Question

I’m trying make a function that lists all subkeys of a specific (windows registry) key.

What’s happening is that only the 1st item is outputted correctly, all the others are truncated or repeated – I think it’s a buffer issue.

I’ve already read the function documentation, but it hasn’t helped me much.

Here’s the code:

#include<stdio.h>
#include<windows.h>

void print_list(HKEY hkey, char* path){

char dwValue[255];
DWORD  dwSize = 0;
DWORD n; // subkeys
HKEY tmp;
int i;

if(RegOpenKeyEx(hkey, path, 0, KEY_READ, &tmp) == ERROR_SUCCESS){

    DWORD  dwSize = sizeof(dwValue);

    RegQueryInfoKey(tmp,NULL,NULL,NULL,&n,NULL,NULL,NULL,NULL,NULL,NULL,NULL);      

    for(i=0; i< n; i++){
        RegEnumKeyEx(tmp,i,dwValue,&dwSize,NULL,NULL,NULL,NULL);
        printf("%s\n", dwValue);
    }

    RegCloseKey(tmp);
}
}

int main(){
print_list(HKEY_LOCAL_MACHINE, "SOFTWARE");
return 0;
}

Answer 1

Add the following line to before the call to RegEnumKeyEx():

dwSize = sizeof(dwValue);

as dwSize is both an input and output parameter. On input it states the size of the buffer. From RegEnumKeyEx():

A pointer to a variable that specifies the size of the buffer specified by the lpName parameter, in characters. This size should include the terminating null character. If the function succeeds, the variable pointed to by lpcName contains the number of characters stored in the buffer, not including the terminating null character.

Note, you should always check return values from functions (like you have done for RegOpenKeyEx()).