Re: [PATCH] Portability of dash to legacy systems, such as AT&T Unix PC : 12-sigaction

[Alain Knaff <alain@xxxxxxxx>]

Hi,

The 12th patch tests for availability of sigaction, and uses signal
instead if not available.

Without sigaction, signals have to be re-activated once triggered,
because signal does an implicit SA_RESETHAND on SYSV platforms.

Regards,

Alain

diff -X ../exclude.txt -urN dash-0.5.12+11-simplify-wait-loop/configure.ac dash-0.5.12+12-sigaction/configure.ac
--- dash-0.5.12+11-simplify-wait-loop/configure.ac	2024-11-10 17:06:50.301341251 +0000
+++ dash-0.5.12+12-sigaction/configure.ac	2024-11-10 17:08:01.155025888 +0000
@@ -73,6 +73,17 @@
 AC_TYPE_SSIZE_T
 AC_TYPE_UINT32_T
 
+AC_CHECK_TYPE([sig_atomic_t],,AC_DEFINE_UNQUOTED([sig_atomic_t],int,[Define atomic signal type]),[
+AC_INCLUDES_DEFAULT
+#include <signal.h>
+])
+
+AC_CHECK_TYPE([sigset_t],,AC_DEFINE_UNQUOTED([sigset_t],int,[Define type for signal mask, may be int where signal blocking is not supported at all]),[
+AC_INCLUDES_DEFAULT
+#include <signal.h>
+])
+
+
 AC_CHECK_TYPE([intmax_t],,AC_DEFINE_UNQUOTED([intmax_t],long,[Define intmax_t type, must also be supported by printf]))
 
 AC_CHECK_TYPE([uintmax_t],,AC_DEFINE_UNQUOTED([uintmax_t],unsigned long,[Define uintmax_t type, must also be supported by printf]))
@@ -106,7 +117,7 @@
 	       mempcpy memmove \
 	       sigsetmask stpcpy strchrnul strsignal strtod strtoimax \
 	       strtoumax sysconf \
-	       vfork lstat dup2 getgroups \
+	       vfork sigaction sigprocmask lstat dup2 getgroups \
 	       strstr stpncpy strcasecmp strerror strdup strtoul vsnprintf \
 	       readdir)
 
diff -X ../exclude.txt -urN dash-0.5.12+11-simplify-wait-loop/src/system.h dash-0.5.12+12-sigaction/src/system.h
--- dash-0.5.12+11-simplify-wait-loop/src/system.h	2024-11-10 16:26:48.720196946 +0000
+++ dash-0.5.12+12-sigaction/src/system.h	2024-11-10 16:26:47.464166999 +0000
@@ -48,9 +48,11 @@
 #pragma GCC diagnostic pop
 #endif
 #else
+# ifdef HAVE_SIGPROCMASK
 	sigset_t set;
 	sigemptyset(&set);
 	sigprocmask(SIG_SETMASK, &set, 0);
+# endif
 #endif
 }
 
diff -X ../exclude.txt -urN dash-0.5.12+11-simplify-wait-loop/src/trap.c dash-0.5.12+12-sigaction/src/trap.c
--- dash-0.5.12+11-simplify-wait-loop/src/trap.c	2024-11-10 14:59:12.583223512 +0000
+++ dash-0.5.12+12-sigaction/src/trap.c	2024-11-10 20:26:44.222071158 +0000
@@ -181,7 +181,16 @@
 	int action;
 	int lvforked;
 	char *t, tsig;
+#ifdef HAVE_SIGACTION
 	struct sigaction act;
+#define SIGNAL(signo) sigaction(signo, &act,0)
+#define HDLR act.sa_handler
+#else
+	typedef void (*sighandler_t)(int);
+	sighandler_t hdlr;
+#define SIGNAL(signo) signal(signo, hdlr)	
+#define HDLR hdlr
+#endif
 
 	lvforked = vforked;
 
@@ -222,6 +231,7 @@
 
 	t = &sigmode[signo - 1];
 	tsig = *t;
+#ifdef HAVE_SIGACTION
 	if (tsig == 0) {
 		/*
 		 * current setting unknown
@@ -244,23 +254,28 @@
 			tsig = S_RESET;	/* force to be set */
 		}
 	}
-	if (tsig == S_HARD_IGN || tsig == action)
+	if (tsig == action)
+		return;
+#endif
+	if (tsig == S_HARD_IGN)
 		return;
 	switch (action) {
 	case S_CATCH:
-		act.sa_handler = onsig;
+		HDLR = onsig;
 		break;
 	case S_IGN:
-		act.sa_handler = SIG_IGN;
+		HDLR = SIG_IGN;
 		break;
 	default:
-		act.sa_handler = SIG_DFL;
+		HDLR = SIG_DFL;
 	}
 	if (!lvforked)
 		*t = action;
+#ifdef HAVE_SIGACTION
 	act.sa_flags = 0;
 	sigfillset(&act.sa_mask);
-	sigaction(signo, &act, 0);
+#endif
+	SIGNAL(signo);
 }
 
 /*
@@ -286,6 +301,9 @@
 void
 onsig(int signo)
 {
+#ifndef HAVE_SIGACTION
+	signal(signo, onsig);
+#endif
 	if (vforked)
 		return;
 
@@ -441,8 +459,13 @@
 
 void sigblockall(sigset_t *oldmask)
 {
+#ifdef HAVE_SIGPROCMASK
 	sigset_t mask;
 
 	sigfillset(&mask);
 	sigprocmask(SIG_SETMASK, &mask, oldmask);
+#else
+	if(oldmask)
+		*oldmask = 0;
+#endif
 }