RFR(XXS): 8242485: Null _file checking in fileStream::flush()

[David Holmes]

Hi,

On 12/04/2020 1:52 am, Denghui Dong wrote:
> Hi,
> Thank you for the review and point out other methods need to check _file.
> In addition to "fileStream::flush", I found there are still four methods need to check _file in fileStream: read, readln, eof, rewind.
> but those methods will crash if _file is NULL, and I didn't find any caller of them(Maybe I am wrong),
> so I think it's more appropriate to add assert check to those methods.

Assertions are really only appropriate if they will be exercised by 
tests - the intent being that tests will expose any cases where the 
assertion fails.

Also it doesn't make sense to me to have assertions in most places but a 
true NULL check in others - that suggests we expect some methods to be 
called when _file is NULL, but others not. I'd prefer just to see the 
missing NULL checks added, rather than using assertions.

Thanks,
David

> Webrev: http://cr.openjdk.java.net/~ddong/8242485/webrev.01/
> 
> Could you review it again, and sponsor it if everything is okay?
> 
> Testing: teir1
> ==============================
> Test summary
> ==============================
>     TEST                                              TOTAL  PASS  FAIL ERROR
>     jtreg:test/hotspot/jtreg:tier1                     1516  1516     0     0
>     jtreg:test/jdk:tier1                               1904  1904     0     0
>  >> jtreg:test/langtools:tier1                         4031  4029     2     0 <<
>     jtreg:test/nashorn:tier1                              0     0     0     0
>     jtreg:test/jaxp:tier1                                 0     0     0     0
> ==============================
> There are two unrelated test failures in 
> langtools: jdk/javadoc/tool/CheckResourceKeys.java  and tools/javac/processing/model/TestSymtabItems.java 
> 
> 
> 
>     ------------------------------------------------------------------
>     From:Yasumasa Suenaga <suenaga at oss.nttdata.com>
>     Send Time:2020年4月11日(星期六) 09:22
>     To:董登辉(卓昂) <denghui.ddh at alibaba-inc.com>; hotspot-dev
>     <hotspot-dev at openjdk.java.net>; hotspot-runtime-dev at openjdk.java.net
>     <hotspot-runtime-dev at openjdk.java.net>
>     Subject:Re: RFR(XXS): 8242485: Null _file checking in
>     fileStream::flush()
> 
>     Hi Denghui,
> 
>     null check lacks in other place too.
>     Can you fix it?
> 
>         http://hg.openjdk.java.net/jdk/jdk/file/97d5d0cd1085/src/hotspot/share/utilities/ostream.cpp#l554
> 
> 
>     Thanks,
> 
>     Yasumasa
> 
> 
>     On 2020/04/10 21:34, Denghui Dong wrote:
>      > Hi team,
>      >
>      > Could you please review this small patch?
>      >
>      > JBS: https://bugs.openjdk.java.net/browse/JDK-8242485
>      > webrev: http://cr.openjdk.java.net/~ddong/8242485/webrev.00/
>      >
>      > I found the method "fileStream::flush()" lacks null check before fflush  which will cause
>      > all open output streams are flushed by fflush() if _file is NULL.
>      >
>      > Thanks,
>      > Denghui Dong
>      > 
>