• Gary Willoughby (27/27) Jun 05 2013 I've been doing some coding and noticed something strange with
• Jesse Phillips (4/4) Jun 05 2013 Not going to look into the file, but I'm pretty sure bsd_signal
• Gary Willoughby (6/10) Jun 05 2013 Ah sorry i wasn't clear.
• Mike Parker (5/16) Jun 05 2013 You are passing a function pointer to a C library, where it will
• Gary Willoughby (1/6) Jun 06 2013 Right ok thanks.

"Gary Willoughby" <dev kalekold.net> writes:

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?

"Jesse Phillips" <Jesse.K.Phillips+D gmail.com> writes:

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.

"Gary Willoughby" <dev kalekold.net> writes:

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.

"Mike Parker" <aldacron gmail.com> writes:

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.

"Gary Willoughby" <dev kalekold.net> writes:

 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.