RFR: 8287102: ImageReaderSpi.canDecodeInput() for standard plugins should return false if a stream is too short

[Phil Race]

On Fri, 13 May 2022 12:23:24 GMT, Martin Desruisseaux <duke at openjdk.java.net> wrote:

> Invoking `ImageReaderSpi.canDecodeInput(Object)` with a stream having less than 8 bytes causes an `EOFException` to be thrown instead of returning `false`. This is caused by BMP, WBMP, GIF, PNG and TIFF reader implementations assuming that those bytes always exist and not checking EOF conditions. The JPEG reader is not impacted.
> 
> The `CanDecodeTest` class in this pull request reproduces the problem and verifies that the patch solves it. The changes in `canDecodeInput(Object)` method bodies are:
> 
> * Use `ImageInputStream.read()` instead of `readByte()` and check for -1 (EOF) return value.
> * Replace `ImageInputStream.readFully(byte[])` calls by a private `tryReadFully` method.

test/jdk/javax/imageio/plugins/shared/CanDecodeTest.java line 49:

> 47:             ImageReader reader =
> 48:                     ImageIO.getImageReadersByFormatName("BMP").next();
> 49:             ImageReaderSpi spi = reader.getOriginatingProvider();

Isn't that supposed to have format, not "BMP" as the arg ?

-------------

PR: https://git.openjdk.java.net/jdk/pull/8700