DBG: fill with NOPs is working now

x64_dbg_dbg/assemble.cpp

@@ -3,6 +3,8 @@
 #include "debugger.h"
 #include "XEDParse\XEDParse.h"
 #include "value.h"
+#include "disasm_helper.h"
+#include "console.h"
 
 static bool cbUnknown(const char* text, ULONGLONG* value)
 {
@@ -35,6 +37,19 @@ bool assembleat(uint addr, const char* instruction, char* error, bool fillnop)
             strcpy(error, parse.error);
         return false;
     }
-    bool ret=memwrite(fdProcessInfo->hProcess, (void*)addr, parse.dest, parse.dest_size, 0);
-    return ret;
+
+    //calculate the number of NOPs to insert
+    int destSize=parse.dest_size;
+    int origLen=disasmgetsize(addr);
+    while(origLen<destSize)
+        origLen+=disasmgetsize(addr+origLen);
+    int nopsize=origLen-destSize;
+    unsigned char nops[16];
+    memset(nops, 0x90, sizeof(nops));
+
+    bool ret=memwrite(fdProcessInfo->hProcess, (void*)addr, parse.dest, destSize, 0);
+    if(ret && fillnop && nopsize)
+        if(!memwrite(fdProcessInfo->hProcess, (void*)(addr+destSize), nops, nopsize, 0))
+            ret=false;
+    return true;
 }

x64_dbg_dbg/disasm_helper.cpp

@@ -419,3 +419,27 @@ bool disasmgetstringat(uint addr, STRING_TYPE* type, char* ascii, char* unicode,
     efree(data, "disasmgetstringat:data");
     return false;
 }
+
+int disasmgetsize(uint addr, unsigned char* data)
+{
+    DISASM disasm;
+    memset(&disasm, 0, sizeof(DISASM));
+    disasm.Options=NoformatNumeral;
+#ifdef _WIN64
+    disasm.Archi=64;
+#endif // _WIN64
+    disasm.VirtualAddr=addr;
+    disasm.EIP=(UIntPtr)data;
+    int len=Disasm(&disasm);
+    if(len==UNKNOWN_OPCODE)
+        len=1;
+    return len;
+}
+
+int disasmgetsize(uint addr)
+{
+    char data[16];
+    if(!memread(fdProcessInfo->hProcess, (const void*)addr, data, sizeof(data), 0))
+        return 1;
+    return disasmgetsize(addr, (unsigned char*)data);
+}

x64_dbg_dbg/disasm_helper.h

@@ -12,5 +12,7 @@ void disasmget(unsigned char* buffer, uint addr, DISASM_INSTR* instr);
 void disasmget(uint addr, DISASM_INSTR* instr);
 bool disasmispossiblestring(uint addr);
 bool disasmgetstringat(uint addr, STRING_TYPE* type, char* ascii, char* unicode, int maxlen);
+int disasmgetsize(uint addr, unsigned char* data);
+int disasmgetsize(uint addr);
 
 #endif // _DISASM_HELPER_H