Harald Welte | 253c462 | 2010-05-25 23:42:57 +0200 | [diff] [blame^] | 1 | /* |
| 2 | * Buffering of output and input. |
| 3 | * Copyright (C) 1998 Kunihiro Ishiguro |
| 4 | * |
| 5 | * This file is part of GNU Zebra. |
| 6 | * |
| 7 | * GNU Zebra is free software; you can redistribute it and/or modify |
| 8 | * it under the terms of the GNU General Public License as published |
| 9 | * by the Free Software Foundation; either version 2, or (at your |
| 10 | * option) any later version. |
| 11 | * |
| 12 | * GNU Zebra is distributed in the hope that it will be useful, but |
| 13 | * WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 15 | * General Public License for more details. |
| 16 | * |
| 17 | * You should have received a copy of the GNU General Public License |
| 18 | * along with GNU Zebra; see the file COPYING. If not, write to the |
| 19 | * Free Software Foundation, Inc., 59 Temple Place - Suite 330, |
| 20 | * Boston, MA 02111-1307, USA. |
| 21 | */ |
| 22 | |
| 23 | #include <stdio.h> |
| 24 | #include <stdlib.h> |
| 25 | #include <unistd.h> |
| 26 | #include <string.h> |
| 27 | #include <errno.h> |
| 28 | #include <stddef.h> |
| 29 | #include <sys/uio.h> |
| 30 | |
| 31 | #include <osmocore/talloc.h> |
| 32 | #include <osmocom/vty/buffer.h> |
| 33 | #include <osmocom/vty/vty.h> |
| 34 | |
| 35 | /* Buffer master. */ |
| 36 | struct buffer { |
| 37 | /* Data list. */ |
| 38 | struct buffer_data *head; |
| 39 | struct buffer_data *tail; |
| 40 | |
| 41 | /* Size of each buffer_data chunk. */ |
| 42 | size_t size; |
| 43 | }; |
| 44 | |
| 45 | /* Data container. */ |
| 46 | struct buffer_data { |
| 47 | struct buffer_data *next; |
| 48 | |
| 49 | /* Location to add new data. */ |
| 50 | size_t cp; |
| 51 | |
| 52 | /* Pointer to data not yet flushed. */ |
| 53 | size_t sp; |
| 54 | |
| 55 | /* Actual data stream (variable length). */ |
| 56 | unsigned char data[0]; /* real dimension is buffer->size */ |
| 57 | }; |
| 58 | |
| 59 | /* It should always be true that: 0 <= sp <= cp <= size */ |
| 60 | |
| 61 | /* Default buffer size (used if none specified). It is rounded up to the |
| 62 | next page boundery. */ |
| 63 | #define BUFFER_SIZE_DEFAULT 4096 |
| 64 | |
| 65 | #define BUFFER_DATA_FREE(D) talloc_free((D)) |
| 66 | |
| 67 | /* Make new buffer. */ |
| 68 | struct buffer *buffer_new(void *ctx, size_t size) |
| 69 | { |
| 70 | struct buffer *b; |
| 71 | |
| 72 | b = talloc_zero(ctx, struct buffer); |
| 73 | |
| 74 | if (size) |
| 75 | b->size = size; |
| 76 | else { |
| 77 | static size_t default_size; |
| 78 | if (!default_size) { |
| 79 | long pgsz = sysconf(_SC_PAGESIZE); |
| 80 | default_size = |
| 81 | ((((BUFFER_SIZE_DEFAULT - 1) / pgsz) + 1) * pgsz); |
| 82 | } |
| 83 | b->size = default_size; |
| 84 | } |
| 85 | |
| 86 | return b; |
| 87 | } |
| 88 | |
| 89 | /* Free buffer. */ |
| 90 | void buffer_free(struct buffer *b) |
| 91 | { |
| 92 | buffer_reset(b); |
| 93 | talloc_free(b); |
| 94 | } |
| 95 | |
| 96 | /* Make string clone. */ |
| 97 | char *buffer_getstr(struct buffer *b) |
| 98 | { |
| 99 | size_t totlen = 0; |
| 100 | struct buffer_data *data; |
| 101 | char *s; |
| 102 | char *p; |
| 103 | |
| 104 | for (data = b->head; data; data = data->next) |
| 105 | totlen += data->cp - data->sp; |
| 106 | if (!(s = _talloc_zero(tall_vty_ctx, (totlen + 1), "buffer_getstr"))) |
| 107 | return NULL; |
| 108 | p = s; |
| 109 | for (data = b->head; data; data = data->next) { |
| 110 | memcpy(p, data->data + data->sp, data->cp - data->sp); |
| 111 | p += data->cp - data->sp; |
| 112 | } |
| 113 | *p = '\0'; |
| 114 | return s; |
| 115 | } |
| 116 | |
| 117 | /* Return 1 if buffer is empty. */ |
| 118 | int buffer_empty(struct buffer *b) |
| 119 | { |
| 120 | return (b->head == NULL); |
| 121 | } |
| 122 | |
| 123 | /* Clear and free all allocated data. */ |
| 124 | void buffer_reset(struct buffer *b) |
| 125 | { |
| 126 | struct buffer_data *data; |
| 127 | struct buffer_data *next; |
| 128 | |
| 129 | for (data = b->head; data; data = next) { |
| 130 | next = data->next; |
| 131 | BUFFER_DATA_FREE(data); |
| 132 | } |
| 133 | b->head = b->tail = NULL; |
| 134 | } |
| 135 | |
| 136 | /* Add buffer_data to the end of buffer. */ |
| 137 | static struct buffer_data *buffer_add(struct buffer *b) |
| 138 | { |
| 139 | struct buffer_data *d; |
| 140 | |
| 141 | d = _talloc_zero(b, |
| 142 | offsetof(struct buffer_data, data[b->size]), |
| 143 | "buffer_add"); |
| 144 | if (!d) |
| 145 | return NULL; |
| 146 | d->cp = d->sp = 0; |
| 147 | d->next = NULL; |
| 148 | |
| 149 | if (b->tail) |
| 150 | b->tail->next = d; |
| 151 | else |
| 152 | b->head = d; |
| 153 | b->tail = d; |
| 154 | |
| 155 | return d; |
| 156 | } |
| 157 | |
| 158 | /* Write data to buffer. */ |
| 159 | void buffer_put(struct buffer *b, const void *p, size_t size) |
| 160 | { |
| 161 | struct buffer_data *data = b->tail; |
| 162 | const char *ptr = p; |
| 163 | |
| 164 | /* We use even last one byte of data buffer. */ |
| 165 | while (size) { |
| 166 | size_t chunk; |
| 167 | |
| 168 | /* If there is no data buffer add it. */ |
| 169 | if (data == NULL || data->cp == b->size) |
| 170 | data = buffer_add(b); |
| 171 | |
| 172 | chunk = |
| 173 | ((size <= |
| 174 | (b->size - data->cp)) ? size : (b->size - data->cp)); |
| 175 | memcpy((data->data + data->cp), ptr, chunk); |
| 176 | size -= chunk; |
| 177 | ptr += chunk; |
| 178 | data->cp += chunk; |
| 179 | } |
| 180 | } |
| 181 | |
| 182 | /* Insert character into the buffer. */ |
| 183 | void buffer_putc(struct buffer *b, u_char c) |
| 184 | { |
| 185 | buffer_put(b, &c, 1); |
| 186 | } |
| 187 | |
| 188 | /* Put string to the buffer. */ |
| 189 | void buffer_putstr(struct buffer *b, const char *c) |
| 190 | { |
| 191 | buffer_put(b, c, strlen(c)); |
| 192 | } |
| 193 | |
| 194 | /* Keep flushing data to the fd until the buffer is empty or an error is |
| 195 | encountered or the operation would block. */ |
| 196 | buffer_status_t buffer_flush_all(struct buffer *b, int fd) |
| 197 | { |
| 198 | buffer_status_t ret; |
| 199 | struct buffer_data *head; |
| 200 | size_t head_sp; |
| 201 | |
| 202 | if (!b->head) |
| 203 | return BUFFER_EMPTY; |
| 204 | head_sp = (head = b->head)->sp; |
| 205 | /* Flush all data. */ |
| 206 | while ((ret = buffer_flush_available(b, fd)) == BUFFER_PENDING) { |
| 207 | if ((b->head == head) && (head_sp == head->sp) |
| 208 | && (errno != EINTR)) |
| 209 | /* No data was flushed, so kernel buffer must be full. */ |
| 210 | return ret; |
| 211 | head_sp = (head = b->head)->sp; |
| 212 | } |
| 213 | |
| 214 | return ret; |
| 215 | } |
| 216 | |
| 217 | #if 0 |
| 218 | /* Flush enough data to fill a terminal window of the given scene (used only |
| 219 | by vty telnet interface). */ |
| 220 | buffer_status_t |
| 221 | buffer_flush_window(struct buffer * b, int fd, int width, int height, |
| 222 | int erase_flag, int no_more_flag) |
| 223 | { |
| 224 | int nbytes; |
| 225 | int iov_alloc; |
| 226 | int iov_index; |
| 227 | struct iovec *iov; |
| 228 | struct iovec small_iov[3]; |
| 229 | char more[] = " --More-- "; |
| 230 | char erase[] = |
| 231 | { 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, |
| 232 | ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', |
| 233 | 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08 |
| 234 | }; |
| 235 | struct buffer_data *data; |
| 236 | int column; |
| 237 | |
| 238 | if (!b->head) |
| 239 | return BUFFER_EMPTY; |
| 240 | |
| 241 | if (height < 1) { |
| 242 | zlog_warn |
| 243 | ("%s called with non-positive window height %d, forcing to 1", |
| 244 | __func__, height); |
| 245 | height = 1; |
| 246 | } else if (height >= 2) |
| 247 | height--; |
| 248 | if (width < 1) { |
| 249 | zlog_warn |
| 250 | ("%s called with non-positive window width %d, forcing to 1", |
| 251 | __func__, width); |
| 252 | width = 1; |
| 253 | } |
| 254 | |
| 255 | /* For erase and more data add two to b's buffer_data count. */ |
| 256 | if (b->head->next == NULL) { |
| 257 | iov_alloc = sizeof(small_iov) / sizeof(small_iov[0]); |
| 258 | iov = small_iov; |
| 259 | } else { |
| 260 | iov_alloc = ((height * (width + 2)) / b->size) + 10; |
| 261 | iov = XMALLOC(MTYPE_TMP, iov_alloc * sizeof(*iov)); |
| 262 | } |
| 263 | iov_index = 0; |
| 264 | |
| 265 | /* Previously print out is performed. */ |
| 266 | if (erase_flag) { |
| 267 | iov[iov_index].iov_base = erase; |
| 268 | iov[iov_index].iov_len = sizeof erase; |
| 269 | iov_index++; |
| 270 | } |
| 271 | |
| 272 | /* Output data. */ |
| 273 | column = 1; /* Column position of next character displayed. */ |
| 274 | for (data = b->head; data && (height > 0); data = data->next) { |
| 275 | size_t cp; |
| 276 | |
| 277 | cp = data->sp; |
| 278 | while ((cp < data->cp) && (height > 0)) { |
| 279 | /* Calculate lines remaining and column position after displaying |
| 280 | this character. */ |
| 281 | if (data->data[cp] == '\r') |
| 282 | column = 1; |
| 283 | else if ((data->data[cp] == '\n') || (column == width)) { |
| 284 | column = 1; |
| 285 | height--; |
| 286 | } else |
| 287 | column++; |
| 288 | cp++; |
| 289 | } |
| 290 | iov[iov_index].iov_base = (char *)(data->data + data->sp); |
| 291 | iov[iov_index++].iov_len = cp - data->sp; |
| 292 | data->sp = cp; |
| 293 | |
| 294 | if (iov_index == iov_alloc) |
| 295 | /* This should not ordinarily happen. */ |
| 296 | { |
| 297 | iov_alloc *= 2; |
| 298 | if (iov != small_iov) { |
| 299 | zlog_warn("%s: growing iov array to %d; " |
| 300 | "width %d, height %d, size %lu", |
| 301 | __func__, iov_alloc, width, height, |
| 302 | (u_long) b->size); |
| 303 | iov = |
| 304 | XREALLOC(MTYPE_TMP, iov, |
| 305 | iov_alloc * sizeof(*iov)); |
| 306 | } else { |
| 307 | /* This should absolutely never occur. */ |
| 308 | zlog_err |
| 309 | ("%s: corruption detected: iov_small overflowed; " |
| 310 | "head %p, tail %p, head->next %p", |
| 311 | __func__, b->head, b->tail, b->head->next); |
| 312 | iov = |
| 313 | XMALLOC(MTYPE_TMP, |
| 314 | iov_alloc * sizeof(*iov)); |
| 315 | memcpy(iov, small_iov, sizeof(small_iov)); |
| 316 | } |
| 317 | } |
| 318 | } |
| 319 | |
| 320 | /* In case of `more' display need. */ |
| 321 | if (b->tail && (b->tail->sp < b->tail->cp) && !no_more_flag) { |
| 322 | iov[iov_index].iov_base = more; |
| 323 | iov[iov_index].iov_len = sizeof more; |
| 324 | iov_index++; |
| 325 | } |
| 326 | #ifdef IOV_MAX |
| 327 | /* IOV_MAX are normally defined in <sys/uio.h> , Posix.1g. |
| 328 | example: Solaris2.6 are defined IOV_MAX size at 16. */ |
| 329 | { |
| 330 | struct iovec *c_iov = iov; |
| 331 | nbytes = 0; /* Make sure it's initialized. */ |
| 332 | |
| 333 | while (iov_index > 0) { |
| 334 | int iov_size; |
| 335 | |
| 336 | iov_size = |
| 337 | ((iov_index > IOV_MAX) ? IOV_MAX : iov_index); |
| 338 | if ((nbytes = writev(fd, c_iov, iov_size)) < 0) { |
| 339 | zlog_warn("%s: writev to fd %d failed: %s", |
| 340 | __func__, fd, safe_strerror(errno)); |
| 341 | break; |
| 342 | } |
| 343 | |
| 344 | /* move pointer io-vector */ |
| 345 | c_iov += iov_size; |
| 346 | iov_index -= iov_size; |
| 347 | } |
| 348 | } |
| 349 | #else /* IOV_MAX */ |
| 350 | if ((nbytes = writev(fd, iov, iov_index)) < 0) |
| 351 | zlog_warn("%s: writev to fd %d failed: %s", |
| 352 | __func__, fd, safe_strerror(errno)); |
| 353 | #endif /* IOV_MAX */ |
| 354 | |
| 355 | /* Free printed buffer data. */ |
| 356 | while (b->head && (b->head->sp == b->head->cp)) { |
| 357 | struct buffer_data *del; |
| 358 | if (!(b->head = (del = b->head)->next)) |
| 359 | b->tail = NULL; |
| 360 | BUFFER_DATA_FREE(del); |
| 361 | } |
| 362 | |
| 363 | if (iov != small_iov) |
| 364 | XFREE(MTYPE_TMP, iov); |
| 365 | |
| 366 | return (nbytes < 0) ? BUFFER_ERROR : |
| 367 | (b->head ? BUFFER_PENDING : BUFFER_EMPTY); |
| 368 | } |
| 369 | #endif |
| 370 | |
| 371 | /* This function (unlike other buffer_flush* functions above) is designed |
| 372 | to work with non-blocking sockets. It does not attempt to write out |
| 373 | all of the queued data, just a "big" chunk. It returns 0 if it was |
| 374 | able to empty out the buffers completely, 1 if more flushing is |
| 375 | required later, or -1 on a fatal write error. */ |
| 376 | buffer_status_t buffer_flush_available(struct buffer * b, int fd) |
| 377 | { |
| 378 | |
| 379 | /* These are just reasonable values to make sure a significant amount of |
| 380 | data is written. There's no need to go crazy and try to write it all |
| 381 | in one shot. */ |
| 382 | #ifdef IOV_MAX |
| 383 | #define MAX_CHUNKS ((IOV_MAX >= 16) ? 16 : IOV_MAX) |
| 384 | #else |
| 385 | #define MAX_CHUNKS 16 |
| 386 | #endif |
| 387 | #define MAX_FLUSH 131072 |
| 388 | |
| 389 | struct buffer_data *d; |
| 390 | size_t written; |
| 391 | struct iovec iov[MAX_CHUNKS]; |
| 392 | size_t iovcnt = 0; |
| 393 | size_t nbyte = 0; |
| 394 | |
| 395 | for (d = b->head; d && (iovcnt < MAX_CHUNKS) && (nbyte < MAX_FLUSH); |
| 396 | d = d->next, iovcnt++) { |
| 397 | iov[iovcnt].iov_base = d->data + d->sp; |
| 398 | nbyte += (iov[iovcnt].iov_len = d->cp - d->sp); |
| 399 | } |
| 400 | |
| 401 | if (!nbyte) |
| 402 | /* No data to flush: should we issue a warning message? */ |
| 403 | return BUFFER_EMPTY; |
| 404 | |
| 405 | /* only place where written should be sign compared */ |
| 406 | if ((ssize_t) (written = writev(fd, iov, iovcnt)) < 0) { |
| 407 | if (ERRNO_IO_RETRY(errno)) |
| 408 | /* Calling code should try again later. */ |
| 409 | return BUFFER_PENDING; |
| 410 | return BUFFER_ERROR; |
| 411 | } |
| 412 | |
| 413 | /* Free printed buffer data. */ |
| 414 | while (written > 0) { |
| 415 | struct buffer_data *d; |
| 416 | if (!(d = b->head)) |
| 417 | break; |
| 418 | if (written < d->cp - d->sp) { |
| 419 | d->sp += written; |
| 420 | return BUFFER_PENDING; |
| 421 | } |
| 422 | |
| 423 | written -= (d->cp - d->sp); |
| 424 | if (!(b->head = d->next)) |
| 425 | b->tail = NULL; |
| 426 | BUFFER_DATA_FREE(d); |
| 427 | } |
| 428 | |
| 429 | return b->head ? BUFFER_PENDING : BUFFER_EMPTY; |
| 430 | |
| 431 | #undef MAX_CHUNKS |
| 432 | #undef MAX_FLUSH |
| 433 | } |
| 434 | |
| 435 | buffer_status_t |
| 436 | buffer_write(struct buffer * b, int fd, const void *p, size_t size) |
| 437 | { |
| 438 | ssize_t nbytes; |
| 439 | |
| 440 | #if 0 |
| 441 | /* Should we attempt to drain any previously buffered data? This could help reduce latency in pushing out the data if we are stuck in a long-running thread that is preventing the main select loop from calling the flush thread... */ |
| 442 | |
| 443 | if (b->head && (buffer_flush_available(b, fd) == BUFFER_ERROR)) |
| 444 | return BUFFER_ERROR; |
| 445 | #endif |
| 446 | if (b->head) |
| 447 | /* Buffer is not empty, so do not attempt to write the new data. */ |
| 448 | nbytes = 0; |
| 449 | else if ((nbytes = write(fd, p, size)) < 0) { |
| 450 | if (ERRNO_IO_RETRY(errno)) |
| 451 | nbytes = 0; |
| 452 | else |
| 453 | return BUFFER_ERROR; |
| 454 | } |
| 455 | /* Add any remaining data to the buffer. */ |
| 456 | { |
| 457 | size_t written = nbytes; |
| 458 | if (written < size) |
| 459 | buffer_put(b, ((const char *)p) + written, |
| 460 | size - written); |
| 461 | } |
| 462 | return b->head ? BUFFER_PENDING : BUFFER_EMPTY; |
| 463 | } |