evbuffer-internal.h (12806B)
1 /* 2 * Copyright (c) 2000-2007 Niels Provos <provos@citi.umich.edu> 3 * Copyright (c) 2007-2012 Niels Provos and Nick Mathewson 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. The name of the author may not be used to endorse or promote products 14 * derived from this software without specific prior written permission. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 */ 27 #ifndef EVBUFFER_INTERNAL_H_INCLUDED_ 28 #define EVBUFFER_INTERNAL_H_INCLUDED_ 29 30 #ifdef __cplusplus 31 extern "C" { 32 #endif 33 34 #include "event2/event-config.h" 35 #include "evconfig-private.h" 36 #include "event2/util.h" 37 #include "event2/event_struct.h" 38 #include "util-internal.h" 39 #include "defer-internal.h" 40 41 /* Experimental cb flag: "never deferred." Implementation note: 42 * these callbacks may get an inaccurate view of n_del/n_added in their 43 * arguments. */ 44 #define EVBUFFER_CB_NODEFER 2 45 46 #ifdef _WIN32 47 #include <winsock2.h> 48 #endif 49 #include <sys/queue.h> 50 51 /* Minimum allocation for a chain. We define this so that we're burning no 52 * more than 5% of each allocation on overhead. It would be nice to lose even 53 * less space, though. */ 54 #if EVENT__SIZEOF_VOID_P < 8 55 #define MIN_BUFFER_SIZE 512 56 #else 57 #define MIN_BUFFER_SIZE 1024 58 #endif 59 60 /** A single evbuffer callback for an evbuffer. This function will be invoked 61 * when bytes are added to or removed from the evbuffer. */ 62 struct evbuffer_cb_entry { 63 /** Structures to implement a doubly-linked queue of callbacks */ 64 LIST_ENTRY(evbuffer_cb_entry) next; 65 /** The callback function to invoke when this callback is called. 66 If EVBUFFER_CB_OBSOLETE is set in flags, the cb_obsolete field is 67 valid; otherwise, cb_func is valid. */ 68 union { 69 evbuffer_cb_func cb_func; 70 evbuffer_cb cb_obsolete; 71 } cb; 72 /** Argument to pass to cb. */ 73 void *cbarg; 74 /** Currently set flags on this callback. */ 75 ev_uint32_t flags; 76 }; 77 78 struct bufferevent; 79 struct evbuffer_chain; 80 struct evbuffer { 81 /** The first chain in this buffer's linked list of chains. */ 82 struct evbuffer_chain *first; 83 /** The last chain in this buffer's linked list of chains. */ 84 struct evbuffer_chain *last; 85 86 /** Pointer to the next pointer pointing at the 'last_with_data' chain. 87 * 88 * To unpack: 89 * 90 * The last_with_data chain is the last chain that has any data in it. 91 * If all chains in the buffer are empty, it is the first chain. 92 * If the buffer has no chains, it is NULL. 93 * 94 * The last_with_datap pointer points at _whatever 'next' pointer_ 95 * pointing at the last_with_data chain. If the last_with_data chain 96 * is the first chain, or it is NULL, then the last_with_datap pointer 97 * is &buf->first. 98 */ 99 struct evbuffer_chain **last_with_datap; 100 101 /** Total amount of bytes stored in all chains.*/ 102 size_t total_len; 103 104 /** Number of bytes we have added to the buffer since we last tried to 105 * invoke callbacks. */ 106 size_t n_add_for_cb; 107 /** Number of bytes we have removed from the buffer since we last 108 * tried to invoke callbacks. */ 109 size_t n_del_for_cb; 110 111 #ifndef EVENT__DISABLE_THREAD_SUPPORT 112 /** A lock used to mediate access to this buffer. */ 113 void *lock; 114 #endif 115 /** True iff we should free the lock field when we free this 116 * evbuffer. */ 117 unsigned own_lock : 1; 118 /** True iff we should not allow changes to the front of the buffer 119 * (drains or prepends). */ 120 unsigned freeze_start : 1; 121 /** True iff we should not allow changes to the end of the buffer 122 * (appends) */ 123 unsigned freeze_end : 1; 124 /** True iff this evbuffer's callbacks are not invoked immediately 125 * upon a change in the buffer, but instead are deferred to be invoked 126 * from the event_base's loop. Useful for preventing enormous stack 127 * overflows when we have mutually recursive callbacks, and for 128 * serializing callbacks in a single thread. */ 129 unsigned deferred_cbs : 1; 130 #ifdef _WIN32 131 /** True iff this buffer is set up for overlapped IO. */ 132 unsigned is_overlapped : 1; 133 #endif 134 /** Zero or more EVBUFFER_FLAG_* bits */ 135 ev_uint32_t flags; 136 137 /** Used to implement deferred callbacks. */ 138 struct event_base *cb_queue; 139 140 /** A reference count on this evbuffer. When the reference count 141 * reaches 0, the buffer is destroyed. Manipulated with 142 * evbuffer_incref and evbuffer_decref_and_unlock and 143 * evbuffer_free. */ 144 int refcnt; 145 146 /** A struct event_callback handle to make all of this buffer's callbacks 147 * invoked from the event loop. */ 148 struct event_callback deferred; 149 150 /** A doubly-linked-list of callback functions */ 151 LIST_HEAD(evbuffer_cb_queue, evbuffer_cb_entry) callbacks; 152 153 /** The parent bufferevent object this evbuffer belongs to. 154 * NULL if the evbuffer stands alone. */ 155 struct bufferevent *parent; 156 }; 157 158 #if EVENT__SIZEOF_OFF_T < EVENT__SIZEOF_SIZE_T 159 typedef ev_ssize_t ev_misalign_t; 160 #define EVBUFFER_CHAIN_MAX ((size_t)EV_SSIZE_MAX) 161 #else 162 typedef ev_off_t ev_misalign_t; 163 #if EVENT__SIZEOF_OFF_T > EVENT__SIZEOF_SIZE_T 164 #define EVBUFFER_CHAIN_MAX EV_SIZE_MAX 165 #else 166 #define EVBUFFER_CHAIN_MAX ((size_t)EV_SSIZE_MAX) 167 #endif 168 #endif 169 170 /** A single item in an evbuffer. */ 171 struct evbuffer_chain { 172 /** points to next buffer in the chain */ 173 struct evbuffer_chain *next; 174 175 /** total allocation available in the buffer field. */ 176 size_t buffer_len; 177 178 /** unused space at the beginning of buffer or an offset into a 179 * file for sendfile buffers. */ 180 ev_misalign_t misalign; 181 182 /** Offset into buffer + misalign at which to start writing. 183 * In other words, the total number of bytes actually stored 184 * in buffer. */ 185 size_t off; 186 187 /** Set if special handling is required for this chain */ 188 unsigned flags; 189 #define EVBUFFER_FILESEGMENT 0x0001 /**< A chain used for a file segment */ 190 #define EVBUFFER_SENDFILE 0x0002 /**< a chain used with sendfile */ 191 #define EVBUFFER_REFERENCE 0x0004 /**< a chain with a mem reference */ 192 #define EVBUFFER_IMMUTABLE 0x0008 /**< read-only chain */ 193 /** a chain that mustn't be reallocated or freed, or have its contents 194 * memmoved, until the chain is un-pinned. */ 195 #define EVBUFFER_MEM_PINNED_R 0x0010 196 #define EVBUFFER_MEM_PINNED_W 0x0020 197 #define EVBUFFER_MEM_PINNED_ANY (EVBUFFER_MEM_PINNED_R|EVBUFFER_MEM_PINNED_W) 198 /** a chain that should be freed, but can't be freed until it is 199 * un-pinned. */ 200 #define EVBUFFER_DANGLING 0x0040 201 /** a chain that is a referenced copy of another chain */ 202 #define EVBUFFER_MULTICAST 0x0080 203 204 /** number of references to this chain */ 205 int refcnt; 206 207 /** Usually points to the read-write memory belonging to this 208 * buffer allocated as part of the evbuffer_chain allocation. 209 * For mmap, this can be a read-only buffer and 210 * EVBUFFER_IMMUTABLE will be set in flags. For sendfile, it 211 * may point to NULL. 212 */ 213 unsigned char *buffer; 214 }; 215 216 /** callback for a reference chain; lets us know what to do with it when 217 * we're done with it. Lives at the end of an evbuffer_chain with the 218 * EVBUFFER_REFERENCE flag set */ 219 struct evbuffer_chain_reference { 220 evbuffer_ref_cleanup_cb cleanupfn; 221 void *extra; 222 }; 223 224 /** File segment for a file-segment chain. Lives at the end of an 225 * evbuffer_chain with the EVBUFFER_FILESEGMENT flag set. */ 226 struct evbuffer_chain_file_segment { 227 struct evbuffer_file_segment *segment; 228 #ifdef _WIN32 229 /** If we're using CreateFileMapping, this is the handle to the view. */ 230 HANDLE view_handle; 231 #endif 232 }; 233 234 /* Declared in event2/buffer.h; defined here. */ 235 struct evbuffer_file_segment { 236 void *lock; /**< lock prevent concurrent access to refcnt */ 237 int refcnt; /**< Reference count for this file segment */ 238 unsigned flags; /**< combination of EVBUF_FS_* flags */ 239 240 /** What kind of file segment is this? */ 241 unsigned can_sendfile : 1; 242 unsigned is_mapping : 1; 243 244 /** The fd that we read the data from. */ 245 int fd; 246 /** If we're using mmap, this is the raw mapped memory. */ 247 void *mapping; 248 #ifdef _WIN32 249 /** If we're using CreateFileMapping, this is the mapping */ 250 HANDLE mapping_handle; 251 #endif 252 /** If we're using mmap or IO, this is the content of the file 253 * segment. */ 254 char *contents; 255 /** Position of this segment within the file. */ 256 ev_off_t file_offset; 257 /** If we're using mmap, this is the offset within 'mapping' where 258 * this data segment begins. */ 259 ev_off_t mmap_offset; 260 /** The length of this segment. */ 261 ev_off_t length; 262 /** Cleanup callback function */ 263 evbuffer_file_segment_cleanup_cb cleanup_cb; 264 /** Argument to be pass to cleanup callback function */ 265 void *cleanup_cb_arg; 266 }; 267 268 /** Information about the multicast parent of a chain. Lives at the 269 * end of an evbuffer_chain with the EVBUFFER_MULTICAST flag set. */ 270 struct evbuffer_multicast_parent { 271 /** source buffer the multicast parent belongs to */ 272 struct evbuffer *source; 273 /** multicast parent for this chain */ 274 struct evbuffer_chain *parent; 275 }; 276 277 #define EVBUFFER_CHAIN_SIZE sizeof(struct evbuffer_chain) 278 /** Return a pointer to extra data allocated along with an evbuffer. */ 279 #define EVBUFFER_CHAIN_EXTRA(t, c) (t *)((struct evbuffer_chain *)(c) + 1) 280 281 /** Assert that we are holding the lock on an evbuffer */ 282 #define ASSERT_EVBUFFER_LOCKED(buffer) \ 283 EVLOCK_ASSERT_LOCKED((buffer)->lock) 284 285 #define EVBUFFER_LOCK(buffer) \ 286 do { \ 287 EVLOCK_LOCK((buffer)->lock, 0); \ 288 } while (0) 289 #define EVBUFFER_UNLOCK(buffer) \ 290 do { \ 291 EVLOCK_UNLOCK((buffer)->lock, 0); \ 292 } while (0) 293 #define EVBUFFER_LOCK2(buffer1, buffer2) \ 294 do { \ 295 EVLOCK_LOCK2((buffer1)->lock, (buffer2)->lock, 0, 0); \ 296 } while (0) 297 #define EVBUFFER_UNLOCK2(buffer1, buffer2) \ 298 do { \ 299 EVLOCK_UNLOCK2((buffer1)->lock, (buffer2)->lock, 0, 0); \ 300 } while (0) 301 302 /** Increase the reference count of buf by one. */ 303 void evbuffer_incref_(struct evbuffer *buf); 304 /** Increase the reference count of buf by one and acquire the lock. */ 305 void evbuffer_incref_and_lock_(struct evbuffer *buf); 306 /** Pin a single buffer chain using a given flag. A pinned chunk may not be 307 * moved or freed until it is unpinned. */ 308 void evbuffer_chain_pin_(struct evbuffer_chain *chain, unsigned flag); 309 /** Unpin a single buffer chain using a given flag. */ 310 void evbuffer_chain_unpin_(struct evbuffer_chain *chain, unsigned flag); 311 /** As evbuffer_free, but requires that we hold a lock on the buffer, and 312 * releases the lock before freeing it and the buffer. */ 313 void evbuffer_decref_and_unlock_(struct evbuffer *buffer); 314 315 /** As evbuffer_expand, but does not guarantee that the newly allocated memory 316 * is contiguous. Instead, it may be split across two or more chunks. */ 317 int evbuffer_expand_fast_(struct evbuffer *, size_t, int); 318 319 /** Helper: prepares for a readv/WSARecv call by expanding the buffer to 320 * hold enough memory to read 'howmuch' bytes in possibly noncontiguous memory. 321 * Sets up the one or two iovecs in 'vecs' to point to the free memory and its 322 * extent, and *chainp to point to the first chain that we'll try to read into. 323 * Returns the number of vecs used. 324 */ 325 int evbuffer_read_setup_vecs_(struct evbuffer *buf, ev_ssize_t howmuch, 326 struct evbuffer_iovec *vecs, int n_vecs, struct evbuffer_chain ***chainp, 327 int exact); 328 329 /* Helper macro: copies an evbuffer_iovec in ei to a win32 WSABUF in i. */ 330 #define WSABUF_FROM_EVBUFFER_IOV(i,ei) do { \ 331 (i)->buf = (ei)->iov_base; \ 332 (i)->len = (unsigned long)(ei)->iov_len; \ 333 } while (0) 334 /* XXXX the cast above is safe for now, but not if we allow mmaps on win64. 335 * See note in buffer_iocp's launch_write function */ 336 337 /** Set the parent bufferevent object for buf to bev */ 338 void evbuffer_set_parent_(struct evbuffer *buf, struct bufferevent *bev); 339 340 void evbuffer_invoke_callbacks_(struct evbuffer *buf); 341 342 343 int evbuffer_get_callbacks_(struct evbuffer *buffer, 344 struct event_callback **cbs, 345 int max_cbs); 346 347 #ifdef __cplusplus 348 } 349 #endif 350 351 #endif /* EVBUFFER_INTERNAL_H_INCLUDED_ */