Add a convenience wrapper for select(2)

2012-04-30 23:16:15 -04:00
parent 5bf681629d
commit 0019b9d92a
2 changed files with 93 additions and 1 deletions
@@ -0,0 +1,92 @@
+/*
+    Mosh: the mobile shell
+    Copyright 2012 Keith Winstein
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef SELECT_HPP
+#define SELECT_HPP
+
+#include <string.h>
+#include <sys/select.h>
+
+/* We don't need these on POSIX.1-2001 systems, but there's little reason
+   not to include them. */
+#include <sys/time.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+static fd_set dummy_fd_set;
+
+/* Convenience wrapper for select(2). */
+class Select {
+public:
+  Select()
+    : max_fd( -1 )
+
+    /* These initializations are not used; they are just
+       here to appease -Weffc++. */
+    , all_fds( dummy_fd_set )
+    , read_fds( dummy_fd_set )
+    , error_fds( dummy_fd_set )
+  {
+    FD_ZERO( &all_fds );
+    FD_ZERO( &read_fds );
+    FD_ZERO( &error_fds );
+  }
+
+  void add_fd( int fd )
+  {
+    if ( fd > max_fd ) {
+      max_fd = fd;
+    }
+    FD_SET( fd, &all_fds );
+  }
+
+  int select( int timeout )
+  {
+    memcpy( &read_fds,  &all_fds, sizeof( read_fds  ) );
+    memcpy( &error_fds, &all_fds, sizeof( error_fds ) );
+
+    struct timeval tv;
+    struct timeval *tvp = NULL;
+
+    if ( timeout >= 0 ) {
+      // timeout in milliseconds
+      tv.tv_sec  = timeout / 1000;
+      tv.tv_usec = 1000 * (timeout % 1000);
+      tvp = &tv;
+    }
+    // negative timeout means wait forever
+
+    return ::select( max_fd + 1, &read_fds, NULL, &error_fds, tvp );
+  }
+
+  bool read( int fd ) const
+  {
+    return FD_ISSET( fd, &read_fds );
+  }
+
+  bool error( int fd ) const
+  {
+    return FD_ISSET( fd, &error_fds );
+  }
+
+private:
+  int max_fd;
+  fd_set all_fds, read_fds, error_fds;
+};
+
+#endif