_num_tag(), i)).collect();
-
         Ok(Exif {
-            buf: buf,
+            buf: data,
-            entries: entries,
+            entries: parser.entries,
             entry_map: entry_map,
-            little_endian: le,
+            little_endian: parser.little_endian,
         })
     }
 

src/tiff.rs

@@ -150,51 +150,67 @@ impl fmt::Display for In {
 /// Returns a Vec of Exif fields and a bool.
 /// The boolean value is true if the data is little endian.
 /// If an error occurred, `exif::Error` is returned.
-pub fn parse_exif_compat03(data: &[u8]) -> Result<(Vec<Field>, bool), Error> {
+pub fn parse_exif(data: &[u8]) -> Result<(Vec<Field>, bool), Error> {
-    parse_exif(data).map(|(entries, le)| {
+    let mut parser = Parser::new();
-        let fields = entries.into_iter()
+    parser.parse(data)?;
-            .map(|e| e.into_field(data, le)).collect();
+    let (entries, le) = (parser.entries, parser.little_endian);
-        (fields, le)
+    Ok((entries.into_iter().map(|e| e.into_field(data, le)).collect(), le))
-    })
 }
 
-pub fn parse_exif(data: &[u8]) -> Result<(Vec<IfdEntry>, bool), Error> {
+#[derive(Debug)]
+pub struct Parser {
+    pub entries: Vec<IfdEntry>,
+    pub little_endian: bool,
+}
+
+impl Parser {
+    pub fn new() -> Self {
+        Self { entries: Vec::new(), little_endian: false }
+    }
+
+    pub fn parse(&mut self, data: &[u8]) -> Result<(), Error> {
         // Check the byte order and call the real parser.
         if data.len() < 8 {
             return Err(Error::InvalidFormat("Truncated TIFF header"));
         }
         match BigEndian::loadu16(data, 0) {
-        TIFF_BE => parse_exif_sub::<BigEndian>(data).map(|v| (v, false)),
+            TIFF_BE => {
-        TIFF_LE => parse_exif_sub::<LittleEndian>(data).map(|v| (v, true)),
+                self.little_endian = false;
+                self.parse_sub::<BigEndian>(data)
+            },
+            TIFF_LE => {
+                self.little_endian = true;
+                self.parse_sub::<LittleEndian>(data)
+            },
             _ => Err(Error::InvalidFormat("Invalid TIFF byte order")),
         }
     }
 
-fn parse_exif_sub<E>(data: &[u8])
+    fn parse_sub<E>(&mut self, data: &[u8])
-                     -> Result<Vec<IfdEntry>, Error> where E: Endian {
+                    -> Result<(), Error> where E: Endian {
         // Parse the rest of the header (42 and the IFD offset).
         if E::loadu16(data, 2) != TIFF_FORTY_TWO {
             return Err(Error::InvalidFormat("Invalid forty two"));
         }
         let mut ifd_offset = E::loadu32(data, 4) as usize;
         let mut ifd_num_ck = Some(0);
-    let mut entries = Vec::new();
         while ifd_offset != 0 {
-        let ifd_num = ifd_num_ck.ok_or(Error::InvalidFormat("Too many IFDs"))?;
+            let ifd_num = ifd_num_ck
+                .ok_or(Error::InvalidFormat("Too many IFDs"))?;
             // Limit the number of IFDs to defend against resource exhaustion
             // attacks.
             if ifd_num >= 8 {
                 return Err(Error::InvalidFormat("Limit the IFD count to 8"));
             }
-        ifd_offset = parse_ifd::<E>(
+            ifd_offset = self.parse_ifd::<E>(
-            &mut entries, data, ifd_offset, Context::Tiff, ifd_num)?;
+                data, ifd_offset, Context::Tiff, ifd_num)?;
             ifd_num_ck = ifd_num.checked_add(1);
         }
-    Ok(entries)
+        Ok(())
     }
 
     // Parse IFD [EXIF23 4.6.2].
-fn parse_ifd<E>(entries: &mut Vec<IfdEntry>, data: &[u8],
+    fn parse_ifd<E>(&mut self, data: &[u8],
                     offset: usize, ctx: Context, ifd_num: u16)
                     -> Result<usize, Error> where E: Endian {
         // Count (the number of the entries).
@@ -229,13 +245,13 @@ fn parse_ifd<E>(entries: &mut Vec<IfdEntry>, data: &[u8],
             // recursively defined.
             let tag = Tag(ctx, tag);
             match tag {
-            Tag::ExifIFDPointer => parse_child_ifd::<E>(
+                Tag::ExifIFDPointer => self.parse_child_ifd::<E>(
-                entries, data, &mut val, Context::Exif, ifd_num)?,
+                    data, &mut val, Context::Exif, ifd_num)?,
-            Tag::GPSInfoIFDPointer => parse_child_ifd::<E>(
+                Tag::GPSInfoIFDPointer => self.parse_child_ifd::<E>(
-                entries, data, &mut val, Context::Gps, ifd_num)?,
+                    data, &mut val, Context::Gps, ifd_num)?,
-            Tag::InteropIFDPointer => parse_child_ifd::<E>(
+                Tag::InteropIFDPointer => self.parse_child_ifd::<E>(
-                entries, data, &mut val, Context::Interop, ifd_num)?,
+                    data, &mut val, Context::Interop, ifd_num)?,
-            _ => entries.push(IfdEntry { field: Field {
+                _ => self.entries.push(IfdEntry { field: Field {
                     tag: tag, ifd_num: In(ifd_num), value: val }.into()}),
             }
         }
@@ -244,11 +260,11 @@ fn parse_ifd<E>(entries: &mut Vec<IfdEntry>, data: &[u8],
         if data.len() - offset - 2 - count * 12 < 4 {
             return Err(Error::InvalidFormat("Truncated next IFD offset"));
         }
-    let next_ifd_offset = E::loadu32(data, offset + 2 + count * 12) as usize;
+        let next_ifd_offset = E::loadu32(data, offset + 2 + count * 12);
-    Ok(next_ifd_offset)
+        Ok(next_ifd_offset as usize)
     }
 
-fn parse_child_ifd<E>(entries: &mut Vec<IfdEntry>, data: &[u8],
+    fn parse_child_ifd<E>(&mut self, data: &[u8],
                           pointer: &mut Value, ctx: Context, ifd_num: u16)
                           -> Result<(), Error> where E: Endian {
         // The pointer is not yet parsed, so do it here.
@@ -259,11 +275,12 @@ fn parse_child_ifd<E>(entries: &mut Vec<IfdEntry>, data: &[u8],
         // element of the field.
         let ofs = pointer.get_uint(0).ok_or(
             Error::InvalidFormat("Invalid pointer"))? as usize;
-    match parse_ifd::<E>(entries, data, ofs, ctx, ifd_num)? {
+        match self.parse_ifd::<E>(data, ofs, ctx, ifd_num)? {
             0 => Ok(()),
             _ => Err(Error::InvalidFormat("Unexpected next IFD")),
         }
     }
+}
 
 pub fn is_tiff(buf: &[u8]) -> bool {
     buf.starts_with(&TIFF_BE_SIG) || buf.starts_with(&TIFF_LE_SIG)
@@ -567,10 +584,9 @@ mod tests {
     fn unknown_field() {
         let data = b"MM\0\x2a\0\0\0\x08\
                      \0\x01\x01\0\xff\xff\0\0\0\x01\0\x14\0\0\0\0\0\0";
-        let (v, le) = parse_exif(data).unwrap();
+        let (v, _le) = parse_exif(data).unwrap();
         assert_eq!(v.len(), 1);
-        assert_pat!(v[0].ref_field(data, le).value,
+        assert_pat!(v[0].value, Value::Unknown(0xffff, 1, 0x12));
-                    Value::Unknown(0xffff, 1, 0x12));
     }
 
     #[test]