Correction Sigaction struct on amd64 #1

[Alogani]

Correction of #23700, sa_sigaction field of struct Sigaction is missing actually but does exists on amd64.

https://github.com/lattera/glibc/blob/895ef79e04a953cac1493863bcae29ad85657ee1/bits/sigaction.h#L32-L55

Also on my machine (Linux fedora 6.8.11-300.fc40.x86_64 #1 SMP PREEMPT_DYNAMIC Mon May 27 14:53:33 UTC 2024 x86_64 GNU/Linux) :

/* Structure describing the action to be taken when a signal arrives.  */
struct sigaction
  {
    /* Signal handler.  */
#if defined __USE_POSIX199309 || defined __USE_XOPEN_EXTENDED
    union
      {
	/* Used if SA_SIGINFO is not set.  */
	__sighandler_t sa_handler;
	/* Used if SA_SIGINFO is set.  */
	void (*sa_sigaction) (int, siginfo_t *, void *);
      }
    __sigaction_handler;
# define sa_handler	__sigaction_handler.sa_handler
# define sa_sigaction	__sigaction_handler.sa_sigaction
#else
    __sighandler_t sa_handler;
#endif

    /* Additional set of signals to be blocked.  */
    __sigset_t sa_mask;

    /* Special flags.  */
    int sa_flags;

    /* Restore handler.  */
    void (*sa_restorer) (void);
  };

(However I don't know why field sa_restorer doesn't appear in online source)

[Araq]

But it is inside a union so I think now the sizeof()s are not correct anymore.

[Alogani]

Like all other lib/posix/posix_* files

I havn't used importc a lot, so not sure how to express those kinds of unions with it.

[beef331]

You'll want to use https://nim-lang.org/docs/manual.html#foreign-function-interface-union-pragma and do something like

type MyUnion {.union.} = object
  typeAName: TypeA
  typeBName: TypeB

[Alogani]

@beef331 not sure if that works if this is nested inside an union:

type
  Sigaction_internal {.union.} = object
    sa_sigaction*: proc (x: cint, y: ptr SigInfo, z: pointer) {.noconv.}
    sa_handler*: proc (x: cint) {.noconv.}  ## Pointer to a signal-catching
                                            ## function or one of the macros
                                            ## SIG_IGN or SIG_DFL.
  Sigaction* {.importc: "struct sigaction",
                header: "<signal.h>", final, pure.} = object ## struct sigaction
    sigaction_union: Sigaction_internal
    sa_mask*: Sigset ## Set of signals to be blocked during execution of
                      ## the signal handling function.
    sa_flags*: cint   ## Special flags.