**Root cause:**
`getPrinterNames()` has two calls to
[`::EnumPrinters`](https://docs.microsoft.com/en-us/windows/win32/printdocs/enumprinters).
The first call is to get the required buffer size to contain the structures
and any strings. The second call is to get the list of printers.
Yet the list of printers or the names of printers can change between the two
calls. If it happens, the second call to `EnumPrinters` fails but it is not
checked.
I couldn't reproduce the crash myself. However, I reproduced the failure in the
second call to `::EnumPrinters` by adding `::Sleep(500)` and by renaming the
printers so that the data doesn't fit into the allocated buffer:
1: bResult: 0, cbNeeded: 504, cReturned: 0
2: bResult: 0, cbNeeded: 512, cReturned: 0
!!! error
During my testing, `cReturned` has always been zero whenever `EnumPrinters`
fails.
The crash dumps show that `cReturned` is non-zero but the `pPrinterEnum` buffer
doesn't contain valid data. Reading `info4->pPrinterName` at the line
utf_str = JNU_NewStringPlatform(env, info4->pPrinterName);
raises Access Violation exception.
**The fix:**
Check the return value of `EnumPrinters` and allow for 5 retries. If the
function still returns failure, make sure `cReturned` is set to zero.
I'm going to close
[JDK-6996051](https://bugs.openjdk.java.net/browse/JDK-6996051) and
[JDK-8182683](https://bugs.openjdk.java.net/browse/JDK-8182683) reported
previously about the same crash as duplicate of the current
[JDK-8262829](https://bugs.openjdk.java.net/browse/JDK-8262829).
**Testing:**
I used
[`RemotePrinterStatusRefresh.java`](https://github.com/openjdk/jdk/blob/master/test/jdk/java/awt/print/RemotePrinterStatusRefresh/RemotePrinterStatusRefresh.java)
for testing, it shows the list of currently available printers. In the
background I ran `PrinterRename.ps1` PowerShell script which remains a printer,
the script is attached to the JBS issue.
Without the fix, the list of available printers was empty occasionally because
`EnumPrinters` returned failure and set `cReturned` to zero. With the fix, the
list of printers is always filled.
-------------
Commit messages:
- 8262829: Native crash in Win32PrintServiceLookup.getAllPrinterNames()
Changes: https://git.openjdk.java.net/jdk/pull/2836/files
Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2836&range=00
Issue: https://bugs.openjdk.java.net/browse/JDK-8262829
Stats: 20 lines in 1 file changed: 13 ins; 0 del; 7 mod
Patch: https://git.openjdk.java.net/jdk/pull/2836.diff
Fetch: git fetch https://git.openjdk.java.net/jdk pull/2836/head:pull/2836
PR: https://git.openjdk.java.net/jdk/pull/2836
