Update and cleanup the readline library support

This commit updates and simplifies the checks for the readline support
in nslookup and nsupdate:

  * Change the autoconf checks to pkg-config only, all supported
    libraries have accompanying .pc files now.
  * Add editline support in addition to libedit and GNU readline
  * Add isc/readline.h shim header that defines dummy readline()
    function when no readline library is available

Makefile.top

@@ -33,6 +33,11 @@ LIBISC_CFLAGS +=					\
 	$(LIBXML2_CFLAGS)
 endif HAVE_LIBXML2
 
+if HAVE_READLINE
+LIBISC_CFLAGS +=					\
+	$(READLINE_CFLAGS)
+endif HAVE_READLINE
+
 LIBISC_LIBS = $(top_builddir)/lib/isc/libisc.la
 
 LIBDNS_CFLAGS = \

bin/dig/Makefile.am

@@ -25,6 +25,10 @@ libdighost_la_SOURCES = \
 
 bin_PROGRAMS = dig host nslookup
 
-nslookup_LDADD =	\
-	$(LDADD)	\
-	$(READLINE_LIB)
+nslookup_LDADD =		\
+	$(LDADD)
+
+if HAVE_READLINE
+nslookup_LDADD +=		\
+	$(READLINE_LIBS)
+endif HAVE_READLINE

bin/dig/nslookup.c

@@ -22,6 +22,7 @@
 #include <isc/netaddr.h>
 #include <isc/parseint.h>
 #include <isc/print.h>
+#include <isc/readline.h>
 #include <isc/string.h>
 #include <isc/task.h>
 #include <isc/util.h>
@@ -38,27 +39,6 @@
 
 #include "dighost.h"
 
-#if defined(HAVE_READLINE)
-#if defined(HAVE_EDIT_READLINE_READLINE_H)
-#include <edit/readline/readline.h>
-#if defined(HAVE_EDIT_READLINE_HISTORY_H)
-#include <edit/readline/history.h>
-#endif /* if defined(HAVE_EDIT_READLINE_HISTORY_H) */
-#elif defined(HAVE_EDITLINE_READLINE_H)
-#include <editline/readline.h>
-#elif defined(HAVE_READLINE_READLINE_H)
-/* Prevent deprecated functions being declared. */
-#define _FUNCTION_DEF 1
-/* Ensure rl_message() gets prototype. */
-#define USE_VARARGS   1
-#define PREFER_STDARG 1
-#include <readline/readline.h>
-#if defined(HAVE_READLINE_HISTORY_H)
-#include <readline/history.h>
-#endif /* if defined(HAVE_READLINE_HISTORY_H) */
-#endif /* if defined(HAVE_EDIT_READLINE_READLINE_H) */
-#endif /* if defined(HAVE_READLINE) */
-
 static bool short_form = true, tcpmode = false, tcpmode_set = false,
 	    identify = false, stats = true, comments = true,
 	    section_question = true, section_answer = true,
@@ -853,38 +833,27 @@ do_next_command(char *input) {
 
 static void
 get_next_command(void) {
-	char *buf;
-	char *ptr;
+	char cmdlinebuf[COMMSIZE];
+	char *cmdline, *ptr = NULL;
 
-	fflush(stdout);
-	buf = isc_mem_allocate(mctx, COMMSIZE);
 	isc_app_block();
 	if (interactive) {
-#ifdef HAVE_READLINE
-		ptr = readline("> ");
-		if (ptr != NULL) {
+		cmdline = ptr = readline("> ");
+		if (ptr != NULL && *ptr != 0) {
 			add_history(ptr);
 		}
-#else  /* ifdef HAVE_READLINE */
-		fprintf(stderr, "> ");
-		fflush(stderr);
-		ptr = fgets(buf, COMMSIZE, stdin);
-#endif /* ifdef HAVE_READLINE */
 	} else {
-		ptr = fgets(buf, COMMSIZE, stdin);
+		cmdline = fgets(cmdlinebuf, COMMSIZE, stdin);
 	}
 	isc_app_unblock();
-	if (ptr == NULL) {
+	if (cmdline == NULL) {
 		in_use = false;
 	} else {
-		do_next_command(ptr);
+		do_next_command(cmdline);
 	}
-#ifdef HAVE_READLINE
-	if (interactive) {
+	if (ptr != NULL) {
 		free(ptr);
 	}
-#endif /* ifdef HAVE_READLINE */
-	isc_mem_free(mctx, buf);
 }
 
 ISC_NORETURN static void

bin/nsupdate/Makefile.am

@@ -18,8 +18,12 @@ LDADD =				\
 	$(LIBISCCFG_LIBS)	\
 	$(LIBIRS_LIBS)		\
 	$(LIBBIND9_LIBS)	\
-	$(READLINE_LIB)		\
 	$(GSSAPI_LIBS)		\
 	$(KRB5_LIBS)
 
+if HAVE_READLINE
+LDADD +=			\
+	$(READLINE_LIBS)
+endif
+
 bin_PROGRAMS = nsupdate

bin/nsupdate/nsupdate.c

@@ -36,6 +36,7 @@
 #include <isc/portset.h>
 #include <isc/print.h>
 #include <isc/random.h>
+#include <isc/readline.h>
 #include <isc/region.h>
 #include <isc/sockaddr.h>
 #include <isc/socket.h>
@@ -94,25 +95,6 @@
 
 #include <bind9/getaddresses.h>
 
-#if defined(HAVE_READLINE)
-#if defined(HAVE_EDIT_READLINE_READLINE_H)
-#include <edit/readline/readline.h>
-#if defined(HAVE_EDIT_READLINE_HISTORY_H)
-#include <edit/readline/history.h>
-#endif /* if defined(HAVE_EDIT_READLINE_HISTORY_H) */
-#elif defined(HAVE_EDITLINE_READLINE_H)
-#include <editline/readline.h>
-#else /* if defined(HAVE_EDIT_READLINE_READLINE_H) */
-/* Prevent deprecated functions being declared. */
-#define _FUNCTION_DEF 1
-/* Ensure rl_message() gets prototype. */
-#define USE_VARARGS   1
-#define PREFER_STDARG 1
-#include <readline/history.h>
-#include <readline/readline.h>
-#endif /* if defined(HAVE_EDIT_READLINE_READLINE_H) */
-#endif /* if defined(HAVE_READLINE) */
-
 #define MAXCMD	     (128 * 1024)
 #define MAXWIRE	     (64 * 1024)
 #define PACKETSIZE   ((64 * 1024) - 1)
@@ -2295,20 +2277,14 @@ static uint16_t
 get_next_command(void) {
 	uint16_t result = STATUS_QUIT;
 	char cmdlinebuf[MAXCMD];
-	char *cmdline;
+	char *cmdline = NULL, *ptr = NULL;
 
 	isc_app_block();
 	if (interactive) {
-#ifdef HAVE_READLINE
-		cmdline = readline("> ");
-		if (cmdline != NULL) {
-			add_history(cmdline);
-		}
-#else  /* ifdef HAVE_READLINE */
-		fprintf(stdout, "> ");
-		fflush(stdout);
-		cmdline = fgets(cmdlinebuf, MAXCMD, input);
-#endif /* ifdef HAVE_READLINE */
+		cmdline = ptr = readline("> ");
+		if (ptr != NULL && *ptr != 0) {
+			add_history(ptr);
+		}
 	} else {
 		cmdline = fgets(cmdlinebuf, MAXCMD, input);
 	}
@@ -2324,11 +2300,10 @@ get_next_command(void) {
 		(void)nsu_strsep(&tmp, "\r\n");
 		result = do_next_command(cmdline);
 	}
-#ifdef HAVE_READLINE
-	if (interactive) {
-		free(cmdline);
+	if (ptr != NULL) {
+		free(ptr);
 	}
-#endif /* ifdef HAVE_READLINE */
+
 	return (result);
 }
 

configure.ac

@@ -976,66 +976,39 @@ AS_IF([test "$enable_tcp_fastopen" = "yes"],
 #
 AC_CHECK_FUNCS([strlcpy strlcat])
 
-AC_SUBST(READLINE_LIB)
-AC_ARG_WITH(readline,
-	    AS_HELP_STRING([--with-readline[=LIBSPEC]],
-			   [specify readline library [default auto]]),
-	    use_readline="$withval", use_readline="auto")
-case "$use_readline" in
-no)	;;
-*)
-	saved_LIBS="$LIBS"
-	case "$use_readline" in
-	yes|auto) try_readline="-ledit"; or_readline="-lreadline" ;;
-	*) try_readline="$use_readline"
-	esac
-	for readline in "$try_readline" $or_readline
-	do
-		LIBS="$readline"
-		AC_MSG_NOTICE(checking for readline with $readline)
-		AC_CHECK_FUNCS(readline)
-		if test "yes" = "$ac_cv_func_readline"
-		then
-			READLINE_LIB="$readline"
-			break
-		fi
-		for lib in -lterminfo -ltermcap -lncurses -lcurses
-		do
-			AC_MSG_NOTICE(checking for readline with $readline $lib)
-			unset ac_cv_func_readline
-			LIBS="$readline $lib"
-			AC_CHECK_FUNCS(readline)
-			if test "yes" = "$ac_cv_func_readline"
-			then
-				READLINE_LIB="$readline $lib"
-				break
-			fi
-		done
-		if test "yes" = "$ac_cv_func_readline"
-		then
-			break
-		fi
-	done
-	if test "auto" != "$use_readline" &&
-	   test "X$READLINE_LIB" = "X"
-	then
-		AC_MSG_ERROR([The readline library was not found.])
-	fi
-	LIBS="$saved_LIBS"
-	;;
-esac
-if test "yes" = "$ac_cv_func_readline"
-then
-	case "$READLINE_LIB" in
-	*edit*)
-		AC_CHECK_HEADERS(editline/readline.h)
-		AC_CHECK_HEADERS(edit/readline/readline.h)
-		AC_CHECK_HEADERS(edit/readline/history.h)
-		;;
-	esac
-	AC_CHECK_HEADERS(readline/readline.h)
-	AC_CHECK_HEADERS(readline/history.h)
-fi
+#
+# Check for readline support
+#
+
+AC_ARG_WITH([readline],
+	    [AS_HELP_STRING([--with-readline=yes|no|libedit|readline],
+			    [specify readline library [default auto]])],
+	    [], [with_readline="auto"])
+
+AS_CASE([$with_readline],
+	[no],[],
+	[auto],
+	[PKG_CHECK_MODULES([READLINE], [libedit],
+			   [AC_DEFINE([HAVE_READLINE_LIBEDIT], [1], [Build with libedit support])],
+			   [PKG_CHECK_MODULES([READLINE], [editline],
+					      [AC_DEFINE([HAVE_READLINE_EDITLINE], [1], [Build with editline support.])],
+					      [PKG_CHECK_MODULES([READLINE], [readline],
+								 [AC_DEFINE([HAVE_READLINE_READLINE], [1], [Build with readline support.])],
+								 [AS_IF([test "$with_readline" = "yes"],
+									[AC_MSG_ERROR([readline support requested, but none of the libraries have been found.])])])])])],
+	[libedit],
+	[PKG_CHECK_MODULES([READLINE], [libedit],
+			   [AC_DEFINE([HAVE_READLINE_LIBEDIT], [1], [Build with libedit support])])],
+	[editline],
+	[PKG_CHECK_MODULES([READLINE], [editline],
+			   [AC_DEFINE([HAVE_READLINE_EDITLINE], [1], [Build with editline support])])],
+	[readline],
+	[PKG_CHECK_MODULES([READLINE], [readline],
+			   [AC_DEFINE([HAVE_READLINE_READLINE], [1], [Build with readline support])])],
+	[AC_MSG_ERROR([Unknown readline '$with_readline' library requested.])])
+AM_CONDITIONAL([HAVE_READLINE], [test -n "$READLINE_LIBS"])
+AC_SUBST([READLINE_CFLAGS])
+AC_SUBST([READLINE_LIBS])
 
 #
 # Security Stuff

lib/isc/Makefile.am

@@ -66,6 +66,7 @@ libisc_la_HEADERS =			\
 	include/isc/radix.h		\
 	include/isc/random.h		\
 	include/isc/ratelimiter.h	\
+	include/isc/readline.h		\
 	include/isc/refcount.h		\
 	include/isc/regex.h		\
 	include/isc/region.h		\

lib/isc/include/isc/readline.h

+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * See the COPYRIGHT file distributed with this work for additional
+ * information regarding copyright ownership.
+ */
+
+#pragma once
+
+/*
+ * A little wrapper around readline(), add_history() and free() to make using
+ * the readline code simpler.
+ */
+
+#if defined(HAVE_READLINE_LIBEDIT)
+#include <editline/readline.h>
+#elif defined(HAVE_READLINE_EDITLINE)
+#include <editline.h>
+#elif defined(HAVE_READLINE_READLINE)
+/* Prevent deprecated functions being declared. */
+#define _FUNCTION_DEF 1
+/* Ensure rl_message() gets prototype. */
+#define USE_VARARGS   1
+#define PREFER_STDARG 1
+#include <readline/history.h>
+#include <readline/readline.h>
+#endif
+
+#if !defined(HAVE_READLINE_LIBEDIT) && !defined(HAVE_READLINE_EDITLINE) && \
+	!defined(HAVE_READLINE_READLINE)
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#define RL_MAXCMD (128 * 1024)
+
+static inline char *
+readline(const char *prompt) {
+	char *line, *buf = malloc(RL_MAXCMD);
+	fprintf(stdout, "%s", prompt);
+	fflush(stdout);
+	line = fgets(buf, RL_MAXCMD, stdin);
+	if (line == NULL) {
+		free(buf);
+		return (NULL);
+	}
+	return (buf);
+};
+
+#define add_history(line)
+
+#endif

util/copyrights

@@ -1832,6 +1832,7 @@
 ./lib/isc/include/isc/radix.h			C	2007,2008,2013,2014,2016,2018,2019,2020
 ./lib/isc/include/isc/random.h			C	1999,2000,2001,2004,2005,2006,2007,2009,2014,2016,2017,2018,2019,2020
 ./lib/isc/include/isc/ratelimiter.h		C	1999,2000,2001,2002,2004,2005,2006,2007,2009,2014,2016,2018,2019,2020
+./lib/isc/include/isc/readline.h		C	2020
 ./lib/isc/include/isc/refcount.h		C	2001,2003,2004,2005,2006,2007,2009,2016,2017,2018,2019,2020
 ./lib/isc/include/isc/regex.h			C	2013,2016,2018,2019,2020
 ./lib/isc/include/isc/region.h			C	1998,1999,2000,2001,2002,2004,2005,2006,2007,2013,2016,2018,2019,2020