read -s: initialise history file in time for reading

When emacs or vi mode is activated in a script, 'read -s' should
allow the user to arrow up to the current shell history file
($HISTFILE, default ~/.sh_history). But it looks like the history
file is not properly initialised for 'read -s' as it does not work
on the first invocation:

$ ksh -c 'set -o emacs; read -s foo'
(type up arrow; beep -- before 7bfcd1e, infinite loop)

$ ksh -c 'set -o emacs; read -s foo; read -s foo'
(type return, then up arrow; shell history appears)

src/cmd/ksh93/bltins/read.c: sh_readline():
- Move the code block that initialises the shell history file to
  immediately before where the first read operation is performed.

Discussion: #701 (comment)

NEWS

@@ -8,6 +8,10 @@ Uppercase BUG_* IDs are shell bug IDs as used by the Modernish shell library.
   an infinite loop after using the up arrow in emacs mode with an empty
   history file.
 
+- Fixed a bug in 'read -s': in a script, the first invocation of that
+  command, with the emacs or vi shell option on, did not allow the user to
+  navigate through the shell history file.
+
 2024-01-11:
 
 - Fixed ancient incorrect behaviour in the 'kill' built-in: it sent SIGCONT

src/cmd/ksh93/bltins/read.c

@@ -361,6 +361,14 @@ int sh_readline(char **names, volatile int fd, int flags, ssize_t size, long tim
 		if(timeout)
 	                timeslot = sh_timeradd(timeout,0,timedout,iop);
 	}
+#if !SHOPT_SCRIPTONLY
+	if((flags&S_FLAG) && !sh.hist_ptr)
+	{
+		sh_histinit();
+		if(!sh.hist_ptr)
+			flags &= ~S_FLAG;
+	}
+#endif
 	if(flags&(N_FLAG|NN_FLAG))
 	{
 		char buf[256],*var=buf,*cur,*end,*up,*v;
@@ -516,14 +524,6 @@ int sh_readline(char **names, volatile int fd, int flags, ssize_t size, long tim
 	}
 	if(timeslot)
 		sh_timerdel(timeslot);
-#if !SHOPT_SCRIPTONLY
-	if((flags&S_FLAG) && !sh.hist_ptr)
-	{
-		sh_histinit();
-		if(!sh.hist_ptr)
-			flags &= ~S_FLAG;
-	}
-#endif
 	if(cp)
 	{
 		cpmax = cp + c;

src/cmd/ksh93/tests/pty.sh

@@ -1267,5 +1267,16 @@ r ^:child-1: kill -s HUP \$\$\r\n$
 r ^Hangup\r\n$
 !
 
+((SHOPT_VSH)) && HISTFILE=$tmp/tmp_histfile tst $LINENO <<"!"
+L 'read -s' reads from history file on first go
+
+d 40
+p :test-1:
+w "$SHELL" -o vi -c 'read -s "foo?:prompt: "'
+p :prompt:
+c \Ek
+r ^:prompt: "\$SHELL" -o vi -c 'read -s "foo\?:prompt: "'$
+!
+
 # ======
 exit $((Errors<125?Errors:125))