mingw: let `mingw_lstat()` error early upon problems with reparse points

When obtaining lstat information for reparse points, we need to call
`FindFirstFile()` in addition to `GetFileInformationEx()` to obtain
the type of the reparse point (symlink, mount point etc.). However,
currently there is no error handling whatsoever if `FindFirstFile()`
fails.

Call `FindFirstFile()` before modifying the `stat *buf` output parameter
and error out if the call fails.

Note: The `FindFirstFile()` return value includes all the data
that we get from `GetFileAttributesEx()`, so we could replace
`GetFileAttributesEx()` with `FindFirstFile()`. We don't do that because
`GetFileAttributesEx()` is about twice as fast for single files. I.e.
we only pay the extra cost of calling `FindFirstFile()` in the rare case
that we encounter a reparse point.

Please also note that the indentation the remaining reparse point
code changed, and hence the best way to look at this diff is with
`--color-moved -w`. That code was _not_ moved because a subsequent
commit will move it to an altogether different function, anyway.

Signed-off-by: Karsten Blees <karsten.blees@gmail.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/compat/mingw.c b/compat/mingw.c
index ec6c2801d3cbf40731dacb6576d82d7b771dfa96..23a926c7d149945de89d718b8ca96bc59fdb6d84 100644 (file)
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -920,6 +920,7 @@ static int has_valid_directory_prefix(wchar_t *wfilename)
 int mingw_lstat(const char *file_name, struct stat *buf)
 {
        WIN32_FILE_ATTRIBUTE_DATA fdata;
+       WIN32_FIND_DATAW findbuf = { 0 };
        wchar_t wfilename[MAX_PATH];
        int wlen = xutftowcs_path(wfilename, file_name);
        if (wlen < 0)
@@ -934,6 +935,13 @@ int mingw_lstat(const char *file_name, struct stat *buf)
        }
 
        if (GetFileAttributesExW(wfilename, GetFileExInfoStandard, &fdata)) {
+               /* for reparse points, use FindFirstFile to get the reparse tag */
+               if (fdata.dwFileAttributes & FILE_ATTRIBUTE_REPARSE_POINT) {
+                       HANDLE handle = FindFirstFileW(wfilename, &findbuf);
+                       if (handle == INVALID_HANDLE_VALUE)
+                               goto error;
+                       FindClose(handle);
+               }
                buf->st_ino = 0;
                buf->st_gid = 0;
                buf->st_uid = 0;
@@ -946,20 +954,16 @@ int mingw_lstat(const char *file_name, struct stat *buf)
                filetime_to_timespec(&(fdata.ftLastWriteTime), &(buf->st_mtim));
                filetime_to_timespec(&(fdata.ftCreationTime), &(buf->st_ctim));
                if (fdata.dwFileAttributes & FILE_ATTRIBUTE_REPARSE_POINT) {
-                       WIN32_FIND_DATAW findbuf;
-                       HANDLE handle = FindFirstFileW(wfilename, &findbuf);
-                       if (handle != INVALID_HANDLE_VALUE) {
-                               if ((findbuf.dwFileAttributes & FILE_ATTRIBUTE_REPARSE_POINT) &&
-                                               (findbuf.dwReserved0 == IO_REPARSE_TAG_SYMLINK)) {
-                                       buf->st_mode = S_IFLNK | S_IREAD;
-                                       if (!(findbuf.dwFileAttributes & FILE_ATTRIBUTE_READONLY))
-                                               buf->st_mode |= S_IWRITE;
-                               }
-                               FindClose(handle);
+                       if ((findbuf.dwFileAttributes & FILE_ATTRIBUTE_REPARSE_POINT) &&
+                                       (findbuf.dwReserved0 == IO_REPARSE_TAG_SYMLINK)) {
+                               buf->st_mode = S_IFLNK | S_IREAD;
+                               if (!(findbuf.dwFileAttributes & FILE_ATTRIBUTE_READONLY))
+                                       buf->st_mode |= S_IWRITE;
                        }
                }
                return 0;
        }
+error:
        switch (GetLastError()) {
        case ERROR_ACCESS_DENIED:
        case ERROR_SHARING_VIOLATION: