From 8b01b900086f83c7f59aa128fbda0b390a0178ed Mon Sep 17 00:00:00 2001
From: Mark Pizzolato <mark@infocomm.com>
Date: Thu, 17 Nov 2011 08:46:15 -0800
Subject: [PATCH] Generalized readline support to dynamically load the readline
 library and avoid the symbol conflicts which happen on some platforms and
 some simulators with a global PC variable.

---
 makefile | 33 ++++++++++++++-------------------
 scp.c    | 47 +++++++++++++++++++++++++++++++++++------------
 2 files changed, 49 insertions(+), 31 deletions(-)

diff --git a/makefile b/makefile
index 15d8375f..b7499af5 100644
--- a/makefile
+++ b/makefile
@@ -15,9 +15,6 @@
 # In general, the logic below will detect and build with the available 
 # features which the host build environment provides. 
 #
-# Readline support can be disabled if GNU make is invoked with 
-# DONT_USE_READLINE=1 on the command line.
-#
 # Internal ROM support can be disabled if GNU make is invoked with
 # DONT_USE_ROMS=1 on the command line.
 #
@@ -67,7 +64,11 @@ ifeq ($(WIN32),)  #*nix Environments (&& cygwin)
             LIBPATH += /usr/pkg/lib
             OS_LDFLAGS += -L/usr/pkg/lib -R/usr/pkg/lib
           endif
-          LIBEXT = a
+          ifneq (,$(findstring NetBSD,$(shell uname))$(findstring FreeBSD,$(shell uname)))
+            LIBEXT = so
+          else
+            LIBEXT = a
+          endif
         endif
       endif
     endif
@@ -92,21 +93,15 @@ ifeq ($(WIN32),)  #*nix Environments (&& cygwin)
       $(info using libpthread: $(call find_lib,pthread) $(call find_include,pthread))
     endif
   endif
-  ifeq ($(DONT_USE_READLINE),)
-    ifneq (,$(call find_include,readline/readline))
-      ifneq (,$(call find_lib,readline))
-        # Use Locally installed and available readline support
-        ifneq (,$(call find_lib,ncurses))
-          OS_CCDEFS += -DHAVE_READLINE 
-          OS_LDFLAGS += -lreadline -lncurses
-          $(info using libreadline and libncurses: $(call find_lib,readline) $(call find_lib,ncurses) $(call find_include,readline/readline))
-        else
-          ifneq (,$(call find_lib,curses))
-            OS_CCDEFS += -DHAVE_READLINE 
-            OS_LDFLAGS += -lreadline -lcurses
-            $(info using libreadline and libcurses: $(call find_lib,readline) $(call find_lib,curses) $(call find_include,readline/readline))
-          endif
-        endif
+  ifneq (,$(call find_include,dlfcn))
+    ifneq (,$(call find_lib,dl))
+      OS_CCDEFS += -DHAVE_DLOPEN=$(LIBEXT)
+      OS_LDFLAGS += -ldl
+      $(info using libdl: $(call find_lib,dl) $(call find_include,dlfcn))
+    else
+      ifeq (BSD,$(findstring BSD,$(shell uname)))
+        OS_CCDEFS += -DHAVE_DLOPEN=so
+        $(info using libdl: $(call find_include,dlfcn))
       endif
     endif
   endif
diff --git a/scp.c b/scp.c
index 9473b947..3920db7d 100644
--- a/scp.c
+++ b/scp.c
@@ -213,9 +213,8 @@
 #include <ctype.h>
 #include <time.h>
 
-#if defined(HAVE_READLINE)
-#include <readline/readline.h>
-#include <readline/history.h>
+#if defined(HAVE_DLOPEN)                                 /* Dynamic Readline support */
+#include <dlfcn.h>
 #endif
 
 #define EX_D            0                               /* deposit */
@@ -3841,15 +3840,39 @@ return read_line_p (NULL, cptr, size, stream);
 char *read_line_p (char *prompt, char *cptr, int32 size, FILE *stream)
 {
 char *tptr;
+#if defined(HAVE_DLOPEN)
+static int initialized = 0;
+static char *(*p_readline)(const char *) = NULL;
+static void (*p_add_history)(const char *) = NULL;
 
-#if defined(HAVE_READLINE)
+if (!initialized) {
+    initialized = 1;
+    void *handle;
+
+#define __STR_QUOTE(tok) #tok
+#define __STR(tok) __STR_QUOTE(tok)
+    handle = dlopen("libncurses." __STR(HAVE_DLOPEN), RTLD_NOW|RTLD_GLOBAL);
+    handle = dlopen("libreadline." __STR(HAVE_DLOPEN), RTLD_NOW|RTLD_GLOBAL);
+    if (handle) {
+        p_readline = dlsym(handle, "readline");
+        p_add_history = dlsym(handle, "add_history");
+        }
+    }
 if (prompt) {                                           /* interactive? */
-    char *tmpc = readline (prompt);                     /* get cmd line */
-    if (tmpc == NULL)                                   /* bad result? */
-        cptr = NULL;
+    char *tmpc;
+
+    if (p_readline) {
+        char *tmpc = p_readline (prompt);               /* get cmd line */
+        if (tmpc == NULL)                               /* bad result? */
+            cptr = NULL;
+        else {
+            strncpy (cptr, tmpc, size);                 /* copy result */
+            free (tmpc) ;                               /* free temp */
+            }
+        }
     else {
-        strncpy (cptr, tmpc, size);                     /* copy result */
-        free (tmpc) ;                                   /* free temp */
+        printf ("%s", prompt);                          /* display prompt */
+        cptr = fgets (cptr, size, stream);              /* get cmd line */
         }
     }
 else cptr = fgets (cptr, size, stream);                 /* get cmd line */
@@ -3875,9 +3898,9 @@ while (isspace (*cptr))                                 /* trim leading spc */
 if (*cptr == ';')                                       /* ignore comment */
     *cptr = 0;
 
-#if defined (HAVE_READLINE)
-if (prompt)
-    add_history (cptr);
+#if defined (HAVE_DLOPEN)
+if (prompt && p_add_history && *cptr)                   /* Save non blank lines in history */
+    p_add_history (cptr);
 #endif
 
 return cptr;