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Win32: mingw_chdir: change to symlink-resolved directory

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If symlinks are enabled, resolve all symlinks when changing directories,
as required by POSIX.

Note: Git's real_path() function bases its link resolution algorithm on
this property of chdir(). Unfortunately, the current directory on Windows
is limited to only MAX_PATH (260) characters. Therefore using symlinks and
long paths in combination may be problematic.

Note: GetFinalPathNameByHandleW() was introduced with symlink support in
Windows Vista. Thus, for compatibility with Windows XP, we need to load it
dynamically and behave gracefully if it isnt's available.

Signed-off-by: Karsten Blees <blees@dcon.de>
This commit is contained in:
Karsten Blees
2015-05-24 01:17:31 +02:00
committed by Jameson Miller
parent ab6b1c007a
commit eebf2dab42
1 changed files with 48 additions and 1 deletions
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49
compat/mingw.c
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@@ -269,6 +269,34 @@ int mingw_core_config(const char *var, const char *value, void *cb)
return 0;
}
/* Normalizes NT paths as returned by some low-level APIs. */
static wchar_t *normalize_ntpath(wchar_t *wbuf)
{
int i;
/* fix absolute path prefixes */
if (wbuf[0] == '\\') {
/* strip NT namespace prefixes */
if (!wcsncmp(wbuf, L"\\??\\", 4) ||
!wcsncmp(wbuf, L"\\\\?\\", 4))
wbuf += 4;
else if (!wcsnicmp(wbuf, L"\\DosDevices\\", 12))
wbuf += 12;
/* replace remaining '...UNC\' with '\\' */
if (!wcsnicmp(wbuf, L"UNC\\", 4)) {
wbuf += 2;
*wbuf = '\\';
}
}
/* convert backslashes to slashes */
for (i = 0; wbuf[i]; i++)
if (wbuf[i] == '\\')
wbuf[i] = '/';
/* remove potential trailing slashes */
while (i && wbuf[i - 1] == '/')
wbuf[--i] = 0;
return wbuf;
}
int mingw_unlink(const char *pathname)
{
int tries = 0;
@@ -598,10 +626,29 @@ static int current_directory_len = 0;
int mingw_chdir(const char *dirname)
{
int result;
DECLARE_PROC_ADDR(kernel32.dll, DWORD, GetFinalPathNameByHandleW,
HANDLE, LPWSTR, DWORD, DWORD);
wchar_t wdirname[MAX_LONG_PATH];
if (xutftowcs_long_path(wdirname, dirname) < 0)
return -1;
result = _wchdir(wdirname);
if (has_symlinks && INIT_PROC_ADDR(GetFinalPathNameByHandleW)) {
HANDLE hnd = CreateFileW(wdirname, 0,
FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE, NULL,
OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, NULL);
if (hnd == INVALID_HANDLE_VALUE) {
errno = err_win_to_posix(GetLastError());
return -1;
}
if (!GetFinalPathNameByHandleW(hnd, wdirname, ARRAY_SIZE(wdirname), 0)) {
errno = err_win_to_posix(GetLastError());
CloseHandle(hnd);
return -1;
}
CloseHandle(hnd);
}
result = _wchdir(normalize_ntpath(wdirname));
current_directory_len = GetCurrentDirectoryW(0, NULL);
return result;
}