fix(deflate): compress_to_vec infinite loop

Fixed bug causing an infinite loop when compress_to_vec was called with empty or 1-length input.

Closes #75

miniz_oxide/src/deflate/mod.rs

@@ -119,7 +119,7 @@ fn compress_to_vec_inner(input: &[u8], level: u8, window_bits: i32, strategy: i3
     // The comp flags function sets the zlib flag if the window_bits parameter is > 0.
     let flags = create_comp_flags_from_zip_params(level.into(), window_bits, strategy);
     let mut compressor = CompressorOxide::new(flags);
-    let mut output = vec![0; input.len() / 2];
+    let mut output = vec![0; std::cmp::max(input.len() / 2, 2)];
 
     let mut in_pos = 0;
     let mut out_pos = 0;

miniz_oxide/tests/test.rs

@@ -148,3 +148,16 @@ fn need_more_input_has_more_output_at_same_time() {
     decomp(&input[..11727]); // Fail: NeedsMoreInput even if the output buffer is also full!
     decomp(&input[..11728]); // Fail: NeedsMoreInput even if the output buffer is also full!
 }
+
+#[test]
+fn issue_75_empty_input_infinite_loop() {
+    // Make sure compression works with empty input,
+    // a bug resulted in this causing an infinite loop in
+    // compress_to_vec_inner.
+    let c = miniz_oxide::deflate::compress_to_vec(&[], 6);
+    let d = miniz_oxide::inflate::decompress_to_vec(&c).expect("decompression failed!");
+    assert_eq!(d.len(), 0);
+    let c = miniz_oxide::deflate::compress_to_vec(&[0], 6);
+    let d = miniz_oxide::inflate::decompress_to_vec(&c).expect("decompression failed!");
+    assert!(&d == &[0]);
+}