Provide better diagnostics on libpng unexpectedeof

imazen · Sep 5, 2024 · 90713c2 · 90713c2
1 parent c8ee27d
commit 90713c2
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Showing 2 changed files with 38 additions and 3 deletions.
diff --git a/imageflow_core/src/codecs/libpng_decoder.rs b/imageflow_core/src/codecs/libpng_decoder.rs
@@ -157,8 +157,26 @@ impl PngDec{
                 true
             },
             Err(err) => {
-                decoder.error = Some(FlowError::from_decoder(err).at(here!()));
-                false
+                if err.kind() == ::std::io::ErrorKind::UnexpectedEof {
+                    let len = decoder.io.try_get_length();
+                    let pos = decoder.io.try_get_position();
+                    let remaining = if len.is_some() && pos.is_some() {
+                        Some(len.unwrap() - pos.unwrap())
+                    } else {
+                        None
+                    };
+                    let missing = remaining.map(|r| (bytes_requested as u64) - r);
+                    let err =
+                    FlowError::without_location(ErrorKind::DecodingIoError,
+                        format!("{:?} (failed to read requested {} bytes (only {:?} remain), pos={:?}, len={:?}, missing={:?})", err, bytes_requested, remaining, pos, len, missing)).at(here!());
+
+                    decoder.error = Some(err);
+
+                    false
+                } else {
+                    decoder.error = Some(FlowError::from_decoder(err).at(here!()));
+                    false
+                }
             }
         }
 
@@ -307,4 +325,4 @@ impl PngDec{
             }
         }
     }
-}
+}
diff --git a/imageflow_core/src/io.rs b/imageflow_core/src/io.rs
@@ -113,6 +113,23 @@ impl IoProxy {
     pub fn io_id(&self) -> i32{
         self.io_id
     }
+    pub fn try_get_length(&mut self) -> Option<u64>{
+        match &self.backend{
+            IoBackend::ReadVec(v) => Some(v.get_ref().len() as u64),
+            IoBackend::ReadSlice(v) => Some(v.get_ref().len() as u64),
+            IoBackend::ReadFile(v) => v.get_ref().metadata().map(|m| m.len()).ok(),
+            _ => None
+        }
+    }
+
+    pub fn try_get_position(&mut self) -> Option<u64>{
+        match &self.backend{
+            IoBackend::ReadVec(v) => Some(v.position()),
+            IoBackend::ReadSlice(v) => Some(v.position()),
+            IoBackend::ReadFile(v) => v.get_ref().stream_position().ok(),
+            _ => None
+        }
+    }
 
     pub fn read_exact(&mut self, buf: &mut [u8]) -> std::io::Result<()>{
         self.backend.get_read().expect("cannot read from writer").read_exact(buf)