From 9f4873bae88bb1dfd9f457d0f6f5f46c4dce9610 Mon Sep 17 00:00:00 2001
From: Etienne Prothon <etienne.prothon@exwexs.fr>
Date: Wed, 15 Jul 2020 16:21:09 +0200
Subject: [PATCH] fix: Read ascii encoded in offset

---
 src/decoder/ifd.rs | 14 +++++++++++---
 src/decoder/mod.rs | 10 ++++++----
 2 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/src/decoder/ifd.rs b/src/decoder/ifd.rs
index 58965d1..b41c981 100644
--- a/src/decoder/ifd.rs
+++ b/src/decoder/ifd.rs
@@ -198,9 +198,17 @@ impl Entry {
                 if n > limits.decoding_buffer_size {
                     return Err(TiffError::LimitsExceeded);
                 }
-                decoder.goto_offset(self.r(bo).read_u32()?)?;
-                let string = decoder.read_string(n)?;
-                Ok(Ascii(string))
+                if n <= 4 {
+                    let mut buf = vec![0; n];
+                    self.r(bo).read_exact(&mut buf ).unwrap();
+                    let v = String::from_utf8(buf).unwrap();
+                    let v = v.trim_matches(char::from(0));
+                    Ok(Ascii(v.into()))
+                } else {
+                    decoder.goto_offset(self.r(bo).read_u32()?)?;
+                    let string = decoder.read_string(n)?;
+                    Ok(Ascii(string))
+                }
             }
             _ => Err(TiffError::UnsupportedError(
                 TiffUnsupportedError::UnsupportedDataType,
diff --git a/src/decoder/mod.rs b/src/decoder/mod.rs
index a2cd6a0..4175352 100644
--- a/src/decoder/mod.rs
+++ b/src/decoder/mod.rs
@@ -424,11 +424,13 @@ impl<R: Read + Seek> Decoder<R> {
     /// Reads a string
     #[inline]
     pub fn read_string(&mut self, length: usize) -> TiffResult<String> {
-        let mut out = String::with_capacity(length);
-        self.reader.read_to_string(&mut out)?;
+        let mut out = vec![0; length];
+        self.reader.read_exact(&mut out)?;
         // Strings may be null-terminated, so we trim anything downstream of the null byte
-        let trimmed = out.bytes().take_while(|&n| n != 0).collect::<Vec<u8>>();
-        Ok(String::from_utf8(trimmed)?)
+        if let Some(first) = out.iter().position(|&b| b == 0) {
+            out.truncate(first);
+        }
+        Ok(String::from_utf8(out)?)
     }
 
     /// Reads a TIFF IFA offset/value field