apr_mmap.h revision 251875 
1/* Licensed to the Apache Software Foundation (ASF) under one or more
2 * contributor license agreements.  See the NOTICE file distributed with
3 * this work for additional information regarding copyright ownership.
4 * The ASF licenses this file to You under the Apache License, Version 2.0
5 * (the "License"); you may not use this file except in compliance with
6 * the License.  You may obtain a copy of the License at
7 *
8 *     http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef APR_MMAP_H
18#define APR_MMAP_H
19
20/**
21 * @file apr_mmap.h
22 * @brief APR MMAP routines
23 */
24
25#include "apr.h"
26#include "apr_pools.h"
27#include "apr_errno.h"
28#include "apr_ring.h"
29#include "apr_file_io.h"        /* for apr_file_t */
30
31#ifdef BEOS
32#include <kernel/OS.h>
33#endif
34
35#ifdef __cplusplus
36extern "C" {
37#endif /* __cplusplus */
38
39/**
40 * @defgroup apr_mmap MMAP (Memory Map) Routines
41 * @ingroup APR
42 * @{
43 */
44
45/** MMap opened for reading */
46#define APR_MMAP_READ    1
47/** MMap opened for writing */
48#define APR_MMAP_WRITE   2
49
50/** @see apr_mmap_t */
51typedef struct apr_mmap_t            apr_mmap_t;
52
53/**
54 * @remark
55 * As far as I can tell the only really sane way to store an MMAP is as a
56 * void * and a length.  BeOS requires this area_id, but that's just a little
57 * something extra.  I am exposing this type, because it doesn't make much
58 * sense to keep it private, and opening it up makes some stuff easier in
59 * Apache.
60 */
61/** The MMAP structure */
62struct apr_mmap_t {
63    /** The pool the mmap structure was allocated out of. */
64    apr_pool_t *cntxt;
65#ifdef BEOS
66    /** An area ID.  Only valid on BeOS */
67    area_id area;
68#endif
69#ifdef WIN32
70    /** The handle of the file mapping */
71    HANDLE mhandle;
72    /** The start of the real memory page area (mapped view) */
73    void *mv;
74    /** The physical start, size and offset */
75    apr_off_t  pstart;
76    apr_size_t psize;
77    apr_off_t  poffset;
78#endif
79    /** The start of the memory mapped area */
80    void *mm;
81    /** The amount of data in the mmap */
82    apr_size_t size;
83    /** ring of apr_mmap_t's that reference the same
84     * mmap'ed region; acts in place of a reference count */
85    APR_RING_ENTRY(apr_mmap_t) link;
86};
87
88#if APR_HAS_MMAP || defined(DOXYGEN)
89
90/** @def APR_MMAP_THRESHOLD
91 * Files have to be at least this big before they're mmap()d.  This is to deal
92 * with systems where the expense of doing an mmap() and an munmap() outweighs
93 * the benefit for small files.  It shouldn't be set lower than 1.
94 */
95#ifdef MMAP_THRESHOLD
96#  define APR_MMAP_THRESHOLD              MMAP_THRESHOLD
97#else
98#  ifdef SUNOS4
99#    define APR_MMAP_THRESHOLD            (8*1024)
100#  else
101#    define APR_MMAP_THRESHOLD            1
102#  endif /* SUNOS4 */
103#endif /* MMAP_THRESHOLD */
104
105/** @def APR_MMAP_LIMIT
106 * Maximum size of MMap region
107 */
108#ifdef MMAP_LIMIT
109#  define APR_MMAP_LIMIT                  MMAP_LIMIT
110#else
111#  define APR_MMAP_LIMIT                  (4*1024*1024)
112#endif /* MMAP_LIMIT */
113
114/** Can this file be MMaped */
115#define APR_MMAP_CANDIDATE(filelength) \
116    ((filelength >= APR_MMAP_THRESHOLD) && (filelength < APR_MMAP_LIMIT))
117
118/*   Function definitions */
119
120/**
121 * Create a new mmap'ed file out of an existing APR file.
122 * @param newmmap The newly created mmap'ed file.
123 * @param file The file turn into an mmap.
124 * @param offset The offset into the file to start the data pointer at.
125 * @param size The size of the file
126 * @param flag bit-wise or of:
127 * <PRE>
128 *          APR_MMAP_READ       MMap opened for reading
129 *          APR_MMAP_WRITE      MMap opened for writing
130 * </PRE>
131 * @param cntxt The pool to use when creating the mmap.
132 */
133APR_DECLARE(apr_status_t) apr_mmap_create(apr_mmap_t **newmmap,
134                                          apr_file_t *file, apr_off_t offset,
135                                          apr_size_t size, apr_int32_t flag,
136                                          apr_pool_t *cntxt);
137
138/**
139 * Duplicate the specified MMAP.
140 * @param new_mmap The structure to duplicate into.
141 * @param old_mmap The mmap to duplicate.
142 * @param p The pool to use for new_mmap.
143 */
144APR_DECLARE(apr_status_t) apr_mmap_dup(apr_mmap_t **new_mmap,
145                                       apr_mmap_t *old_mmap,
146                                       apr_pool_t *p);
147
148/**
149 * Remove a mmap'ed.
150 * @param mm The mmap'ed file.
151 */
152APR_DECLARE(apr_status_t) apr_mmap_delete(apr_mmap_t *mm);
153
154/**
155 * Move the pointer into the mmap'ed file to the specified offset.
156 * @param addr The pointer to the offset specified.
157 * @param mm The mmap'ed file.
158 * @param offset The offset to move to.
159 */
160APR_DECLARE(apr_status_t) apr_mmap_offset(void **addr, apr_mmap_t *mm,
161                                          apr_off_t offset);
162
163#endif /* APR_HAS_MMAP */
164
165/** @} */
166
167#ifdef __cplusplus
168}
169#endif
170
171#endif  /* ! APR_MMAP_H */
172