include/apr-0/apr_mmap.h

   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
  36 extern "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 */
  51 typedef 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 */
  62 struct 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     /** @deprecated this field is no longer used and will be removed
  84      * in APR 1.0 */
  85     int unused;
  86     /** ring of apr_mmap_t's that reference the same
  87      * mmap'ed region; acts in place of a reference count */
  88     APR_RING_ENTRY(apr_mmap_t) link;
  89 };
  90
  91 #if APR_HAS_MMAP || defined(DOXYGEN)
  92
  93 /** @def APR_MMAP_THRESHOLD
  94  * Files have to be at least this big before they're mmap()d.  This is to deal
  95  * with systems where the expense of doing an mmap() and an munmap() outweighs
  96  * the benefit for small files.  It shouldn't be set lower than 1.
  97  */
  98 #ifdef MMAP_THRESHOLD
  99 #  define APR_MMAP_THRESHOLD              MMAP_THRESHOLD
 100 #else
 101 #  ifdef SUNOS4
 102 #    define APR_MMAP_THRESHOLD            (8*1024)
 103 #  else
 104 #    define APR_MMAP_THRESHOLD            1
 105 #  endif /* SUNOS4 */
 106 #endif /* MMAP_THRESHOLD */
 107
 108 /** @def APR_MMAP_LIMIT
 109  * Maximum size of MMap region
 110  */
 111 #ifdef MMAP_LIMIT
 112 #  define APR_MMAP_LIMIT                  MMAP_LIMIT
 113 #else
 114 #  define APR_MMAP_LIMIT                  (4*1024*1024)
 115 #endif /* MMAP_LIMIT */
 116
 117 /** Can this file be MMaped */
 118 #define APR_MMAP_CANDIDATE(filelength) \
 119     ((filelength >= APR_MMAP_THRESHOLD) && (filelength < APR_MMAP_LIMIT))
 120
 121 /*   Function definitions */
 122
 123 /**
 124  * Create a new mmap'ed file out of an existing APR file.
 125  * @param newmmap The newly created mmap'ed file.
 126  * @param file The file turn into an mmap.
 127  * @param offset The offset into the file to start the data pointer at.
 128  * @param size The size of the file
 129  * @param flag bit-wise or of:
 130  * <PRE>
 131  *          APR_MMAP_READ       MMap opened for reading
 132  *          APR_MMAP_WRITE      MMap opened for writing
 133  * </PRE>
 134  * @param cntxt The pool to use when creating the mmap.
 135  */
 136 APR_DECLARE(apr_status_t) apr_mmap_create(apr_mmap_t **newmmap,
 137                                           apr_file_t *file, apr_off_t offset,
 138                                           apr_size_t size, apr_int32_t flag,
 139                                           apr_pool_t *cntxt);
 140
 141 /**
 142  * Duplicate the specified MMAP.
 143  * @param new_mmap The structure to duplicate into.
 144  * @param old_mmap The mmap to duplicate.
 145  * @param p The pool to use for new_mmap.
 146  * @param transfer_ownership DEPRECATED: this param is now ignored
 147  *  and should be removed prior to APR 1.0
 148  */
 149 APR_DECLARE(apr_status_t) apr_mmap_dup(apr_mmap_t **new_mmap,
 150                                        apr_mmap_t *old_mmap,
 151                                        apr_pool_t *p,
 152                                        int transfer_ownership);
 153
 154 #if defined(DOXYGEN)
 155 /**
 156  * Transfer the specified MMAP to a different pool
 157  * @param new_mmap The structure to duplicate into.
 158  * @param old_mmap The file to transfer.
 159  * @param p The pool to use for new_mmap.
 160  * @deprecated Just use apr_mmap_dup().  The transfer_ownership flag will
 161  *  go away soon anyway.
 162  */
 163 APR_DECLARE(apr_status_t) apr_mmap_setaside(apr_mmap_t **new_mmap,
 164                                             apr_mmap_t *old_mmap,
 165                                             apr_pool_t *p);
 166 #else
 167 #define apr_mmap_setaside(new_mmap, old_mmap, p) apr_mmap_dup(new_mmap, old_mmap, p, 1)
 168 #endif /* DOXYGEN */
 169
 170 /**
 171  * Remove a mmap'ed.
 172  * @param mm The mmap'ed file.
 173  */
 174 APR_DECLARE(apr_status_t) apr_mmap_delete(apr_mmap_t *mm);
 175
 176 /**
 177  * Move the pointer into the mmap'ed file to the specified offset.
 178  * @param addr The pointer to the offset specified.
 179  * @param mm The mmap'ed file.
 180  * @param offset The offset to move to.
 181  */
 182 APR_DECLARE(apr_status_t) apr_mmap_offset(void **addr, apr_mmap_t *mm,
 183                                           apr_off_t offset);
 184
 185 #endif /* APR_HAS_MMAP */
 186
 187 /** @} */
 188
 189 #ifdef __cplusplus
 190 }
 191 #endif
 192
 193 #endif  /* ! APR_MMAP_H */