Merge pull request #94 from pali/dladdr

dladdr() - Retrieve symbol name and address from export table

1 files changed, 52 insertions, 48 deletions

diff --git a/src/dlfcn.c b/src/dlfcn.c
index 5dd1ccf..abbd58d 100644
--- a/src/dlfcn.c
+++ b/src/dlfcn.c
@@ -512,37 +512,38 @@ static BOOL get_image_section( HMODULE module, int index, void **ptr, DWORD *siz
     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 )

+/* Return symbol name for a given address from export table */

+static const char *get_export_symbol_name( HMODULE module, IMAGE_EXPORT_DIRECTORY *ied, void *addr, void **func_address )

 {

-    int i;

+    DWORD i;

     void *candidateAddr = NULL;

-    const char *candidateName = NULL;

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

+    int candidateIndex = -1;

+    BYTE *base = (BYTE *) module;

+    DWORD *functionAddressesOffsets = (DWORD *) (base + ied->AddressOfFunctions);

+    DWORD *functionNamesOffsets = (DWORD *) (base + ied->AddressOfNames);

+    USHORT *functionNameOrdinalsIndexes = (USHORT *) (base + ied->AddressOfNameOrdinals);

 

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

+    for( i = 0; i < ied->NumberOfFunctions; i++ )

     {

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

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

+        if( (void *) ( base + functionAddressesOffsets[i] ) > addr || candidateAddr >= (void *) ( base + functionAddressesOffsets[i] ) )

+            continue;

 

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

-        {

-            IMAGE_IMPORT_BY_NAME *nameData;

+        candidateAddr = (void *) ( base + functionAddressesOffsets[i] );

+        candidateIndex = i;

+    }

 

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

-                continue;

+    if( candidateIndex == -1 )

+        return NULL;

 

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

-                continue;

+    *func_address = candidateAddr;

 

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

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

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

-        }

+    for( i = 0; i < ied->NumberOfNames; i++ )

+    {

+        if( functionNameOrdinalsIndexes[i] == candidateIndex )

+            return (const char *) ( base + functionNamesOffsets[i] );

     }

 

-    *func_address = candidateAddr;

-    return candidateName;

+    return NULL;

 }

 

 static BOOL is_valid_address( void *addr )

@@ -608,11 +609,14 @@ static void *get_address_from_import_address_table( void *iat, DWORD iat_size, v
 /* Holds module filename */

 static char module_filename[2*MAX_PATH];

 

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

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

 {

     HMODULE hModule;

     DWORD dwSize;

+    IMAGE_EXPORT_DIRECTORY *ied;

+    void *funcAddress = NULL;

 

+    /* Get module of the specified address */

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

         return FALSE;

 

@@ -621,8 +625,16 @@ static BOOL fill_module_info( void *addr, Dl_info *info )
     if( dwSize == 0 || dwSize == sizeof( module_filename ) )

         return FALSE;

 

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

     info->dli_fname = module_filename;

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

+

+    /* Find function name and function address in module's export table */

+    if( get_image_section( hModule, IMAGE_DIRECTORY_ENTRY_EXPORT, (void **) &ied, NULL ) )

+        info->dli_sname = get_export_symbol_name( hModule, ied, addr, &funcAddress );

+    else

+        info->dli_sname = NULL;

+

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

 

     return TRUE;

 }

@@ -630,36 +642,32 @@ static BOOL fill_module_info( void *addr, Dl_info *info )
 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 )

+    if( info == 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;

+        DWORD iatSize;

+        HMODULE hModule;

+

+        /* Get module of the import thunk address */

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

+            return 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 */

+            IMAGE_IMPORT_DESCRIPTOR *iid;

+            DWORD iidSize;

+

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

+                return 0;

+

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

                 return 0;

 

@@ -668,19 +676,15 @@ int dladdr( void *addr, Dl_info *info )
             iatSize = iidSize - (DWORD) ( (BYTE *) iat - (BYTE *) iid );

         }

 

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

-        if( iatAddr == NULL )

-            return 0;

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

 

-        realAddr = iatAddr;

+        if( !is_valid_address( addr ) )

+            return 0;

     }

 

-    if( !fill_module_info( realAddr, info ) )

+    if( !fill_info( addr, 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;

 }