Github user myui commented on a diff in the pull request:
https://github.com/apache/incubator-hivemall/pull/97#discussion_r127502672
--- Diff: core/src/main/java/hivemall/utils/io/IOUtils.java ---
@@ -129,6 +131,29 @@ public static int readInt(final InputStream in) throws
IOException {
return ((ch1 << 24) + (ch2 << 16) + (ch3 << 8) + (ch4 << 0));
}
+ /**
+ * Look ahead InputStream and decompress it as GZIPInputStream if
needed
+ *
+ * @link https://stackoverflow.com/a/4818946
+ */
+ public static InputStream decompressStream(final InputStream is)
throws IOException {
+ final PushbackInputStream pb = new PushbackInputStream(is, 2);
+
+ // look ahead
+ int b1 = pb.read();
--- End diff --
a potential bug. `read()` could return -1 on EOF.
Here is a revised version.
```java
// look ahead
final byte[] signature = new byte[2];
// If no byte is available because the stream is at the end of the
file, the value -1 is returned;
// otherwise, at least one byte is read and stored into b.
final int nread = pb.read(signature);
if (nread > 0) {// may be -1 (EOF) or 1 or 2
pb.unread(signature, 0, nread); // push back
}
final int streamHeader = ((int) signature[0] & 0xff) |
((signature[1] << 8) & 0xff00);
if (streamHeader == GZIPInputStream.GZIP_MAGIC) {
return new GZIPInputStream(pb);
} else {
return pb;
}
```
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