RFR 8158023: SocketExceptions contain too little information sometimes

Mark Sheppard mark.sheppard at oracle.com
Mon Jun 27 13:48:07 UTC 2016

Hi Christoph,
     thanks for the response ... yes, you do check the 
getLastErrorString return ... sorry about that!


On 27/06/2016 14:28, Langer, Christoph wrote:
> Hi Mark,
> thanks for looking at this. Please see my comments inline.
>>       wrt JNU_ThrowByNameWithMessaheAndLastError, it would appear that it
>> doesn't allow for malloc to fail and hence
>> str1 could be null  and a problematic input to jio_snprintf which could
>> result in a de-referencing of zero.
> You are right, thanks. I should check for null and return "OutOfMemory" appropriately. I fixed that and updated the webrev in place.
>> in the call flow would it not be more appropriate to manipulate native
>> buffers first to produce the desired error string and
>> then allocate the java string object?
>> c.f. src/java.base/unic/native/libnet/net_util_md.c
>> NET_ThrowUnknownHostExceptionWithGaiError
> Well, in the case of NET_ThrowUnknownHostExceptionWithGaiError you will probably have the hostname as well as the error text encoded in platform encoding. So for that it is perfectly fine to do the native buffers first and then convert to a Java String. But in my case for JNU_ThrowByNameWithMessageAndLastError, the errno text will be in platform encoding but the other message and formatting will be UTF-8 strings from the executable. So I have to handle both parts differently when creating a String object out of it. Or am I wrong in my assumption here?
>> should you allow for getLastErrorString not to return an error string or
>> return an error result?
>> as in JNU_ThrowByNameWithLastError
> I do, don't I? I'm checking the return value of getLastErrorString: "if (n > 0)".
> Best regards
> Christoph
>> On 27/06/2016 08:42, Langer, Christoph wrote:
>>> Hi,
>>> eventually here is the - hopefully final - version of this fix:
>>> http://cr.openjdk.java.net/~clanger/webrevs/8158023.3/
>>> Now I leave JNU_ThrowByNameWithLastError untouched and I've also added
>> conversion to the new function JNU_ThrowByNameWithMessageAndLastError.
>> I've replaced JNU_ThrowByNameWithLastError with
>> JNU_ThrowByNameWithMessageAndLastError in the java/net coding where I
>> think it is appropriate (mostly in occasions when a SocketException is thrown
>> kind of generically). @Paul: thanks for your suggestion regarding the output
>> format but I would still prefer an output like "java.net.SocketException: ioctl
>> SIOCGSIZIFCONF failed: Bad file number" vs. " java.net.SocketException: Bad
>> file number (ioctl SIOCGSIZIFCONF failed)" as I'm always handing down a
>> message to the new throw routine.
>>> Hoping for a review :)
>>> Best regards
>>> Christoph
>>>> -----Original Message-----
>>>> From: Kenji Kazumura [mailto:kzr at jp.fujitsu.com]
>>>> Sent: Mittwoch, 8. Juni 2016 02:51
>>>> To: Langer, Christoph <christoph.langer at sap.com>
>>>> Cc: net-dev at openjdk.java.net; nio-dev at openjdk.java.net; core-libs-
>>>> dev at openjdk.java.net
>>>> Subject: Re: RFR 8158023: SocketExceptions contain too little information
>>>> sometimes
>>>> Christoph,
>>>> You should not remove conversion codes (platform string to Java String)
>>>> at JNU_ThrowByNameWithLastError,
>>>> and you have to add conversion codes at
>>>> JNU_ThrowByNameWithMessageAndLastError.
>>>> It seems that you assume strerror returns only ascii characters, but actually
>>>> not.
>>>> It depends on the locale of your environment where java programs runs.
>>>> -Kenji Kazumura
>>>> In message
>>>> <decc19cdab854bbeac7126cb8e236f1e at DEWDFE13DE11.global.corp.sap>
>>>>      RFR 8158023: SocketExceptions contain too little information sometimes
>>>>      "Langer, Christoph" <christoph.langer at sap.com> wrote:
>>>>> Hi all,
>>>>> please review the following change:
>>>>> Webrev: http://cr.openjdk.java.net/~clanger/webrevs/8158023.1/
>>>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8158023
>>>>> During error analysis I stumbled over a place where I encountered a
>>>> SocketException which was thrown along with some strerror information as
>>>> message. I found it hard to find the originating code spot with that
>> information.
>>>>> So I looked at the places where we throw exceptions, namely JNU_Throw...
>>>> and NET_Throw... functions and came up with the following enhancement:
>>>>> - NET_ThrowByNameWithLastError can go completely as it does not
>> provide
>>>> any benefit over JNU_ThrowByNameWithLastError.
>>>>> - JNU_ThrowByNameWithLastError can be cleaned up.
>>>>> - I added JNU_ThrowByNameWithMessageAndLastError to print out a
>> string
>>>> like message + ": " + last error.
>>>>> - I went over all places where NET_ThrowByNameWithLastError is used
>> and
>>>> replaced it appropriately.
>>>>> Do you think this change is desirable/possible?
>>>>> Though it's mainly a net topic, I'm posting it to nio-dev and core-libs-dev as
>>>> well as JNU_Throw... code affects all.
>>>>> Best regards
>>>>> Christoph

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