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authorAnton Serbulov <aserbulov@plesk.com>2018-10-23 10:52:49 (GMT)
committerJunio C Hamano <gitster@pobox.com>2018-10-24 05:48:57 (GMT)
commit4745feeb8b501b309f2eb2e0330abd6c24d6fb60 (patch)
tree40e3c95d787989a6668157b71092d8113eee4d6f
parent937974fc65f517a67bfb09086b3726e3498d65b2 (diff)
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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>
-rw-r--r--compat/mingw.c39
1 files changed, 39 insertions, 0 deletions
diff --git a/compat/mingw.c b/compat/mingw.c
index 2c3e27c..19addfa 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -202,6 +202,31 @@ static int ask_yes_no_if_possible(const char *format, ...)
}
}
+/* 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] = '/';
+ return wbuf;
+}
+
int mingw_unlink(const char *pathname)
{
int ret, tries = 0;
@@ -925,6 +950,20 @@ char *mingw_getcwd(char *pointer, int len)
return NULL;
}
ret = GetLongPathNameW(cwd, wpointer, ARRAY_SIZE(wpointer));
+ if (!ret && GetLastError() == ERROR_ACCESS_DENIED) {
+ 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)