buckets/apr_buckets_mmap.c

   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 #include "apr_buckets.h"
  18
  19 #if APR_HAS_MMAP
  20
  21 static apr_status_t mmap_bucket_read(apr_bucket *b, const char **str,
  22                                      apr_size_t *length, apr_read_type_e block)
  23 {
  24     apr_bucket_mmap *m = b->data;
  25     apr_status_t ok;
  26     void *addr;
  27
  28     if (!m->mmap) {
  29         /* the apr_mmap_t was already cleaned up out from under us */
  30         return APR_EINVAL;
  31     }
  32
  33     ok = apr_mmap_offset(&addr, m->mmap, b->start);
  34     if (ok != APR_SUCCESS) {
  35         return ok;
  36     }
  37     *str = addr;
  38     *length = b->length;
  39     return APR_SUCCESS;
  40 }
  41
  42 static apr_status_t mmap_bucket_cleanup(void *data)
  43 {
  44     /* the apr_mmap_t is about to disappear out from under us, so we
  45      * have no choice but to pretend it doesn't exist anymore.  the
  46      * refcount is now useless because there's nothing to refer to
  47      * anymore.  so the only valid action on any remaining referrer
  48      * is to delete it.  no more reads, no more anything. */
  49     apr_bucket_mmap *m = data;
  50
  51     m->mmap = NULL;
  52     return APR_SUCCESS;
  53 }
  54
  55 static void mmap_bucket_destroy(void *data)
  56 {
  57     apr_bucket_mmap *m = data;
  58
  59     if (apr_bucket_shared_destroy(m)) {
  60         if (m->mmap) {
  61             apr_pool_cleanup_kill(m->mmap->cntxt, m, mmap_bucket_cleanup);
  62             apr_mmap_delete(m->mmap);
  63         }
  64         apr_bucket_free(m);
  65     }
  66 }
  67
  68 /*
  69  * XXX: are the start and length arguments useful?
  70  */
  71 APU_DECLARE(apr_bucket *) apr_bucket_mmap_make(apr_bucket *b, apr_mmap_t *mm,
  72                                                apr_off_t start,
  73                                                apr_size_t length)
  74 {
  75     apr_bucket_mmap *m;
  76
  77     m = apr_bucket_alloc(sizeof(*m), b->list);
  78     m->mmap = mm;
  79
  80     apr_pool_cleanup_register(mm->cntxt, m, mmap_bucket_cleanup,
  81                               apr_pool_cleanup_null);
  82
  83     b = apr_bucket_shared_make(b, m, start, length);
  84     b->type = &apr_bucket_type_mmap;
  85
  86     return b;
  87 }
  88
  89
  90 APU_DECLARE(apr_bucket *) apr_bucket_mmap_create(apr_mmap_t *mm,
  91                                                  apr_off_t start,
  92                                                  apr_size_t length,
  93                                                  apr_bucket_alloc_t *list)
  94 {
  95     apr_bucket *b = apr_bucket_alloc(sizeof(*b), list);
  96
  97     APR_BUCKET_INIT(b);
  98     b->free = apr_bucket_free;
  99     b->list = list;
 100     return apr_bucket_mmap_make(b, mm, start, length);
 101 }
 102
 103 static apr_status_t mmap_bucket_setaside(apr_bucket *b, apr_pool_t *p)
 104 {
 105     apr_bucket_mmap *m = b->data;
 106     apr_mmap_t *mm = m->mmap;
 107     apr_mmap_t *new_mm;
 108     apr_status_t ok;
 109
 110     if (!mm) {
 111         /* the apr_mmap_t was already cleaned up out from under us */
 112         return APR_EINVAL;
 113     }
 114
 115     /* shortcut if possible */
 116     if (apr_pool_is_ancestor(mm->cntxt, p)) {
 117         return APR_SUCCESS;
 118     }
 119
 120     /* duplicate apr_mmap_t into new pool */
 121     ok = apr_mmap_dup(&new_mm, mm, p);
 122     if (ok != APR_SUCCESS) {
 123         return ok;
 124     }
 125
 126     /* decrement refcount on old apr_bucket_mmap */
 127     mmap_bucket_destroy(m);
 128
 129     /* create new apr_bucket_mmap pointing to new apr_mmap_t */
 130     apr_bucket_mmap_make(b, new_mm, b->start, b->length);
 131
 132     return APR_SUCCESS;
 133 }
 134
 135 APU_DECLARE_DATA const apr_bucket_type_t apr_bucket_type_mmap = {
 136     "MMAP", 5, APR_BUCKET_DATA,
 137     mmap_bucket_destroy,
 138     mmap_bucket_read,
 139     mmap_bucket_setaside,
 140     apr_bucket_shared_split,
 141     apr_bucket_shared_copy
 142 };
 143
 144 #endif