Security-55163.44.tar.gz

[apple/security.git] / libsecurity_utilities / lib / fdsel.h

diff --git a/libsecurity_utilities/lib/fdsel.h b/libsecurity_utilities/lib/fdsel.h
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+/*
+ * Copyright (c) 2000-2001,2003-2004 Apple Computer, Inc. All Rights Reserved.
+ * 
+ * @APPLE_LICENSE_HEADER_START@
+ * 
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this
+ * file.
+ * 
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ * 
+ * @APPLE_LICENSE_HEADER_END@
+ */
+
+
+//
+// fdsel - select-style file descriptor set management
+//
+#ifndef _H_FDSEL
+#define _H_FDSEL
+
+#include <security_utilities/utilities.h>
+#include <sys/types.h>
+#include <security_utilities/debugging.h>
+
+
+namespace Security {
+namespace UnixPlusPlus {
+
+
+//
+// An FDSet object maintains a single select(2) compatible bitmap.
+// Size is implicitly kept by the caller (who needs to call grow() as
+// needed, starting at zero). As long as this is done correctly, we are
+// not bound by the FD_SETSIZE limit.
+// An FDSet can self-copy for select(2) use; after that, the [] operator
+// investigates the copy.
+//
+// Why are we using the FD_* macros even though we know these
+// are fd_mask arrays? Some implementations use optimized assembly
+// for these operations, and we want to pick those up.
+//
+// This whole mess is completely UNIX specific. If your system has
+// the poll(2) system call, ditch this and use it.
+//
+class FDSet {
+public:
+    FDSet() : mBits(NULL), mUseBits(NULL) { }
+    ~FDSet();
+
+    void grow(int oldWords, int newWords);
+    void set(int fd, bool on);
+    
+    fd_set *make(int words);
+    bool operator [] (int fd) const    { return FD_ISSET(fd, (fd_set *)mUseBits); }
+    
+    inline static int words(int fd)    { return (fd - 1) / NFDBITS + 1; }
+
+private:
+    fd_mask *mBits;                                    // base bits
+    fd_mask *mUseBits;                         // mutable copy for select(2)
+    
+    void grow(fd_mask * &bits, int oldWords, int newWords);
+};
+
+
+}      // end namespace UnixPlusPlus
+}      // end namespace Security
+
+
+#endif //_H_FDSEL