Re: [issue1528] ktrace does not show proper return values for pi
Stathis Kamperis (via DragonFly issue tracker) wrote:
> Stathis Kamperis <ekamperi@gmail.com> added the comment:
>
> I've added a kprintf in ktrsysret() and here is what printed:
>
> 1126 a.out CALL pipe
> 1126 a.out RET ret=3 error=0 code=42 pipe 3
>
> Question is why `ret' contains the first file descriptor of the pair at all.
> (and not zero as ought to)
This is because sys_pipe returns both fds as return value, namely
sysmsg_fds[0] and sysmsg_fds[1]. However ktrsysret is only called with
sysmsg_result, which covers only the first fd.
I guess the pipe libc glue code copies this result into the array.
cheers
simon
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