RFR(S) 8190737: use unicode version of the canonicalize() function to handle long path on windows

[Ioi Lam]

Looks good. Thanks!

Ioi

> On Sep 10, 2018, at 11:42 AM, Calvin Cheung <calvin.cheung at oracle.com> wrote:
> 
> bug: https://bugs.openjdk.java.net/browse/JDK-8190737
> 
> webrev: http://cr.openjdk.java.net/~ccheung/8190737/webrev.00/
> 
> Please review this change for handling long path specified in the -Xbootclasspath/a on windows.
> 
> Highlight of changes:
> - canonicalize_md.c
>    it makes use of the unicode version of canonicalize (wcanonicalize) if the original path is >= MAX_PATH.
> 
> - zip_util.c
>    it uses the unicode version of CreateFile (CreateFileW) if the original path is >= MAX_PATH.
> 
> - io_util_md.c
>    Since zip_util.c (libzip) calls the getPrefixed() function in canonicalize_md.c (libjava), the getPrefixed() function needs to be exported.
> 
> - java_md.h
>    The JVM_MAXPATHLEN has been increased from _MAX_PATH to 1024. It is because the the current usage of the canonicalize() function from vm code is to preallocate the output buffer as follows:
>            char* canonical_path = NEW_RESOURCE_ARRAY_IN_THREAD(thread, char, JVM_MAXPATHLEN);
>            if (!get_canonical_path(path, canonical_path, JVM_MAXPATHLEN)) {
>    Also the unix version of canonicalize() function has the following check:
>            int
>           canonicalize(char *original, char *resolved, int len)
>           {
>               if (len < PATH_MAX) {
>               errno = EINVAL;
>               return -1;
>           }
>   So dynamically allocating the output buffer requires more work beyond the scope of this change.
> 
> - LongBCP.java
>    added a scenario to the test - a long path to a jar file in -Xbootclasspath/a.
> 
> Testing: tier-[1,2,3].
> 
> thanks,
> Calvin