1 /* $NetBSD: evbuffer-internal.h,v 1.2 2013/04/11 16:56:41 christos Exp $ */ 2 /* 3 * Copyright (c) 2000-2007 Niels Provos <provos@citi.umich.edu> 4 * Copyright (c) 2007-2012 Niels Provos and Nick Mathewson 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. The name of the author may not be used to endorse or promote products 15 * derived from this software without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 */ 28 #ifndef _EVBUFFER_INTERNAL_H_ 29 #define _EVBUFFER_INTERNAL_H_ 30 31 #ifdef __cplusplus 32 extern "C" { 33 #endif 34 35 #include "event2/event-config.h" 36 #include "event2/util.h" 37 #include "util-internal.h" 38 #include "defer-internal.h" 39 40 /* Experimental cb flag: "never deferred." Implementation note: 41 * these callbacks may get an inaccurate view of n_del/n_added in their 42 * arguments. */ 43 #define EVBUFFER_CB_NODEFER 2 44 45 #ifdef WIN32 46 #include <winsock2.h> 47 #endif 48 #include <sys/queue.h> 49 50 /* Minimum allocation for a chain. We define this so that we're burning no 51 * more than 5% of each allocation on overhead. It would be nice to lose even 52 * less space, though. */ 53 #if _EVENT_SIZEOF_VOID_P < 8 54 #define MIN_BUFFER_SIZE 512 55 #else 56 #define MIN_BUFFER_SIZE 1024 57 #endif 58 59 /** A single evbuffer callback for an evbuffer. This function will be invoked 60 * when bytes are added to or removed from the evbuffer. */ 61 struct evbuffer_cb_entry { 62 /** Structures to implement a doubly-linked queue of callbacks */ 63 TAILQ_ENTRY(evbuffer_cb_entry) next; 64 /** The callback function to invoke when this callback is called. 65 If EVBUFFER_CB_OBSOLETE is set in flags, the cb_obsolete field is 66 valid; otherwise, cb_func is valid. */ 67 union { 68 evbuffer_cb_func cb_func; 69 evbuffer_cb cb_obsolete; 70 } cb; 71 /** Argument to pass to cb. */ 72 void *cbarg; 73 /** Currently set flags on this callback. */ 74 ev_uint32_t flags; 75 }; 76 77 struct bufferevent; 78 struct evbuffer_chain; 79 struct evbuffer { 80 /** The first chain in this buffer's linked list of chains. */ 81 struct evbuffer_chain *first; 82 /** The last chain in this buffer's linked list of chains. */ 83 struct evbuffer_chain *last; 84 85 /** Pointer to the next pointer pointing at the 'last_with_data' chain. 86 * 87 * To unpack: 88 * 89 * The last_with_data chain is the last chain that has any data in it. 90 * If all chains in the buffer are empty, it is the first chain. 91 * If the buffer has no chains, it is NULL. 92 * 93 * The last_with_datap pointer points at _whatever 'next' pointer_ 94 * points at the last_with_datap chain. If the last_with_data chain 95 * is the first chain, or it is NULL, then the last_with_datap pointer 96 * is &buf->first. 97 */ 98 struct evbuffer_chain **last_with_datap; 99 100 /** Total amount of bytes stored in all chains.*/ 101 size_t total_len; 102 103 /** Number of bytes we have added to the buffer since we last tried to 104 * invoke callbacks. */ 105 size_t n_add_for_cb; 106 /** Number of bytes we have removed from the buffer since we last 107 * tried to invoke callbacks. */ 108 size_t n_del_for_cb; 109 110 #ifndef _EVENT_DISABLE_THREAD_SUPPORT 111 /** A lock used to mediate access to this buffer. */ 112 void *lock; 113 #endif 114 /** True iff we should free the lock field when we free this 115 * evbuffer. */ 116 unsigned own_lock : 1; 117 /** True iff we should not allow changes to the front of the buffer 118 * (drains or prepends). */ 119 unsigned freeze_start : 1; 120 /** True iff we should not allow changes to the end of the buffer 121 * (appends) */ 122 unsigned freeze_end : 1; 123 /** True iff this evbuffer's callbacks are not invoked immediately 124 * upon a change in the buffer, but instead are deferred to be invoked 125 * from the event_base's loop. Useful for preventing enormous stack 126 * overflows when we have mutually recursive callbacks, and for 127 * serializing callbacks in a single thread. */ 128 unsigned deferred_cbs : 1; 129 #ifdef WIN32 130 /** True iff this buffer is set up for overlapped IO. */ 131 unsigned is_overlapped : 1; 132 #endif 133 /** Zero or more EVBUFFER_FLAG_* bits */ 134 ev_uint32_t flags; 135 136 /** Used to implement deferred callbacks. */ 137 struct deferred_cb_queue *cb_queue; 138 139 /** A reference count on this evbuffer. When the reference count 140 * reaches 0, the buffer is destroyed. Manipulated with 141 * evbuffer_incref and evbuffer_decref_and_unlock and 142 * evbuffer_free. */ 143 int refcnt; 144 145 /** A deferred_cb handle to make all of this buffer's callbacks 146 * invoked from the event loop. */ 147 struct deferred_cb deferred; 148 149 /** A doubly-linked-list of callback functions */ 150 TAILQ_HEAD(evbuffer_cb_queue, evbuffer_cb_entry) callbacks; 151 152 /** The parent bufferevent object this evbuffer belongs to. 153 * NULL if the evbuffer stands alone. */ 154 struct bufferevent *parent; 155 }; 156 157 /** A single item in an evbuffer. */ 158 struct evbuffer_chain { 159 /** points to next buffer in the chain */ 160 struct evbuffer_chain *next; 161 162 /** total allocation available in the buffer field. */ 163 size_t buffer_len; 164 165 /** unused space at the beginning of buffer or an offset into a 166 * file for sendfile buffers. */ 167 ev_off_t misalign; 168 169 /** Offset into buffer + misalign at which to start writing. 170 * In other words, the total number of bytes actually stored 171 * in buffer. */ 172 size_t off; 173 174 /** Set if special handling is required for this chain */ 175 unsigned flags; 176 #define EVBUFFER_MMAP 0x0001 /**< memory in buffer is mmaped */ 177 #define EVBUFFER_SENDFILE 0x0002 /**< a chain used for sendfile */ 178 #define EVBUFFER_REFERENCE 0x0004 /**< a chain with a mem reference */ 179 #define EVBUFFER_IMMUTABLE 0x0008 /**< read-only chain */ 180 /** a chain that mustn't be reallocated or freed, or have its contents 181 * memmoved, until the chain is un-pinned. */ 182 #define EVBUFFER_MEM_PINNED_R 0x0010 183 #define EVBUFFER_MEM_PINNED_W 0x0020 184 #define EVBUFFER_MEM_PINNED_ANY (EVBUFFER_MEM_PINNED_R|EVBUFFER_MEM_PINNED_W) 185 /** a chain that should be freed, but can't be freed until it is 186 * un-pinned. */ 187 #define EVBUFFER_DANGLING 0x0040 188 189 /** Usually points to the read-write memory belonging to this 190 * buffer allocated as part of the evbuffer_chain allocation. 191 * For mmap, this can be a read-only buffer and 192 * EVBUFFER_IMMUTABLE will be set in flags. For sendfile, it 193 * may point to NULL. 194 */ 195 unsigned char *buffer; 196 }; 197 198 /* this is currently used by both mmap and sendfile */ 199 /* TODO(niels): something strange needs to happen for Windows here, I am not 200 * sure what that is, but it needs to get looked into. 201 */ 202 struct evbuffer_chain_fd { 203 int fd; /**< the fd associated with this chain */ 204 }; 205 206 /** callback for a reference buffer; lets us know what to do with it when 207 * we're done with it. */ 208 struct evbuffer_chain_reference { 209 evbuffer_ref_cleanup_cb cleanupfn; 210 void *extra; 211 }; 212 213 #define EVBUFFER_CHAIN_SIZE sizeof(struct evbuffer_chain) 214 /** Return a pointer to extra data allocated along with an evbuffer. */ 215 #define EVBUFFER_CHAIN_EXTRA(t, c) (t *)((struct evbuffer_chain *)(c) + 1) 216 217 /** Assert that we are holding the lock on an evbuffer */ 218 #define ASSERT_EVBUFFER_LOCKED(buffer) \ 219 EVLOCK_ASSERT_LOCKED((buffer)->lock) 220 221 #define EVBUFFER_LOCK(buffer) \ 222 do { \ 223 EVLOCK_LOCK((buffer)->lock, 0); \ 224 } while (/*CONSTCOND*/0) 225 #define EVBUFFER_UNLOCK(buffer) \ 226 do { \ 227 EVLOCK_UNLOCK((buffer)->lock, 0); \ 228 } while (/*CONSTCOND*/0) 229 #define EVBUFFER_LOCK2(buffer1, buffer2) \ 230 do { \ 231 EVLOCK_LOCK2((buffer1)->lock, (buffer2)->lock, 0, 0); \ 232 } while (/*CONSTCOND*/0) 233 #define EVBUFFER_UNLOCK2(buffer1, buffer2) \ 234 do { \ 235 EVLOCK_UNLOCK2((buffer1)->lock, (buffer2)->lock, 0, 0); \ 236 } while (/*CONSTCOND*/0) 237 238 /** Increase the reference count of buf by one. */ 239 void _evbuffer_incref(struct evbuffer *buf); 240 /** Increase the reference count of buf by one and acquire the lock. */ 241 void _evbuffer_incref_and_lock(struct evbuffer *buf); 242 /** Pin a single buffer chain using a given flag. A pinned chunk may not be 243 * moved or freed until it is unpinned. */ 244 void _evbuffer_chain_pin(struct evbuffer_chain *chain, unsigned flag); 245 /** Unpin a single buffer chain using a given flag. */ 246 void _evbuffer_chain_unpin(struct evbuffer_chain *chain, unsigned flag); 247 /** As evbuffer_free, but requires that we hold a lock on the buffer, and 248 * releases the lock before freeing it and the buffer. */ 249 void _evbuffer_decref_and_unlock(struct evbuffer *buffer); 250 251 /** As evbuffer_expand, but does not guarantee that the newly allocated memory 252 * is contiguous. Instead, it may be split across two or more chunks. */ 253 int _evbuffer_expand_fast(struct evbuffer *, size_t, int); 254 255 /** Helper: prepares for a readv/WSARecv call by expanding the buffer to 256 * hold enough memory to read 'howmuch' bytes in possibly noncontiguous memory. 257 * Sets up the one or two iovecs in 'vecs' to point to the free memory and its 258 * extent, and *chainp to point to the first chain that we'll try to read into. 259 * Returns the number of vecs used. 260 */ 261 int _evbuffer_read_setup_vecs(struct evbuffer *buf, ev_ssize_t howmuch, 262 struct evbuffer_iovec *vecs, int n_vecs, struct evbuffer_chain ***chainp, 263 int exact); 264 265 /* Helper macro: copies an evbuffer_iovec in ei to a win32 WSABUF in i. */ 266 #define WSABUF_FROM_EVBUFFER_IOV(i,ei) do { \ 267 (i)->buf = (ei)->iov_base; \ 268 (i)->len = (unsigned long)(ei)->iov_len; \ 269 } while (/*CONSTCOND*/0) 270 /* XXXX the cast above is safe for now, but not if we allow mmaps on win64. 271 * See note in buffer_iocp's launch_write function */ 272 273 /** Set the parent bufferevent object for buf to bev */ 274 void evbuffer_set_parent(struct evbuffer *buf, struct bufferevent *bev); 275 276 void evbuffer_invoke_callbacks(struct evbuffer *buf); 277 278 #ifdef __cplusplus 279 } 280 #endif 281 282 #endif /* _EVBUFFER_INTERNAL_H_ */ 283