Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 1 | /* Copyright 1997,2001-2003 Alain Knaff. |
| 2 | * This file is part of mtools. |
| 3 | * |
| 4 | * Mtools is free software: you can redistribute it and/or modify |
| 5 | * it under the terms of the GNU General Public License as published by |
| 6 | * the Free Software Foundation, either version 3 of the License, or |
| 7 | * (at your option) any later version. |
| 8 | * |
| 9 | * Mtools is distributed in the hope that it will be useful, |
| 10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 12 | * GNU General Public License for more details. |
| 13 | * |
| 14 | * You should have received a copy of the GNU General Public License |
| 15 | * along with Mtools. If not, see <http://www.gnu.org/licenses/>. |
| 16 | * |
| 17 | * Buffer read/write module |
| 18 | */ |
| 19 | |
| 20 | #include "sysincludes.h" |
| 21 | #include "msdos.h" |
| 22 | #include "mtools.h" |
| 23 | #include "buffer.h" |
| 24 | |
| 25 | typedef struct Buffer_t { |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 26 | struct Stream_t head; |
| 27 | |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 28 | size_t size; /* size of read/write buffer */ |
| 29 | int dirty; /* is the buffer dirty? */ |
| 30 | |
| 31 | size_t sectorSize; /* sector size: all operations happen |
| 32 | * in multiples of this */ |
| 33 | size_t cylinderSize; /* cylinder size: preferred alignment, |
| 34 | * but for efficiency, less data may be read */ |
| 35 | int ever_dirty; /* was the buffer ever dirty? */ |
| 36 | size_t dirty_pos; |
| 37 | size_t dirty_end; |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 38 | mt_off_t current; /* first sector in buffer */ |
| 39 | size_t cur_size; /* the current size */ |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 40 | char *buf; /* disk read/write buffer */ |
| 41 | } Buffer_t; |
| 42 | |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 43 | /* Convert position relative to buffer to absolute position */ |
| 44 | static mt_off_t abs_pos(Buffer_t *Buffer, size_t rel) { |
| 45 | return Buffer->current + (mt_off_t) rel; |
| 46 | } |
| 47 | |
| 48 | /* End of currently valid buffer */ |
| 49 | static mt_off_t cur_end(Buffer_t *Buffer) { |
| 50 | return abs_pos(Buffer, Buffer->cur_size); |
| 51 | } |
| 52 | |
| 53 | /* distance from absolute position until next full cylinder. If position already |
| 54 | * *is* on a full cylinder boundary, return size of full cylinder */ |
| 55 | static size_t pos_to_next_full_cyl(Buffer_t *Buffer, mt_off_t pos) { |
| 56 | return Buffer->cylinderSize - |
| 57 | (size_t) (pos % (mt_off_t) Buffer->cylinderSize); |
| 58 | } |
| 59 | |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 60 | /* |
| 61 | * Flush a dirty buffer to disk. Resets Buffer->dirty to zero. |
| 62 | * All errors are fatal. |
| 63 | */ |
| 64 | |
| 65 | static int _buf_flush(Buffer_t *Buffer) |
| 66 | { |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 67 | ssize_t ret; |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 68 | |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 69 | #ifdef HAVE_ASSERT_H |
| 70 | assert(Buffer->head.Next != NULL); |
| 71 | #endif |
| 72 | |
| 73 | if (!Buffer->dirty) |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 74 | return 0; |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 75 | #ifdef DEBUG |
| 76 | fprintf(stderr, "write %08x -- %02x %08x %08x\n", |
| 77 | Buffer, |
| 78 | (unsigned char) Buffer->buf[0], |
| 79 | Buffer->current + Buffer->dirty_pos, |
| 80 | Buffer->dirty_end - Buffer->dirty_pos); |
| 81 | #endif |
| 82 | |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 83 | ret = force_pwrite(Buffer->head.Next, |
| 84 | Buffer->buf + Buffer->dirty_pos, |
| 85 | Buffer->current + (mt_off_t) Buffer->dirty_pos, |
| 86 | Buffer->dirty_end - Buffer->dirty_pos); |
| 87 | if(ret < 0) { |
| 88 | perror("buffer_flush: write"); |
| 89 | return -1; |
| 90 | } |
| 91 | |
| 92 | if((size_t) ret != Buffer->dirty_end - Buffer->dirty_pos) { |
| 93 | fprintf(stderr,"buffer_flush: short write\n"); |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 94 | return -1; |
| 95 | } |
| 96 | Buffer->dirty = 0; |
| 97 | Buffer->dirty_end = 0; |
| 98 | Buffer->dirty_pos = 0; |
| 99 | return 0; |
| 100 | } |
| 101 | |
| 102 | static int invalidate_buffer(Buffer_t *Buffer, mt_off_t start) |
| 103 | { |
| 104 | if(_buf_flush(Buffer) < 0) |
| 105 | return -1; |
| 106 | |
| 107 | /* start reading at the beginning of start's sector |
| 108 | * don't start reading too early, or we might not even reach |
| 109 | * start */ |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 110 | Buffer->current = ROUND_DOWN(start, (mt_off_t) Buffer->sectorSize); |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 111 | Buffer->cur_size = 0; |
| 112 | return 0; |
| 113 | } |
| 114 | |
| 115 | #undef OFFSET |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 116 | #define OFFSET ((size_t)(start - This->current)) |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 117 | |
| 118 | typedef enum position_t { |
| 119 | OUTSIDE, |
| 120 | APPEND, |
| 121 | INSIDE, |
| 122 | ERROR |
| 123 | } position_t; |
| 124 | |
| 125 | static position_t isInBuffer(Buffer_t *This, mt_off_t start, size_t *len) |
| 126 | { |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 127 | if(start >= This->current && start < cur_end(This)) { |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 128 | maximize(*len, This->cur_size - OFFSET); |
| 129 | return INSIDE; |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 130 | } else if(start == cur_end(This) && |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 131 | This->cur_size < This->size && |
| 132 | *len >= This->sectorSize) { |
| 133 | /* append to the buffer for this, three conditions have to |
| 134 | * be met: |
| 135 | * 1. The start falls exactly at the end of the currently |
| 136 | * loaded data |
| 137 | * 2. There is still space |
| 138 | * 3. We append at least one sector |
| 139 | */ |
| 140 | maximize(*len, This->size - This->cur_size); |
| 141 | *len = ROUND_DOWN(*len, This->sectorSize); |
| 142 | return APPEND; |
| 143 | } else { |
| 144 | if(invalidate_buffer(This, start) < 0) |
| 145 | return ERROR; |
| 146 | maximize(*len, This->cylinderSize - OFFSET); |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 147 | maximize(*len, pos_to_next_full_cyl(This, This->current)); |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 148 | return OUTSIDE; |
| 149 | } |
| 150 | } |
| 151 | |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 152 | static ssize_t buf_pread(Stream_t *Stream, char *buf, |
| 153 | mt_off_t start, size_t len) |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 154 | { |
| 155 | size_t length; |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 156 | size_t offset; |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 157 | char *disk_ptr; |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 158 | ssize_t ret; |
| 159 | DeclareThis(Buffer_t); |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 160 | |
| 161 | if(!len) |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 162 | return 0; |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 163 | |
| 164 | /*fprintf(stderr, "buf read %x %x %x\n", Stream, start, len);*/ |
| 165 | switch(isInBuffer(This, start, &len)) { |
| 166 | case OUTSIDE: |
| 167 | case APPEND: |
| 168 | /* always load until the end of the cylinder */ |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 169 | length = pos_to_next_full_cyl(This, cur_end(This)); |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 170 | maximize(length, This->size - This->cur_size); |
| 171 | |
| 172 | /* read it! */ |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 173 | ret=PREADS(This->head.Next, |
| 174 | This->buf + This->cur_size, |
| 175 | This->current + (mt_off_t) This->cur_size, |
| 176 | length); |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 177 | if ( ret < 0 ) |
| 178 | return ret; |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 179 | This->cur_size += (size_t) ret; |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 180 | if (This->current+(mt_off_t)This->cur_size < start) { |
| 181 | fprintf(stderr, "Short buffer fill\n"); |
| 182 | exit(1); |
| 183 | } |
| 184 | break; |
| 185 | case INSIDE: |
| 186 | /* nothing to do */ |
| 187 | break; |
| 188 | case ERROR: |
| 189 | return -1; |
| 190 | } |
| 191 | |
| 192 | offset = OFFSET; |
| 193 | disk_ptr = This->buf + offset; |
| 194 | maximize(len, This->cur_size - offset); |
| 195 | memcpy(buf, disk_ptr, len); |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 196 | return (ssize_t) len; |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 197 | } |
| 198 | |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 199 | static ssize_t buf_pwrite(Stream_t *Stream, char *buf, |
| 200 | mt_off_t start, size_t len) |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 201 | { |
| 202 | char *disk_ptr; |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 203 | DeclareThis(Buffer_t); |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 204 | size_t offset=0; |
| 205 | |
| 206 | if(!len) |
| 207 | return 0; |
| 208 | |
| 209 | This->ever_dirty = 1; |
| 210 | |
| 211 | #ifdef DEBUG |
| 212 | fprintf(stderr, "buf write %x %02x %08x %08x -- %08x %08x -- %08x\n", |
| 213 | Stream, (unsigned char) This->buf[0], |
| 214 | start, len, This->current, This->cur_size, This->size); |
| 215 | fprintf(stderr, "%d %d %d %x %x\n", |
| 216 | start == This->current + This->cur_size, |
| 217 | This->cur_size < This->size, |
| 218 | len >= This->sectorSize, len, This->sectorSize); |
| 219 | #endif |
| 220 | switch(isInBuffer(This, start, &len)) { |
| 221 | case OUTSIDE: |
| 222 | #ifdef DEBUG |
| 223 | fprintf(stderr, "outside\n"); |
| 224 | #endif |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 225 | if(start % (mt_off_t) This->cylinderSize || |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 226 | len < This->sectorSize) { |
| 227 | size_t readSize; |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 228 | ssize_t ret; |
| 229 | size_t bytes_read; |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 230 | |
| 231 | readSize = This->cylinderSize - |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 232 | (size_t)(This->current % (mt_off_t) This->cylinderSize); |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 233 | |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 234 | ret=PREADS(This->head.Next, This->buf, |
| 235 | (mt_off_t)This->current, readSize); |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 236 | /* read it! */ |
| 237 | if ( ret < 0 ) |
| 238 | return ret; |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 239 | bytes_read = (size_t) ret; |
| 240 | if(bytes_read % This->sectorSize) { |
| 241 | fprintf(stderr, "Weird: read size (%zd) not a multiple of sector size (%d)\n", bytes_read, (int) This->sectorSize); |
| 242 | bytes_read -= bytes_read % This->sectorSize; |
| 243 | if(bytes_read == 0) { |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 244 | fprintf(stderr, "Nothing left\n"); |
| 245 | exit(1); |
| 246 | } |
| 247 | } |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 248 | This->cur_size = bytes_read; |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 249 | /* for dosemu. Autoextend size */ |
| 250 | if(!This->cur_size) { |
| 251 | memset(This->buf,0,readSize); |
| 252 | This->cur_size = readSize; |
| 253 | } |
| 254 | offset = OFFSET; |
| 255 | break; |
| 256 | } |
| 257 | /* FALL THROUGH */ |
| 258 | case APPEND: |
| 259 | #ifdef DEBUG |
| 260 | fprintf(stderr, "append\n"); |
| 261 | #endif |
| 262 | len = ROUND_DOWN(len, This->sectorSize); |
| 263 | offset = OFFSET; |
| 264 | maximize(len, This->size - offset); |
| 265 | This->cur_size += len; |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 266 | if(This->head.Next->Class->pre_allocate) |
| 267 | PRE_ALLOCATE(This->head.Next, cur_end(This)); |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 268 | break; |
| 269 | case INSIDE: |
| 270 | /* nothing to do */ |
| 271 | #ifdef DEBUG |
| 272 | fprintf(stderr, "inside\n"); |
| 273 | #endif |
| 274 | offset = OFFSET; |
| 275 | maximize(len, This->cur_size - offset); |
| 276 | break; |
| 277 | case ERROR: |
| 278 | return -1; |
| 279 | #ifdef DEBUG |
| 280 | default: |
| 281 | fprintf(stderr, "Should not happen\n"); |
| 282 | exit(1); |
| 283 | #endif |
| 284 | } |
| 285 | |
| 286 | disk_ptr = This->buf + offset; |
| 287 | |
| 288 | /* extend if we write beyond end */ |
| 289 | if(offset + len > This->cur_size) { |
| 290 | len -= (offset + len) % This->sectorSize; |
| 291 | This->cur_size = len + offset; |
| 292 | } |
| 293 | |
| 294 | memcpy(disk_ptr, buf, len); |
| 295 | if(!This->dirty || offset < This->dirty_pos) |
| 296 | This->dirty_pos = ROUND_DOWN(offset, This->sectorSize); |
| 297 | if(!This->dirty || offset + len > This->dirty_end) |
| 298 | This->dirty_end = ROUND_UP(offset + len, This->sectorSize); |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 299 | |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 300 | if(This->dirty_end > This->cur_size) { |
| 301 | fprintf(stderr, |
| 302 | "Internal error, dirty end too big dirty_end=%x cur_size=%x len=%x offset=%d sectorSize=%x\n", |
| 303 | (unsigned int) This->dirty_end, |
| 304 | (unsigned int) This->cur_size, |
| 305 | (unsigned int) len, |
| 306 | (int) offset, (int) This->sectorSize); |
| 307 | fprintf(stderr, "offset + len + grain - 1 = %x\n", |
| 308 | (int) (offset + len + This->sectorSize - 1)); |
| 309 | fprintf(stderr, "ROUNDOWN(offset + len + grain - 1) = %x\n", |
| 310 | (int)ROUND_DOWN(offset + len + This->sectorSize - 1, |
| 311 | This->sectorSize)); |
| 312 | fprintf(stderr, "This->dirty = %d\n", This->dirty); |
| 313 | exit(1); |
| 314 | } |
| 315 | |
| 316 | This->dirty = 1; |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 317 | return (ssize_t) len; |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 318 | } |
| 319 | |
| 320 | static int buf_flush(Stream_t *Stream) |
| 321 | { |
| 322 | int ret; |
| 323 | DeclareThis(Buffer_t); |
| 324 | |
| 325 | if (!This->ever_dirty) |
| 326 | return 0; |
| 327 | ret = _buf_flush(This); |
| 328 | if(ret == 0) |
| 329 | This->ever_dirty = 0; |
| 330 | return ret; |
| 331 | } |
| 332 | |
| 333 | |
| 334 | static int buf_free(Stream_t *Stream) |
| 335 | { |
| 336 | DeclareThis(Buffer_t); |
| 337 | |
| 338 | if(This->buf) |
| 339 | free(This->buf); |
| 340 | This->buf = 0; |
| 341 | return 0; |
| 342 | } |
| 343 | |
| 344 | static Class_t BufferClass = { |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 345 | 0, |
| 346 | 0, |
| 347 | buf_pread, |
| 348 | buf_pwrite, |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 349 | buf_flush, |
| 350 | buf_free, |
| 351 | 0, /* set_geom */ |
| 352 | get_data_pass_through, /* get_data */ |
| 353 | 0, /* pre-allocate */ |
| 354 | get_dosConvert_pass_through, /* dos convert */ |
| 355 | 0, /* discard */ |
| 356 | }; |
| 357 | |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 358 | Stream_t *buf_init(Stream_t *Next, size_t size, |
| 359 | size_t cylinderSize, |
| 360 | size_t sectorSize) |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 361 | { |
| 362 | Buffer_t *Buffer; |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 363 | |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 364 | #ifdef HAVE_ASSERT_H |
| 365 | assert(size != 0); |
| 366 | assert(cylinderSize != 0); |
| 367 | assert(sectorSize != 0); |
| 368 | assert(Next != NULL); |
| 369 | #endif |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 370 | |
| 371 | if(size % cylinderSize != 0) { |
| 372 | fprintf(stderr, "size not multiple of cylinder size\n"); |
| 373 | exit(1); |
| 374 | } |
| 375 | if(cylinderSize % sectorSize != 0) { |
| 376 | fprintf(stderr, "cylinder size not multiple of sector size\n"); |
| 377 | exit(1); |
| 378 | } |
| 379 | |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 380 | Buffer = New(Buffer_t); |
| 381 | if(!Buffer) |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 382 | return 0; |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 383 | init_head(&Buffer->head, &BufferClass, Next); |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 384 | Buffer->buf = malloc(size); |
| 385 | if ( !Buffer->buf){ |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 386 | Free(Buffer); |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 387 | return 0; |
| 388 | } |
| 389 | Buffer->size = size; |
| 390 | Buffer->dirty = 0; |
| 391 | Buffer->cylinderSize = cylinderSize; |
| 392 | Buffer->sectorSize = sectorSize; |
| 393 | |
| 394 | Buffer->ever_dirty = 0; |
| 395 | Buffer->dirty_pos = 0; |
| 396 | Buffer->dirty_end = 0; |
| 397 | Buffer->current = 0L; |
| 398 | Buffer->cur_size = 0; /* buffer currently empty */ |
| 399 | |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 400 | return &Buffer->head; |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 401 | } |
| 402 | |