@matheusbsbs / matheus-bagliano / commits / 4745feeb8b

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 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 <aserbulov@plesk.com> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Anton Serbulov committed Oct 23, 2018 at 03:52 UTC 4745feeb8b501b309f2eb2e0330abd6c24d6fb60

1 file changed +39

compat/mingw.c

+39

@@ -202,6 +202,31 @@ static int ask_yes_no_if_possible(const char *format, ...)

202 }

203 }

204

205 +/* Normalizes NT paths as returned by some low-level APIs. */

206 +static wchar_t *normalize_ntpath(wchar_t *wbuf)

207 +{

208 + int i;

209 + /* fix absolute path prefixes */

210 + if (wbuf[0] == '\\') {

211 + /* strip NT namespace prefixes */

212 + if (!wcsncmp(wbuf, L"\\??\\", 4) ||

213 + !wcsncmp(wbuf, L"\\\\?\\", 4))

214 + wbuf += 4;

215 + else if (!wcsnicmp(wbuf, L"\\DosDevices\\", 12))

216 + wbuf += 12;

217 + /* replace remaining '...UNC\' with '\\' */

218 + if (!wcsnicmp(wbuf, L"UNC\\", 4)) {

219 + wbuf += 2;

220 + *wbuf = '\\';

221 + }

222 + }

223 + /* convert backslashes to slashes */

224 + for (i = 0; wbuf[i]; i++)

225 + if (wbuf[i] == '\\')

226 + wbuf[i] = '/';

227 + return wbuf;

228 +}

229 +

230 int mingw_unlink(const char *pathname)

231 {

232 int ret, tries = 0;

@@ -925,6 +950,20 @@ char *mingw_getcwd(char *pointer, int len)

950 return NULL;

951 }

952 ret = GetLongPathNameW(cwd, wpointer, ARRAY_SIZE(wpointer));

953 + if (!ret && GetLastError() == ERROR_ACCESS_DENIED) {

954 + HANDLE hnd = CreateFileW(cwd, 0,

955 + FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE, NULL,

956 + OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, NULL);

957 + if (hnd == INVALID_HANDLE_VALUE)

958 + return NULL;

959 + ret = GetFinalPathNameByHandleW(hnd, wpointer, ARRAY_SIZE(wpointer), 0);

960 + CloseHandle(hnd);

961 + if (!ret || ret >= ARRAY_SIZE(wpointer))

962 + return NULL;

963 + if (xwcstoutf(pointer, normalize_ntpath(wpointer), len) < 0)

964 + return NULL;

965 + return pointer;

966 + }

967 if (!ret || ret >= ARRAY_SIZE(wpointer))

968 return NULL;

969 if (xwcstoutf(pointer, wpointer, len) < 0)