Fix I/O redirection in -c script (Solaris patch 280-23332860)

This change is pulled from here:
https://github.com/oracle/solaris-userland/blob/master/components/ksh93/patches/280-23332860.patch

Info and reproducers:
https://github.com/att/ast/issues/36

In a -c script (like ksh -c 'commands'), the last command
misredirects standard output if an EXIT or ERR trap is set.
This appears to be a side effect of the optimisation that
runs the last command without forking.

This applies a patch by George Lijo that flags these specific
cases and disables the optimisation.

src/cmd/ksh93/include/defs.h,
src/cmd/ksh93/bltins/trap.c,
src/cmd/ksh93/sh/init.c,
src/cmd/ksh93/sh/main.c,
src/cmd/ksh93/sh/xec.c:
- Apply patch as above.

src/cmd/ksh93/tests/io.sh:
- Add the reproducers from the bug report as regression tests.

src/cmd/ksh93/bltins/trap.c

@@ -127,6 +127,14 @@ int	b_trap(int argc,char *argv[],Shbltin_t *context)
 						shp->trapnote |= SH_SIGTRAP;
 					else
 						shp->trapnote = 0;
+
+				}
+				if(sig == SH_ERRTRAP)
+				{
+					if(clear)
+						shp->errtrap = 0;
+					else if(!shp->fn_depth || shp->end_fn)
+						shp->errtrap = 1;
 				}
 				continue;
 			}
@@ -144,6 +152,8 @@ int	b_trap(int argc,char *argv[],Shbltin_t *context)
 			else if(clear)
 			{
 				sh_sigclear(sig);
+				if(sig == 0)
+					shp->exittrap = 0;
 				if(dflag)
 					signal(sig,SIG_DFL);
 			}
@@ -156,6 +166,8 @@ int	b_trap(int argc,char *argv[],Shbltin_t *context)
 				shp->st.trapcom[sig] = (shp->sigflag[sig]&SH_SIGOFF) ? Empty : strdup(action);
 				if(arg && arg != Empty)
 					free(arg);
+				if(sig == 0 && (!shp->fn_depth || shp->end_fn))
+					shp->exittrap = 1;
 			}
 		}
 	}

src/cmd/ksh93/include/defs.h

@@ -272,7 +272,10 @@ struct shared
 	Namfun_t	nvfun; \
 	char		*mathnodes; \
 	char		*bltin_dir; \
-	struct Regress_s*regress;
+	struct Regress_s*regress; \
+	char 		exittrap; \
+	char 		errtrap; \
+	char 		end_fn;
 
 #include	<shell.h>
 

src/cmd/ksh93/sh/init.c

@@ -1479,6 +1479,9 @@ Shell_t *sh_init(register int argc,register char *argv[], Shinit_f userinit)
 #endif
 	if(shp->userinit=userinit)
 		(*userinit)(shp, 0);
+	shp->exittrap = 0;
+	shp->errtrap = 0;
+	shp->end_fn = 0;
 	return(shp);
 }
 
@@ -1580,6 +1583,9 @@ int sh_reinit(char *argv[])
 	shp->inpipe = shp->outpipe = 0;
 	job_clear();
 	job.in_critical = 0;
+	shp->exittrap = 0;
+	shp->errtrap = 0;
+	shp->end_fn = 0;
 	/* update ${.sh.pid}, $$, $PPID */
 	shgd->current_pid = shgd->pid = getpid();
 	shgd->ppid = getppid();

src/cmd/ksh93/sh/main.c

@@ -455,6 +455,9 @@ static void	exfile(register Shell_t *shp, register Sfio_t *iop,register int fno)
 	error_info.line = 1;
 	shp->inlineno = 1;
 	shp->binscript = 0;
+	shp->exittrap = 0;
+	shp->errtrap = 0;
+	shp->end_fn = 0;
 	if(sfeof(iop))
 		goto eof_or_error;
 	/* command loop */

src/cmd/ksh93/sh/xec.c

@@ -987,6 +987,8 @@ int sh_exec(register const Shnode_t *t, int flags)
 		shp->exitval=0;
 		shp->lastsig = 0;
 		shp->lastpath = 0;
+		if(shp->exittrap || shp->errtrap)
+			execflg = 0;
 		switch(type&COMMSK)
 		{
 		    case TCOM:
@@ -3119,6 +3121,8 @@ int sh_funscope(int argn, char *argv[],int(*fun)(void*),void *arg,int execflg)
 		nv_putval(SH_PATHNAMENOD,shp->st.filename,NV_NOFREE);
 		nv_putval(SH_FUNNAMENOD,shp->st.funname,NV_NOFREE);
 	}
+	if((execflg & sh_state(SH_NOFORK)))
+		shp->end_fn = 1;
 	jmpval = sigsetjmp(buffp->buff,0);
 	if(jmpval == 0)
 	{
@@ -3166,6 +3170,7 @@ int sh_funscope(int argn, char *argv[],int(*fun)(void*),void *arg,int execflg)
 	shp->st = *prevscope;
 	shp->topscope = (Shscope_t*)prevscope;
 	nv_getval(sh_scoped(shp,IFSNOD));
+	shp->end_fn = 0;
 	if(nsig)
 	{
 		for (isig = 0; isig < nsig; ++isig)

src/cmd/ksh93/tests/io.sh

@@ -649,5 +649,53 @@ err=$(
 ((!(e = $?))) || err_exit 'crash on null-command redirection with DEBUG trap' \
 	"(got status $e$( ((e>128)) && print -n / && kill -l "$e"), $(printf %q "$got"))"
 
+# ======
+# stdout was misdirected if an EXIT/ERR trap handler was defined in a -c script
+# https://github.com/att/ast/issues/36
+exp=$'exit to stdout\ntrap to stdout'
+exp2=$'exit to file\ntrap to file'
+got=$(export tmp; "$SHELL" -ec \
+'	function log
+	{
+		echo "$* to stdout"
+		echo "$* to file" >> $tmp/ast36_a.test.log
+	}
+	function test_exit
+	{
+		log trap
+	}
+	trap test_exit EXIT
+	log exit
+')
+[[ $got == "$exp" ]] || err_exit 'stdout misdirected to file with EXIT/ERR trap defined (1)' \
+	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
+[[ $(< $tmp/ast36_a.test.log) == "$exp2" ]] || err_exit 'stdout not correctly redirected to file with EXIT/ERR trap defined (1)' \
+	"(expected $(printf %q "$exp2"), wrote $(printf %q "$(< $tmp/ast36_a.test.log)"))"
+
+exp=$'trap to stdout\nexit to stdout'
+exp2=$'trap to file\nexit to file'
+got=$(export tmp; "$SHELL" -ec \
+'	function log
+	{
+		echo "$* to stdout"
+		echo "$* to file" >> $tmp/ast36_b.test.log
+	}
+	function test_exit
+	{
+		trap test_exittrap EXIT
+		log trap
+	}
+	function test_exittrap
+	{
+		log exit
+	}
+	test_exit
+')
+[[ $got == "$exp" ]] || err_exit 'stdout misdirected to file with EXIT/ERR trap defined (2)' \
+	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
+[[ $(< $tmp/ast36_b.test.log) == "$exp2" ]] || err_exit 'stdout not correctly redirected to file with EXIT/ERR trap defined (2)' \
+	"(expected $(printf %q "$exp2"), wrote $(printf %q "$(< $tmp/ast36_b.test.log)"))"
+
+
 # ======
 exit $((Errors<125?Errors:125))