[Bootstrap] Add a sample shared library to used with ffi api

bootstrap/examples/ffi/foo.srn

@@ -0,0 +1,16 @@
+(ns examples.ffi.foo
+    :require  '[adssa
+                [serene.ffi.libllvm]])
+
+(defmacro deffi.....)
+
+(ffi/deffi some-function
+  :fn-name "some_function"
+  :args {:x :i32
+         :y :char_ptr}
+
+  :return :void)
+
+
+
+(some-function 12 "asdasd")

bootstrap/examples/ffi/foo/Makefile

@@ -0,0 +1,5 @@
+foo:
+	gcc -c -Wall -Werror -fpic foo.c
+	gcc -shared -o libfoo.so foo.o
+
+all: foo

bootstrap/examples/ffi/foo/foo.c

@@ -0,0 +1,7 @@
+#include <stdio.h>
+
+
+void bar(void)
+{
+    puts("Hello, I am a shared library");
+}

bootstrap/examples/ffi/foo/foo.h

@@ -0,0 +1,6 @@
+#ifndef foo_h__
+#define foo_h__
+
+extern void baz(void);
+
+#endif  // foo_h__

bootstrap/pkg/dl/dl.go

@@ -0,0 +1,86 @@
+/*
+ Serene --- Yet an other Lisp
+
+Copyright (c) 2020  Sameer Rahmani <lxsameer@gnu.org>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 2 of the License.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package dl
+
+/*
+#cgo linux LDFLAGS: -ldl
+#cgo pkg-config: libffi
+#include <dlfcn.h>
+#include <limits.h>
+#include <stdlib.h>
+#include <stdint.h>
+
+#include <stdio.h>
+
+static uintptr_t openShareLib(const char* path, char** err) {
+	void* h = dlopen(path, RTLD_NOW|RTLD_GLOBAL);
+	if (h == NULL) {
+		*err = (char*)dlerror();
+	}
+	return (uintptr_t)h;
+}
+
+static void* shareLibLookup(uintptr_t h, const char* name, char** err) {
+	void* r = dlsym((void*)h, name);
+	if (r == NULL) {
+		*err = (char*)dlerror();
+	}
+	return r;
+}
+*/
+import "C"
+import (
+	"fmt"
+	"unsafe"
+)
+
+type SharedLib struct{}
+
+func Open(libPath string) (*SharedLib, error) {
+	cPath := make([]byte, C.PATH_MAX+1)
+	cRelName := make([]byte, len(libPath)+1)
+	copy(cRelName, libPath)
+
+	// If the given libPath exists, fill the cPath with the absolute path
+	// to the file (it follows symlinks).
+	if C.realpath(
+		(*C.char)(unsafe.Pointer(&cRelName[0])),
+		(*C.char)(unsafe.Pointer(&cPath[0]))) == nil {
+		return nil, fmt.Errorf("can't find the shared library '%s'", libPath)
+	}
+
+	//filepath := C.GoString((*C.char)(unsafe.Pointer(&cPath[0])))
+
+	var cErr *C.char
+	h := C.openShareLib((*C.char)(unsafe.Pointer(&cPath[0])), &cErr)
+
+	if h == 0 {
+		// lock.Unlock()
+		return nil, fmt.Errorf("failed to open shared library: '%s' due to: '%s'", libPath, C.GoString(cErr))
+	}
+
+	// if plugins == nil {
+	// 	plugins = make(map[string]*Plugin)
+	// }
+	initTask := C.shareLibLookup(h, C.CString("bar"), &cErr)
+
+	fmt.Printf(">> %p \n", initTask)
+
+	return &SharedLib{}, nil
+}