Add comment explaining fdeflate fallback

image-rs · Dec 31, 2022 · 1144b3d · 1144b3d
1 parent f0ef6fd
commit 1144b3d
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Showing 2 changed files with 6 additions and 3 deletions.
diff --git a/Cargo.toml b/Cargo.toml
@@ -22,7 +22,7 @@ include = [
 [dependencies]
 bitflags = "1.0"
 crc32fast = "1.2.0"
-fdeflate = "0.2.0"
+fdeflate = "0.2.1"
 flate2 = "1.0"
 miniz_oxide = "0.6.0"
 

diff --git a/src/decoder/zlib.rs b/src/decoder/zlib.rs
@@ -40,9 +40,12 @@ impl Compressor {
                         (TINFLStatus::HasMoreOutput, in_consumed, out_consumed)
                     }
                     Err(fdeflate::DecompressionError::NotFDeflate) => {
-                        *self = Compressor::FullZlib(DecompressorOxide::new());
-
+                        // fdeflate guarantees that it will detect non-fdeflate streams before
+                        // consuming any input. If that happens, sanity check that no output
+                        // has been produced and feed the same input to a full zlib decoder.
                         assert_eq!(output_position, 0);
+
+                        *self = Compressor::FullZlib(DecompressorOxide::new());
                         self.decompress(input, output, output_position, end_of_input)
                     }
                     Err(_) => (TINFLStatus::Failed, 0, 0),