add PERL_USE_3ARG_SIGHANDLER macro

There are a bunch of places in core that do

   #if defined(HAS_SIGACTION) && defined(SA_SIGINFO)

to decide whether the C signal handler function should be declared with,
and called with, 1 arg or 3 args.

This commit just adds

   #if defined(HAS_SIGACTION) && defined(SA_SIGINFO)
   #  define PERL_USE_3ARG_SIGHANDLER
   #endif

Then uses the new macro in all other places rather than checking
HAS_SIGACTION and SA_SIGINFO. Thus there is no functional change; it just
makes the code more readable.

However, it turns out that all is not well with core's use of 1-arg
versus 3-arg, and the few commits will fix this.

6 files changed, 36 insertions, 30 deletions

diff --git a/embed.fnc b/embed.fnc
index 4a55e2ccd3..016d5bb548 100644
--- a/embed.fnc
+++ b/embed.fnc
@@ -1683,7 +1683,7 @@ Axpd	|OP*	|op_scope	|NULLOK OP* o
 pe	|void	|set_caret_X
 Apd	|void	|setdefout	|NN GV* gv
 Ap	|HEK*	|share_hek	|NN const char* str|SSize_t len|U32 hash
-#if defined(HAS_SIGACTION) && defined(SA_SIGINFO)
+#ifdef PERL_USE_3ARG_SIGHANDLER
 : Used in perl.c
 Tp	|Signal_t |sighandler	|int sig|NULLOK Siginfo_t *info|NULLOK void *uap
 ATp	|Signal_t |csighandler	|int sig|NULLOK Siginfo_t *info|NULLOK void *uap
diff --git a/embed.h b/embed.h
index a3255155ab..0bfaaa8163 100644
--- a/embed.h
+++ b/embed.h
@@ -761,7 +761,7 @@
 #define whichsig_sv(a)		Perl_whichsig_sv(aTHX_ a)
 #define wrap_keyword_plugin(a,b)	Perl_wrap_keyword_plugin(aTHX_ a,b)
 #define wrap_op_checker(a,b,c)	Perl_wrap_op_checker(aTHX_ a,b,c)
-#if !(defined(HAS_SIGACTION) && defined(SA_SIGINFO))
+#if !(defined(PERL_USE_3ARG_SIGHANDLER))
 #define csighandler		Perl_csighandler
 #endif
 #if !defined(EBCDIC)
@@ -808,9 +808,6 @@
 #define pad_setsv(a,b)		Perl_pad_setsv(aTHX_ a,b)
 #define pad_sv(a)		Perl_pad_sv(aTHX_ a)
 #endif
-#if defined(HAS_SIGACTION) && defined(SA_SIGINFO)
-#define csighandler		Perl_csighandler
-#endif
 #if defined(HAVE_INTERP_INTERN)
 #define sys_intern_clear()	Perl_sys_intern_clear(aTHX)
 #define sys_intern_init()	Perl_sys_intern_init(aTHX)
@@ -848,6 +845,9 @@
 #define warn_nocontext		Perl_warn_nocontext
 #define warner_nocontext	Perl_warner_nocontext
 #endif
+#if defined(PERL_USE_3ARG_SIGHANDLER)
+#define csighandler		Perl_csighandler
+#endif
 #if defined(UNLINK_ALL_VERSIONS)
 #define unlnk(a)		Perl_unlnk(aTHX_ a)
 #endif
@@ -1446,12 +1446,12 @@
 #define my_nl_langinfo		S_my_nl_langinfo
 #    endif
 #  endif
-#  if !(defined(HAS_SIGACTION) && defined(SA_SIGINFO))
-#define sighandler		Perl_sighandler
-#  endif
 #  if !(defined(PERL_DEFAULT_DO_EXEC3_IMPLEMENTATION))
 #define do_exec(a)		Perl_do_exec(aTHX_ a)
 #  endif
+#  if !(defined(PERL_USE_3ARG_SIGHANDLER))
+#define sighandler		Perl_sighandler
+#  endif
 #  if !(defined(_MSC_VER))
 #define magic_regdatum_set(a,b)	Perl_magic_regdatum_set(aTHX_ a,b)
 #  endif
@@ -1550,9 +1550,6 @@
 #  if defined(HAS_PIPE)
 #define PerlProc_pipe_cloexec(a)	Perl_PerlProc_pipe_cloexec(aTHX_ a)
 #  endif
-#  if defined(HAS_SIGACTION) && defined(SA_SIGINFO)
-#define sighandler		Perl_sighandler
-#  endif
 #  if defined(HAS_SOCKET)
 #define PerlSock_accept_cloexec(a,b,c)	Perl_PerlSock_accept_cloexec(aTHX_ a,b,c)
 #define PerlSock_socket_cloexec(a,b,c)	Perl_PerlSock_socket_cloexec(aTHX_ a,b,c)
@@ -1944,6 +1941,9 @@
 #  if defined(PERL_USES_PL_PIDSTATUS) && defined(PERL_IN_UTIL_C)
 #define pidgone(a,b)		S_pidgone(aTHX_ a,b)
 #  endif
+#  if defined(PERL_USE_3ARG_SIGHANDLER)
+#define sighandler		Perl_sighandler
+#  endif
 #  if defined(USE_C_BACKTRACE)
 #define get_c_backtrace(a,b)	Perl_get_c_backtrace(aTHX_ a,b)
 #  endif
diff --git a/iperlsys.h b/iperlsys.h
index b4a92ea574..de2dad65bb 100644
--- a/iperlsys.h
+++ b/iperlsys.h
@@ -51,7 +51,7 @@
 #include "perlio.h"
 
 #ifndef Sighandler_t
-#  if defined(HAS_SIGACTION) && defined(SA_SIGINFO)
+#  ifdef PERL_USE_3ARG_SIGHANDLER
 typedef Signal_t (*Sighandler_t) (int, Siginfo_t*, void*);
 #  else
 typedef Signal_t (*Sighandler_t) (int);
diff --git a/mg.c b/mg.c
index 7b7bd5ac0f..998b4d8f92 100644
--- a/mg.c
+++ b/mg.c
@@ -62,7 +62,7 @@ tie.
 #  include <sys/prctl.h>
 #endif
 
-#if defined(HAS_SIGACTION) && defined(SA_SIGINFO)
+#ifdef PERL_USE_3ARG_SIGHANDLER
 Signal_t Perl_csighandler(int sig, Siginfo_t *, void *);
 #else
 Signal_t Perl_csighandler(int sig);
@@ -1487,7 +1487,7 @@ Perl_magic_clearsig(pTHX_ SV *sv, MAGIC *mg)
 }
 
 Signal_t
-#if defined(HAS_SIGACTION) && defined(SA_SIGINFO)
+#ifdef PERL_USE_3ARG_SIGHANDLER
 Perl_csighandler(int sig, Siginfo_t *sip PERL_UNUSED_DECL, void *uap PERL_UNUSED_DECL)
 #else
 Perl_csighandler(int sig)
@@ -1498,7 +1498,8 @@ Perl_csighandler(int sig)
 #else
     dTHX;
 #endif
-#if defined(HAS_SIGACTION) && defined(SA_SIGINFO)
+
+#ifdef PERL_USE_3ARG_SIGHANDLER
 #if defined(__cplusplus) && defined(__GNUC__)
     /* g++ doesn't support PERL_UNUSED_DECL, so the sip and uap
      * parameters would be warned about. */
@@ -1506,6 +1507,7 @@ Perl_csighandler(int sig)
     PERL_UNUSED_ARG(uap);
 #endif
 #endif
+
 #ifdef FAKE_PERSISTENT_SIGNAL_HANDLERS
     (void) rsignal(sig, PL_csighandlerp);
     if (PL_sig_ignoring[sig]) return;
@@ -1531,7 +1533,7 @@ Perl_csighandler(int sig)
 	   (PL_signals & PERL_SIGNALS_UNSAFE_FLAG))
 	/* Call the perl level handler now--
 	 * with risk we may be in malloc() or being destructed etc. */
-#if defined(HAS_SIGACTION) && defined(SA_SIGINFO)
+#ifdef PERL_USE_3ARG_SIGHANDLER
 	(*PL_sighandlerp)(sig, NULL, NULL);
 #else
 	(*PL_sighandlerp)(sig);
@@ -1613,7 +1615,7 @@ Perl_despatch_signals(pTHX)
 	    }
 #endif
  	    PL_psig_pend[sig] = 0;
-#if defined(HAS_SIGACTION) && defined(SA_SIGINFO)
+#ifdef PERL_USE_3ARG_SIGHANDLER
 	    (*PL_sighandlerp)(sig, NULL, NULL);
 #else
 	    (*PL_sighandlerp)(sig);
@@ -3318,7 +3320,7 @@ Perl_whichsig_pvn(pTHX_ const char *sig, STRLEN len)
 }
 
 Signal_t
-#if defined(HAS_SIGACTION) && defined(SA_SIGINFO)
+#ifdef PERL_USE_3ARG_SIGHANDLER
 Perl_sighandler(int sig, Siginfo_t *sip, void *uap)
 #else
 Perl_sighandler(int sig)
diff --git a/perl.h b/perl.h
index c94a1f48ad..7d7a465851 100644
--- a/perl.h
+++ b/perl.h
@@ -2794,6 +2794,10 @@ typedef struct padname PADNAME;
 #endif
 
 
+#if defined(HAS_SIGACTION) && defined(SA_SIGINFO)
+#  define PERL_USE_3ARG_SIGHANDLER
+#endif
+
 /* Siginfo_t:
  * This is an alias for the OS's siginfo_t, except that where the OS
  * doesn't support it, declare a dummy version instead. This allows us to
diff --git a/proto.h b/proto.h
index c3cd7c871d..8c3018f3cf 100644
--- a/proto.h
+++ b/proto.h
@@ -4094,12 +4094,6 @@ STATIC const char*	S_my_nl_langinfo(const int item, bool toggle);
 #define PERL_ARGS_ASSERT_MY_NL_LANGINFO
 #  endif
 #endif
-#if !(defined(HAS_SIGACTION) && defined(SA_SIGINFO))
-PERL_CALLCONV Signal_t	Perl_csighandler(int sig);
-#define PERL_ARGS_ASSERT_CSIGHANDLER
-PERL_CALLCONV Signal_t	Perl_sighandler(int sig);
-#define PERL_ARGS_ASSERT_SIGHANDLER
-#endif
 #if !(defined(PERL_DEFAULT_DO_EXEC3_IMPLEMENTATION))
 PERL_CALLCONV bool	Perl_do_exec(pTHX_ const char* cmd);
 #define PERL_ARGS_ASSERT_DO_EXEC	\
@@ -4112,6 +4106,12 @@ PERL_CALLCONV void*	Perl_my_cxt_init(pTHX_ int *indexp, size_t size);
 	assert(indexp)
 #  endif
 #endif
+#if !(defined(PERL_USE_3ARG_SIGHANDLER))
+PERL_CALLCONV Signal_t	Perl_csighandler(int sig);
+#define PERL_ARGS_ASSERT_CSIGHANDLER
+PERL_CALLCONV Signal_t	Perl_sighandler(int sig);
+#define PERL_ARGS_ASSERT_SIGHANDLER
+#endif
 #if !(defined(_MSC_VER))
 PERL_CALLCONV_NO_RET int	Perl_magic_regdatum_set(pTHX_ SV* sv, MAGIC* mg)
 			__attribute__noreturn__;
@@ -4564,12 +4564,6 @@ PERL_CALLCONV int	Perl_PerlProc_pipe_cloexec(pTHX_ int *pipefd)
 	assert(pipefd)
 
 #endif
-#if defined(HAS_SIGACTION) && defined(SA_SIGINFO)
-PERL_CALLCONV Signal_t	Perl_csighandler(int sig, Siginfo_t *info, void *uap);
-#define PERL_ARGS_ASSERT_CSIGHANDLER
-PERL_CALLCONV Signal_t	Perl_sighandler(int sig, Siginfo_t *info, void *uap);
-#define PERL_ARGS_ASSERT_SIGHANDLER
-#endif
 #if defined(HAS_SOCKET)
 PERL_CALLCONV int	Perl_PerlSock_accept_cloexec(pTHX_ int listenfd, struct sockaddr *addr, Sock_size_t *addrlen)
 			__attribute__warn_unused_result__;
@@ -6441,6 +6435,12 @@ PERL_CALLCONV Malloc_t	Perl_mem_log_realloc(const UV n, const UV typesize, const
 STATIC void	S_pidgone(pTHX_ Pid_t pid, int status);
 #define PERL_ARGS_ASSERT_PIDGONE
 #endif
+#if defined(PERL_USE_3ARG_SIGHANDLER)
+PERL_CALLCONV Signal_t	Perl_csighandler(int sig, Siginfo_t *info, void *uap);
+#define PERL_ARGS_ASSERT_CSIGHANDLER
+PERL_CALLCONV Signal_t	Perl_sighandler(int sig, Siginfo_t *info, void *uap);
+#define PERL_ARGS_ASSERT_SIGHANDLER
+#endif
 #if defined(UNLINK_ALL_VERSIONS)
 PERL_CALLCONV I32	Perl_unlnk(pTHX_ const char* f);
 #define PERL_ARGS_ASSERT_UNLNK	\