From e4449f06a8989ff22947309151855b388c311aed Mon Sep 17 00:00:00 2001
From: Jared Baur <jaredbaur@fastmail.com>
Date: Mon, 22 Jan 2024 20:42:48 -0800
Subject: [PATCH] Add dlopen discoverer

---
 internal/lookup/dlopen.go  | 57 ++++++++++++++++++++++++++++++++++++++
 internal/lookup/library.go |  3 ++
 2 files changed, 60 insertions(+)
 create mode 100644 internal/lookup/dlopen.go

diff --git a/internal/lookup/dlopen.go b/internal/lookup/dlopen.go
new file mode 100644
index 00000000..7cd84522
--- /dev/null
+++ b/internal/lookup/dlopen.go
@@ -0,0 +1,57 @@
+package lookup
+
+// #cgo LDFLAGS: -ldl
+// #define _GNU_SOURCE
+// #include <dlfcn.h>
+// #include <stdlib.h>
+import "C"
+
+import (
+	"fmt"
+	"path/filepath"
+	"unsafe"
+)
+
+// dlopenLocator can be used to locate libraries given a system's dynamic
+// linker.
+type dlopenLocator struct {
+	file
+}
+
+// NewDlopenLocator creats a locator that can be used for locating libraries
+// through the dlopen mechanism.
+func NewDlopenLocator(opts ...Option) Locator {
+	f := newFileLocator(opts...)
+	d := dlopenLocator{file: *f}
+	return &d
+}
+
+// Locate finds the specified pattern if the systems' dynamic linker can find
+// it via dlopen. Note that patterns with wildcard patterns will likely not be
+// found as it is uncommon for libraries to have wildcard patterns in their
+// file name.
+func (d dlopenLocator) Locate(pattern string) ([]string, error) {
+	libname := C.CString(pattern)
+	defer C.free(unsafe.Pointer(libname))
+
+	d.logger.Debugf("Calling dlopen for %s", pattern)
+
+	handle := C.dlopen(libname, C.RTLD_LAZY)
+	if handle == nil {
+		return nil, fmt.Errorf("dlopen %s failed", pattern)
+	}
+	defer C.dlclose(handle)
+
+	libParentPath := C.CString("")
+
+	d.logger.Debugf("Calling dlinfo on handle for %s", pattern)
+	ret := C.dlinfo(handle, C.RTLD_DI_ORIGIN, unsafe.Pointer(libParentPath))
+	if ret == -1 {
+		return nil, fmt.Errorf("dlinfo on handle for %s failed", pattern)
+	}
+
+	libAbsolutePath := filepath.Join(C.GoString(libParentPath), pattern)
+	d.logger.Debugf("Found library for %s at %s", pattern, libAbsolutePath)
+
+	return []string{libAbsolutePath}, nil
+}
diff --git a/internal/lookup/library.go b/internal/lookup/library.go
index 7f5cf7c8..916edde2 100644
--- a/internal/lookup/library.go
+++ b/internal/lookup/library.go
@@ -61,7 +61,10 @@ func NewLibraryLocator(opts ...Option) Locator {
 	// We construct a symlink locator for expected library locations.
 	symlinkLocator := NewSymlinkLocator(opts...)
 
+	dlopenLocator := NewDlopenLocator(opts...)
+
 	l := First(
+		dlopenLocator,
 		symlinkLocator,
 		newLdcacheLocator(opts...),
 	)
--