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Author Topic: SIGSEGV only while debug  (Read 6969 times)

Offline MoonKid

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SIGSEGV only while debug
« on: March 29, 2007, 09:21:53 pm »
I got a program that runs (F9) normal without any errors.
But If I start it with a a debug (F8) it recieves a SIGSEGV.

<err>
Program received signal SIGSEGV, Segmentation fault.
In RpcRaiseException () (C:\WINDOWS\system32\rpcrt4.dll)
</err>

I do not know what it is. Any idea?

I am using the nightlys with gcc under WinXPSP2.
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Offline thomas

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Re: SIGSEGV only while debug
« Reply #1 on: March 29, 2007, 09:25:20 pm »
This is a "feature".

Windows sends signals, exceptions, and whatever during normal operation, for example during drag-and-drop, file selection dialogs, RPC, and some other actions. The debugger catches them, and shows them (not knowing that they are "normal").
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Offline MoonKid

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Re: SIGSEGV only while debug
« Reply #2 on: March 29, 2007, 09:30:49 pm »
Ok, but a Segmentation fault is something wrong, isn't it?
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Offline thomas

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Re: SIGSEGV only while debug
« Reply #3 on: March 29, 2007, 10:17:00 pm »
Possibly, but not necessarily. Try dragging a file over Code::Blocks when it runs in the debugger, it will segfault, too.

Most of the time (99%), if it crashes in "normal" mode but runs fine in the debugger, you forgot to zero-initialise a variable. The debugger initialises all variables, thus the bug is hidden.

Most of the time (99%), if it runs fine in "normal" mode but crashes only in the debugger, it's plain normal.
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"We should forget about small efficiencies, say about 97% of the time: Premature quotation is the root of public humiliation."

Offline MoonKid

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Re: SIGSEGV only while debug
« Reply #4 on: March 29, 2007, 10:26:21 pm »
Quote from: thomas on March 29, 2007, 10:17:00 pm
Possibly, but not necessarily. Try dragging a file over Code::Blocks when it runs in the debugger, it will segfault, too.

My application just crashes on startup before I see any window/dialog!

I checked some older versions in my svn. There is the same behavior.
I checke some older versions of code::blocks (from 1.february). There is the same behavior.
I am driving crazy! ;)

Quote from: thomas on March 29, 2007, 10:17:00 pm
Most of the time (99%), if it runs fine in "normal" mode but crashes only in the debugger, it's plain normal.

It is normal, ok! But I need to debug my application?
How can I do this?
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Offline MoonKid

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Re: SIGSEGV only while debug
« Reply #5 on: March 29, 2007, 10:39:40 pm »
Hm... I just restarted my WinXP. That's all.
I do not shutdown my system. I did a supend-to-disk for two weeks.
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Offline byo

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Re: SIGSEGV only while debug
« Reply #6 on: March 30, 2007, 12:03:48 am »
If debugger gets some possible SEGFAULT which is normal due to situations Thomas described, after recieving such signal you should simply select continue and it will work. If it's really a bug, it will rethrow SEGFAULT.

BYO
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Offline cyplo

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    • Cyryl Plotnicki-Chudyk
Re: SIGSEGV only while debug
« Reply #7 on: May 06, 2007, 04:32:47 pm »
same problem with 5th May 2007 build on windows XP ; gdb 6.5 with cygwin environ
there is infinite number of sigsevs after clicking continue
all refer to ntdll.dll
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Cyryl Plotnicki-Chudyk
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