Hi,
just noticed a small thing:
The magic is 4 bytes, but readUnsignedShort reads two bytes.
- Johannes
On 28-May-20 19:25, Mandy Chung wrote:
On 5/28/20 6:55 AM, Alan Bateman wrote:
On 28/05/2020 05:13, Mandy Chung wrote:
Updated webrev:
http://cr.openjdk.java.net/~mchung/jdk15/webrevs/8245432/webrev.01/
I modify this patch to check the class file version and throws CFE
if unsupported before creating ClassReader. This also fixes
JDK-8245061 that it reads the value of `this_class` as a constant
(as ASM will throw an exception if it's not a constant) and also
ensures that `this_class` is a CONSTANT_Class_info by checking the
descriptor string from Type.
I don't want to complicate this further but the --enable-preview
handling in the VM doesn't seem to expose an internal property that
allows code in the libraries know if preview feature are enabled or
not. I was assuming that isSupportedClassFileVersion would need to
check that.
The runtime will ensure if --enable-preview is set if a class file
with minor is loaded. I will prefer to keep
VM::isSupportedClassFileVersion to validate the given major/minor
version. At runtime, it will fail when such class file is loaded if
preview is not enabled.
I'll add a comment to describe that.
Will readUnsignedShort throw AIOBE if the offset is beyond the length?
Good catch. I add the check to throw CFE.
+ private static int readUnsignedShort(byte[] bytes, int
offset) {
+ if (offset >= bytes.length) {
+ throw new ClassFormatError("Invalid ClassFile
structure");
+ }
+ return ((bytes[offset] & 0xFF) << 8) | (bytes[offset
+ 1] & 0xFF);
+ }
Also are you sure about "& 0xCAFEBABE", I assumed it would just check
the magic number is equal to that.
It should check ==. Fixed.
thanks
Mandy
