fix: rewind stream when reading c2pa_io and add source to incorrect format error

Author: ok-nick

sdk/src/asset_handlers/c2pa_io.rs

@@ -33,6 +33,8 @@ pub struct C2paIO {}
 
 impl CAIReader for C2paIO {
     fn read_cai(&self, asset_reader: &mut dyn CAIRead) -> Result<Vec<u8>> {
+        asset_reader.rewind()?;
+
         let mut cai_data = Vec::new();
         // read the whole file
         asset_reader.read_to_end(&mut cai_data)?;

sdk/src/asset_handlers/jpeg_io.rs

@@ -14,7 +14,7 @@
 use std::{
     collections::HashMap,
     fs::File,
-    io::{BufReader, Cursor, SeekFrom, Write},
+    io::{BufReader, Cursor, Write},
     path::*,
 };
 

sdk/src/asset_handlers/pdf_io.rs

@@ -11,7 +11,7 @@
 // specific language governing permissions and limitations under
 // each license.
 
-use std::{fs::File, io::SeekFrom, path::Path};
+use std::{fs::File, path::Path};
 
 use crate::{
     asset_handlers::pdf::{C2paPdf, Pdf},

sdk/src/error.rs

@@ -228,8 +228,12 @@ pub enum Error {
     #[error("thumbnail format {0} is unsupported")]
     UnsupportedThumbnailFormat(String),
 
-    #[error("the specified stream is not of format {0}")]
-    IncorrectFormat(String),
+    #[error("the specified stream is not of format {format}")]
+    IncorrectFormat {
+        format: String,
+        #[source]
+        source: Option<Box<dyn std::error::Error + Send + Sync>>,
+    },
 
     #[error("`trust.signer_info` is missing from settings")]
     MissingSignerSettings,

sdk/src/jumbf_io.rs

@@ -104,14 +104,24 @@ pub(crate) fn is_bmff_format(asset_type: &str) -> bool {
 /// [Error::IncorrectFormat].
 pub fn check_stream_supported(asset_type: &str, stream: &mut dyn CAIRead) -> Result<()> {
     match get_assetio_handler(asset_type) {
-        Some(asset_handler) => {
-            if !asset_handler.supports_stream(stream)? {
-                Err(Error::IncorrectFormat(asset_type.to_owned()))
-            } else {
-                Ok(())
-            }
-        }
-        None => Err(Error::IncorrectFormat(asset_type.to_owned())),
+        Some(asset_handler) => match asset_handler.supports_stream(stream) {
+            // Failed to check if asset supports the stream.
+            Err(err) => Err(Error::IncorrectFormat {
+                format: asset_type.to_owned(),
+                source: Some(Box::new(err)),
+            }),
+            // Did not fail, although the asset doesn't support the stream.
+            Ok(false) => Err(Error::IncorrectFormat {
+                format: asset_type.to_owned(),
+                source: None,
+            }),
+            // Stream supported.
+            Ok(true) => Ok(()),
+        },
+        None => Err(Error::IncorrectFormat {
+            format: asset_type.to_owned(),
+            source: None,
+        }),
     }
 }
 
@@ -530,8 +540,12 @@ pub mod tests {
             .unwrap();
         removed.set_position(0);
         let result = load_jumbf_from_stream(asset_type, &mut removed);
-        if (asset_type != "wav")
-            && (asset_type != "avi" && asset_type != "mp3" && asset_type != "webp")
+        // For c2pa this is expected to return `Error::IncorrectFormat`.
+        if asset_type != "wav"
+            && asset_type != "avi"
+            && asset_type != "mp3"
+            && asset_type != "webp"
+            && asset_type != "c2pa"
         {
             assert!(matches!(&result.err().unwrap(), Error::JumbfNotFound));
         }

sdk/src/store.rs

@@ -5797,11 +5797,14 @@ pub mod tests {
             &mut report,
             &Settings::default(),
         );
-        assert!(matches!(result, Err(Error::IncorrectFormat(_))));
+        assert!(matches!(result, Err(Error::IncorrectFormat { .. })));
         println!("Error report: {report:?}");
         assert!(!report.logged_items().is_empty());
 
-        assert!(report.has_error(Error::IncorrectFormat(format.to_owned())));
+        assert!(report.has_error(Error::IncorrectFormat {
+            format: format.to_owned(),
+            source: None
+        }));
     }
 
     #[test]