RFR(S) 8190737: use unicode version of the canonicalize() function to handle long path on windows
Xueming Shen
xueming.shen at oracle.com
Tue Sep 11 00:05:14 UTC 2018
On 9/10/18, 11:42 AM, Calvin Cheung 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.
So we are converting mb->wc->mb in wcanonicalize (when > max_path), and
then feed the
resulting path into ZFILE_Open, in which we again do mb->wc-> + prefix
-> CreateFileW(...)?
Maybe it's time to consider a "wchar" interface between vm and
libraries. Maybe it's fine here given we
are only do this for > max_path case?
Alan, now reading the win version canonicalize(...), remind me what's
the real purpose of doing
FindFirstFile/FindClose() here? the API appears to suggest it is used to
find the first match if there
is/are wildcards but we actually have checked/rejected the wildcards at
the very beginning ? To
get the "real name" for case?
>
> - 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.
I kinda remembered that we once wanted to avoid export an variant of
winFileHandleOpen() from
libjava to libzip ... in this case the alternative is to simply
copy/paste the getPrefix into libzip ...
but I don't remember the exact concern back then.
-Sherman
>
>
> - 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
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