os: Add NotifyFd interfaces

This provides a callback-based interface to monitor file
descriptors beyond the usual client and device interfaces.

Modules within the server using file descriptors for reading and/or
writing can call

    Bool SetNotifyFd(int fd, NotifyFdProcPtr notify_fd, int mask, void *data);

mask can be any combination of X_NOTIFY_READ and X_NOTIFY_WRITE.

When 'fd' becomes readable or writable, the notify_fd function will be
called with the 'fd', the ready conditions and 'data' values as arguments,

When the module no longer needs to monitor the fd, it will call

    void RemoveNotifyFd(int fd);

RemoveNotifyFd may be called from the notify function.

Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Keith Packard <keithp@keithp.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/os/osinit.c b/os/osinit.c
index 6ec2f1167..54b39a0e8 100644
--- a/os/osinit.c
+++ b/os/osinit.c
@@ -314,6 +314,7 @@ OsInit(void)
         LockServer();
         been_here = TRUE;
     }
+    InitNotifyFds();
     TimerInit();
     OsVendorInit();
     OsResetSignals();