Calling standard open dialog with LuaJIT gives access violation
문제
Followed MSDN's GetOpenFileName example using the FFI of LuaJIT. I've been trying to get this working for two days, not only the dialog doesn't opens but it crashes the entire thing.
When debugged with OllyDdb it throws an ugly access violation somewhere in comdlg32.dll.
Here's the proof of concept with just the essential code. If I specify that the struct size is zero it exits without problem, with GetLastError() throwing a 87 (ERROR_INVALID_PARAMETER)
So I suppose that the problem is struct or FFI related.
If somebody is able to shed some light over here... thankies.
ffi = require"ffi"
bit = require"bit"
collectgarbage("stop")
ffi.cdef[[
static const int OFN_FILEMUSTEXIST = 0x1000;
static const int OFN_NOCHANGEDIR = 8;
static const int OFN_PATHMUSTEXIST = 0x800;
typedef bool BOOL;
typedef char CHAR;
typedef unsigned short WORD;
typedef unsigned long DWORD;
typedef void *PVOID;
typedef void *LPVOID;
typedef void *LPOFNHOOKPROC;
typedef unsigned long HANDLE;
typedef HANDLE HWND;
typedef HANDLE HINSTANCE;
typedef const char *LPCSTR;
typedef const char *LPCTSTR;
typedef char *LPSTR;
typedef char *LPTSTR;
typedef unsigned long LPARAM;
typedef struct {
DWORD lStructSize;
HWND hwndOwner;
HINSTANCE hInstance;
LPCTSTR lpstrFilter;
LPTSTR lpstrCustomFilter;
DWORD nMaxCustFilter;
DWORD nFilterIndex;
LPTSTR lpstrFile;
DWORD nMaxFile;
LPTSTR lpstrFileTitle;
DWORD nMaxFileTitle;
LPCTSTR lpstrInitialDir;
LPCTSTR lpstrTitle;
DWORD flags;
WORD nFileOffset;
WORD nFileExtension;
LPCTSTR lpstrDefExt;
LPARAM lCustData;
LPOFNHOOKPROC lpfnHook;
LPCTSTR lpTemplateName;
LPVOID pvReserved;
DWORD dwReserved;
DWORD flagsEx;
}OPENFILENAME;
BOOL GetSaveFileNameA( OPENFILENAME lpofn );
BOOL GetOpenFileNameA( OPENFILENAME lpofn );
]]
com=ffi.load("comdlg32")
ffi.cdef[[
DWORD GetLastError(void);
]]
krnl=ffi.load("kernel32")
function OpenDialog()
Ofn=ffi.new("OPENFILENAME")
ffi.fill(Ofn,ffi.sizeof(Ofn)) --zero fill the structure
local szFile = ffi.new("char[260]","\0")
local hwnd = ffi.new("HWND",0)
Ofn.lStructSize = ffi.sizeof(Ofn)
Ofn.hwndOwner = hwnd
Ofn.lpstrFile = szFile
Ofn.nMaxFile = ffi.sizeof(szFile)
Ofn.lpstrFilter = "All\0*.*\0Text\0*.TXT\0"
Ofn.nFilterIndex = 1
Ofn.lpstrFileTitle = nil
Ofn.nMaxFileTitle = 0
Ofn.lpstrInitialDir = nil
Ofn.flags = bit.bor(com.OFN_PATHMUSTEXIST, com.OFN_FILEMUSTEXIST, com.OFN_NOCHANGEDIR)
print("displaying...")
if com.GetOpenFileNameA(Ofn) then --luajit converts bool automatically
print("file->",ffi.string(Ofn.lpstrFile, Ofn.nMaxFile))
end
print("lasterror->",krnl.GetLastError())
end
OpenDialog()
해결책
These C functions take a pointer to the struct. The correct declaration is: GetOpenFilenameA(OPENFILENAME *lpofn)
etc.
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