+/* This structure is used to hold all the data that is exchanged between
+ parent and child. */
+struct fake_fork_info
+{
+ HANDLE event;
+ bool logfile_changed;
+ char lfilename[MAX_PATH + 1];
+};
+
+/* Determines if we are the child and if so performs the child logic.
+ Return values:
+ < 0 error
+ 0 parent
+ > 0 child
+*/
+static int
+fake_fork_child (void)
+{
+ HANDLE section, event;
+ struct fake_fork_info *info;
+ char *name;
+
+ name = make_section_name (GetCurrentProcessId ());
+ section = OpenFileMapping (FILE_MAP_WRITE, FALSE, name);
+ xfree (name);
+ /* It seems that Windows 9x and NT set last-error inconsistently when
+ OpenFileMapping() fails; so we assume it failed because the section
+ object does not exist. */
+ if (!section)
+ return 0; /* We are the parent. */
+
+ info = MapViewOfFile (section, FILE_MAP_WRITE, 0, 0, 0);
+ if (!info)
+ {
+ CloseHandle (section);
+ return -1;
+ }
+
+ event = info->event;
+
+ info->logfile_changed = false;
+ if (!opt.lfilename && (!opt.quiet || opt.server_response))
+ {
+ /* See utils:fork_to_background for explanation. */
+ FILE *new_log_fp = unique_create (DEFAULT_LOGFILE, false, &opt.lfilename);
+ if (new_log_fp)
+ {
+ info->logfile_changed = true;
+ strncpy (info->lfilename, opt.lfilename, sizeof (info->lfilename));
+ info->lfilename[sizeof (info->lfilename) - 1] = '\0';
+ fclose (new_log_fp);
+ }
+ }
+
+ UnmapViewOfFile (info);
+ CloseHandle (section);
+
+ /* Inform the parent that we've done our part. */
+ if (!SetEvent (event))
+ return -1;
+
+ CloseHandle (event);
+ return 1; /* We are the child. */
+}
+
+/* Windows doesn't support the fork() call; so we fake it by invoking
+ another copy of Wget with the same arguments with which we were
+ invoked. The child copy of Wget should perform the same initialization
+ sequence as the parent; so we should have two processes that are
+ essentially identical. We create a specially named section object that
+ allows the child to distinguish itself from the parent and is used to
+ exchange information between the two processes. We use an event object
+ for synchronization. */
+static void
+fake_fork (void)
+{
+ char exe[MAX_PATH + 1];
+ DWORD exe_len, le;
+ SECURITY_ATTRIBUTES sa;
+ HANDLE section, event, h[2];
+ STARTUPINFO si;
+ PROCESS_INFORMATION pi;
+ struct fake_fork_info *info;
+ char *name;
+ BOOL rv;
+
+ section = pi.hProcess = pi.hThread = NULL;
+
+ /* Get the fully qualified name of our executable. This is more reliable
+ than using argv[0]. */
+ exe_len = GetModuleFileName (GetModuleHandle (NULL), exe, sizeof (exe));
+ if (!exe_len || (exe_len >= sizeof (exe)))
+ return;
+
+ sa.nLength = sizeof (sa);
+ sa.lpSecurityDescriptor = NULL;
+ sa.bInheritHandle = TRUE;
+
+ /* Create an anonymous inheritable event object that starts out
+ non-signaled. */
+ event = CreateEvent (&sa, FALSE, FALSE, NULL);
+ if (!event)
+ return;
+
+ /* Create the child process detached form the current console and in a
+ suspended state. */
+ xzero (si);
+ si.cb = sizeof (si);
+ rv = CreateProcess (exe, GetCommandLine (), NULL, NULL, TRUE,
+ CREATE_SUSPENDED | DETACHED_PROCESS,
+ NULL, NULL, &si, &pi);
+ if (!rv)
+ goto cleanup;
+
+ /* Create a named section object with a name based on the process id of
+ the child. */
+ name = make_section_name (pi.dwProcessId);
+ section =
+ CreateFileMapping (INVALID_HANDLE_VALUE, NULL, PAGE_READWRITE, 0,
+ sizeof (struct fake_fork_info), name);
+ le = GetLastError();
+ xfree (name);
+ /* Fail if the section object already exists (should not happen). */
+ if (!section || (le == ERROR_ALREADY_EXISTS))
+ {
+ rv = FALSE;
+ goto cleanup;
+ }
+
+ /* Copy the event handle into the section object. */
+ info = MapViewOfFile (section, FILE_MAP_WRITE, 0, 0, 0);
+ if (!info)
+ {
+ rv = FALSE;
+ goto cleanup;
+ }
+
+ info->event = event;
+
+ UnmapViewOfFile (info);
+
+ /* Start the child process. */
+ rv = ResumeThread (pi.hThread);
+ if (!rv)
+ {
+ TerminateProcess (pi.hProcess, (DWORD) -1);
+ goto cleanup;
+ }
+
+ /* Wait for the child to signal to us that it has done its part. If it
+ terminates before signaling us it's an error. */
+
+ h[0] = event;
+ h[1] = pi.hProcess;
+ rv = WAIT_OBJECT_0 == WaitForMultipleObjects (2, h, FALSE, 5 * 60 * 1000);
+ if (!rv)
+ goto cleanup;
+
+ info = MapViewOfFile (section, FILE_MAP_READ, 0, 0, 0);
+ if (!info)
+ {
+ rv = FALSE;
+ goto cleanup;
+ }
+
+ /* Ensure string is properly terminated. */
+ if (info->logfile_changed &&
+ !memchr (info->lfilename, '\0', sizeof (info->lfilename)))
+ {
+ rv = FALSE;
+ goto cleanup;
+ }
+
+ printf (_("Continuing in background, pid %lu.\n"), pi.dwProcessId);
+ if (info->logfile_changed)
+ printf (_("Output will be written to %s.\n"), quote (info->lfilename));
+
+ UnmapViewOfFile (info);
+
+cleanup:
+
+ if (event)
+ CloseHandle (event);
+ if (section)
+ CloseHandle (section);
+ if (pi.hThread)
+ CloseHandle (pi.hThread);
+ if (pi.hProcess)
+ CloseHandle (pi.hProcess);
+
+ /* We're the parent. If all is well, terminate. */
+ if (rv)
+ exit (0);
+
+ /* We failed, return. */
+}
+
+/* This is the corresponding Windows implementation of the
+ fork_to_background() function in utils.c. */