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[scala-bts] #3161: XML.saveFull swallows real NPE
Tue, 2010-03-09, 16:29
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Reporter: davids_s | Owner: scala-xml_team
Type: defect | Status: new
Priority: normal | Component: XML support
Keywords: |
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this is in 2.7.7 and trunk (2.8.x)
{{{
scala> scala.xml.XML.saveFull(null, , "UTF-8", true, null)
java.lang.NullPointerException
at scala.xml.XML$.saveFull(XML.scala:138)
at .(:5)
at .()
at RequestResult$.(:3)
at RequestResult$.()
at RequestResult$result()
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at...
}}}
the NPE reported is caused by `w.close` -- the correct NPE would be the
one caused by !FileOutputStream(null):
{{{
java.lang.NullPointerException
at java.io.FileOutputStream.(FileOutputStream.java:172)
at java.io.FileOutputStream.(FileOutputStream.java:131)
at .(:6)
at .()
at RequestResult$.(:3)
at RequestResult$.()
at RequestResult$result()
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
a...
}}}
The solution would be to check for null in finally/ultimately:
{{{
if (w != null) w.close()
}}}
Closing the writer automatically closes the underlying stream so there is
no reason for the additional `fos.close()`
Wed, 2010-03-10, 17:27
#2
Re: [scala-bts] #3161: XML.saveFull swallows real NPE
---------------------+------------------------------------------------------
Reporter: davids_s | Owner: scala-xml_team
Type: defect | Status: closed
Priority: normal | Component: XML support
Version: | Resolution: fixed
Keywords: |
---------------------+------------------------------------------------------
Changes (by harrah):
* cc: harrah@… (added)
Comment:
`Channels.newWriter` can throw an exception and in that case, you wouldn't
close `fos`. So, there should probably be two nested `ultimately`s.
Wed, 2010-03-10, 17:37
#3
Re: [scala-bts] #3161: XML.saveFull swallows real NPE
---------------------+------------------------------------------------------
Reporter: davids_s | Owner: scala-xml_team
Type: defect | Status: closed
Priority: normal | Component: XML support
Version: | Resolution: fixed
Keywords: |
---------------------+------------------------------------------------------
Comment(by extempore):
Replying to [comment:2 harrah]:
> `Channels.newWriter` can throw an exception and in that case, you
wouldn't close `fos`. So, there should probably be two nested
`ultimately`s.
I realize you are correct, but I'm going to place that squarely in the
category of "we need proper arm blocks" because it's not like anything
else in the compiler or library is that meticulous.
---------------------+------------------------------------------------------
Reporter: davids_s | Owner: scala-xml_team
Type: defect | Status: closed
Priority: normal | Component: XML support
Version: | Resolution: fixed
Keywords: |
---------------------+------------------------------------------------------
Changes (by extempore):
* cc: paulp@… (added)
* status: new => closed
* resolution: => fixed
Comment:
I was going to say "how could this bug be in trunk as the FOS NPE happens
before it even enters the try/finally block", but then I realized it's not
in trunk. In fact, calling saveFull in trunk immediately puts the
compiler into an infinite loop. So I fixed that, and I removed the
unnecessary close in r21124.