Add function dladdr() and associated test application test-dladdr

3 files changed, 236 insertions, 5 deletions

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index d5296b1..27f9030 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -1,15 +1,20 @@
 set(headers dlfcn.h)
 set(sources dlfcn.c)
 
-if (BUILD_SHARED_LIBS)
-  add_definitions(-DSHARED)
-endif (BUILD_SHARED_LIBS)
 
 add_library(dl ${sources})
 
 # Correctly export the location of installed includes in the target
 target_include_directories(dl INTERFACE $<INSTALL_INTERFACE:include>)
 
+# dot not add -D<target>_EXPORTS
+set_target_properties(dl PROPERTIES DEFINE_SYMBOL "")
+
+# set shared mode for compiling library and propagate mode to cmake clients
+if (BUILD_SHARED_LIBS)
+    target_compile_definitions(dl PUBLIC DLFCN_WIN32_SHARED)
+endif (BUILD_SHARED_LIBS)
+
 install (TARGETS dl EXPORT dlfcn-win32-targets
                     RUNTIME DESTINATION bin
                     LIBRARY DESTINATION lib${LIB_SUFFIX}
diff --git a/src/dlfcn.c b/src/dlfcn.c
index 3251661..5dd1ccf 100644
--- a/src/dlfcn.c
+++ b/src/dlfcn.c
@@ -3,6 +3,7 @@
  * Copyright (c) 2007 Ramiro Polla

  * Copyright (c) 2015 Tiancheng "Timothy" Gu

  * Copyright (c) 2019 Pali Rohár <pali.rohar@gmail.com>

+ * Copyright (c) 2020 Ralf Habacker <ralf.habacker@freenet.de>

  *

  * Permission is hereby granted, free of charge, to any person obtaining a copy

  * of this software and associated documentation files (the "Software"), to deal

@@ -45,7 +46,7 @@
 #endif

 #endif

 

-#ifdef SHARED

+#ifdef DLFCN_WIN32_SHARED

 #define DLFCN_WIN32_EXPORTS

 #endif

 #include "dlfcn.h"

@@ -222,6 +223,7 @@ static BOOL MyEnumProcessModules( HANDLE hProcess, HMODULE *lphModule, DWORD cb,
     return EnumProcessModulesPtr( hProcess, lphModule, cb, lpcbNeeded );

 }

 

+DLFCN_EXPORT

 void *dlopen( const char *file, int mode )

 {

     HMODULE hModule;

@@ -329,6 +331,7 @@ void *dlopen( const char *file, int mode )
     return (void *) hModule;

 }

 

+DLFCN_EXPORT

 int dlclose( void *handle )

 {

     HMODULE hModule = (HMODULE) handle;

@@ -353,6 +356,7 @@ int dlclose( void *handle )
 }

 

 __declspec(noinline) /* Needed for _ReturnAddress() */

+DLFCN_EXPORT

 void *dlsym( void *handle, const char *name )

 {

     FARPROC symbol;

@@ -460,6 +464,7 @@ end:
     return *(void **) (&symbol);

 }

 

+DLFCN_EXPORT

 char *dlerror( void )

 {

     /* If this is the second consecutive call to dlerror, return NULL */

@@ -474,7 +479,212 @@ char *dlerror( void )
     return error_buffer;

 }

 

-#ifdef SHARED

+/* See https://docs.microsoft.com/en-us/archive/msdn-magazine/2002/march/inside-windows-an-in-depth-look-into-the-win32-portable-executable-file-format-part-2

+ * for details */

+

+/* Get specific image section */

+static BOOL get_image_section( HMODULE module, int index, void **ptr, DWORD *size )

+{

+    IMAGE_DOS_HEADER *dosHeader;

+    IMAGE_OPTIONAL_HEADER *optionalHeader;

+

+    dosHeader = (IMAGE_DOS_HEADER *) module;

+

+    if( dosHeader->e_magic != 0x5A4D )

+        return FALSE;

+

+    optionalHeader = (IMAGE_OPTIONAL_HEADER *) ( (BYTE *) module + dosHeader->e_lfanew + 24 );

+

+    if( optionalHeader->Magic != IMAGE_NT_OPTIONAL_HDR_MAGIC )

+        return FALSE;

+

+    if( index < 0 || index > IMAGE_DIRECTORY_ENTRY_COM_DESCRIPTOR )

+        return FALSE;

+

+    if( optionalHeader->DataDirectory[index].Size == 0 || optionalHeader->DataDirectory[index].VirtualAddress == 0 )

+        return FALSE;

+

+    if( size != NULL )

+        *size = optionalHeader->DataDirectory[index].Size;

+

+    *ptr = (void *)( (BYTE *) module + optionalHeader->DataDirectory[index].VirtualAddress );

+

+    return TRUE;

+}

+

+/* Return symbol name for a given address */

+static const char *get_symbol_name( HMODULE module, IMAGE_IMPORT_DESCRIPTOR *iid, void *addr, void **func_address )

+{

+    int i;

+    void *candidateAddr = NULL;

+    const char *candidateName = NULL;

+    BYTE *base = (BYTE *) module; /* Required to have correct calculations */

+

+    for( i = 0; iid[i].Characteristics != 0 && iid[i].FirstThunk != 0; i++ )

+    {

+        IMAGE_THUNK_DATA *thunkILT = (IMAGE_THUNK_DATA *)( base + iid[i].Characteristics );

+        IMAGE_THUNK_DATA *thunkIAT = (IMAGE_THUNK_DATA *)( base + iid[i].FirstThunk );

+

+        for( ; thunkILT->u1.AddressOfData != 0; thunkILT++, thunkIAT++ )

+        {

+            IMAGE_IMPORT_BY_NAME *nameData;

+

+            if( IMAGE_SNAP_BY_ORDINAL( thunkILT->u1.Ordinal ) )

+                continue;

+

+            if( (void *) thunkIAT->u1.Function > addr || candidateAddr >= (void *) thunkIAT->u1.Function )

+                continue;

+

+            candidateAddr = (void *) thunkIAT->u1.Function;

+            nameData = (IMAGE_IMPORT_BY_NAME *)( base + (ULONG_PTR) thunkILT->u1.AddressOfData );

+            candidateName = (const char *) nameData->Name;

+        }

+    }

+

+    *func_address = candidateAddr;

+    return candidateName;

+}

+

+static BOOL is_valid_address( void *addr )

+{

+    MEMORY_BASIC_INFORMATION info;

+    SIZE_T result;

+

+    if( addr == NULL )

+        return FALSE;

+

+    /* check valid pointer */

+    result = VirtualQuery( addr, &info, sizeof( info ) );

+

+    if( result == 0 || info.AllocationBase == NULL || info.AllocationProtect == 0 || info.AllocationProtect == PAGE_NOACCESS )

+        return FALSE;

+

+    return TRUE;

+}

+

+/* Return state if address points to an import thunk

+ *

+ * An import thunk is setup with a 'jmp' instruction followed by an

+ * absolute address (32bit) or relative offset (64bit) pointing into

+ * the import address table (iat), which is partially maintained by

+ * the runtime linker.

+ */

+static BOOL is_import_thunk( void *addr )

+{

+    return *(short *) addr == 0x25ff ? TRUE : FALSE;

+}

+

+/* Return adress from the import address table (iat),

+ * if the original address points to a thunk table entry.

+ */

+static void *get_address_from_import_address_table( void *iat, DWORD iat_size, void *addr )

+{

+    BYTE *thkp = (BYTE *) addr;

+    /* Get offset from thunk table (after instruction 0xff 0x25)

+     *   4018c8 <_VirtualQuery>: ff 25 4a 8a 00 00

+     */

+    ULONG offset = *(ULONG *)( thkp + 2 );

+#ifdef _WIN64

+    /* On 64 bit the offset is relative

+     *      4018c8:   ff 25 4a 8a 00 00    jmpq    *0x8a4a(%rip)    # 40a318 <__imp_VirtualQuery>

+     * And can be also negative (MSVC in WDK)

+     *   100002f20:   ff 25 3a e1 ff ff    jmpq   *-0x1ec6(%rip)    # 0x100001060

+     * So cast to signed LONG type

+     */

+    BYTE *ptr = (BYTE *)( thkp + 6 + (LONG) offset );

+#else

+    /* On 32 bit the offset is absolute

+     *   4019b4:    ff 25 90 71 40 00    jmp    *0x40719

+     */

+    BYTE *ptr = (BYTE *) offset;

+#endif

+

+    if( !is_valid_address( ptr ) || ptr < (BYTE *) iat || ptr > (BYTE *) iat + iat_size )

+        return NULL;

+

+    return *(void **) ptr;

+}

+

+/* Holds module filename */

+static char module_filename[2*MAX_PATH];

+

+static BOOL fill_module_info( void *addr, Dl_info *info )

+{

+    HMODULE hModule;

+    DWORD dwSize;

+

+    if( !GetModuleHandleExA( GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS | GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT, addr, &hModule ) || hModule == NULL )

+        return FALSE;

+

+    dwSize = GetModuleFileNameA( hModule, module_filename, sizeof( module_filename ) );

+

+    if( dwSize == 0 || dwSize == sizeof( module_filename ) )

+        return FALSE;

+

+    info->dli_fbase = (void *) hModule;

+    info->dli_fname = module_filename;

+

+    return TRUE;

+}

+

+DLFCN_EXPORT

+int dladdr( void *addr, Dl_info *info )

+{

+    void *realAddr, *funcAddress = NULL;

+    HMODULE hModule;

+    IMAGE_IMPORT_DESCRIPTOR *iid;

+    DWORD iidSize = 0;

+

+    if( addr == NULL || info == NULL )

+        return 0;

+

+    hModule = GetModuleHandleA( NULL );

+    if( hModule == NULL )

+        return 0;

+

+    if( !is_valid_address( addr ) )

+        return 0;

+

+    realAddr = addr;

+

+    if( !get_image_section( hModule, IMAGE_DIRECTORY_ENTRY_IMPORT, (void **) &iid, &iidSize ) )

+        return 0;

+

+    if( is_import_thunk( addr ) )

+    {

+        void *iat;

+        void *iatAddr = NULL;

+        DWORD iatSize = 0;

+

+        if( !get_image_section( hModule, IMAGE_DIRECTORY_ENTRY_IAT, &iat, &iatSize ) )

+        {

+            /* Fallback for cases where the iat is not defined,

+             * for example i586-mingw32msvc-gcc */

+            if( iid == NULL || iid->Characteristics == 0 || iid->FirstThunk == 0 )

+                return 0;

+

+            iat = (void *)( (BYTE *) hModule + iid->FirstThunk );

+            /* We assume that in this case iid and iat's are in linear order */

+            iatSize = iidSize - (DWORD) ( (BYTE *) iat - (BYTE *) iid );

+        }

+

+        iatAddr = get_address_from_import_address_table( iat, iatSize, addr );

+        if( iatAddr == NULL )

+            return 0;

+

+        realAddr = iatAddr;

+    }

+

+    if( !fill_module_info( realAddr, info ) )

+        return 0;

+

+    info->dli_sname = get_symbol_name( hModule, iid, realAddr, &funcAddress );

+

+    info->dli_saddr = !info->dli_sname ? NULL : funcAddress ? funcAddress : realAddr;

+    return 1;

+}

+

+#ifdef DLFCN_WIN32_SHARED

 BOOL WINAPI DllMain( HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpvReserved )

 {

     (void) hinstDLL;

diff --git a/src/dlfcn.h b/src/dlfcn.h
index 9ddbba3..164216f 100644
--- a/src/dlfcn.h
+++ b/src/dlfcn.h
@@ -28,9 +28,13 @@
 extern "C" {

 #endif

 

+#if defined(DLFCN_WIN32_SHARED)

 #if defined(DLFCN_WIN32_EXPORTS)

 #   define DLFCN_EXPORT __declspec(dllexport)

 #else

+#   define DLFCN_EXPORT __declspec(dllimport)

+#endif

+#else

 #   define DLFCN_EXPORT

 #endif

 

@@ -59,6 +63,15 @@ extern "C" {
 /* Specifies the next object after this one that defines name. */

 #define RTLD_NEXT       ((void *)-1)

 

+/* Structure filled in by dladdr() */

+typedef struct dl_info

+{

+   const char *dli_fname;  /* Filename of defining object (thread unsafe and reused on every call to dladdr) */

+   void       *dli_fbase;  /* Load address of that object */

+   const char *dli_sname;  /* Name of nearest lower symbol */

+   void       *dli_saddr;  /* Exact value of nearest symbol */

+} Dl_info;

+

 /* Open a symbol table handle. */

 DLFCN_EXPORT void *dlopen(const char *file, int mode);

 

@@ -71,6 +84,9 @@ DLFCN_EXPORT void *dlsym(void *handle, const char *name);
 /* Get diagnostic information. */

 DLFCN_EXPORT char *dlerror(void);

 

+/* Translate address to symbolic information (no POSIX standard) */

+DLFCN_EXPORT int dladdr(void *addr, Dl_info *info);

+

 #ifdef __cplusplus

 }

 #endif