Properly fix ignored SIGINT on interactive (re: 55dc80c, 7e5fd3e)

The kludge added in the first referenced commit was one I found
experimentally without understanding it properly at the time.

It was necessary because the Red Hat patch kept the subsequent
siglongjmp() after changing the sh_fault() call to killpg().

But changing it to killpg() made the siglongjmp inappropriate
either way: it is not reached if SIGINT is handled, and it should
not be executed if SIGINT is ignored.

So, that kludge was actually a compensation for the latter case.

src/cmd/ksh93/edit/edit.c:
- Remove the siglongjmp() call so that ed_getchar() simply
  continues as if nothing happened if the killpg() call returns.
  This means the interrupt character is now ignored properly along
  with SIGINT and longer causes a new prompt to be started.
     (If the interrupt character hasn't been changed from the
  default Ctrl+C using 'stty intr', then in emacs, the Ctrl+C
  feature (capitalise current character) is exposed as a result.)

src/cmd/ksh93/sh/main.c:
- Remove the kludge added to exfile().

src/cmd/ksh93/edit/edit.c

@@ -943,10 +943,7 @@ int ed_getchar(Edit_t *ep,int mode)
 		if((c = ep->e_lbuf[--ep->e_lookahead]) < 0)
 		{
 			if(mode<=0 && -c == ep->e_intr)
-			{
 				killpg(getpgrp(),SIGINT);
-				siglongjmp(ep->e_env, UINTR);
-			}
 			if(mode<=0 && sh.st.trap[SH_KEYTRAP]
 			/* workaround for <https://github.com/ksh93/ksh/issues/307>:
 			 * do not trigger KEYBD for non-ASCII in multibyte locale */

src/cmd/ksh93/include/version.h

@@ -18,7 +18,7 @@
 
 #define SH_RELEASE_FORK	"93u+m"		/* only change if you develop a new ksh93 fork */
 #define SH_RELEASE_SVER	"1.1.0-alpha"	/* semantic version number: https://semver.org */
-#define SH_RELEASE_DATE	"2024-02-11"	/* must be in this format for $((.sh.version)) */
+#define SH_RELEASE_DATE	"2024-02-12"	/* must be in this format for $((.sh.version)) */
 #define SH_RELEASE_CPYR	"(c) 2020-2024 Contributors to ksh " SH_RELEASE_FORK
 
 /* Scripts sometimes field-split ${.sh.version}, so don't change amount of whitespace. */

src/cmd/ksh93/sh/main.c

@@ -550,12 +550,6 @@ static void	exfile(Sfio_t *iop,int fno)
 					else if(job_close()<0)
 						continue;
 				}
-				else if(errno)
-				{
-					/* Ctrl+C with SIGINT ignored */
-					sfputc(sfstderr,'\n');
-					continue;
-				}
 			}
 			else if(errno && sferr)
 			{

src/cmd/ksh93/tests/pty.sh

@@ -957,6 +957,11 @@ r : \.\./\r\n$
 tst $LINENO <<"!"
 L Ctrl+C with SIGINT ignored
 # https://github.com/ksh93/ksh/issues/343
+# Fix improved on 2024-02-12.
+# Note: without emacs, the Ctrl+C should be echoed as ^C.
+#
+# TODO: a bug in the regex engine seems to make it impossible to match a
+# literal '^' in any way, so we substitute a '.' metacharacter for now.
 
 d 40
 
@@ -966,20 +971,16 @@ w PS1=':child-!: ' "$SHELL"
 p :child-1:
 w trap '' INT
 p :child-2:
-c \\\cC
-r :child-2:
-w echo "OK $PS1"
-u ^OK :child-!: \r\n$
+w : lorem\cCipsum
+r ^:child-2: : lorem.Cipsum\r\n$
 w exit
 
 # SIGINT ignored by parent
 p :test-2:
 w (trap '' INT; ENV=/./dev/null PS1=':child-!: ' "$SHELL")
 p :child-1:
-c \\\cC
-r :child-1:
-w echo "OK $PS1"
-u ^OK :child-!: \r\n$
+w : lorem\cCipsum
+r ^:child-1: : lorem.Cipsum\r\n$
 w exit
 
 # SIGINT ignored by parent, trapped in child
@@ -988,10 +989,8 @@ w (trap '' INT; ENV=/./dev/null PS1=':child-!: ' "$SHELL")
 p :child-1:
 w trap 'echo test' INT
 p :child-2:
-c \\\cC
-r :child-2:
-w echo "OK $PS1"
-u ^OK :child-!: \r\n$
+w : lorem\cCipsum
+r ^:child-2: : lorem.Cipsum\r\n$
 w exit
 !
 
@@ -1080,20 +1079,29 @@ u @ !non_existent\r\n$
 
 ((SHOPT_VSH)) && tst $LINENO <<"!"
 L reverse search isn't canceled after an interrupt in vi mode
+# note: must unignore SIGINT with undocumented 'trap + INT'
 
 d 15
 p :test-1:
-w echo WRONG
+w trap + INT; echo WRONG
+r echo WRONG
+r WRONG
 p :test-2:
 w print CORREC
+r print CORREC
+r CORREC
 p :test-3:
 w echo foo
+r echo foo
+r foo
 p :test-4:
 w sleep 0
+r sleep 0
 p :test-5:
 c e\E[A\E[A\cC\E[A\E[A\E[A
 w $aT
-u CORRECT
+r :test-5:
+r :test-5: print CORRECT
 !
 
 ((SHOPT_ESH)) && VISUAL=emacs tst $LINENO <<"!"