LibDl: Move the dlfcn implementation to LibC

Userland/Libraries/LibC/dlfcn.cpp

@@ -4,10 +4,82 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <AK/String.h>
+#include <AK/Types.h>
+#include <dlfcn.h>
 #include <dlfcn_integration.h>
+#include <string.h>
 
-// These are used by libdl and are filled in by the dynamic loader.
+// These are filled in by the dynamic loader.
 DlCloseFunction __dlclose;
 DlOpenFunction __dlopen;
 DlSymFunction __dlsym;
 DlAddrFunction __dladdr;
+
+// FIXME: use thread_local and a String once TLS works
+#ifdef NO_TLS
+char* s_dlerror_text = NULL;
+bool s_dlerror_retrieved = false;
+#else
+__thread char* s_dlerror_text = NULL;
+__thread bool s_dlerror_retrieved = false;
+#endif
+
+static void store_error(String const& error)
+{
+    free(s_dlerror_text);
+    s_dlerror_text = strdup(error.characters());
+    s_dlerror_retrieved = false;
+}
+
+int dlclose(void* handle)
+{
+    auto result = __dlclose(handle);
+    if (result.is_error()) {
+        store_error(result.error().text);
+        return -1;
+    }
+    return 0;
+}
+
+char* dlerror()
+{
+    if (s_dlerror_retrieved) {
+        free(s_dlerror_text);
+        s_dlerror_text = nullptr;
+    }
+    s_dlerror_retrieved = true;
+    return const_cast<char*>(s_dlerror_text);
+}
+
+void* dlopen(char const* filename, int flags)
+{
+    auto result = __dlopen(filename, flags);
+    if (result.is_error()) {
+        store_error(result.error().text);
+        return nullptr;
+    }
+    return result.value();
+}
+
+void* dlsym(void* handle, char const* symbol_name)
+{
+    auto result = __dlsym(handle, symbol_name);
+    if (result.is_error()) {
+        store_error(result.error().text);
+        return nullptr;
+    }
+    return result.value();
+}
+
+int dladdr(void* addr, Dl_info* info)
+{
+    auto result = __dladdr(addr, info);
+    if (result.is_error()) {
+        // FIXME: According to the man page glibc does _not_ make the error
+        // available via dlerror(), however we do. Does this break anything?
+        store_error(result.error().text);
+        return 0;
+    }
+    return 1;
+}

Userland/Libraries/LibC/dlfcn.h

@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+#define RTLD_DEFAULT 0
+#define RTLD_LAZY 2
+#define RTLD_NOW 4
+#define RTLD_GLOBAL 8
+#define RTLD_LOCAL 16
+
+typedef struct __Dl_info {
+    char const* dli_fname;
+    void* dli_fbase;
+    char const* dli_sname;
+    void* dli_saddr;
+} Dl_info;
+
+int dlclose(void*);
+char* dlerror(void);
+void* dlopen(char const*, int);
+void* dlsym(void*, char const*);
+int dladdr(void*, Dl_info*);
+
+__END_DECLS

Userland/Libraries/LibC/dlfcn_integration.h

@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) 2021, Gunnar Beutner <gunnar@beutner.name>
+ * Copyright (c) 2022, the SerenityOS developers.
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Result.h>
+#include <AK/String.h>
+
+struct DlErrorMessage {
+    DlErrorMessage(String&& other)
+        : text(move(other))
+    {
+    }
+
+    // The virtual destructor is required because we're passing this
+    // struct to the dynamic loader - whose operator delete differs
+    // from the one in libc.so
+    virtual ~DlErrorMessage() = default;
+
+    String text;
+};
+
+struct __Dl_info;
+typedef struct __Dl_info Dl_info;
+
+typedef Result<void, DlErrorMessage> (*DlCloseFunction)(void*);
+typedef Result<void*, DlErrorMessage> (*DlOpenFunction)(char const*, int);
+typedef Result<void*, DlErrorMessage> (*DlSymFunction)(void*, char const*);
+typedef Result<void, DlErrorMessage> (*DlAddrFunction)(void*, Dl_info*);
+
+extern "C" {
+extern DlCloseFunction __dlclose;
+extern DlOpenFunction __dlopen;
+extern DlSymFunction __dlsym;
+extern DlAddrFunction __dladdr;
+}