I've been doing some coding and noticed something strange with core.sys.posix.signal. In the following snippet you will see that i have to decorate the handleTermination function with extern(C) to satisfy the type requirements of the bsd_signal function.

import core.sys.posix.signal;
import std.c.stdlib;
import std.stdio;

void main(string[] args)
{
	bsd_signal(SIGINT, &handleTermination);

	while (true)
	{
		
	}
}

extern(C) void handleTermination(int signal)
{
	writefln("Caught signal: %s", signal);
	exit(signal);
}

This seems really odd until you take a look at the header file. In signal.d you will see extern(C): specified at the top and then further down this:

   private alias void function(int) sigfn_t;

essentially decorating this alias with extern(C).

Is this right? Should this alias be decorated like that in the header file?

Not going to look into the file, but I'm pretty sure bsd_signal is function for an external C library right?

If that is the case, it must use C calling convention, so yes this is correct.

On Wednesday, 5 June 2013 at 18:54:45 UTC, Jesse Phillips wrote:
> Not going to look into the file, but I'm pretty sure bsd_signal is function for an external C library right?
>
> If that is the case, it must use C calling convention, so yes this is correct.

Ah sorry i wasn't clear.

The question i have is, why do i need to decorate the function (with extern(C)) that i pass to bsd_signal.

The only reason i can see is that the type hint is decorated but surely it doesn't need to be.

On Wednesday, 5 June 2013 at 20:40:59 UTC, Gary Willoughby wrote:
> On Wednesday, 5 June 2013 at 18:54:45 UTC, Jesse Phillips wrote:
>> Not going to look into the file, but I'm pretty sure bsd_signal is function for an external C library right?
>>
>> If that is the case, it must use C calling convention, so yes this is correct.
>
> Ah sorry i wasn't clear.
>
> The question i have is, why do i need to decorate the function (with extern(C)) that i pass to bsd_signal.
>
> The only reason i can see is that the type hint is decorated but surely it doesn't need to be.

You are passing a function pointer to a C library, where it will be expected that the function uses the C calling convention. So you have to declare the function as extern(C), otherwise DMD will not compile it as such. That can cause segfaults.

> You are passing a function pointer to a C library, where it will be expected that the function uses the C calling convention. So you have to declare the function as extern(C), otherwise DMD will not compile it as such. That can cause segfaults.

Right ok thanks.