I am programming in QB64, which is a programming language that allows for QBASIC-like syntax, and is translated into C++ code and compiled.
If we want to use a struct in our code, then we have to declare it and create it manually. In 32-bit, no problem, as it matches the WinAPI MSDN pages and will almost always work. For 64-bit, however, structures have different byte packing and I cannot figure out the correct packing for the STARTUPINFO struct.
Below is my declaration of the struct as it works in 32-bit. I know that the struct needs to be 104 bytes and I am currently 8 bytes short; I have made sure that all my variables match the 64-bit sizing but I'm missing 8 bytes of padding somewhere in my struct. Can someone who knows about byte packing and about WinAPI structs help me solve this?
Type STARTUPINFO
cb As Long '4 bytes
lpReserved As _Offset '4 bytes in 32, 8 in 64
lpDesktop As _Offset '4 bytes in 32, 8 in 64
lpTitle As _Offset '4 bytes in 32, 8 in 64
dwX As Long '4 bytes
dwY As Long '4 bytes
dwXSize As Long '4 bytes
dwYSize As Long '4 bytes
dwXCountChars As Long '4 bytes
dwYCountChars As Long '4 bytes
dwFillAttribute As Long '4 bytes
dwFlags As Long '4 bytes
wShowWindow As Integer '2 bytes
cbReserved2 As Integer '2 bytes
lpReserved2 As _Offset '4 bytes in 32, 8 in 64
hStdInput As _Offset '4 bytes in 32, 8 in 64
hStdOutput As _Offset '4 bytes in 32, 8 in 64
hStdError As _Offset '4 bytes in 32, 8 in 64
End Type
The field sizes and positions for the STARTUPINFOW structure in 32-bit and 64-bit builds are summarized below. (Note that these sizes and offsets are the same for the equivalent STARTUPINFOA version of the structure, used for non-Unicode builds.)
32-bit Windows (note that no padding is required – almost certainly by design):
typedef struct _STARTUPINFOW {
DWORD cb; // 4 bytes -> 4 total
LPWSTR lpReserved; // 4 8
LPWSTR lpDesktop; // 4 12
LPWSTR lpTitle; // 4 16
DWORD dwX; // 4 20
DWORD dwY; // 4 24
DWORD dwXSize; // 4 28
DWORD dwYSize; // 4 32
DWORD dwXCountChars; // 4 36
DWORD dwYCountChars; // 4 40
DWORD dwFillAttribute;// 4 44
DWORD dwFlags; // 4 48
WORD wShowWindow; // 2 50
WORD cbReserved2; // 2 52
LPBYTE lpReserved2; // 4 56
HANDLE hStdInput; // 4 60
HANDLE hStdOutput; // 4 64
HANDLE hStdError; // 4 68 bytes total
};
64-bit Windows (padding now required, as the 8-byte pointers should be 8-byte aligned):
typedef struct _STARTUPINFOW {
DWORD cb; // 4 bytes -> 4 total
// 4 b padding to align next pointer: 8
LPWSTR lpReserved; // 8 16
LPWSTR lpDesktop; // 8 24
LPWSTR lpTitle; // 8 32
DWORD dwX; // 4 36
DWORD dwY; // 4 40
DWORD dwXSize; // 4 44
DWORD dwYSize; // 4 48
DWORD dwXCountChars; // 4 52
DWORD dwYCountChars; // 4 56
DWORD dwFillAttribute;// 4 60
DWORD dwFlags; // 4 64
WORD wShowWindow; // 2 66
WORD cbReserved2; // 2 68
// 4 b padding to align next pointer: 72
LPBYTE lpReserved2; // 8 80
HANDLE hStdInput; // 8 88
HANDLE hStdOutput; // 8 96
HANDLE hStdError; // 8 104
};