Originally Posted by
beta3designs
Off course, you are right
But what I wanted to emphasize is that it is a file and it is used for a program it is not plain text so the next line or word right after the magic key is not necessarily user input and, in my case, it is in fact program data so it is impossible that it happens to be the same as the magic key
so as to say that I don't think that a better system is needed, the system seems to me robust. And as far as I'm concerned and as you have confirmed I'm not the first to use it and many image formats use it.
Never say "impossible"... as unlikely as it is, my example corresponds to an unsigned short int with a value of 0x7D51 or 32,081 on a little endian system.
Just to give you some idea how screwy this can get... Here's what it takes to sort out what kind of file you are opening in the wonderful world of Unicode...
Code:
// open and translate file
BOOL M3ULaunch(PWCHAR FileName)
{ PBYTE rf; // raw file data
DWORD br; // bytes read
// load the raw file
{ HANDLE pl; // playlist file handle
DWORD fs; // file size
// get path to file
wcsncpy(FilePath,FileName,MAX_PATH);
PathRemoveFileSpec(FilePath);
wcscat(FilePath,L"\\");
// open the file
pl = CreateFile(FileName,GENERIC_READ,0,NULL,OPEN_EXISTING,FILE_ATTRIBUTE_NORMAL,NULL);
if (pl == INVALID_HANDLE_VALUE)
Exception(GetLastError());
fs = GetFileSize(pl,NULL);
rf = calloc(fs + 2, sizeof(BYTE));
if (! ReadFile(pl, rf, fs, &br, NULL))
Exception(GetLastError());
CloseHandle(pl);
if (br != fs)
Exception(0xE00640007); }
try
{ DWORD bom = *(DWORD*)rf;
if ((bom == 0x0000FEFF) || (bom == 0xFFFE0000)) // utf32le bom
Exception(0xE0640002); // utf32be bom
else if ((bom & 0xFFFF) == 0xFFFE) // utf16be bom
{ FlipEndian(rf,br);
CopyWChar((PWCHAR) rf + 1); }
else if ((bom & 0xFFFF) == 0xFEFF) // utf16le bom
CopyWChar((PWCHAR) rf + 1);
else if ((bom & 0xFFFFFF) == 0xBFBBEF) // utf8 bom
CopyMByte(rf + 3, br - 3);
else // no known bom, probe the file
{ if (! memchr(rf, 0x00, br)) // 8 bit text has no nulls
CopyMByte(rf,br); // ansi / utf8 no bom
else
{ PBYTE lf = memchr(rf,0x0A,br); // lf is always present as 1 byte.
if (!lf)
Exception(0xE0640003);
if ((!(*(DWORD*)(lf - 3) & 0x00FFFFFF)) || //utf32be no bom
(!(*(DWORD*)lf & 0xFFFFFF00))) //utf32le no bom
Exception(0xE0640002);
if ((lf - rf) & 1) // big endian? (lf at odd offset)
FlipEndian(rf,br); // utf16be no bom
CopyWChar((PWCHAR) rf); } } } // utf16le no bom
finally
{ free(rf); }
return 1; }