Fix a Windows-specific FIXME in signal handling code.

src/xz/main.c

@@ -13,10 +13,15 @@
 #include "private.h"
 #include <ctype.h>
 
-
 /// Exit status to use. This can be changed with set_exit_status().
 static enum exit_status_type exit_status = E_SUCCESS;
 
+#if defined(_WIN32) && !defined(__CYGWIN__)
+/// exit_status has to be protected with a critical section due to
+/// how "signal handling" is done on Windows. See signals.c for details.
+static CRITICAL_SECTION exit_status_cs;
+#endif
+
 /// True if --no-warn is specified. When this is true, we don't set
 /// the exit status to E_WARNING when something worth a warning happens.
 static bool no_warn = false;
@@ -27,9 +32,17 @@ set_exit_status(enum exit_status_type new_status)
 {
 	assert(new_status == E_WARNING || new_status == E_ERROR);
 
+#if defined(_WIN32) && !defined(__CYGWIN__)
+	EnterCriticalSection(&exit_status_cs);
+#endif
+
 	if (exit_status != E_ERROR)
 		exit_status = new_status;
 
+#if defined(_WIN32) && !defined(__CYGWIN__)
+	LeaveCriticalSection(&exit_status_cs);
+#endif
+
 	return;
 }
 
@@ -129,6 +142,10 @@ read_name(const args_info *args)
 int
 main(int argc, char **argv)
 {
+#if defined(_WIN32) && !defined(__CYGWIN__)
+	InitializeCriticalSection(&exit_status_cs);
+#endif
+
 	// Set up the progname variable.
 	tuklib_progname_init(argv);
 
@@ -262,11 +279,24 @@ main(int argc, char **argv)
 	// of calling tuklib_exit().
 	signals_exit();
 
+	// Make a local copy of exit_status to keep the Windows code
+	// thread safe. At this point it is fine if we miss the user
+	// pressing C-c and don't set the exit_status to E_ERROR on
+	// Windows.
+#if defined(_WIN32) && !defined(__CYGWIN__)
+	EnterCriticalSection(&exit_status_cs);
+#endif
+
+	enum exit_status_type es = exit_status;
+
+#if defined(_WIN32) && !defined(__CYGWIN__)
+	LeaveCriticalSection(&exit_status_cs);
+#endif
+
 	// Suppress the exit status indicating a warning if --no-warn
 	// was specified.
-	if (exit_status == E_WARNING && no_warn)
-		exit_status = E_SUCCESS;
+	if (es == E_WARNING && no_warn)
+		es = E_SUCCESS;
 
-	tuklib_exit(exit_status, E_ERROR,
-			message_verbosity_get() != V_SILENT);
+	tuklib_exit(es, E_ERROR, message_verbosity_get() != V_SILENT);
 }

src/xz/private.h

@@ -26,6 +26,11 @@
 #include "tuklib_progname.h"
 #include "tuklib_exit.h"
 
+#if defined(_WIN32) && !defined(__CYGWIN__)
+#	define WIN32_LEAN_AND_MEAN
+#	include <windows.h>
+#endif
+
 #ifndef STDIN_FILENO
 #	define STDIN_FILENO (fileno(stdin))
 #endif

src/xz/signals.c

@@ -156,11 +156,14 @@ signals_exit(void)
 #else
 
 // While Windows has some very basic signal handling functions as required
-// by C89, they are not really used, or so I understood. Instead, we use
-// SetConsoleCtrlHandler() to catch user pressing C-c.
-
-#include <windows.h>
-
+// by C89, they are not really used, and e.g. SIGINT doesn't work exactly
+// the way it does on POSIX (Windows creates a new thread for the signal
+// handler). Instead, we use SetConsoleCtrlHandler() to catch user
+// pressing C-c, because that seems to be the recommended way to do it.
+//
+// NOTE: This doesn't work under MSYS. Trying with SIGINT doesn't work
+// either even if it appeared to work at first. So test using Windows
+// console window.
 
 static BOOL WINAPI
 signal_handler(DWORD type lzma_attribute((unused)))
@@ -168,9 +171,6 @@ signal_handler(DWORD type lzma_attribute((unused)))
 	// Since we don't get a signal number which we could raise() at
 	// signals_exit() like on POSIX, just set the exit status to
 	// indicate an error, so that we cannot return with zero exit status.
-	//
-	// FIXME: Since this function runs in its own thread,
-	// set_exit_status() should have a mutex.
 	set_exit_status(E_ERROR);
 	user_abort = true;
 	return TRUE;