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#include <Windows.h>
#include <memory>
#include <string>
#include <algorithm>
DWORD ShortToLongPathName(
LPCTSTR lpszShortPath,
LPTSTR lpszLongPath,
DWORD cchBuffer)
{
// Catch null pointers.
if (!lpszShortPath || !lpszLongPath)
{
SetLastError(ERROR_INVALID_PARAMETER);
return 0;
}
// Check whether the input path is valid.
if (0xffffffff == GetFileAttributes(lpszShortPath))
return 0;
// Special characters.
TCHAR const sep = _T('\\');
TCHAR const colon = _T(':');
// Make some short aliases for basic_strings of
TCHAR.
typedef std::basic_string<TCHAR> tstring;
typedef tstring::traits_type traits;
typedef tstring::size_type size;
size const npos = tstring::npos;
// Copy the short path into the work buffer and
convert forward
// slashes to backslashes.
tstring path = lpszShortPath;
std::replace(path.begin(), path.end(), _T('/'),
sep);
// We need a couple of markers for stepping through
the path.
size left = 0;
size right = 0;
// Parse the first bit of the path.
if (path.length() >= 2 &&
isalpha(path[0]) && colon == path[1]) // Drive letter?
{
if (2 == path.length()) // 'bare' drive
letter
{
right = npos; // skip main
block
}
else if (sep == path[2]) // drive
letter + backslash
{
// FindFirstFile doesn't
like "X:\"
if (3 == path.length())
{
right = npos;
// skip main block
}
else
{
left = right =
3;
}
}
else return 0; // parsing failure
}
else if (path.length() >= 1 && sep ==
path[0])
{
if (1 == path.length()) // 'bare'
backslash
{
right = npos; // skip main block
}
else
{
if (sep == path[1]) // is
it UNC?
{
// Find end of
machine name
right =
path.find_first_of(sep, 2);
if (npos ==
right)
return
0;
// Find end of
share name
right =
path.find_first_of(sep, right + 1);
if (npos ==
right)
return
0;
}
++right;
}
}
// else FindFirstFile will handle relative paths
// The data block for FindFirstFile.
WIN32_FIND_DATA fd;
// Main parse block - step through path.
while (npos != right)
{
left = right; // catch up
// Find next separator.
right = path.find_first_of(sep, right);
// Is it "." or
".."?
tstring next = path.substr(left, (npos
!= right) ? right - left : npos);
if (next == tstring(_T("."))
|| next == tstring(_T("..")))
{
if (npos != right)
++right;
}
else // no
{
// Temporarily replace the
separator with a null character so that
// the path so far can be
passed to FindFirstFile.
if (npos != right)
path[right] =
0;
// See what FindFirstFile
makes of the path so far.
HANDLE hf =
FindFirstFile(path.c_str(), &fd);
if (INVALID_HANDLE_VALUE ==
hf)
return 0;
FindClose(hf);
// Put back the separator.
if (npos != right)
path[right] =
sep;
// The file was found -
replace the short name with the long.
size old_len = (npos ==
right) ? path.length() - left : right - left;
size new_len =
traits::length(fd.cFileName);
path.replace(left, old_len,
fd.cFileName, new_len);
// More to do?
if (npos != right)
{
// Yes - move
past separator .
right = left +
new_len + 1;
// Did we
overshoot the end? (i.e. path ends with a separator).
if (right >=
path.length())
right
= npos;
}
}
}
// If buffer is too small then return the required
size.
if (cchBuffer <= path.length())
return path.length() + 1;
// Copy the buffer and return the number of
characters copied.
traits::copy(lpszLongPath, path.c_str(),
path.length() + 1);
return path.length();
}
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