RFR: 8299329: Assertion failure with fastdebug build when trying to use CDS without classpath [v4]

[Calvin Cheung]

On Wed, 4 Jan 2023 21:28:52 GMT, Ashutosh Mehra <duke at openjdk.org> wrote:

>> It appears longest_common_app_classpath_prefix_len() is not returning correct value when there is no file separator in the path being searched backwards. Instead of returning 0 it return 1.
>> 
>> In case of empty classpath, it can result in assertion failure in check_paths():
>> 
>> `assert(strlen(rp_array->at(i)) > (size_t)runtime_prefix_len, "sanity");`
>> 
>> It can also result in incorrectly validating the app classpaths if they only differ by first character. Eg:
>> 
>> Dump time:
>>   -cp hello.jar
>> Run time:
>>   -cp mello.jar
>> 
>> This would not result in classpath mismatch!
>> 
>> This fix updates longest_common_app_classpath_prefix_len() to return 0 if no file separator character is found.
>> 
>> Signed-off-by: Ashutosh Mehra <asmehra at redhat.com>
>
> Ashutosh Mehra has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Simplify test
>   
>   Signed-off-by: Ashutosh Mehra <asmehra at redhat.com>

Thanks for fixing this. Just one nit below.

src/hotspot/share/cds/filemap.cpp line 886:

> 884:       while (pos > 0) {
> 885:         if (rp_array->at(0)[--pos] == *os::file_separator()) {
> 886:           return pos+1;

Please add a space before and after the '+'.

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Marked as reviewed by ccheung (Reviewer).

PR: https://git.openjdk.org/jdk/pull/11781