kc3-lang/dlfcn-win32

diff --git a/CMakeLists.txt b/CMakeLists.txt
index a13cf99..07addbb 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -63,6 +63,9 @@ if (BUILD_TESTS)
   enable_testing()
   add_library(testdll SHARED testdll.c)
   set_target_properties(testdll PROPERTIES PREFIX "")
+  add_library(testdll2 SHARED testdll2.c)
+  set_target_properties(testdll2 PROPERTIES PREFIX "")
+  target_link_libraries(testdll2 dl)
   add_library(testdll3 SHARED testdll3.c)
   set_target_properties(testdll3 PROPERTIES PREFIX "")
   add_executable(t_dlfcn test.c)
diff --git a/Makefile b/Makefile
index a0f5cb9..efac5af 100644
--- a/Makefile
+++ b/Makefile
@@ -66,10 +66,13 @@ test.exe: test.o $(TARGETS)
 testdll.dll: testdll.c
 	$(CC) -shared -o $@ $^
 
+testdll2.dll: testdll2.c $(TARGETS)
+	$(CC) -shared -o $@ $< -L. -ldl $(LIBS)
+
 testdll3.dll: testdll3.c
 	$(CC) -shared -o $@ $^
 
-test: $(TARGETS) test.exe testdll.dll testdll3.dll
+test: $(TARGETS) test.exe testdll.dll testdll2.dll testdll3.dll
 	$(WINE) test.exe
 
 clean::
@@ -77,7 +80,7 @@ clean::
 		dlfcn.o \
 		libdl.dll libdl.a libdl.def libdl.dll.a libdl.lib libdl.exp \
 		tmptest.c tmptest.dll \
-		test.exe testdll.dll testdll3.dll
+		test.exe testdll.dll testdll2.dll testdll3.dll
 
 distclean: clean
 	rm -f config.mak
diff --git a/cmake-test/CMakeLists.txt b/cmake-test/CMakeLists.txt
index b853920..659a79a 100644
--- a/cmake-test/CMakeLists.txt
+++ b/cmake-test/CMakeLists.txt
@@ -8,6 +8,9 @@ find_package(dlfcn-win32 REQUIRED)
 
 add_library(testdll SHARED ../testdll.c)
 set_target_properties(testdll PROPERTIES PREFIX "")
+add_library(testdll2 SHARED ../testdll2.c)
+set_target_properties(testdll2 PROPERTIES PREFIX "")
+target_link_libraries(testdll2 dlfcn-win32::dl)
 add_library(testdll3 SHARED ../testdll3.c)
 set_target_properties(testdll3 PROPERTIES PREFIX "")
 add_executable(t_dlfcn ../test.c)
diff --git a/dlfcn.c b/dlfcn.c
index 1e706f0..8d3c793 100644
--- a/dlfcn.c
+++ b/dlfcn.c
@@ -30,6 +30,17 @@
 #include <stdio.h>
 #include <stdlib.h>
 
+#ifdef _MSC_VER
+/* https://docs.microsoft.com/en-us/cpp/intrinsics/returnaddress */
+#include <intrin.h>
+#pragma intrinsic(_ReturnAddress)
+#else
+/* https://gcc.gnu.org/onlinedocs/gcc/Return-Address.html */
+#ifndef _ReturnAddress
+#define _ReturnAddress() (__builtin_extract_return_addr(__builtin_return_address(0)))
+#endif
+#endif
+
 #ifdef SHARED
 #define DLFCN_WIN32_EXPORTS
 #endif
@@ -312,9 +323,11 @@ int dlclose( void *handle )
     return (int) ret;
 }
 
+__declspec(noinline) /* Needed for _ReturnAddress() */
 void *dlsym( void *handle, const char *name )
 {
     FARPROC symbol;
+    HMODULE hCaller;
     HMODULE hModule;
     HANDLE hCurrentProc;
 
@@ -324,20 +337,53 @@ void *dlsym( void *handle, const char *name )
 #endif
 
     current_error = NULL;
+    symbol = NULL;
+    hCaller = NULL;
+    hModule = GetModuleHandle( NULL );
     hCurrentProc = GetCurrentProcess( );
 
-    symbol = GetProcAddress( (HMODULE) handle, name );
+    if( handle == RTLD_DEFAULT )
+    {
+        /* The symbol lookup happens in the normal global scope; that is,
+         * a search for a symbol using this handle would find the same
+         * definition as a direct use of this symbol in the program code.
+         * So use same lookup procedure as when filename is NULL.
+         */
+        handle = hModule;
+    }
+    else if( handle == RTLD_NEXT )
+    {
+        /* Specifies the next object after this one that defines name.
+         * This one refers to the object containing the invocation of dlsym().
+         * The next object is the one found upon the application of a load
+         * order symbol resolution algorithm. To get caller function of dlsym()
+         * use _ReturnAddress() intrinsic. To get HMODULE of caller function
+         * use undocumented hack from https://stackoverflow.com/a/2396380
+         * The HMODULE of a DLL is the same value as the module's base address.
+         */
+        MEMORY_BASIC_INFORMATION info;
+        size_t sLen;
+        sLen = VirtualQueryEx( hCurrentProc, _ReturnAddress(), &info, sizeof( info ) );
+        if( sLen != sizeof( info ) )
+            goto end;
+        hCaller = (HMODULE) info.AllocationBase;
+        if(!hCaller)
+            goto end;
+    }
+
+    if( handle != RTLD_NEXT )
+    {
+        symbol = GetProcAddress( (HMODULE) handle, name );
 
-    if( symbol != NULL )
-        goto end;
+        if( symbol != NULL )
+            goto end;
+    }
 
     /* If the handle for the original program file is passed, also search
      * in all globally loaded objects.
      */
 
-    hModule = GetModuleHandle( NULL );
-
-    if( hModule == handle )
+    if( hModule == handle || handle == RTLD_NEXT )
     {
         HMODULE *modules;
         DWORD cbNeeded;
@@ -357,6 +403,13 @@ void *dlsym( void *handle, const char *name )
                 {
                     for( i = 0; i < dwSize / sizeof( HMODULE ); i++ )
                     {
+                        if( handle == RTLD_NEXT && hCaller )
+                        {
+                            /* Next modules can be used for RTLD_NEXT */
+                            if( hCaller == modules[i] )
+                                hCaller = NULL;
+                            continue;
+                        }
                         if( local_search( modules[i] ) )
                             continue;
                         symbol = GetProcAddress( modules[i], name );
diff --git a/dlfcn.h b/dlfcn.h
index 711e431..c0d7777 100644
--- a/dlfcn.h
+++ b/dlfcn.h
@@ -44,8 +44,8 @@ extern "C" {
  * Note: All other RTLD_* flags in any dlfcn.h are not standard compliant.
  */
 
-#define RTLD_DEFAULT    0
-#define RTLD_NEXT       0
+#define RTLD_DEFAULT    ((void *)0)
+#define RTLD_NEXT       ((void *)-1)
 
 DLFCN_EXPORT void *dlopen ( const char *file, int mode );
 DLFCN_EXPORT int   dlclose(void *handle);
diff --git a/test.c b/test.c
index 10c655e..814aca1 100644
--- a/test.c
+++ b/test.c
@@ -73,10 +73,13 @@
 int main()
 {
     void *global;
+    void *library2;
     void *library;
     char *error;
     int (*function)( void );
+    int (*function2_from_library2)( void );
     size_t (*fwrite_local) ( const void *, size_t, size_t, FILE * );
+    size_t (*fputs_default) ( const char *, FILE * );
     int (*nonexistentfunction)( void );
     int ret;
     HMODULE library3;
@@ -90,6 +93,16 @@ int main()
     _CrtSetReportFile(_CRT_ASSERT, _CRTDBG_FILE_STDOUT);
 #endif
 
+    library2 = dlopen( "testdll2.dll", RTLD_GLOBAL );
+    if( !library2 )
+    {
+        error = dlerror( );
+        printf( "ERROR\tCould not open library2 globally: %s\n", error ? error : "" );
+        RETURN_ERROR; 
+    }
+    else
+        printf( "SUCCESS\tOpened library2 globally: %p\n", library2 );
+
     library = dlopen( "testdll.dll", RTLD_GLOBAL );
     if( !library )
     {
@@ -127,6 +140,22 @@ int main()
     fwrite_local(hello_world,sizeof(char),strlen(hello_world),stderr);
     fflush(stderr);
 
+    fputs_default = dlsym(RTLD_DEFAULT, "fputs");
+    if (!fputs_default)
+    {
+        error = dlerror();
+        printf("ERROR\tCould not get symbol from default handle: %s\n",
+            error ? error : "");
+        CLOSE_LIB;
+        CLOSE_GLOBAL;
+        RETURN_ERROR;
+    }
+    else
+        printf("SUCCESS\tGot symbol from default handle: %p\n", fputs_default);
+    char * hello_world_fputs = "Hello world from default fputs!\n";
+    fputs_default(hello_world_fputs, stderr);
+    fflush(stderr);
+
     function = dlsym( library, "function" );
     if( !function )
     {
@@ -142,6 +171,27 @@ int main()
 
     RUNFUNC;
 
+    function2_from_library2 = dlsym( library2, "function2" );
+    if( !function2_from_library2 )
+    {
+        error = dlerror( );
+        printf( "ERROR\tCould not get symbol from library2 handle: %s\n",
+                error ? error : "" );
+        CLOSE_LIB;
+        CLOSE_GLOBAL;
+        RETURN_ERROR;
+    }
+    else
+        printf( "SUCCESS\tGot symbol from library2 handle: %p\n", function2_from_library2 );
+
+    ret = function2_from_library2 ();
+    if( ret != 2 )
+    {
+        CLOSE_LIB;
+        CLOSE_GLOBAL;
+        RETURN_ERROR;
+    }
+
     nonexistentfunction = dlsym( library, "nonexistentfunction" );
     if( nonexistentfunction )
     {
@@ -197,6 +247,16 @@ int main()
     else
         printf( "SUCCESS\tClosed library.\n" );
 
+    ret = dlclose( library2 );
+    if( ret )
+    {
+        error = dlerror( );
+        printf( "ERROR\tCould not close library2: %s\n", error ? error : "" );
+        RETURN_ERROR;
+    }
+    else
+        printf( "SUCCESS\tClosed library2.\n" );
+
     library = dlopen( "testdll.dll", RTLD_LOCAL );
     if( !library )
     {
diff --git a/testdll.c b/testdll.c
index ff99f87..3df2234 100644
--- a/testdll.c
+++ b/testdll.c
@@ -30,6 +30,12 @@
 #define EXPORT
 #endif
 
+EXPORT int function2( void )
+{
+    printf( "Hello, world! from original library\n" );
+    return 0;
+}
+
 EXPORT int function( void )
 {
     printf( "Hello, world!\n" );
diff --git a/testdll2.c b/testdll2.c
new file mode 100644
index 0000000..910c820
--- /dev/null
+++ b/testdll2.c
@@ -0,0 +1,55 @@
+/*
+ * dlfcn-win32
+ * Copyright (c) 2007 Ramiro Polla
+ * Copyright (c) 2019 Pali Rohár <pali.rohar@gmail.com>
+ *
+ * dlfcn-win32 is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * dlfcn-win32 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with dlfcn-win32; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#ifdef _DEBUG
+#define _CRTDBG_MAP_ALLOC
+#include <stdlib.h>
+#include <crtdbg.h>
+#endif
+#include <stdio.h>
+
+#include "dlfcn.h"
+
+#if defined(_WIN32)
+#define EXPORT __declspec(dllexport)
+#else
+#define EXPORT
+#endif
+
+EXPORT int function2( void )
+{
+    char *error;
+    int (*function2_orig)(void);
+    printf( "Hello, world! from wrapper library\n" );
+    function2_orig = dlsym(RTLD_NEXT, "function2");
+    if (!function2_orig)
+    {
+        error = dlerror( );
+        printf( "ERROR\tCould not get symbol from RTLD_NEXT handle: %s\n",
+                error ? error : "" );
+        return 1;
+    }
+    if (function2_orig() != 0)
+    {
+        printf( "ERROR\tOriginal function from RTLD_NEXT handle did not return correct value\n" );
+        return 1;
+    }
+    return 2;
+}