Merge branch 'sigio-vt-switch-issues' into for-keith

Conflicts:
	test/Makefile.am

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

hw/dmx/input/dmxevents.c

@@ -227,25 +227,25 @@ dmxCoreMotion(DevicePtr pDev, int x, int y, int delta, DMXBlockType block)
             && pScreen->myNum == dmxScreen->index) {
             /* Screen is old screen */
             if (block)
-                dmxSigioBlock();
+                OsBlockSIGIO();
             if (pDev)
                 enqueueMotion(pDev, localX, localY);
             if (block)
-                dmxSigioUnblock();
+                OsReleaseSIGIO();
         }
         else {
             /* Screen is new */
             DMXDBG4("   New screen: old=%d new=%d localX=%d localY=%d\n",
                     pScreen->myNum, dmxScreen->index, localX, localY);
             if (block)
-                dmxSigioBlock();
+                OsBlockSIGIO();
             mieqProcessInputEvents();
             miPointerSetScreen(inputInfo.pointer, dmxScreen->index,
                                localX, localY);
             if (pDev)
                 enqueueMotion(pDev, localX, localY);
             if (block)
-                dmxSigioUnblock();
+                OsReleaseSIGIO();
         }
 #if 00
         miPointerGetPosition(inputInfo.pointer, &localX, &localY);
@@ -387,12 +387,12 @@ dmxExtMotion(DMXLocalInputInfoPtr dmxLocal,
     }
 
     if (block)
-        dmxSigioBlock();
+        OsBlockSIGIO();
     valuator_mask_set_range(&mask, firstAxis, axesCount, v);
     QueuePointerEvents(pDevice, MotionNotify, 0, POINTER_ABSOLUTE, &mask);
 
     if (block)
-        dmxSigioUnblock();
+        OsReleaseSIGIO();
 }
 
 static int
@@ -492,10 +492,10 @@ dmxTranslateAndEnqueueExtEvent(DMXLocalInputInfoPtr dmxLocal,
         valuator_mask_set_range(&mask, ke->first_axis, ke->axes_count,
                                 valuators);
         if (block)
-            dmxSigioBlock();
+            OsBlockSIGIO();
         QueueKeyboardEvents(pDevice, event, ke->keycode, &mask);
         if (block)
-            dmxSigioUnblock();
+            OsReleaseSIGIO();
         break;
     case XI_DeviceButtonPress:
     case XI_DeviceButtonRelease:
@@ -503,11 +503,11 @@ dmxTranslateAndEnqueueExtEvent(DMXLocalInputInfoPtr dmxLocal,
         valuator_mask_set_range(&mask, ke->first_axis, ke->axes_count,
                                 valuators);
         if (block)
-            dmxSigioBlock();
+            OsBlockSIGIO();
         QueuePointerEvents(pDevice, event, ke->keycode,
                            POINTER_ABSOLUTE, &mask);
         if (block)
-            dmxSigioUnblock();
+            OsReleaseSIGIO();
         break;
     case XI_ProximityIn:
     case XI_ProximityOut:
@@ -515,10 +515,10 @@ dmxTranslateAndEnqueueExtEvent(DMXLocalInputInfoPtr dmxLocal,
         valuator_mask_set_range(&mask, ke->first_axis, ke->axes_count,
                                 valuators);
         if (block)
-            dmxSigioBlock();
+            OsBlockSIGIO();
         QueueProximityEvents(pDevice, event, &mask);
         if (block)
-            dmxSigioUnblock();
+            OsReleaseSIGIO();
         break;
 
         break;

hw/dmx/input/dmxsigio.c

@@ -84,28 +84,6 @@ dmxSigioHandler(int sig)
     }
 }
 
-/** Block SIGIO handling. */
-void
-dmxSigioBlock(void)
-{
-    sigset_t s;
-
-    sigemptyset(&s);
-    sigaddset(&s, SIGIO);
-    sigprocmask(SIG_BLOCK, &s, 0);
-}
-
-/** Unblock SIGIO handling. */
-void
-dmxSigioUnblock(void)
-{
-    sigset_t s;
-
-    sigemptyset(&s);
-    sigaddset(&s, SIGIO);
-    sigprocmask(SIG_UNBLOCK, &s, 0);
-}
-
 static void
 dmxSigioHook(void)
 {

hw/dmx/input/dmxsigio.h

@@ -36,8 +36,6 @@
 
 #ifndef _DMXSIGIO_H_
 #define _DMXSIGIO_H_
-extern void dmxSigioBlock(void);
-extern void dmxSigioUnblock(void);
 extern void dmxSigioEnableInput(void);
 extern void dmxSigioDisableInput(void);
 extern void dmxSigioRegister(DMXInputInfo * dmxInput, int fd);

hw/kdrive/ephyr/ephyr.c

@@ -772,26 +772,6 @@ ephyrUpdateModifierState(unsigned int state)
     }
 }
 
-static void
-ephyrBlockSigio(void)
-{
-    sigset_t set;
-
-    sigemptyset(&set);
-    sigaddset(&set, SIGIO);
-    sigprocmask(SIG_BLOCK, &set, 0);
-}
-
-static void
-ephyrUnblockSigio(void)
-{
-    sigset_t set;
-
-    sigemptyset(&set);
-    sigaddset(&set, SIGIO);
-    sigprocmask(SIG_UNBLOCK, &set, 0);
-}
-
 static Bool
 ephyrCursorOffScreen(ScreenPtr *ppScreen, int *x, int *y)
 {
@@ -808,11 +788,11 @@ int ephyrCurScreen;             /*current event screen */
 static void
 ephyrWarpCursor(DeviceIntPtr pDev, ScreenPtr pScreen, int x, int y)
 {
-    ephyrBlockSigio();
+    OsBlockSIGIO();
     ephyrCurScreen = pScreen->myNum;
     miPointerWarpCursor(inputInfo.pointer, pScreen, x, y);
 
-    ephyrUnblockSigio();
+    OsReleaseSIGIO();
 }
 
 miPointerScreenFuncRec ephyrPointerScreenFuncs = {

hw/kdrive/src/kinput.c

@@ -102,26 +102,6 @@ KdSigio(int sig)
         (*kdInputFds[i].read) (kdInputFds[i].fd, kdInputFds[i].closure);
 }
 
-static void
-KdBlockSigio(void)
-{
-    sigset_t set;
-
-    sigemptyset(&set);
-    sigaddset(&set, SIGIO);
-    sigprocmask(SIG_BLOCK, &set, 0);
-}
-
-static void
-KdUnblockSigio(void)
-{
-    sigset_t set;
-
-    sigemptyset(&set);
-    sigaddset(&set, SIGIO);
-    sigprocmask(SIG_UNBLOCK, &set, 0);
-}
-
 #ifdef DEBUG_SIGIO
 
 void
@@ -261,7 +241,7 @@ KdDisableInput(void)
     KdPointerInfo *pi;
     int found = 0, i = 0;
 
-    KdBlockSigio();
+    OsBlockSIGIO();
 
     for (ki = kdKeyboards; ki; ki = ki->next) {
         if (ki->driver && ki->driver->Disable)
@@ -343,7 +323,7 @@ KdEnableInput(void)
     NoticeEventTime(&ev, pi->dixdev);
     NoticeEventTime(&ev, ki->dixdev);
 
-    KdUnblockSigio();
+    OsReleaseSIGIO();
 }
 
 static KdKeyboardDriver *
@@ -1801,7 +1781,7 @@ KdReleaseAllKeys(void)
     int key;
     KdKeyboardInfo *ki;
 
-    KdBlockSigio();
+    OsBlockSIGIO();
 
     for (ki = kdKeyboards; ki; ki = ki->next) {
         for (key = ki->keySyms.minKeyCode; key < ki->keySyms.maxKeyCode; key++) {
@@ -1812,7 +1792,7 @@ KdReleaseAllKeys(void)
         }
     }
 
-    KdUnblockSigio();
+    OsReleaseSIGIO();
 #endif
 }
 
@@ -2008,18 +1988,18 @@ KdWakeupHandler(ScreenPtr pScreen, unsigned long lresult, pointer readmask)
     if (kdInputEnabled && result > 0) {
         for (i = 0; i < kdNumInputFds; i++)
             if (FD_ISSET(kdInputFds[i].fd, pReadmask)) {
-                KdBlockSigio();
+                OsBlockSIGIO();
                 (*kdInputFds[i].read) (kdInputFds[i].fd, kdInputFds[i].closure);
-                KdUnblockSigio();
+                OsReleaseSIGIO();
             }
     }
     for (pi = kdPointers; pi; pi = pi->next) {
         if (pi->timeoutPending) {
             if ((long) (GetTimeInMillis() - pi->emulationTimeout) >= 0) {
                 pi->timeoutPending = FALSE;
-                KdBlockSigio();
+                OsBlockSIGIO();
                 KdReceiveTimeout(pi);
-                KdUnblockSigio();
+                OsReleaseSIGIO();
             }
         }
     }
@@ -2116,10 +2096,10 @@ int KdCurScreen;                /* current event screen */
 static void
 KdWarpCursor(DeviceIntPtr pDev, ScreenPtr pScreen, int x, int y)
 {
-    KdBlockSigio();
+    OsBlockSIGIO();
     KdCurScreen = pScreen->myNum;
     miPointerWarpCursor(pDev, pScreen, x, y);
-    KdUnblockSigio();
+    OsReleaseSIGIO();
 }
 
 miPointerScreenFuncRec kdPointerScreenFuncs = {

hw/xfree86/common/xf86Cursor.c

@@ -199,7 +199,7 @@ xf86SwitchMode(ScreenPtr pScreen, DisplayModePtr mode)
     ScrnInfoPtr pScr = xf86ScreenToScrn(pScreen);
     ScreenPtr pCursorScreen;
     Bool Switched;
-    int px, py, was_blocked;
+    int px, py;
     DeviceIntPtr dev, it;
 
     if (!pScr->vtSema || !mode || !pScr->SwitchMode)
@@ -228,7 +228,7 @@ xf86SwitchMode(ScreenPtr pScreen, DisplayModePtr mode)
     if (pScreen == pCursorScreen)
         miPointerGetPosition(dev, &px, &py);
 
-    was_blocked = xf86BlockSIGIO();
+    OsBlockSIGIO();
     Switched = (*pScr->SwitchMode) (pScr, mode);
     if (Switched) {
         pScr->currentMode = mode;
@@ -267,7 +267,7 @@ xf86SwitchMode(ScreenPtr pScreen, DisplayModePtr mode)
             pScr->frameY1 = pScr->virtualY - 1;
         }
     }
-    xf86UnblockSIGIO(was_blocked);
+    OsReleaseSIGIO();
 
     if (pScr->AdjustFrame)
         (*pScr->AdjustFrame) (pScr, pScr->frameX0, pScr->frameY0);
@@ -469,13 +469,11 @@ xf86CrossScreen(ScreenPtr pScreen, Bool entering)
 static void
 xf86WarpCursor(DeviceIntPtr pDev, ScreenPtr pScreen, int x, int y)
 {
-    int sigstate;
+    OsBlockSIGIO();
-
-    sigstate = xf86BlockSIGIO();
     miPointerWarpCursor(pDev, pScreen, x, y);
 
     xf86Info.currentScreen = pScreen;
-    xf86UnblockSIGIO(sigstate);
+    OsReleaseSIGIO();
 }
 
 void *

hw/xfree86/common/xf86Events.c

@@ -254,7 +254,7 @@ xf86Wakeup(pointer blockData, int err, pointer pReadmask)
             while (pInfo) {
                 if (pInfo->read_input && pInfo->fd >= 0 &&
                     (FD_ISSET(pInfo->fd, &devicesWithInput) != 0)) {
-                    int sigstate = xf86BlockSIGIO();
+                    OsBlockSIGIO();
 
                     /*
                      * Remove the descriptior from the set because more than one
@@ -263,7 +263,7 @@ xf86Wakeup(pointer blockData, int err, pointer pReadmask)
                     FD_CLR(pInfo->fd, &devicesWithInput);
 
                     pInfo->read_input(pInfo);
-                    xf86UnblockSIGIO(sigstate);
+                    OsReleaseSIGIO();
                 }
                 pInfo = pInfo->next;
             }
@@ -397,9 +397,9 @@ xf86ReleaseKeys(DeviceIntPtr pDev)
     for (i = keyc->xkbInfo->desc->min_key_code;
          i < keyc->xkbInfo->desc->max_key_code; i++) {
         if (key_is_down(pDev, i, KEY_POSTED)) {
-            sigstate = xf86BlockSIGIO();
+            OsBlockSIGIO();
             QueueKeyboardEvents(pDev, KeyRelease, i, NULL);
-            xf86UnblockSIGIO(sigstate);
+            OsReleaseSIGIO();
         }
     }
 }
@@ -457,7 +457,7 @@ xf86VTSwitch(void)
             }
         }
 
-        prevSIGIO = xf86BlockSIGIO();
+        OsBlockSIGIO();
         for (i = 0; i < xf86NumScreens; i++)
             xf86Screens[i]->LeaveVT(xf86Screens[i]);
 
@@ -492,7 +492,7 @@ xf86VTSwitch(void)
             for (ih = InputHandlers; ih; ih = ih->next)
                 xf86EnableInputHandler(ih);
 
-            xf86UnblockSIGIO(prevSIGIO);
+            OsReleaseSIGIO();
 
         }
         else {
@@ -549,7 +549,7 @@ xf86VTSwitch(void)
         for (ih = InputHandlers; ih; ih = ih->next)
             xf86EnableInputHandler(ih);
 
-        xf86UnblockSIGIO(prevSIGIO);
+        OsReleaseSIGIO();
     }
 }
 

hw/xfree86/common/xf86Init.c

@@ -394,7 +394,7 @@ InstallSignalHandlers(void)
 void
 InitOutput(ScreenInfo * pScreenInfo, int argc, char **argv)
 {
-    int i, j, k, scr_index, was_blocked = 0;
+    int i, j, k, scr_index;
     char **modulelist;
     pointer *optionlist;
     Pix24Flags screenpix24, pix24;
@@ -806,7 +806,7 @@ InitOutput(ScreenInfo * pScreenInfo, int argc, char **argv)
             ioctl(xf86Info.consoleFd, VT_RELDISP, VT_ACKACQ);
 #endif
             xf86AccessEnter();
-            was_blocked = xf86BlockSIGIO();
+            OsBlockSIGIO();
         }
     }
 
@@ -879,7 +879,7 @@ InitOutput(ScreenInfo * pScreenInfo, int argc, char **argv)
     }
 
     xf86VGAarbiterWrapFunctions();
-    xf86UnblockSIGIO(was_blocked);
+    OsReleaseSIGIO();
 
     xf86InitOrigins();
 
@@ -964,6 +964,7 @@ OsVendorInit(void)
     }
 #endif
 #endif
+    OsReleaseSIGIO();
 
     beenHere = TRUE;
 }
@@ -1022,7 +1023,7 @@ AbortDDX(enum ExitCode error)
 {
     int i;
 
-    xf86BlockSIGIO();
+    OsBlockSIGIO();
 
     /*
      * try to restore the original video state

hw/xfree86/common/xf86PM.c

@@ -92,8 +92,6 @@ eventName(pmEvent event, const char **str)
     }
 }
 
-static int sigio_blocked_for_suspend;
-
 static void
 suspend(pmEvent event, Bool undo)
 {
@@ -109,7 +107,7 @@ suspend(pmEvent event, Bool undo)
         DisableDevice(pInfo->dev, TRUE);
         pInfo = pInfo->next;
     }
-    sigio_blocked_for_suspend = xf86BlockSIGIO();
+    OsBlockSIGIO();
     for (i = 0; i < xf86NumScreens; i++) {
         if (xf86Screens[i]->PMEvent)
             xf86Screens[i]->PMEvent(xf86Screens[i], event, undo);
@@ -137,7 +135,7 @@ resume(pmEvent event, Bool undo)
             xf86Screens[i]->EnterVT(xf86Screens[i]);
         }
     }
-    xf86UnblockSIGIO(sigio_blocked_for_suspend);
+    OsReleaseSIGIO();
     for (i = 0; i < xf86NumScreens; i++) {
         if (xf86Screens[i]->EnableDisableFBAccess)
             (*xf86Screens[i]->EnableDisableFBAccess) (xf86Screens[i], TRUE);
@@ -153,7 +151,7 @@ resume(pmEvent event, Bool undo)
 static void
 DoApmEvent(pmEvent event, Bool undo)
 {
-    int i, was_blocked;
+    int i;
 
     switch (event) {
 #if 0
@@ -184,13 +182,13 @@ DoApmEvent(pmEvent event, Bool undo)
         }
         break;
     default:
-        was_blocked = xf86BlockSIGIO();
+        OsBlockSIGIO();
         for (i = 0; i < xf86NumScreens; i++) {
             if (xf86Screens[i]->PMEvent) {
                 xf86Screens[i]->PMEvent(xf86Screens[i], event, undo);
             }
         }
-        xf86UnblockSIGIO(was_blocked);
+        OsReleaseSIGIO();
         break;
     }
 }

hw/xfree86/os-support/shared/sigio.c

@@ -136,7 +136,6 @@ xf86InstallSIGIOHandler(int fd, void (*f) (int, void *), void *closure)
     struct sigaction sa;
     struct sigaction osa;
     int i;
-    int blocked;
     int installed = FALSE;
 
     if (!xf86Info.useSIGIO)
@@ -146,7 +145,7 @@ xf86InstallSIGIOHandler(int fd, void (*f) (int, void *), void *closure)
         if (!xf86SigIOFuncs[i].f) {
             if (xf86IsPipe(fd))
                 return 0;
-            blocked = xf86BlockSIGIO();
+            OsBlockSIGIO();
 #ifdef O_ASYNC
             if (fcntl(fd, F_SETFL, fcntl(fd, F_GETFL) | O_ASYNC) == -1) {
                 xf86Msg(X_WARNING, "fcntl(%d, O_ASYNC): %s\n",
@@ -174,7 +173,7 @@ xf86InstallSIGIOHandler(int fd, void (*f) (int, void *), void *closure)
             }
 #endif
             if (!installed) {
-                xf86UnblockSIGIO(blocked);
+                OsReleaseSIGIO();
                 return 0;
             }
             sigemptyset(&sa.sa_mask);
@@ -190,7 +189,7 @@ xf86InstallSIGIOHandler(int fd, void (*f) (int, void *), void *closure)
             if (fd >= xf86SigIOMaxFd)
                 xf86SigIOMaxFd = fd + 1;
             FD_SET(fd, &xf86SigIOMask);
-            xf86UnblockSIGIO(blocked);
+            OsReleaseSIGIO();
             return 1;
         }
         /* Allow overwriting of the closure and callback */
@@ -263,26 +262,13 @@ xf86RemoveSIGIOHandler(int fd)
 int
 xf86BlockSIGIO(void)
 {
-    sigset_t set, old;
+    return OsBlockSIGIO();
-    int ret;
-
-    sigemptyset(&set);
-    sigaddset(&set, SIGIO);
-    sigprocmask(SIG_BLOCK, &set, &old);
-    ret = sigismember(&old, SIGIO);
-    return ret;
 }
 
 void
 xf86UnblockSIGIO(int wasset)
 {
-    sigset_t set;
+    OsReleaseSIGIO();
-
-    if (!wasset) {
-        sigemptyset(&set);
-        sigaddset(&set, SIGIO);
-        sigprocmask(SIG_UNBLOCK, &set, NULL);
-    }
 }
 
 void

include/os.h

@@ -334,6 +334,12 @@ OsBlockSignals(void);
 extern _X_EXPORT void
 OsReleaseSignals(void);
 
+extern _X_EXPORT int
+OsBlockSIGIO(void);
+
+extern _X_EXPORT void
+OsReleaseSIGIO(void);
+
 extern _X_EXPORT void
 OsAbort(void)
     _X_NORETURN;

os/utils.c

@@ -1167,14 +1167,14 @@ OsBlockSignals(void)
     if (BlockedSignalCount++ == 0) {
         sigset_t set;
 
+#ifdef SIGIO
+        OsBlockSIGIO();
+#endif
         sigemptyset(&set);
         sigaddset(&set, SIGALRM);
         sigaddset(&set, SIGVTALRM);
 #ifdef SIGWINCH
         sigaddset(&set, SIGWINCH);
-#endif
-#ifdef SIGIO
-        sigaddset(&set, SIGIO);
 #endif
         sigaddset(&set, SIGTSTP);
         sigaddset(&set, SIGTTIN);
@@ -1185,12 +1185,60 @@ OsBlockSignals(void)
 #endif
 }
 
+#ifdef SIG_BLOCK
+static sig_atomic_t sigio_blocked;
+#endif
+
+/**
+ * returns zero if this call caused SIGIO to be blocked now, non-zero if it
+ * was already blocked by a previous call to this function.
+ */
+int
+OsBlockSIGIO(void)
+{
+#ifdef SIGIO
+#ifdef SIG_BLOCK
+    if (sigio_blocked++ == 0) {
+        sigset_t set, old;
+        int ret;
+
+        sigemptyset(&set);
+        sigaddset(&set, SIGIO);
+        sigprocmask(SIG_BLOCK, &set, &old);
+        ret = sigismember(&old, SIGIO);
+        return ret;
+    } else
+        return 1;
+#endif
+#endif
+}
+
+void
+OsReleaseSIGIO(void)
+{
+#ifdef SIGIO
+#ifdef SIG_BLOCK
+    if (--sigio_blocked == 0) {
+        sigset_t set;
+
+        sigemptyset(&set);
+        sigaddset(&set, SIGIO);
+        sigprocmask(SIG_UNBLOCK, &set, NULL);
+    } else if (sigio_blocked < 0) {
+        BUG_WARN(sigio_blocked < 0);
+        sigio_blocked = 0;
+    }
+#endif
+#endif
+}
+
 void
 OsReleaseSignals(void)
 {
 #ifdef SIG_BLOCK
     if (--BlockedSignalCount == 0) {
         sigprocmask(SIG_SETMASK, &PreviousSignalMask, 0);
+        OsReleaseSIGIO();
     }
 #endif
 }

test/Makefile.am

@@ -5,7 +5,7 @@ if XORG
 # Tests that require at least some DDX functions in order to fully link
 # For now, requires xf86 ddx, could be adjusted to use another
 SUBDIRS += xi2
-noinst_PROGRAMS += xkb input xtest misc fixes xfree86 hashtabletest signal-logging
+noinst_PROGRAMS += xkb input xtest misc fixes xfree86 hashtabletest os signal-logging
 endif
 check_LTLIBRARIES = libxservertest.la
 
@@ -38,6 +38,7 @@ xfree86_LDADD=$(TEST_LDADD)
 touch_LDADD=$(TEST_LDADD)
 signal_logging_LDADD=$(TEST_LDADD)
 hashtabletest_LDADD=$(TEST_LDADD) $(top_srcdir)/Xext/hashtable.c
+os_LDADD=$(TEST_LDADD)
 
 libxservertest_la_LIBADD = $(XSERVER_LIBS)
 if XORG

test/os.c

@@ -0,0 +1,130 @@
+/**
+ * Copyright © 2012 Red Hat, Inc.
+ *
+ *  Permission is hereby granted, free of charge, to any person obtaining a
+ *  copy of this software and associated documentation files (the "Software"),
+ *  to deal in the Software without restriction, including without limitation
+ *  the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ *  and/or sell copies of the Software, and to permit persons to whom the
+ *  Software is furnished to do so, subject to the following conditions:
+ *
+ *  The above copyright notice and this permission notice (including the next
+ *  paragraph) shall be included in all copies or substantial portions of the
+ *  Software.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ *  THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ *  FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ *  DEALINGS IN THE SOFTWARE.
+ */
+
+#ifdef HAVE_DIX_CONFIG_H
+#include <dix-config.h>
+#endif
+
+#include <signal.h>
+#include "os.h"
+
+static int
+sig_is_blocked(int sig)
+{
+    sigset_t current;
+
+    sigemptyset(&current);
+    assert(sigprocmask(SIG_BLOCK, NULL, &current) == 0);
+    return sigismember(&current, sig);
+}
+
+static void block_sigio_test(void)
+{
+#ifdef SIG_BLOCK
+    sigset_t current;
+
+    sigemptyset(&current);
+    assert(!sig_is_blocked(SIGIO));
+
+    /* block once */
+    OsBlockSIGIO();
+    assert(sig_is_blocked(SIGIO));
+    OsReleaseSIGIO();
+    assert(!sig_is_blocked(SIGIO));
+
+    /* block twice, nested */
+    OsBlockSIGIO();
+    assert(sig_is_blocked(SIGIO));
+    OsBlockSIGIO();
+    assert(sig_is_blocked(SIGIO));
+    OsReleaseSIGIO();
+    assert(sig_is_blocked(SIGIO));
+    OsReleaseSIGIO();
+    assert(!sig_is_blocked(SIGIO));
+
+    /* block all */
+    OsBlockSignals();
+    assert(sig_is_blocked(SIGIO));
+    OsReleaseSignals();
+    assert(!sig_is_blocked(SIGIO));
+
+    /* block all nested */
+    OsBlockSignals();
+    assert(sig_is_blocked(SIGIO));
+    OsBlockSignals();
+    assert(sig_is_blocked(SIGIO));
+    OsReleaseSignals();
+    assert(sig_is_blocked(SIGIO));
+    OsReleaseSignals();
+    assert(!sig_is_blocked(SIGIO));
+
+    /* mix the two */
+    /* ABBA */
+    OsBlockSignals();
+    assert(sig_is_blocked(SIGIO));
+    OsBlockSIGIO();
+    assert(sig_is_blocked(SIGIO));
+    OsReleaseSIGIO();
+    assert(sig_is_blocked(SIGIO));
+    OsReleaseSignals();
+    assert(!sig_is_blocked(SIGIO));
+
+    /* ABAB */
+    OsBlockSignals();
+    assert(sig_is_blocked(SIGIO));
+    OsBlockSIGIO();
+    assert(sig_is_blocked(SIGIO));
+    OsReleaseSignals();
+    assert(sig_is_blocked(SIGIO));
+    OsReleaseSIGIO();
+    assert(!sig_is_blocked(SIGIO));
+
+    /* BAAB */
+    OsBlockSIGIO();
+    assert(sig_is_blocked(SIGIO));
+    OsBlockSignals();
+    assert(sig_is_blocked(SIGIO));
+    OsReleaseSignals();
+    assert(sig_is_blocked(SIGIO));
+    OsReleaseSIGIO();
+    assert(!sig_is_blocked(SIGIO));
+
+    /* BABA */
+    OsBlockSIGIO();
+    assert(sig_is_blocked(SIGIO));
+    OsBlockSignals();
+    assert(sig_is_blocked(SIGIO));
+    OsReleaseSIGIO();
+    assert(sig_is_blocked(SIGIO));
+    OsReleaseSignals();
+    assert(!sig_is_blocked(SIGIO));
+
+#endif
+}
+
+int
+main(int argc, char **argv)
+{
+    block_sigio_test();
+    return 0;
+}