From 3700315f0dbe8d808b3878aadd55f34d2906ab29 Mon Sep 17 00:00:00 2001 From: Anton Serbulov Date: Fri, 15 Jan 2016 12:25:02 +0600 Subject: [PATCH] mingw: fix getcwd when the parent directory cannot be queried `GetLongPathName()` function may fail when it is unable to query the parent directory of a path component to determine the long name for that component. It happens, because of it uses `FindFirstFile()` function for each next short part of path. The `FindFirstFile()` requires `List Directory` and `Synchronize` desired access for a calling process. In case of lacking such permission for some part of path, the `GetLongPathName()` returns 0 as result and `GetLastError()` returns ERROR_ACCESS_DENIED. `GetFinalPathNameByHandle()` function can help in such cases, because it requires `Read Attributes` and `Synchronize` desired access to the target path only. The `GetFinalPathNameByHandle()` function was introduced on `Windows Server 2008/Windows Vista`. So we need to load it dynamically. `CreateFile()` parameters: `lpFileName` = path to the current directory `dwDesiredAccess` = 0 (it means `Read Attributes` and `Synchronize`) `dwShareMode` = FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE (it prevents `Sharing Violation`) `lpSecurityAttributes` = NULL (default security attributes) `dwCreationDisposition` = OPEN_EXISTING (required to obtain a directory handle) `dwFlagsAndAttributes` = FILE_FLAG_BACKUP_SEMANTICS (required to obtain a directory handle) `hTemplateFile` = NULL (when opening an existing file or directory, `CreateFile` ignores this parameter) The string that is returned by `GetFinalPathNameByHandle()` function uses the \\?\ syntax. To skip the prefix and convert backslashes to slashes, the `normalize_ntpath()` mingw function will be used. Note: `GetFinalPathNameByHandle()` function returns a final path. It is the path that is returned when a path is fully resolved. For example, for a symbolic link named "C:\tmp\mydir" that points to "D:\yourdir", the final path would be "D:\yourdir". Signed-off-by: Anton Serbulov --- compat/mingw.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/compat/mingw.c b/compat/mingw.c index d420431b1de8c3..833aa5cec326c3 100644 --- a/compat/mingw.c +++ b/compat/mingw.c @@ -952,11 +952,28 @@ char *mingw_getcwd(char *pointer, int len) { int i; wchar_t cwd[MAX_PATH], wpointer[MAX_PATH]; + DECLARE_PROC_ADDR(kernel32.dll, DWORD, GetFinalPathNameByHandleW, + HANDLE, LPWSTR, DWORD, DWORD); DWORD ret = GetCurrentDirectoryW(ARRAY_SIZE(cwd), cwd); if (ret < 0 || ret >= ARRAY_SIZE(cwd)) return NULL; ret = GetLongPathNameW(cwd, wpointer, ARRAY_SIZE(wpointer)); + if (!ret && GetLastError() == ERROR_ACCESS_DENIED && + INIT_PROC_ADDR(GetFinalPathNameByHandleW)) { + HANDLE hnd = CreateFileW(cwd, 0, + FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE, NULL, + OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, NULL); + if (hnd == INVALID_HANDLE_VALUE) + return NULL; + ret = GetFinalPathNameByHandleW(hnd, wpointer, ARRAY_SIZE(wpointer), 0); + CloseHandle(hnd); + if (!ret || ret >= ARRAY_SIZE(wpointer)) + return NULL; + if (xwcstoutf(pointer, normalize_ntpath(wpointer), len) < 0) + return NULL; + return pointer; + } if (!ret || ret >= ARRAY_SIZE(wpointer)) return NULL; if (xwcstoutf(pointer, wpointer, len) < 0)