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RegQueryValueEx problem

Started by decebal Oct 8, 2002 at 9:16 AM 0 replies 250+ views

Original Post

Oct 8, 2002 at 9:16 AM

I''ve got this class that has these two functions:

  
OpenKey(HKEY Pred_Key,char *SubKey_Name,REGSAM Sam,HKEY &Key)
QueryValueEx(HKEY hKey,char *SubKey_Name,DWORD &Type,DWORD &dwBufferLen,char *buffer)

the first one should open a key and the other one should read a value from this key. The code for these functions:

  
LONG cRegistry::OpenKey(HKEY Pred_Key,char *SubKey_Name,REGSAM Sam,HKEY &Key)
{
m_Error=RegOpenKeyEx(Pred_Key,SubKey_Name,NULL,Sam,&Key);

return m_Error;
}
LONG cRegistry::QueryValueEx(HKEY hKey,char *SubKey_Name,DWORD &Type,DWORD &dwBufferLen,char *buffer)
{
    m_Error=RegQueryValueEx(hKey,SubKey_Name,NULL,&Type,(BYTE*)&buffer,&dwBufferLen);
	return m_Error;
}

and this is the way i call these functions:

  
HKEY Key;
char *buffer3;
DWORD Type=REG_SZ;
DWORD dwBufferLen;
cRegistry Registry;

Registry.OpenKey(HKEY_LOCAL_MACHINE,"Software\\Microsoft\\Windows\\CurrentVersion\\Run",KEY_ALL_ACCESS,Key);
Registry.QueryValueEx(Key,"kernel.dll",Type,dwBufferLen,buffer3);

This code compiles and I can run the program but queryvalueex returns 87 and doesn''t return the value of the key. The first function returns 0. Mankind must put an end to war before war puts an end to mankind. John F. Kennedy

Anthracks

Oct 8, 2002 at 5:56 PM

You need to actually allocate a buffer, and give a value for how long it is (at least in your sample code, you don''t). In your example, you''re just giving it a pointer to some random spot in memory. Do something more like this:

  
  
HKEY Key;
char buffer3[256];
DWORD Type=REG_SZ;
DWORD dwBufferLen = 256;
cRegistry Registry;

Registry.OpenKey(HKEY_LOCAL_MACHINE,"Software\\Microsoft\\Windows\\CurrentVersion\\Run",KEY_ALL_ACCESS,Key);
Registry.QueryValueEx(Key,"kernel.dll",Type,dwBufferLen,buffer3);

Also, you realize that the value you get from the registry goes into the buffer, right? It''s not the return value of the function.

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