Make it possible to load Perl dynamically on Unix. (James Vega)
diff --git a/src/Makefile b/src/Makefile
index 5d858bd..59aca22 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -384,8 +384,10 @@
 #CONF_OPT_PLTHOME  = --with-plthome=/home/me/mz
 
 # PERL
-# Uncomment this when you want to include the Perl interface.
+# Uncomment one of these when you want to include the Perl interface.
+# First one is for static linking, second one for dynamic loading.
 # The Perl option sometimes causes problems, because it adds extra flags
+#
 # to the command line.	If you see strange flags during compilation, check in
 # auto/config.mk where they come from.  If it's PERL_CFLAGS, try commenting
 # the next line.
@@ -393,6 +395,7 @@
 # one: "touch perl.exp".
 # This requires at least "small" features, "tiny" doesn't work.
 #CONF_OPT_PERL = --enable-perlinterp
+#CONF_OPT_PERL = --enable-perlinterp=dynamic
 
 # PYTHON
 # Uncomment this when you want to include the Python interface.
@@ -1311,7 +1314,7 @@
 .SUFFIXES: .c .o .pro
 
 PRE_DEFS = -Iproto $(DEFS) $(GUI_DEFS) $(GUI_IPATH) $(CPPFLAGS) $(EXTRA_IPATHS)
-POST_DEFS = $(X_CFLAGS) $(LUA_CFLAGS) $(MZSCHEME_CFLAGS) $(PERL_CFLAGS) $(ECL_CFLAGS) $(TCL_CFLAGS) $(RUBY_CFLAGS) $(EXTRA_DEFS)
+POST_DEFS = $(X_CFLAGS) $(LUA_CFLAGS) $(MZSCHEME_CFLAGS) $(TCL_CFLAGS) $(RUBY_CFLAGS) $(EXTRA_DEFS)
 
 ALL_CFLAGS = $(PRE_DEFS) $(CFLAGS) $(PROFILE_CFLAGS) $(POST_DEFS)
 
@@ -2494,10 +2497,10 @@
 	$(MZSCHEME_MZC) --c-mods mzscheme_base.c ++lib scheme/base
 
 objects/if_perl.o: auto/if_perl.c
-	$(CCC) -o $@ auto/if_perl.c
+	$(CCC) $(PERL_CFLAGS) -o $@ auto/if_perl.c
 
 objects/if_perlsfio.o: if_perlsfio.c
-	$(CCC) -o $@ if_perlsfio.c
+	$(CCC) $(PERL_CFLAGS) -o $@ if_perlsfio.c
 
 objects/py_config.o: $(PYTHON_CONFDIR)/config.c
 	$(CCC) $(PYTHON_CFLAGS) -o $@ $(PYTHON_CONFDIR)/config.c \
diff --git a/src/auto/configure b/src/auto/configure
index 9d7a719..12ec721 100755
--- a/src/auto/configure
+++ b/src/auto/configure
@@ -1423,7 +1423,7 @@
   --disable-xsmp-interact Disable XSMP interaction
   --enable-luainterp      Include Lua interpreter.
   --enable-mzschemeinterp   Include MzScheme interpreter.
-  --enable-perlinterp     Include Perl interpreter.
+  --enable-perlinterp=OPTS     Include Perl interpreter.  default=no OPTS=no/yes/dynamic
   --enable-pythoninterp   Include Python interpreter.
   --enable-python3interp   Include Python3 interpreter.
   --enable-tclinterp      Include Tcl interpreter.
@@ -4241,7 +4241,7 @@
     */*) ;;
     no)
       # avoid adding local dir to LDFLAGS and CPPFLAGS
-      have_local_dir=yes
+      have_local_include=yes
       have_local_lib=yes
       ;;
     *) as_fn_error "must pass path argument to --with-local-dir" "$LINENO" 5 ;;
@@ -4924,7 +4924,7 @@
 
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: $enable_perlinterp" >&5
 $as_echo "$enable_perlinterp" >&6; }
-if test "$enable_perlinterp" = "yes"; then
+if test "$enable_perlinterp" = "yes" -o "$enable_perlinterp" = "dynamic"; then
 
   # Extract the first word of "perl", so it can be a program name with args.
 set dummy perl; ac_word=$2
@@ -4971,6 +4971,7 @@
 $as_echo_n "checking Perl version... " >&6; }
     if $vi_cv_path_perl -e 'require 5.003_01' >/dev/null 2>/dev/null; then
      eval `$vi_cv_path_perl -V:usethreads`
+     eval `$vi_cv_path_perl -V:libperl`
      if test "X$usethreads" = "XUNKNOWN" -o "X$usethreads" = "Xundef"; then
        badthreads=no
      else
@@ -5077,6 +5078,13 @@
       PERL_LIBS="-L$darwindir/CORE -lperl"
     fi
   fi
+  if test "$enable_perlinterp" = "dynamic"; then
+    if test "$perl_ok" = "yes" -a "X$libperl" != "X"; then
+      $as_echo "#define DYNAMIC_PERL 1" >>confdefs.h
+
+      PERL_CFLAGS="-DDYNAMIC_PERL_DLL=\\\"$libperl\\\" $PERL_CFLAGS"
+    fi
+  fi
 fi
 
 
diff --git a/src/config.h.in b/src/config.h.in
index 5570f2b..3e86b84 100644
--- a/src/config.h.in
+++ b/src/config.h.in
@@ -325,6 +325,9 @@
 /* Define if you want to include the Perl interpreter. */
 #undef FEAT_PERL
 
+/* Define for linking via dlopen() or LoadLibrary() */
+#undef DYNAMIC_PERL
+
 /* Define if you want to include the Python interpreter. */
 #undef FEAT_PYTHON
 
diff --git a/src/configure.in b/src/configure.in
index 112f8a6..b10d5c9 100644
--- a/src/configure.in
+++ b/src/configure.in
@@ -213,7 +213,7 @@
     */*) ;;
     no)
       # avoid adding local dir to LDFLAGS and CPPFLAGS
-      have_local_dir=yes
+      have_local_include=yes
       have_local_lib=yes
       ;;
     *) AC_MSG_ERROR(must pass path argument to --with-local-dir) ;;
@@ -620,16 +620,17 @@
 
 AC_MSG_CHECKING(--enable-perlinterp argument)
 AC_ARG_ENABLE(perlinterp,
-	[  --enable-perlinterp     Include Perl interpreter.], ,
+	[  --enable-perlinterp[=OPTS]     Include Perl interpreter.  [default=no] [OPTS=no/yes/dynamic]], ,
 	[enable_perlinterp="no"])
 AC_MSG_RESULT($enable_perlinterp)
-if test "$enable_perlinterp" = "yes"; then
+if test "$enable_perlinterp" = "yes" -o "$enable_perlinterp" = "dynamic"; then
   AC_SUBST(vi_cv_path_perl)
   AC_PATH_PROG(vi_cv_path_perl, perl)
   if test "X$vi_cv_path_perl" != "X"; then
     AC_MSG_CHECKING(Perl version)
     if $vi_cv_path_perl -e 'require 5.003_01' >/dev/null 2>/dev/null; then
      eval `$vi_cv_path_perl -V:usethreads`
+     eval `$vi_cv_path_perl -V:libperl`
      if test "X$usethreads" = "XUNKNOWN" -o "X$usethreads" = "Xundef"; then
        badthreads=no
      else
@@ -722,6 +723,12 @@
       PERL_LIBS="-L$darwindir/CORE -lperl"
     fi
   fi
+  if test "$enable_perlinterp" = "dynamic"; then
+    if test "$perl_ok" = "yes" -a "X$libperl" != "X"; then
+      AC_DEFINE(DYNAMIC_PERL)
+      PERL_CFLAGS="-DDYNAMIC_PERL_DLL=\\\"$libperl\\\" $PERL_CFLAGS"
+    fi
+  fi
 fi
 AC_SUBST(shrpenv)
 AC_SUBST(PERL_SRC)
diff --git a/src/if_perl.xs b/src/if_perl.xs
index 1a83de4..636e704 100644
--- a/src/if_perl.xs
+++ b/src/if_perl.xs
@@ -84,9 +84,32 @@
 EXTERN_C void boot_DynaLoader __ARGS((pTHX_ CV*));
 
 /*
- * For dynamic linked perl. (Windows)
+ * For dynamic linked perl.
  */
 #if defined(DYNAMIC_PERL) || defined(PROTO)
+
+#ifndef DYNAMIC_PERL /* just generating prototypes */
+#ifdef _MSWIN
+typedef int HANDLE;
+#endif
+typedef int XSINIT_t;
+typedef int XSUBADDR_t;
+typedef int perl_key;
+#endif
+
+#ifndef _MSWIN
+#include <dlfcn.h>
+#define HANDLE void*
+#define PERL_PROC void*
+#define load_dll(n) dlopen((n), RTLD_LAZY|RTLD_GLOBAL)
+#define symbol_from_dll dlsym
+#define close_dll dlclose
+#else
+#define PERL_PROC FARPROC
+#define load_dll LoadLibrary
+#define symbol_from_dll GetProcAddress
+#define close_dll FreeLibrary
+#endif
 /*
  * Wrapper defines
  */
@@ -173,6 +196,7 @@
 # define Perl_Ierrgv_ptr dll_Perl_Ierrgv_ptr
 # define Perl_Isv_yes_ptr dll_Perl_Isv_yes_ptr
 # define boot_DynaLoader dll_boot_DynaLoader
+# define Perl_Gthr_key_ptr dll_Perl_Gthr_key_ptr
 
 # define Perl_sys_init dll_Perl_sys_init
 # define Perl_sys_term dll_Perl_sys_term
@@ -191,12 +215,6 @@
 # define Perl_Iscopestack_ix_ptr dll_Perl_Iscopestack_ix_ptr
 # define Perl_Iunitcheckav_ptr dll_Perl_Iunitcheckav_ptr
 
-#ifndef DYNAMIC_PERL /* just generating prototypes */
-typedef int HANDLE;
-typedef int XSINIT_t;
-typedef int XSUBADDR_t;
-#endif
-
 /*
  * Declare HANDLE for perl.dll and function pointers.
  */
@@ -265,6 +283,7 @@
 static void (*Perl_sv_setsv)(pTHX_ SV*, SV*);
 #endif
 static bool (*Perl_sv_upgrade)(pTHX_ SV*, U32);
+#if (PERL_REVISION == 5) && (PERL_VERSION < 10)
 static SV*** (*Perl_Tstack_sp_ptr)(register PerlInterpreter*);
 static OP** (*Perl_Top_ptr)(register PerlInterpreter*);
 static SV*** (*Perl_Tstack_base_ptr)(register PerlInterpreter*);
@@ -276,12 +295,7 @@
 static SV** (*Perl_TSv_ptr)(register PerlInterpreter*);
 static XPV** (*Perl_TXpv_ptr)(register PerlInterpreter*);
 static STRLEN* (*Perl_Tna_ptr)(register PerlInterpreter*);
-static GV** (*Perl_Idefgv_ptr)(register PerlInterpreter*);
-static GV** (*Perl_Ierrgv_ptr)(register PerlInterpreter*);
-static SV* (*Perl_Isv_yes_ptr)(register PerlInterpreter*);
-static void (*boot_DynaLoader)_((pTHX_ CV*));
-
-#if (PERL_REVISION == 5) && (PERL_VERSION >= 10)
+#else
 static void (*Perl_sv_free2)(pTHX_ SV*);
 static void (*Perl_sys_init)(int* argc, char*** argv);
 static void (*Perl_sys_term)(void);
@@ -301,10 +315,15 @@
 static AV** (*Perl_Iunitcheckav_ptr)(register PerlInterpreter*);
 #endif
 
+static GV** (*Perl_Idefgv_ptr)(register PerlInterpreter*);
+static GV** (*Perl_Ierrgv_ptr)(register PerlInterpreter*);
+static SV* (*Perl_Isv_yes_ptr)(register PerlInterpreter*);
+static void (*boot_DynaLoader)_((pTHX_ CV*));
+static perl_key* (*Perl_Gthr_key_ptr)_((pTHX));
+
 /*
  * Table of name to function pointer of perl.
  */
-#define PERL_PROC FARPROC
 static struct {
     char* name;
     PERL_PROC* ptr;
@@ -389,17 +408,16 @@
     {"Perl_sys_init", (PERL_PROC*)&Perl_sys_init},
     {"Perl_sys_term", (PERL_PROC*)&Perl_sys_term},
     {"Perl_ISv_ptr", (PERL_PROC*)&Perl_ISv_ptr},
-    {"Perl_Istack_sp_ptr", (PERL_PROC*)&Perl_Istack_sp_ptr},
-    {"Perl_Iop_ptr", (PERL_PROC*)&Perl_Iop_ptr},
-    {"Perl_Istack_base_ptr", (PERL_PROC*)&Perl_Istack_base_ptr},
     {"Perl_Istack_max_ptr", (PERL_PROC*)&Perl_Istack_max_ptr},
+    {"Perl_Istack_base_ptr", (PERL_PROC*)&Perl_Istack_base_ptr},
+    {"Perl_IXpv_ptr", (PERL_PROC*)&Perl_IXpv_ptr},
     {"Perl_Itmps_ix_ptr", (PERL_PROC*)&Perl_Itmps_ix_ptr},
     {"Perl_Itmps_floor_ptr", (PERL_PROC*)&Perl_Itmps_floor_ptr},
+    {"Perl_Ina_ptr", (PERL_PROC*)&Perl_Ina_ptr},
     {"Perl_Imarkstack_ptr_ptr", (PERL_PROC*)&Perl_Imarkstack_ptr_ptr},
     {"Perl_Imarkstack_max_ptr", (PERL_PROC*)&Perl_Imarkstack_max_ptr},
-    {"Perl_ISv_ptr", (PERL_PROC*)&Perl_ISv_ptr},
-    {"Perl_IXpv_ptr", (PERL_PROC*)&Perl_IXpv_ptr},
-    {"Perl_Ina_ptr", (PERL_PROC*)&Perl_Ina_ptr},
+    {"Perl_Istack_sp_ptr", (PERL_PROC*)&Perl_Istack_sp_ptr},
+    {"Perl_Iop_ptr", (PERL_PROC*)&Perl_Iop_ptr},
     {"Perl_call_list", (PERL_PROC*)&Perl_call_list},
     {"Perl_Iscopestack_ix_ptr", (PERL_PROC*)&Perl_Iscopestack_ix_ptr},
     {"Perl_Iunitcheckav_ptr", (PERL_PROC*)&Perl_Iunitcheckav_ptr},
@@ -408,6 +426,7 @@
     {"Perl_Ierrgv_ptr", (PERL_PROC*)&Perl_Ierrgv_ptr},
     {"Perl_Isv_yes_ptr", (PERL_PROC*)&Perl_Isv_yes_ptr},
     {"boot_DynaLoader", (PERL_PROC*)&boot_DynaLoader},
+    {"Perl_Gthr_key_ptr", (PERL_PROC*)&Perl_Gthr_key_ptr},
     {"", NULL},
 };
 
@@ -428,7 +447,7 @@
 
     if (hPerlLib != NULL)
 	return OK;
-    if (!(hPerlLib = LoadLibraryEx(libname, NULL, 0)))
+    if ((hPerlLib = load_dll(libname)) == NULL)
     {
 	if (verbose)
 	    EMSG2(_("E370: Could not load library %s"), libname);
@@ -436,10 +455,10 @@
     }
     for (i = 0; perl_funcname_table[i].ptr; ++i)
     {
-	if (!(*perl_funcname_table[i].ptr = GetProcAddress(hPerlLib,
+	if (!(*perl_funcname_table[i].ptr = symbol_from_dll(hPerlLib,
 			perl_funcname_table[i].name)))
 	{
-	    FreeLibrary(hPerlLib);
+	    close_dll(hPerlLib);
 	    hPerlLib = NULL;
 	    if (verbose)
 		EMSG2(_(e_loadfunc), perl_funcname_table[i].name);
@@ -508,7 +527,7 @@
 #ifdef DYNAMIC_PERL
     if (hPerlLib)
     {
-	FreeLibrary(hPerlLib);
+	close_dll(hPerlLib);
 	hPerlLib = NULL;
     }
 #endif
diff --git a/src/link.sh b/src/link.sh
index 6e16168..3d90f3c 100755
--- a/src/link.sh
+++ b/src/link.sh
@@ -41,7 +41,7 @@
   if sh link.cmd; then
     touch auto/link.sed
     cp link.cmd linkit.sh
-    for libname in SM ICE nsl dnet dnet_stub inet socket dir elf iconv Xt Xmu Xp Xpm X11 Xdmcp x w dl pthread thread readline m perl crypt attr; do
+    for libname in SM ICE nsl dnet dnet_stub inet socket dir elf iconv Xt Xmu Xp Xpm X11 Xdmcp x w perl dl pthread thread readline m crypt attr; do
       cont=yes
       while test -n "$cont"; do
         if grep "l$libname " linkit.sh >/dev/null; then