win32_create_file(): Handle access problems
authorEric Biggers <ebiggers3@gmail.com>
Sat, 28 Dec 2013 19:30:17 +0000 (13:30 -0600)
committerEric Biggers <ebiggers3@gmail.com>
Sat, 28 Dec 2013 19:30:17 +0000 (13:30 -0600)
src/win32_apply.c

index c8f65ef..312bd87 100644 (file)
@@ -81,21 +81,63 @@ win32_start_extract(const wchar_t *path, struct apply_ctx *ctx)
        return 0;
 }
 
+/* Create a normal file, overwriting one already present.  */
 static int
 win32_create_file(const wchar_t *path, struct apply_ctx *ctx, u64 *cookie_ret)
 {
        HANDLE h;
-
-       h = CreateFile(path, 0, 0, NULL, CREATE_ALWAYS,
-                      FILE_ATTRIBUTE_NORMAL | FILE_FLAG_BACKUP_SEMANTICS, NULL);
-       if (h == INVALID_HANDLE_VALUE)
-               goto error;
+       unsigned retry_count = 0;
+       DWORD dwFlagsAndAttributes = FILE_FLAG_BACKUP_SEMANTICS;
+
+retry:
+       /* WRITE_OWNER and WRITE_DAC privileges are required for some reason,
+        * even through we're creating a new file.  */
+       h = CreateFile(path, WRITE_OWNER | WRITE_DAC, 0, NULL,
+                      CREATE_ALWAYS, dwFlagsAndAttributes, NULL);
+       if (h == INVALID_HANDLE_VALUE) {
+               /* File couldn't be created.  */
+               DWORD err = GetLastError();
+               if (err == ERROR_ACCESS_DENIED && retry_count == 0) {
+
+                       /* Access denied error for the first time.  Try
+                        * adjusting file attributes.  */
+
+                       /* Get attributes of the existing file.  */
+                       DWORD attribs = GetFileAttributes(path);
+                       if (attribs != INVALID_FILE_ATTRIBUTES &&
+                           (attribs & (FILE_ATTRIBUTE_HIDDEN |
+                                       FILE_ATTRIBUTE_SYSTEM |
+                                       FILE_ATTRIBUTE_READONLY)))
+                       {
+                               /* If the existing file has
+                                * FILE_ATTRIBUTE_HIDDEN and/or
+                                * FILE_ATTRIBUTE_SYSTEM, they must be set in
+                                * the call to CreateFile().  This is true even
+                                * when FILE_ATTRIBUTE_NORMAL was not specified,
+                                * contrary to the MS "documentation".  */
+                               dwFlagsAndAttributes |= (attribs &
+                                                        (FILE_ATTRIBUTE_HIDDEN |
+                                                         FILE_ATTRIBUTE_SYSTEM));
+                               /* If the existing file has
+                                * FILE_ATTRIBUTE_READONLY, it must be cleared
+                                * before attempting to create a new file over
+                                * it.  This is true even when the process has
+                                * the SE_RESTORE_NAME privilege and requested
+                                * the FILE_FLAG_BACKUP_SEMANTICS flag to
+                                * CreateFile().  */
+                               if (attribs & FILE_ATTRIBUTE_READONLY) {
+                                       SetFileAttributes(path,
+                                                         attribs & ~FILE_ATTRIBUTE_READONLY);
+                               }
+                               retry_count++;
+                               goto retry;
+                       }
+               }
+               set_errno_from_win32_error(err);
+               return WIMLIB_ERR_OPEN;
+       }
        CloseHandle(h);
        return 0;
-
-error:
-       set_errno_from_GetLastError();
-       return WIMLIB_ERR_OPEN;
 }
 
 static int