RFR(S): 8188122: Path length limits on Windows leads to obscure class loading failures

Calvin Cheung calvin.cheung at oracle.com
Mon Nov 20 20:05:58 UTC 2017


I've had some off-list discussion with Ioi resulting in another update 
to the webrev.

- added relative path scenario to the test. Currently, this fix doesn't 
handle relative path on windows yet. The following RFE has been filed to 
cover long relative paths on windows: 
https://bugs.openjdk.java.net/browse/JDK-8191521
- renamed the test LongPath.java to LongBCP.java to better reflect what 
is being tested;
- some comments update on os_windows.cpp

updated webrev:
     http://cr.openjdk.java.net/~ccheung/8188122/webrev.05/

thanks,
Calvin

On 11/9/17, 9:23 AM, Calvin Cheung wrote:
> Hi Thomas,
>
> On 11/8/17, 10:40 PM, Thomas Stüfe wrote:
>> Hi Calvin,
>>
>> On Wed, Nov 8, 2017 at 6:27 PM, Calvin Cheung 
>> <calvin.cheung at oracle.com <mailto:calvin.cheung at oracle.com>> wrote:
>>
>>
>>
>>     On 11/7/17, 6:12 AM, Thomas Stüfe wrote:
>>>     Hi Calvin,
>>>
>>>     On Wed, Nov 1, 2017 at 8:07 PM, Calvin Cheung
>>>     <calvin.cheung at oracle.com <mailto:calvin.cheung at oracle.com>> wrote:
>>>
>>>
>>>
>>>         On 10/27/17, 12:55 AM, Thomas Stüfe wrote:
>>>>         Hi Calvin,
>>>>
>>>>         On Fri, Oct 27, 2017 at 2:03 AM, Calvin Cheung
>>>>         <calvin.cheung at oracle.com
>>>>         <mailto:calvin.cheung at oracle.com>> wrote:
>>>>
>>>>             Hi Thomas,
>>>>
>>>>             On 10/25/17, 11:54 PM, Thomas Stüfe wrote:
>>>>
>>>>                 Hi Calvin,
>>>>
>>>>                 this is a worthwhile addition, thank you for your work!
>>>>
>>>>             Thanks for your review.
>>>>
>>>>
>>>>         Thanks for your work :)
>>>>
>>>>         First off, there is another issue in
>>>>         file_attribute_data_to_stat(). We actually had this issue
>>>>         before, but your work uncovered it:
>>>>
>>>>         According to POSIX
>>>>         (http://pubs.opengroup.org/onlinepubs/009695399/basedefs/sys/stat.h.html
>>>>         <http://pubs.opengroup.org/onlinepubs/009695399/basedefs/sys/stat.h.html>)
>>>>         and every unix manpage I looked at (solaris, linux, aix..),
>>>>         st_ctime is not the file creation time but the last time
>>>>         file status was changed. Only Microsoft gets this wrong in
>>>>         their posix layer, its stat() function returns
>>>>          (https://msdn.microsoft.com/en-us/library/14h5k7ff.aspx
>>>>         <https://msdn.microsoft.com/en-us/library/14h5k7ff.aspx>)
>>>>         creation time in st_ctime.
>>>>
>>>>         But as os::stat() is a platform independent layer, I'd say
>>>>         we should behave the same on all platforms, and that would
>>>>         be the Posix way.
>>>>
>>>>         I did not find any code calling os::stat() and using
>>>>         st_ctime, so this is still save to change for windows.
>>>>         (Note that I found that perfMemory_xxx.cpp uses plain OS
>>>>         ::stat and misuses ctime as "creation time" - I opened a
>>>>         bug for that
>>>>         (https://bugs.openjdk.java.net/browse/JDK-8190260
>>>>         <https://bugs.openjdk.java.net/browse/JDK-8190260> - but
>>>>         that does not affect us, as they do not call os::stat()).
>>>>
>>>>         There is one more complication: in os::stat() we use plain
>>>>         ::stat() in the single byte case.:
>>>>
>>>>         *+ if (strlen(path) < MAX_PATH) {*
>>>>         *+     ret = ::stat(pathbuf, sbuf);*
>>>>         *+   } else {*
>>>>         *
>>>>         *
>>>>         But ::stat() on Windows is broken, as I wrote above. We
>>>>         should not use it, especially not if we change the meaing
>>>>         of st_ctime in the double byte path.
>>>>
>>>>         My suggestion would be to just always call
>>>>         GetFileAttributes(), also for the single byte path. A very
>>>>         simple solution would be to just always go the double byte
>>>>         path with UNC translation, regardless of the path
>>>>         length. Or, if you are worried about performance, for paths
>>>>         shorter than MAX_PATH we use GetFileAttributesA(), for
>>>>         longer paths GetFileAttributesW with UNC translation. In
>>>>         both cases you get a WIN32_FILE_ATTRIBUTE_DATA which you
>>>>         can feed tp your  file_attribute_data_to_stat() routine and
>>>>         have the struct stat you return be always consistent.
>>>         I ran into an issue with the dwFileAttributes value for a
>>>         jar file. On Windows Server O/S, the value is set to 0x2020
>>>         which is (FILE_ATTRIBUTE_NOT_CONTENT_INDEXED |
>>>         FILE_ATTRIBUTE_ARCHIVE) but on a desktop O/S like Windows 7,
>>>         it is set to 0x0020 which is just FILE_ATTRIBUTE_ARCHIVE.
>>>         I've fixed it in file_attribute_data_to_stat().
>>>
>>>
>>>     Oh.. :( good catch! But that opens a new can of worms I did not
>>>     see before:
>>>
>>>     FILE_ATTRIBUTE_NORMAL is documented as "A file that does not
>>>     have other attributes set. This attribute is valid only when
>>>     used alone." In addition to this flag, we have a multitude of
>>>     things like FILE_ATTRIBUTE_ARCHIVE, FILE_ATTRIBUTE_ENCRYPTED,
>>>     FILE_ATTRIBUTE_READONLY ... etc, all cases where we assume this
>>>     is a normal file in Unix terminology and where we would expect
>>>     os::stat to return S_IFREG, but where according to the msdn doc
>>>     FILE_ATTRIBUTE_NORMAL is not set.
>>>
>>>     Looking at what others do in this scenario (Looked at mingw
>>>     sources and at ReactOS - I am not posting any source code here
>>>     for legal reasons but feel free to look for yourself), the usual
>>>     way to translate WIN32_FILE_ATTRIBUTES to struct stat seems to be:
>>>     "if FILE_ATTRIBUTE_DIRECTORY then set S_IFDIR else S_IFREG" (so,
>>>     no dependency on FILE_ATTRIBUTE_NORMAL).
>>     This makes sense but I ran into similar problem as before - the
>>     dwFileAttributes has a different value on a windows server O/S vs
>>     desktop O/S. So I need to do the check as follows:
>>
>>     +   // A directory has the dwFileAttributes value of 0x2010 which is
>>     +   // (FILE_ATTRIBUTE_NOT_CONTENT_INDEXED | FILE_ATTRIBUTE_ARCHIVE)
>>     +   // on Windows Server O/S but the value is 0x0010 on Windows desktop O/S
>>     +   // such as Windows 7.
>>     +   if ((file_data.dwFileAttributes&  FILE_ATTRIBUTE_DIRECTORY) != 0) {
>>     +     sbuf->st_mode |= S_IFDIR;
>>     +   } else {
>>     +     sbuf->st_mode |= S_IFREG;
>>     +   }
>>
>> I scratched my head a bit about the comment till I understood that 
>> you mean "if FILE_ATTRIBUTE_DIRECTORY bit is set it is a directory 
>> regardless of which other flags are set" instead of "if 
>> flags==FILE_ATTRIBUTE_DIRECTORY it is a directory". Sure, I guess my 
>> comment above was sloppy, but this was what I meant. I am not even 
>> sure the comment is needed, this is quite self-explaining.
> I've noticed a typo in the above comment:
> +   // (FILE_ATTRIBUTE_NOT_CONTENT_INDEXED | FILE_ATTRIBUTE_ARCHIVE)
>
> FILE_ATTRIBUTE_ARCHIVE should be FILE_ATTRIBUTE_DIRECTORY
>
> I'll correct it before push.
>
>>
>>     updated webrev:
>>     http://cr.openjdk.java.net/~ccheung/8188122/webrev.04/
>>     <http://cr.openjdk.java.net/%7Eccheung/8188122/webrev.04/>
>>
>>
>> I am fine with all the changes now. Thank you for your work and patience.
> Thanks for your discussions and review.
>
> thanks,
> Calvin
>>
>> Kind Regards, Thomas
>>
>>
>>
>>
>>     Diff from webrev.03:
>>
>>     < --- old/src/hotspot/os/windows/os_windows.cpp 2017-11-08
>>     08:50:40.170786397 -0800
>>     < +++ new/src/hotspot/os/windows/os_windows.cpp 2017-11-08
>>     08:50:39.803751877 -0800
>>     < @@ -4060,41 +4060,119 @@
>>     ---
>>     > --- old/src/hotspot/os/windows/os_windows.cpp 2017-11-01
>>     09:40:13.657460425 -0700
>>     > +++ new/src/hotspot/os/windows/os_windows.cpp 2017-11-01
>>     09:40:13.261423192 -0700
>>     > @@ -4060,41 +4060,121 @@
>>     25,29c25
>>     < +  // A directory has the dwFileAttributes value of 0x2010 which is
>>     < +  // (FILE_ATTRIBUTE_NOT_CONTENT_INDEXED | FILE_ATTRIBUTE_ARCHIVE)
>>     < +  // on Windows Server O/S but the value is 0x0010 on Windows
>>     desktop O/S
>>     < +  // such as Windows 7.
>>     < +  if ((file_data.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY)
>>     != 0) {
>>     ---
>>     > +  if (file_data.dwFileAttributes == FILE_ATTRIBUTE_DIRECTORY) {
>>     31c27,33
>>     < +  } else {
>>     ---
>>     > +  }
>>     > +  if ((file_data.dwFileAttributes == FILE_ATTRIBUTE_NORMAL) ||
>>     > +      // an archive file such as a jar file has the
>>     dwFileAttributes value of
>>     > +      // 0x2020 (FILE_ATTRIBUTE_NOT_CONTENT_INDEXED |
>>     FILE_ATTRIBUTE_ARCHIVE)
>>     > +      // on Windows Server O/S but the value is 0x0020 on
>>     > +      // Windows desktop O/S such as Windows 7.
>>     > +      ((file_data.dwFileAttributes & FILE_ATTRIBUTE_ARCHIVE)
>>     != 0)) {
>>
>>>
>>>     I wonder about other special cases which should work too:
>>>     - read-only files should be S_IFREG and !S_IWRITE,
>>     For a read-only system file under the user's home dir.
>>
>>     st_mode & 0xFF00 = 0x8100 = S_IFREG | S_IREAD
>>     dwFileAttributes = 39 = (FILE_ATTRIBUTE_ARCHIVE |
>>     FILE_ATTRIBUTE_HIDDEN | FILE_ATTRIBUTE_SYSTEM |
>>     FILE_ATTRIBUTE_READONLY)
>>>     read-only directories should be S_IFDIR and !S_IWRITE.
>>     I've tried the C:\progra~1 dir.
>>
>>     st_mode & 0xFF00 = 0x4100 = S_IFDIR | S_IREAD
>>     dwFileAttributes = 17 = (FILE_ATTRIBUTE_DIRECTORY |
>>     FILE_ATTRIBUTE_READONLY)
>>>     - We should tread the device root ("C:\") as a directory (so,
>>>     os::stat("c:\") should return S_IFDIR). Does this work?
>>     This one works too.
>>
>>     st_mode & 0xFF00 = 0x4100 = S_IFDIR | S_IREAD
>>     dwFileAttributes = 22 = (FILE_ATTRIBUTE_DIRECTORY |
>>     FILE_ATTRIBUTE_HIDDEN | FILE_ATTRIBUTE_SYSTEM)
>>>
>>>         I've also used GetTickCounts() to measure the performance of
>>>         ::stat() vs GetFileAttributesA() plus
>>>         file_attribute_data_to_stat(). There's no difference at the
>>>         ms resolution. Using the high-resolution timestamp
>>>         (https://msdn.microsoft.com/en-us/library/windows/desktop/dn553408(v=vs.85).aspx)
>>>         <https://msdn.microsoft.com/en-us/library/windows/desktop/dn553408%28v=vs.85%29.aspx%29>,
>>>         it doesn't show much difference.
>>>
>>>
>>>     stat() seems to be implemented using FindFirstFile() (see crt
>>>     sources if you can), and we call GetFileAttributesA(), so I do
>>>     not think this differs much.
>>     Yes, I saw the same in my Visual Studio installation.
>>
>>     thanks,
>>     Calvin
>>
>>>>
>>>>         But onward:
>>>>
>>>>
>>>>
>>>>                 =========================
>>>>
>>>>                 src/hotspot/os/windows/os_windows.cpp
>>>>
>>>>                 Could you please use wchar_t instead of WCHAR?
>>>>
>>>>             Fixed.
>>>>
>>>>
>>>>                 ---------------
>>>>                 in os::stat():
>>>>
>>>>                 This cumbersome malloc/strcpy sequence:
>>>>
>>>>                 !   size_t path_len = strlen(path) + 1;
>>>>                 +   char* pathbuf = (char*)os::malloc(path_len *
>>>>                 sizeof(char), mtInternal);
>>>>                 +   if (pathbuf == NULL) {
>>>>                 +     errno = ENOMEM;
>>>>                       return -1;
>>>>                     }
>>>>                     os::native_path(strcpy(pathbuf, path));
>>>>
>>>>                  can be reduced to a simple strdup:
>>>>
>>>>                 char* pathbuf = os::strdup(path, mtInternal);
>>>>                 if (pathbuf == NULL) {
>>>>                   errno = ENOMEM;
>>>>                   return -1;
>>>>                 }
>>>>                 os::native_path(pathbuf);
>>>>
>>>>                 This also would separate strcpy() from
>>>>                 os::native_path() which is a bit unreadable.
>>>>
>>>>             I've made the change.
>>>>
>>>>
>>>>                 --------------------
>>>>
>>>>                 The single-byte path (strdup, ::stat()), together
>>>>                 with its free(), can be moved inside the
>>>>                 (strlen(path) < MAX_PATH) condition.
>>>>                 os::native_path will not change the path length (it
>>>>                 better not, as it operates on the input buffer).
>>>>                 That avoids  having two allocations on the
>>>>                 doublebyte path.
>>>>
>>>>
>>>>             os::native_path() converts a path like C:\\\\somedir to
>>>>             C:\\somedir
>>>>             So I'll need the converted path in the wchar_t case
>>>>             too. The freeing of the pathbuf is being done at the
>>>>             end of the function or in the middle of the wchar_t
>>>>             case if there's an error.
>>>>
>>>>
>>>>         Oh, you are right,of course. I missed that it this is
>>>>         needed for both paths.
>>>>
>>>>
>>>>
>>>>                 -----------------------
>>>>
>>>>                 But seeing that translation to UNC paths is
>>>>                 something we might want more often, I would combine
>>>>                 allocation and UNC prefix adding to one function
>>>>                 like this, to avoid the memove and increase
>>>>                 reusability:
>>>>
>>>>                 // Creates an unc path from a single byte path.
>>>>                 Return buffer is allocated in C heap and needs to
>>>>                 be freed by caller. Returns NULL on error.
>>>>                 static whchar_t* create_unc_path(const char* s) {
>>>>                   - does s start with \\?\ ?
>>>>                 - yes:
>>>>                             - os::malloc(strlen(s) + 1) and mbstowcs_s
>>>>                         - no:
>>>>                             - os::malloc(strlen(s) + 1 + 4),
>>>>                 mbstowcs_s to fourth position in string, prefix
>>>>                 with L"\\?\"
>>>>                 }
>>>>
>>>>
>>>>             I also include the case for adding  L"\\\\?\\UNC\0" at
>>>>             the beginning to be consistent with
>>>>             libjava/canonicalize_md.c. 
>>>>
>>>>
>>>>                 We also need error checking to mbstowcs_s.
>>>>
>>>>             I've added assert like the following after the call:
>>>>
>>>>             assert(converted_chars == path_len, "sanity");
>>>>
>>>>
>>>>
>>>>         create_unc_path() :
>>>>
>>>>         - could you convert the /**/ to // comments, please?
>>>         Fixed.
>>>
>>>
>>>     thanks.
>>>
>>>
>>>>
>>>>         - not sure about the assert after mbstowcs_s: if we happen
>>>>         to encounter an invalid multibyte character, function will
>>>>         fail and return an error:
>>>>
>>>>         https://msdn.microsoft.com/en-us/library/eyktyxsx.aspx
>>>>         <https://msdn.microsoft.com/en-us/library/eyktyxsx.aspx>
>>>>         "If mbstowcs_s encounters an invalid multibyte character,
>>>>         it puts 0 in *``pReturnValue, sets the destination buffer
>>>>         to an empty string, sets errno to EILSEQ, and returns EILSEQ."
>>>         I've changed create_unc_path() so that the caller will get
>>>         the errno and removed the assert.
>>>
>>>         static wchar_t* create_unc_path(const char* path, errno_t &err)
>>>
>>>
>>>     Okay, works for me.
>>>
>>>
>>>>
>>>>          As this is dependent on user data, we should not assert,
>>>>         but handle the return code of mbstowcs_s gracefully. Same
>>>>         goes for libjava/canonicalize_md.c.
>>>>
>>>>         - Here: ::mbstowcs_s(&converted_chars, &wpath[7], path_len
>>>>         + 7, path, path_len);
>>>>         third parameter is wrong, as we hand in an offset into the
>>>>         buffer, we must decrement the buffer size by this offset,
>>>>         so correct would be path_len +7 - 7 or just path_len.
>>>>
>>>>         - Same error below: + ::mbstowcs_s(&converted_chars,
>>>>         &wpath[4], path_len + 4, path, path_len);
>>>         Fixed in both places.
>>>
>>>
>>>     Okay.
>>>
>>>
>>>>
>>>>
>>>>                 Just for cleanliness, I would then wrap
>>>>                 deallocation into an own function.
>>>>
>>>>                 static viud destroy_unc_path(whchar_t* s) {
>>>>                 os::free(s); }
>>>>
>>>>             I've added the destroy function.
>>>>
>>>>
>>>>                 These two functions could be candidates of putting
>>>>                 into os::win32 namespace, as this form of ANSI->UNC
>>>>                 path translation is quite common - whoever wants to
>>>>                 use the xxxxW() functions must do this.
>>>>
>>>>             I'm leaving them in os_windows.cpp since they're being
>>>>             used only within that file.
>>>>
>>>>
>>>>         Fine by me.
>>>>
>>>>
>>>>
>>>>                 -----------------------
>>>>
>>>>                 FindFirstFileW:
>>>>
>>>>                 I am pretty sure that you can achieve the same
>>>>                 result with GetFileAttributesExW(). It also returns
>>>>                 WIN32_FIND_DATAW.
>>>>
>>>>             It actually returns WIN32_FILE_ATTRIBUTE_DATA and is
>>>>             very similar to WIN32_FIND_DATAW.
>>>>
>>>>
>>>>                 It is way more straightforward to use than
>>>>                 FindFirstFileW, as it does not require you to write
>>>>                 a callback hook.
>>>>
>>>>             I've switched to using GetFileAttributesExW().
>>>>
>>>>
>>>>         Thank you, this is way more readable.
>>>>         Another issue: do we still need the fix for 6539723 if we
>>>>         switch from stat() to GetFileAttributesExW()? This fix
>>>>         looks important, but the comment
>>>>         indicates that it could break things if the original bug is
>>>>         not present.
>>>>
>>>>         Btw, this is another strong argument for scrapping ::stat()
>>>>         altogether on all code paths, not only for long input
>>>>         paths, because stat() and GetFileAttributesExW() may behave
>>>>         differently. So it would be good to use the same API on all
>>>>         code paths, in order to get the best test coverage.
>>>         For this round of change, I'm using
>>>         GetFileAttributesEx[A|W]() for both code paths.
>>>
>>>         webrev:
>>>         http://cr.openjdk.java.net/~ccheung/8188122/webrev.03/
>>>         <http://cr.openjdk.java.net/%7Eccheung/8188122/webrev.03/>
>>>
>>>         thanks,
>>>         Calvin
>>>
>>>
>>>     Okay, all good apart from the issues mentioned above. Thanks for
>>>     your work!
>>>
>>>     Best Regards, Thomas
>>>
>>>
>>>
>>>>
>>>>
>>>>
>>>>                 -------
>>>>
>>>>                 eval_find_data(): This is more of a generic helper
>>>>                 function, could you rename this to something
>>>>                 clearer, e.g. make_double_word() ?
>>>>
>>>>             Ok. I've renamed it.
>>>>
>>>>
>>>>                 Also, setup_stat(), could this be renamed more
>>>>                 clearly to something like WIN32_FIND_DATA_to_stat?
>>>>                 or lowercase if this bothers you :)
>>>>
>>>>             I'm naming the function as
>>>>             file_attribute_data_to_stat() to match with the data
>>>>             structure name.
>>>>
>>>>
>>>>         Thanks for taking my suggestions.
>>>>
>>>>
>>>>
>>>>                 ==================================
>>>>                 src/hotspot/share/classfile/classLoader.cpp
>>>>
>>>>                 In ClassPathDirEntry::open_stream(), I would feel
>>>>                 better if we were asserting _dir and name to be !=
>>>>                 NULL before feeding it to strlen.
>>>>
>>>>             I've added an assert statement.
>>>>
>>>>
>>>>                 ===================
>>>>
>>>>             Here's an updated webrev:
>>>>             http://cr.openjdk.java.net/~ccheung/8188122/webrev.02/
>>>>             <http://cr.openjdk.java.net/%7Eccheung/8188122/webrev.02/>
>>>>
>>>>
>>>>         Thanks!
>>>>
>>>>         Thomas
>>>>
>>>>             thanks,
>>>>             Calvin
>>>>
>>>>
>>>>                 Thanks!
>>>>
>>>>                 Thomas
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>                 On Wed, Oct 25, 2017 at 9:48 PM, Calvin Cheung
>>>>                 <calvin.cheung at oracle.com
>>>>                 <mailto:calvin.cheung at oracle.com>
>>>>                 <mailto:calvin.cheung at oracle.com
>>>>                 <mailto:calvin.cheung at oracle.com>>> wrote:
>>>>
>>>>                     I've reworked this fix by using the Unicode
>>>>                 version of open
>>>>                     (wopen) to handle path name longer than max
>>>>                 path with the path
>>>>                     prefixed to indicate an extended length path as
>>>>                 described in [1].
>>>>
>>>>                     The Unicode version of stat (wstat) doesn't
>>>>                 work well with long
>>>>                     path [2]. So FindFirstFileW will be used.The
>>>>                 data in
>>>>                     WIN32_FIND_DATA returned from FindFirstFileW
>>>>                 needs to be
>>>>                     transferred to the stat structure since the
>>>>                 caller expects a
>>>>                     return stat structure and other platforms
>>>>                 return a stat structure.
>>>>
>>>>                     In classLoader.cpp, calculate the size of
>>>>                 buffer required instead
>>>>                     of limiting it to JVM_MAXPATHLEN.
>>>>                     In os_windows.cpp, dynamically allocate buffers
>>>>                 in os::open and
>>>>                     os::stat.
>>>>
>>>>                     updated webrev:
>>>>                 http://cr.openjdk.java.net/~ccheung/8188122/webrev.01/
>>>>                 <http://cr.openjdk.java.net/%7Eccheung/8188122/webrev.01/>
>>>>                 <http://cr.openjdk.java.net/%7Eccheung/8188122/webrev.01/
>>>>                 <http://cr.openjdk.java.net/%7Eccheung/8188122/webrev.01/>>
>>>>
>>>>                     It passed hs-tier2 testing using mach5.
>>>>
>>>>                     thanks,
>>>>                     Calvin
>>>>
>>>>                     [1]
>>>>                 https://msdn.microsoft.com/en-us/library/windows/desktop/aa365247(v=vs.85).aspx#MAX_PATH
>>>>                 <https://msdn.microsoft.com/en-us/library/windows/desktop/aa365247%28v=vs.85%29.aspx#MAX_PATH>
>>>>                 <https://msdn.microsoft.com/en-us/library/windows/desktop/aa365247%28v=vs.85%29.aspx#MAX_PATH
>>>>                 <https://msdn.microsoft.com/en-us/library/windows/desktop/aa365247%28v=vs.85%29.aspx#MAX_PATH>>
>>>>
>>>>                     [2]
>>>>                 https://social.msdn.microsoft.com/Forums/vstudio/en-US/3c093ea9-f0aa-446d-b648-2dabe8480430/stat-and-long-names?forum=vcgeneral
>>>>                 <https://social.msdn.microsoft.com/Forums/vstudio/en-US/3c093ea9-f0aa-446d-b648-2dabe8480430/stat-and-long-names?forum=vcgeneral>
>>>>                 <https://social.msdn.microsoft.com/Forums/vstudio/en-US/3c093ea9-f0aa-446d-b648-2dabe8480430/stat-and-long-names?forum=vcgeneral
>>>>                 <https://social.msdn.microsoft.com/Forums/vstudio/en-US/3c093ea9-f0aa-446d-b648-2dabe8480430/stat-and-long-names?forum=vcgeneral>>
>>>>
>>>>
>>>>
>>>>                     On 10/16/17, 3:15 PM, Calvin Cheung wrote:
>>>>
>>>>                         JBS:
>>>>                 https://bugs.openjdk.java.net/browse/JDK-8188122
>>>>                 <https://bugs.openjdk.java.net/browse/JDK-8188122>
>>>>                 <https://bugs.openjdk.java.net/browse/JDK-8188122
>>>>                 <https://bugs.openjdk.java.net/browse/JDK-8188122>>
>>>>
>>>>                         Adding a warning message if the full path
>>>>                 or the directory
>>>>                         length exceeds MAX_PATH on windows.
>>>>
>>>>                         Example warning messages.
>>>>
>>>>                         1) The full path exceeds MAX_PATH:
>>>>
>>>>                         Java HotSpot(TM) 64-Bit Server VM warning:
>>>>                 construct full path
>>>>                         name failed: total length 270 exceeds max
>>>>                 length of 260
>>>>                             dir
>>>>                        
>>>>                 T:\\testoutput\\jtreg\\JTwork\\classes\\2\\runtime\\LoadClass\\LongPath.d\\xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>>>>                         length 259
>>>>                             name Hello.class length 11
>>>>
>>>>                         2) The directory path exceeds MAX_PATH:
>>>>
>>>>                         Java HotSpot(TM) 64-Bit Server VM warning:
>>>>                 os::stat failed:
>>>>                         path length 265 exceeds max length 260
>>>>                             path
>>>>                        
>>>>                 T:\\testoutput\\jtreg\\JTwork\\classes\\2\\runtime\\LoadClass\\LongPath.d\\xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx\\xxxxx
>>>>
>>>>                         webrev:
>>>>                 http://cr.openjdk.java.net/~ccheung/8188122/webrev.00/
>>>>                 <http://cr.openjdk.java.net/%7Eccheung/8188122/webrev.00/>
>>>>                 <http://cr.openjdk.java.net/%7Eccheung/8188122/webrev.00/
>>>>                 <http://cr.openjdk.java.net/%7Eccheung/8188122/webrev.00/>>
>>>>
>>>>                         Testing:
>>>>                             JPRT (including the new test)
>>>>
>>>>                         thanks,
>>>>                         Calvin
>>>>
>>>>
>>>>
>>>
>>


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