[DaGuy]

I'm learning gdb and have one example that is supposed to core dump but instead I get a bus error and no core dump file to look at -bummer.

Below is the example that I'm using. It tries to set the 0x0 address which is illegal.


/* ---------------------------


char **nowhere;
void setbad();

int main(int argc, char *argv[])
{
setbad();
printf("%s\n", *nowhere);
}

void setbad(){
nowhere = 0;
*nowhere = "This is a string\n";
}


/* ---------------------------

So, it would be great if you folks can provide this newbie with some code that would actually generate a core dump file.

Thanks!

[hayesk]

Try a random address instead of 0.
Or try reading a random address instead of writing to it.

[VValdo]

Wouldn't just dividing by zero cause a core dump?

W

[Pavao]

MacOS X doesn't dump cores by default. Here's what the 'limit' command reveals on the shell:

[dhcp249:~] jpp% limit
cputime unlimited
filesize unlimited
datasize 6144 kbytes
stacksize 512 kbytes
coredumpsize 0 kbytes
memoryuse unlimited
descriptors 256
memorylocked unlimited
maxproc 100
[dhcp249:~] jpp%

You must override that 0kb limit for coredumps. Type 'limit coredump 1000000' or with any other arbitrarily large number to enable core dumps. You can verify the change by running 'limit' without any arguments again. This change will only be valid for the currently running shell. Other shells will not be afected.

[int69h]

You might finds this useful as well.

NAME
abort - cause abnormal program termination

LIBRARY
Standard C Library (libc, -lc)