Include the container in the Error::NotFound message.

src/error.rs

@@ -61,7 +61,7 @@ impl fmt::Display for Error {
         match *self {
             Error::InvalidFormat(msg) => f.write_str(msg),
             Error::Io(ref err) => err.fmt(f),
-            Error::NotFound(msg) => f.write_str(msg),
+            Error::NotFound(ctn) => write!(f, "No Exif data found in {}", ctn),
             Error::BlankValue(msg) => f.write_str(msg),
             Error::TooBig(msg) => f.write_str(msg),
             Error::NotSupported(msg) => f.write_str(msg),

src/isobmff.rs

@@ -124,7 +124,7 @@ impl<R> Parser<R> where R: io::BufRead + io::Seek {
                 _ => self.skip_file_level_box(size)?,
             }
         }
-        Err(Error::NotFound("No Exif data found"))
+        Err(Error::NotFound("HEIF"))
     }
 
     // Reads size, type, and largesize,
@@ -201,7 +201,7 @@ impl<R> Parser<R> where R: io::BufRead + io::Seek {
             }
         }
 
-        self.item_id.ok_or(Error::NotFound("No Exif data found"))?;
+        self.item_id.ok_or(Error::NotFound("HEIF"))?;
         self.parse_iloc(iloc.ok_or("No ItemLocationBox")?)?;
         let location = self.item_location.as_ref()
             .ok_or("No matching item in ItemLocationBox")?;

src/jpeg.rs

@@ -81,7 +81,7 @@ fn get_exif_attr_sub<R>(reader: &mut R)
         match code {
             marker::Z | marker::TEM | marker::RST0..=marker::RST7 => continue,
             marker::SOI => return Err(Error::InvalidFormat("Unexpected SOI")),
-            marker::EOI => return Err(Error::NotFound("No Exif data found")),
+            marker::EOI => return Err(Error::NotFound("JPEG")),
             _ => {},
         }
         // Read marker segments.