CODEWITHSUNDEEP
c++winapi
dsp_099
dsp_099

Reputation: 6121

RegKeyValue returning nonsense data

char value[255];
DWORD BufferSize = 8192;

RegGetValue(HKEY_LOCAL_MACHINE, L"SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion", L"ProductName", RRF_RT_ANY, NULL, &value, &BufferSize);

cout << value;

After RegKeyValue() runs, it appears that value is

    value   0x0034f50c "ÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌ...  char[255]

What's going on here?

Note: RegKeyValue() returns 0

Upvotes: 1

Views: 142

Answers (2)

David Heffernan
David Heffernan

Reputation: 613262

You didn't check the return value of RegGetValue. Most likely the call failed and the buffer value was never assigned anything. Always check return values.

From the code we can see, I note that you are lying about the buffer size. You say that it is 8192 bytes. But you only allocated 255 bytes. You are also calling the Unicode version of the API, but passing in a char buffer. If you are expecting string data then you need to supply a buffer of wide characters. The Unicode version of this API will return string data as UTF-16 encoded text.

Once you get all that sorted you next need to check what type is stored in that value. You are passing NULL for the type parameter. Pass a pointer to a variable and find out whether or not a string really is stored there. You will also need to read how many bytes are read and set the null-terminator in your buffer accordingly.

Upvotes: 2

Reed Copsey
Reed Copsey

Reputation: 564641

There are two issues here.

  1. Make sure the return value of RegGetValue is ERROR_SUCCESS. If it is not, the routine failed. Also, you can check to see what was written into BufferSize, as RegGetValue specifies the number of bytes written.

  2. You're passing in a buffer defined as char value[255];, then specifying it's length as 8192. This can cause a buffer overrun.

Upvotes: 3

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