The patch compiles smooth with gcc when you modify it as follows:
--- common\rfb\LogWriter.h (broken)
+++ common\rfb\LogWriter.h (fixed)
@@ -35 +35 @@
- void name(const char* fmt, any, ...) { \
+ void name(any* fmt, ...) { \
@@ -63 +63 @@
- void write(int level, const char* format, any, ...) {
+ void write(int level, any* format, ...) {
Alternatively, you could fix the couple of existing catch blocks which pass
the e.str() in place of the format string, and probably even __attribute__
LogWriter methods in such way that gcc warns about possible wrong usages
that might creep back into the code base as awareness of the issue fades.
Regards,
Jochen
----- Original Message -----
From: "Adam Tkac" <at...@redhat.com>
To: "Jochen Neubeck" <j.tu...@arcor.de>
Cc: <tigervnc-devel@lists.sourceforge.net>
Sent: Tuesday, May 03, 2011 1:29 PM
Subject: Re: [Tigervnc-devel] [PATCH] Help avoid improper use of LogWriter
output methods
>I mobilized all my programming skills but I wasn't able to get rid of
> warnings written below so I must reject this change.
>
> In long term the only way seems to use C++ I/O operators in LogWriter
> class which can safely deal with your example code.
>
> I checked source code and it seems there aren't wrong usages of
> LogWriter method, please correct me if I'm wrong.
>
> Regards, Adam
>
> On 04/29/2011 02:16 PM, Adam Tkac wrote:
>> Sorry for late response, this mail got lost in my queue.
>>
>> You are right that current LogWriter implementation will have problems
>> with your example. However your patch causes following compilation
>> warnings:
>>
>> In file included from CConnection.cxx:28:0:
>> ../../common/rfb/LogWriter.h: In member function 'void
>> rfb::LogWriter::error(const char*, any, ...) [with any = int]':
>> ../../common/rfb/LogWriter.h:92:5: warning: second parameter of
>> 'va_start' not last named argument
>>
>> I'm trying to find a way how to get rid of this warning but I haven't
>> been successful, yet.
>>
>> Regards, Adam
>>
>> On 02/11/2011 12:14 AM, Jochen Neubeck wrote:
>>> Consider the following example:
>>>
>>> try {
>>> static const char silly_example[] = "just a %silly% example";
>>> char expanded[100];
>>> if (!ExpandEnvironmentStrings(silly_example, expanded, sizeof
>>> expanded))
>>> throw rdr::Exception("failed to expand %s", silly_example);
>>> } catch (rdr::exception &e) {
>>> vlog.error(e.str());
>>> }
>>>
>>> The %s from %silly% directs vlog.error() to substitute a non-existing
>>> char * argument, which might cause odd things including crash.
>>>
>>> Regards,
>>> Jochen
>>>
>>
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