1/*
2 * Copyright (c) 2000-2001,2003-2004 Apple Computer, Inc. All Rights Reserved.
3 *
4 * @APPLE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. Please obtain a copy of the License at
10 * http://www.opensource.apple.com/apsl/ and read it before using this
11 * file.
12 *
13 * The Original Code and all software distributed under the License are
14 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
15 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
16 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
18 * Please see the License for the specific language governing rights and
19 * limitations under the License.
20 *
21 * @APPLE_LICENSE_HEADER_END@
22 */
23
24
25//
26// fdsel - select-style file descriptor set management
27//
28#ifndef _H_FDSEL
29#define _H_FDSEL
30
31#include <security_utilities/utilities.h>
32#include <sys/types.h>
33#include <security_utilities/debugging.h>
34
35
36namespace Security {
37namespace UnixPlusPlus {
38
39
40//
41// An FDSet object maintains a single select(2) compatible bitmap.
42// Size is implicitly kept by the caller (who needs to call grow() as
43// needed, starting at zero). As long as this is done correctly, we are
44// not bound by the FD_SETSIZE limit.
45// An FDSet can self-copy for select(2) use; after that, the [] operator
46// investigates the copy.
47//
48// Why are we using the FD_* macros even though we know these
49// are fd_mask arrays? Some implementations use optimized assembly
50// for these operations, and we want to pick those up.
51//
52// This whole mess is completely UNIX specific. If your system has
53// the poll(2) system call, ditch this and use it.
54//
55class FDSet {
56public:
57    FDSet() : mBits(NULL), mUseBits(NULL) { }
58    ~FDSet();
59
60    void grow(int oldWords, int newWords);
61    void set(int fd, bool on);
62
63    fd_set *make(int words);
64    bool operator [] (int fd) const	{ return FD_ISSET(fd, (fd_set *)mUseBits); }
65
66    inline static int words(int fd)	{ return (fd - 1) / NFDBITS + 1; }
67
68private:
69    fd_mask *mBits;					// base bits
70    fd_mask *mUseBits;				// mutable copy for select(2)
71
72    void grow(fd_mask * &bits, int oldWords, int newWords);
73};
74
75
76}	// end namespace UnixPlusPlus
77}	// end namespace Security
78
79
80#endif //_H_FDSEL
81