Fix for `Bug#219343 backslash is swallowed in HERE document' from OpenBSD:
       * exec.c (1.42), lex.c (1.37), lex.h (1.10): Fix " handling in here
         documents. POSIX says they are not special, so cat << EOF \" EOF
         should print \" Fixes PR 4472; testing jmc@ and Adam Montague. ok
(from OpenBSD)

Index: pdksh-5.2.14/exec.c
===================================================================
--- pdksh-5.2.14.orig/exec.c	2009-09-17 00:32:31.000000000 +0200
+++ pdksh-5.2.14/exec.c	2009-09-17 00:32:59.000000000 +0200
@@ -1480,7 +1480,7 @@
 		s = pushs(SSTRING, ATEMP);
 		s->start = s->str = content;
 		source = s;
-		if (yylex(ONEWORD) != LWORD)
+		if (yylex(ONEWORD|HEREDOC) != LWORD)
 			internal_errorf(1, "herein: yylex");
 		source = osource;
 		shf_puts(evalstr(yylval.cp, 0), shf);
Index: pdksh-5.2.14/lex.c
===================================================================
--- pdksh-5.2.14.orig/lex.c	2009-09-17 00:32:52.000000000 +0200
+++ pdksh-5.2.14/lex.c	2009-09-17 00:32:59.000000000 +0200
@@ -240,10 +240,16 @@
 			  case '\\':
 				c = getsc();
 				switch (c) {
-				  case '"': case '\\':
+				  case '\\':
 				  case '$': case '`':
 					*wp++ = QCHAR, *wp++ = c;
 					break;
+				  case '"':
+					if ((cf & HEREDOC) == 0) {
+						*wp++ = QCHAR, *wp++ = c;
+						break;
+					}
+					/* FALLTROUGH */
 				  default:
 					Xcheck(ws, wp);
 					if (c) { /* trailing \ is lost */
Index: pdksh-5.2.14/lex.h
===================================================================
--- pdksh-5.2.14.orig/lex.h	2009-09-17 00:31:55.000000000 +0200
+++ pdksh-5.2.14/lex.h	2009-09-17 00:32:59.000000000 +0200
@@ -113,6 +113,7 @@
 #define ESACONLY BIT(7)		/* only accept esac keyword */
 #define CMDWORD BIT(8)		/* parsing simple command (alias related) */
 #define HEREDELIM BIT(9)	/* parsing <<,<<- delimiter */
+#define HEREDOC BIT(10)		/* parsing heredoc */
 
 #define	HERES	10		/* max << in line */