1 /* $NetBSD: evbuffer-internal.h,v 1.3 2015/01/29 07:26:02 spz 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 #if _EVENT_SIZEOF_OFF_T < _EVENT_SIZEOF_SIZE_T 158 typedef ev_ssize_t ev_misalign_t; 159 #define EVBUFFER_CHAIN_MAX ((size_t)EV_SSIZE_MAX) 160 #else 161 typedef ev_off_t ev_misalign_t; 162 #if _EVENT_SIZEOF_OFF_T > _EVENT_SIZEOF_SIZE_T 163 #define EVBUFFER_CHAIN_MAX EV_SIZE_MAX 164 #else 165 #define EVBUFFER_CHAIN_MAX ((size_t)EV_SSIZE_MAX) 166 #endif 167 #endif 168 169 /** A single item in an evbuffer. */ 170 struct evbuffer_chain { 171 /** points to next buffer in the chain */ 172 struct evbuffer_chain *next; 173 174 /** total allocation available in the buffer field. */ 175 size_t buffer_len; 176 177 /** unused space at the beginning of buffer or an offset into a 178 * file for sendfile buffers. */ 179 ev_misalign_t misalign; 180 181 /** Offset into buffer + misalign at which to start writing. 182 * In other words, the total number of bytes actually stored 183 * in buffer. */ 184 size_t off; 185 186 /** Set if special handling is required for this chain */ 187 unsigned flags; 188 #define EVBUFFER_MMAP 0x0001 /**< memory in buffer is mmaped */ 189 #define EVBUFFER_SENDFILE 0x0002 /**< a chain used for sendfile */ 190 #define EVBUFFER_REFERENCE 0x0004 /**< a chain with a mem reference */ 191 #define EVBUFFER_IMMUTABLE 0x0008 /**< read-only chain */ 192 /** a chain that mustn't be reallocated or freed, or have its contents 193 * memmoved, until the chain is un-pinned. */ 194 #define EVBUFFER_MEM_PINNED_R 0x0010 195 #define EVBUFFER_MEM_PINNED_W 0x0020 196 #define EVBUFFER_MEM_PINNED_ANY (EVBUFFER_MEM_PINNED_R|EVBUFFER_MEM_PINNED_W) 197 /** a chain that should be freed, but can't be freed until it is 198 * un-pinned. */ 199 #define EVBUFFER_DANGLING 0x0040 200 201 /** Usually points to the read-write memory belonging to this 202 * buffer allocated as part of the evbuffer_chain allocation. 203 * For mmap, this can be a read-only buffer and 204 * EVBUFFER_IMMUTABLE will be set in flags. For sendfile, it 205 * may point to NULL. 206 */ 207 unsigned char *buffer; 208 }; 209 210 /* this is currently used by both mmap and sendfile */ 211 /* TODO(niels): something strange needs to happen for Windows here, I am not 212 * sure what that is, but it needs to get looked into. 213 */ 214 struct evbuffer_chain_fd { 215 int fd; /**< the fd associated with this chain */ 216 }; 217 218 /** callback for a reference buffer; lets us know what to do with it when 219 * we're done with it. */ 220 struct evbuffer_chain_reference { 221 evbuffer_ref_cleanup_cb cleanupfn; 222 void *extra; 223 }; 224 225 #define EVBUFFER_CHAIN_SIZE sizeof(struct evbuffer_chain) 226 /** Return a pointer to extra data allocated along with an evbuffer. */ 227 #define EVBUFFER_CHAIN_EXTRA(t, c) (t *)((struct evbuffer_chain *)(c) + 1) 228 229 /** Assert that we are holding the lock on an evbuffer */ 230 #define ASSERT_EVBUFFER_LOCKED(buffer) \ 231 EVLOCK_ASSERT_LOCKED((buffer)->lock) 232 233 #define EVBUFFER_LOCK(buffer) \ 234 do { \ 235 EVLOCK_LOCK((buffer)->lock, 0); \ 236 } while (/*CONSTCOND*/0) 237 #define EVBUFFER_UNLOCK(buffer) \ 238 do { \ 239 EVLOCK_UNLOCK((buffer)->lock, 0); \ 240 } while (/*CONSTCOND*/0) 241 #define EVBUFFER_LOCK2(buffer1, buffer2) \ 242 do { \ 243 EVLOCK_LOCK2((buffer1)->lock, (buffer2)->lock, 0, 0); \ 244 } while (/*CONSTCOND*/0) 245 #define EVBUFFER_UNLOCK2(buffer1, buffer2) \ 246 do { \ 247 EVLOCK_UNLOCK2((buffer1)->lock, (buffer2)->lock, 0, 0); \ 248 } while (/*CONSTCOND*/0) 249 250 /** Increase the reference count of buf by one. */ 251 void _evbuffer_incref(struct evbuffer *buf); 252 /** Increase the reference count of buf by one and acquire the lock. */ 253 void _evbuffer_incref_and_lock(struct evbuffer *buf); 254 /** Pin a single buffer chain using a given flag. A pinned chunk may not be 255 * moved or freed until it is unpinned. */ 256 void _evbuffer_chain_pin(struct evbuffer_chain *chain, unsigned flag); 257 /** Unpin a single buffer chain using a given flag. */ 258 void _evbuffer_chain_unpin(struct evbuffer_chain *chain, unsigned flag); 259 /** As evbuffer_free, but requires that we hold a lock on the buffer, and 260 * releases the lock before freeing it and the buffer. */ 261 void _evbuffer_decref_and_unlock(struct evbuffer *buffer); 262 263 /** As evbuffer_expand, but does not guarantee that the newly allocated memory 264 * is contiguous. Instead, it may be split across two or more chunks. */ 265 int _evbuffer_expand_fast(struct evbuffer *, size_t, int); 266 267 /** Helper: prepares for a readv/WSARecv call by expanding the buffer to 268 * hold enough memory to read 'howmuch' bytes in possibly noncontiguous memory. 269 * Sets up the one or two iovecs in 'vecs' to point to the free memory and its 270 * extent, and *chainp to point to the first chain that we'll try to read into. 271 * Returns the number of vecs used. 272 */ 273 int _evbuffer_read_setup_vecs(struct evbuffer *buf, ev_ssize_t howmuch, 274 struct evbuffer_iovec *vecs, int n_vecs, struct evbuffer_chain ***chainp, 275 int exact); 276 277 /* Helper macro: copies an evbuffer_iovec in ei to a win32 WSABUF in i. */ 278 #define WSABUF_FROM_EVBUFFER_IOV(i,ei) do { \ 279 (i)->buf = (ei)->iov_base; \ 280 (i)->len = (unsigned long)(ei)->iov_len; \ 281 } while (/*CONSTCOND*/0) 282 /* XXXX the cast above is safe for now, but not if we allow mmaps on win64. 283 * See note in buffer_iocp's launch_write function */ 284 285 /** Set the parent bufferevent object for buf to bev */ 286 void evbuffer_set_parent(struct evbuffer *buf, struct bufferevent *bev); 287 288 void evbuffer_invoke_callbacks(struct evbuffer *buf); 289 290 #ifdef __cplusplus 291 } 292 #endif 293 294 #endif /* _EVBUFFER_INTERNAL_H_ */ 295