Fix polling for writeability of a screen buffer.

* lib/poll.c: Distinguish input and screen buffers for the
Win32 implementation.
* lib/select.c: Likewise.

diff --git a/ChangeLog b/ChangeLog
index 2161c2b..aae0ae0 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2009-08-20  Paolo Bonzini  <bonzini@gnu.org>
+
+       Fix polling for writeability of a screen buffer.
+       * lib/poll.c: Distinguish input and screen buffers for the
+       Win32 implementation.
+       * lib/select.c: Likewise.
+
 2009-08-19  Eric Blake  <ebb9@byu.net>
 
        popen-safer: prevent popen from clobbering std descriptors

diff --git a/lib/poll.c b/lib/poll.c
index ed76098..3fa8872 100644 (file)
--- a/lib/poll.c
+++ b/lib/poll.c
@@ -67,6 +67,23 @@
 
 #ifdef WIN32_NATIVE
 
+#define IsConsoleHandle(h) (((long) (h) & 3) == 3)
+
+static BOOL
+IsSocketHandle(HANDLE h)
+{
+  WSANETWORKEVENTS ev;
+
+  if (IsConsoleHandle (h))
+    return FALSE;
+
+  /* Under Wine, it seems that getsockopt returns 0 for pipes too.
+     WSAEnumNetworkEvents instead distinguishes the two correctly.  */
+  ev.lNetworkEvents = 0xDEADBEEF;
+  WSAEnumNetworkEvents ((SOCKET) h, NULL, &ev);
+  return ev.lNetworkEvents != 0xDEADBEEF;
+}
+
 /* Declare data structures for ntdll functions.  */
 typedef struct _FILE_PIPE_LOCAL_INFORMATION {
   ULONG NamedPipeType;
@@ -101,10 +118,11 @@ typedef DWORD (WINAPI *PNtQueryInformationFile)
 #  define PIPE_BUF     512
 # endif
 
-/* Compute revents values for file handle H.  */
+/* Compute revents values for file handle H.  If some events cannot happen
+   for the handle, eliminate them from *P_SOUGHT.  */
 
 static int
-win32_compute_revents (HANDLE h, int sought)
+win32_compute_revents (HANDLE h, int *p_sought)
 {
   int i, ret, happened;
   INPUT_RECORD *irbuffer;
@@ -130,7 +148,7 @@ win32_compute_revents (HANDLE h, int sought)
       if (PeekNamedPipe (h, NULL, 0, NULL, &avail, NULL) != 0)
        {
          if (avail)
-           happened |= sought & (POLLIN | POLLRDNORM);
+           happened |= *p_sought & (POLLIN | POLLRDNORM);
        }
 
       else
@@ -151,18 +169,25 @@ win32_compute_revents (HANDLE h, int sought)
              || fpli.WriteQuotaAvailable >= PIPE_BUF
              || (fpli.OutboundQuota < PIPE_BUF &&
                  fpli.WriteQuotaAvailable == fpli.OutboundQuota))
-           happened |= sought & (POLLOUT | POLLWRNORM | POLLWRBAND);
+           happened |= *p_sought & (POLLOUT | POLLWRNORM | POLLWRBAND);
        }
       return happened;
 
     case FILE_TYPE_CHAR:
       ret = WaitForSingleObject (h, 0);
-      if (ret == WAIT_OBJECT_0)
-        {
-         nbuffer = avail = 0;
-         bRet = GetNumberOfConsoleInputEvents (h, &nbuffer);
-         if (!bRet || nbuffer == 0)
+      if (!IsConsoleHandle (h))
+       return ret == WAIT_OBJECT_0 ? *p_sought & ~(POLLPRI | POLLRDBAND) : 0;
+
+      nbuffer = avail = 0;
+      bRet = GetNumberOfConsoleInputEvents (h, &nbuffer);
+      if (bRet)
+       {
+         /* Input buffer.  */
+         *p_sought &= POLLIN | POLLRDNORM;
+         if (nbuffer == 0)
            return POLLHUP;
+         if (!*p_sought)
+           return 0;
 
          irbuffer = (INPUT_RECORD *) alloca (nbuffer * sizeof (INPUT_RECORD));
          bRet = PeekConsoleInput (h, irbuffer, nbuffer, &avail);
@@ -171,19 +196,23 @@ win32_compute_revents (HANDLE h, int sought)
 
          for (i = 0; i < avail; i++)
            if (irbuffer[i].EventType == KEY_EVENT)
-             return sought & ~(POLLPRI | POLLRDBAND);
+             return *p_sought;
+         return 0;
+       }
+      else
+       {
+         /* Screen buffer.  */
+         *p_sought &= POLLOUT | POLLWRNORM | POLLWRBAND;
+         return *p_sought;
        }
-      break;
 
     default:
       ret = WaitForSingleObject (h, 0);
       if (ret == WAIT_OBJECT_0)
-        return sought & ~(POLLPRI | POLLRDBAND);
+        return *p_sought & ~(POLLPRI | POLLRDBAND);
 
-      break;
+      return *p_sought & (POLLOUT | POLLWRNORM | POLLWRBAND);
     }
-
-  return sought & (POLLOUT | POLLWRNORM | POLLWRBAND);
 }
 
 /* Convert fd_sets returned by select into revents values.  */
@@ -430,36 +459,32 @@ poll (pfd, nfd, timeout)
   /* Classify socket handles and create fd sets. */
   for (i = 0; i < nfd; i++)
     {
+      int sought = pfd[i].events;
       pfd[i].revents = 0;
       if (pfd[i].fd < 0)
         continue;
-      if (!(pfd[i].events & (POLLIN | POLLRDNORM |
-                             POLLOUT | POLLWRNORM | POLLWRBAND)))
+      if (!(sought & (POLLIN | POLLRDNORM | POLLOUT | POLLWRNORM | POLLWRBAND
+                     | POLLPRI | POLLRDBAND)))
        continue;
 
       h = (HANDLE) _get_osfhandle (pfd[i].fd);
       assert (h != NULL);
-
-      /* Under Wine, it seems that getsockopt returns 0 for pipes too.
-        WSAEnumNetworkEvents instead distinguishes the two correctly.  */
-      ev.lNetworkEvents = 0xDEADBEEF;
-      WSAEnumNetworkEvents ((SOCKET) h, NULL, &ev);
-      if (ev.lNetworkEvents != 0xDEADBEEF)
+      if (IsSocketHandle (h))
         {
           int requested = FD_CLOSE;
 
           /* see above; socket handles are mapped onto select.  */
-          if (pfd[i].events & (POLLIN | POLLRDNORM))
+          if (sought & (POLLIN | POLLRDNORM))
            {
               requested |= FD_READ | FD_ACCEPT;
              FD_SET ((SOCKET) h, &rfds);
            }
-          if (pfd[i].events & (POLLOUT | POLLWRNORM | POLLWRBAND))
+          if (sought & (POLLOUT | POLLWRNORM | POLLWRBAND))
            {
               requested |= FD_WRITE | FD_CONNECT;
              FD_SET ((SOCKET) h, &wfds);
            }
-          if (pfd[i].events & (POLLPRI | POLLRDBAND))
+          if (sought & (POLLPRI | POLLRDBAND))
            {
               requested |= FD_OOB;
              FD_SET ((SOCKET) h, &xfds);
@@ -470,10 +495,13 @@ poll (pfd, nfd, timeout)
         }
       else
         {
-          handle_array[nhandles++] = h;
-
-         /* Poll now.  If we get an event, do not poll again.  */
-          pfd[i].revents = win32_compute_revents (h, pfd[i].events);
+         /* Poll now.  If we get an event, do not poll again.  Also,
+            screen buffer handles are waitable, and they'll block until
+            a character is available.  win32_compute_revents eliminates
+            bits for the "wrong" direction. */
+          pfd[i].revents = win32_compute_revents (h, &sought);
+         if (sought)
+           handle_array[nhandles++] = h;
           if (pfd[i].revents)
            wait_timeout = 0;
         }
@@ -553,8 +581,9 @@ poll (pfd, nfd, timeout)
       else
         {
           /* Not a socket.  */
+          int sought = pfd[i].events;
+          happened = win32_compute_revents (h, &sought);
           nhandles++;
-          happened = win32_compute_revents (h, pfd[i].events);
         }
 
        if ((pfd[i].revents |= happened) != 0)

diff --git a/lib/select.c b/lib/select.c
index 8496c15..12d3e51 100644 (file)
--- a/lib/select.c
+++ b/lib/select.c
@@ -21,6 +21,7 @@
 
 #include <config.h>
 #include <alloca.h>
+#include <assert.h>
 
 #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
 /* Native Win32.  */
@@ -76,6 +77,23 @@ typedef DWORD (WINAPI *PNtQueryInformationFile)
 #define PIPE_BUF       512
 #endif
 
+#define IsConsoleHandle(h) (((long) (h) & 3) == 3)
+
+static BOOL
+IsSocketHandle(HANDLE h)
+{
+  WSANETWORKEVENTS ev;
+
+  if (IsConsoleHandle (h))
+    return FALSE;
+
+  /* Under Wine, it seems that getsockopt returns 0 for pipes too.
+     WSAEnumNetworkEvents instead distinguishes the two correctly.  */
+  ev.lNetworkEvents = 0xDEADBEEF;
+  WSAEnumNetworkEvents ((SOCKET) h, NULL, &ev);
+  return ev.lNetworkEvents != 0xDEADBEEF;
+}
+
 /* Compute output fd_sets for libc descriptor FD (whose Win32 handle is H).  */
 
 static int
@@ -138,19 +156,37 @@ win32_poll_handle (HANDLE h, int fd, struct bitset *rbits, struct bitset *wbits,
       break;
 
     case FILE_TYPE_CHAR:
-      ret = WaitForSingleObject (h, 0);
       write = TRUE;
+      if (!(rbits->in[fd / CHAR_BIT] & (1 << (fd & (CHAR_BIT - 1)))))
+       break;
+
+      ret = WaitForSingleObject (h, 0);
       if (ret == WAIT_OBJECT_0)
         {
+         if (!IsConsoleHandle (h))
+           {
+             read = TRUE;
+             break;
+           }
+
          nbuffer = avail = 0;
          bRet = GetNumberOfConsoleInputEvents (h, &nbuffer);
-         if (!bRet || nbuffer == 0)
-           except = TRUE;
+
+         /* Screen buffers handles are filtered earlier.  */
+         assert (bRet);
+         if (nbuffer == 0)
+           {
+             except = TRUE;
+             break;
+           }
 
          irbuffer = (INPUT_RECORD *) alloca (nbuffer * sizeof (INPUT_RECORD));
          bRet = PeekConsoleInput (h, irbuffer, nbuffer, &avail);
          if (!bRet || avail == 0)
-           except = TRUE;
+           {
+             except = TRUE;
+             break;
+           }
 
          for (i = 0; i < avail; i++)
            if (irbuffer[i].EventType == KEY_EVENT)
@@ -199,7 +235,7 @@ rpl_select (int nfds, fd_set *rfds, fd_set *wfds, fd_set *xfds,
   fd_set handle_rfds, handle_wfds, handle_xfds;
   struct bitset rbits, wbits, xbits;
   unsigned char anyfds_in[FD_SETSIZE / CHAR_BIT];
-  DWORD ret, wait_timeout, nhandles, nsock;
+  DWORD ret, wait_timeout, nhandles, nsock, nbuffer;
   MSG msg;
   int i, fd, rc;
 
@@ -227,7 +263,10 @@ rpl_select (int nfds, fd_set *rfds, fd_set *wfds, fd_set *xfds,
   nhandles = 1;
   nsock = 0;
 
-  /* Copy descriptors to bitsets.  */
+  /* Copy descriptors to bitsets.  At the same time, eliminate
+     bits in the "wrong" direction for console input buffers
+     and screen buffers, because screen buffers are waitable
+     and they will block until a character is available.  */
   memset (&rbits, 0, sizeof (rbits));
   memset (&wbits, 0, sizeof (wbits));
   memset (&xbits, 0, sizeof (xbits));
@@ -236,6 +275,11 @@ rpl_select (int nfds, fd_set *rfds, fd_set *wfds, fd_set *xfds,
     for (i = 0; i < rfds->fd_count; i++)
       {
         fd = rfds->fd_array[i];
+       h = (HANDLE) _get_osfhandle (fd);
+       if (IsConsoleHandle (h)
+           && !GetNumberOfConsoleInputEvents (h, &nbuffer))
+         continue;
+
         rbits.in[fd / CHAR_BIT] |= 1 << (fd & (CHAR_BIT - 1));
         anyfds_in[fd / CHAR_BIT] |= 1 << (fd & (CHAR_BIT - 1));
       }
@@ -246,6 +290,11 @@ rpl_select (int nfds, fd_set *rfds, fd_set *wfds, fd_set *xfds,
     for (i = 0; i < wfds->fd_count; i++)
       {
         fd = wfds->fd_array[i];
+       h = (HANDLE) _get_osfhandle (fd);
+       if (IsConsoleHandle (h)
+           && GetNumberOfConsoleInputEvents (h, &nbuffer))
+         continue;
+
         wbits.in[fd / CHAR_BIT] |= 1 << (fd & (CHAR_BIT - 1));
         anyfds_in[fd / CHAR_BIT] |= 1 << (fd & (CHAR_BIT - 1));
       }
@@ -285,11 +334,7 @@ rpl_select (int nfds, fd_set *rfds, fd_set *wfds, fd_set *xfds,
          return -1;
         }
 
-      /* Under Wine, it seems that getsockopt returns 0 for pipes too.
-        WSAEnumNetworkEvents instead distinguishes the two correctly.  */
-      ev.lNetworkEvents = 0xDEADBEEF;
-      WSAEnumNetworkEvents ((SOCKET) h, NULL, &ev);
-      if (ev.lNetworkEvents != 0xDEADBEEF)
+      if (IsSocketHandle (h))
         {
           int requested = FD_CLOSE;