| 1 | /*-␊ |
| 2 | * Copyright (c) 1990, 1993␊ |
| 3 | *␉The Regents of the University of California. All rights reserved.␊ |
| 4 | *␊ |
| 5 | * This code is derived from software contributed to Berkeley by␊ |
| 6 | * Chris Torek.␊ |
| 7 | *␊ |
| 8 | * Redistribution and use in source and binary forms, with or without␊ |
| 9 | * modification, are permitted provided that the following conditions␊ |
| 10 | * are met:␊ |
| 11 | * 1. Redistributions of source code must retain the above copyright␊ |
| 12 | * notice, this list of conditions and the following disclaimer.␊ |
| 13 | * 2. Redistributions in binary form must reproduce the above copyright␊ |
| 14 | * notice, this list of conditions and the following disclaimer in the␊ |
| 15 | * documentation and/or other materials provided with the distribution.␊ |
| 16 | * 4. Neither the name of the University nor the names of its contributors␊ |
| 17 | * may be used to endorse or promote products derived from this software␊ |
| 18 | * without specific prior written permission.␊ |
| 19 | *␊ |
| 20 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND␊ |
| 21 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE␊ |
| 22 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE␊ |
| 23 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE␊ |
| 24 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL␊ |
| 25 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS␊ |
| 26 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)␊ |
| 27 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT␊ |
| 28 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY␊ |
| 29 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF␊ |
| 30 | * SUCH DAMAGE.␊ |
| 31 | */␊ |
| 32 | ␊ |
| 33 | #if defined(LIBC_SCCS) && !defined(lint)␊ |
| 34 | static char sccsid[] = "@(#)fseek.c␉8.3 (Berkeley) 1/2/94";␊ |
| 35 | #endif /* LIBC_SCCS and not lint */␊ |
| 36 | #include <sys/cdefs.h>␊ |
| 37 | __FBSDID("$FreeBSD: src/lib/libc/stdio/fseek.c,v 1.44 2008/04/17 22:17:54 jhb Exp $");␊ |
| 38 | ␊ |
| 39 | #include "namespace.h"␊ |
| 40 | #include <sys/types.h>␊ |
| 41 | #include <sys/stat.h>␊ |
| 42 | #include <errno.h>␊ |
| 43 | #include <fcntl.h>␊ |
| 44 | #include <limits.h>␊ |
| 45 | #include <stdio.h>␊ |
| 46 | #include <stdlib.h>␊ |
| 47 | #include "un-namespace.h"␊ |
| 48 | #include "local.h"␊ |
| 49 | #include "_fbsd_compat_.h"␊ |
| 50 | ␊ |
| 51 | ␊ |
| 52 | #define␉POS_ERR␉(-(fpos_t)1)␊ |
| 53 | ␊ |
| 54 | int␊ |
| 55 | fseek(fp, offset, whence)␊ |
| 56 | ␉FILE *fp;␊ |
| 57 | ␉long offset;␊ |
| 58 | ␉int whence;␊ |
| 59 | {␊ |
| 60 | ␉int ret;␊ |
| 61 | ␉int serrno = errno;␊ |
| 62 | ␊ |
| 63 | ␉/* make sure stdio is set up */␊ |
| 64 | ␉if (!__sdidinit)␊ |
| 65 | ␉␉__sinit();␊ |
| 66 | ␊ |
| 67 | ␉ret = _fseeko(fp, (off_t)offset, whence, 1);␊ |
| 68 | ␉if (ret == 0)␊ |
| 69 | ␉␉errno = serrno;␊ |
| 70 | ␉return (ret);␊ |
| 71 | }␊ |
| 72 | ␊ |
| 73 | int␊ |
| 74 | fseeko(fp, offset, whence)␊ |
| 75 | ␉FILE *fp;␊ |
| 76 | ␉off_t offset;␊ |
| 77 | ␉int whence;␊ |
| 78 | {␊ |
| 79 | ␉int ret;␊ |
| 80 | int serrno = errno;␊ |
| 81 | ␊ |
| 82 | ␉/* make sure stdio is set up */␊ |
| 83 | ␉if (!__sdidinit)␊ |
| 84 | ␉␉__sinit();␊ |
| 85 | ␊ |
| 86 | ␉ret = _fseeko(fp, offset, whence, 0);␊ |
| 87 | ␉if (ret == 0)␊ |
| 88 | ␉␉errno = serrno;␊ |
| 89 | ␊ |
| 90 | ␉return (ret);␊ |
| 91 | }␊ |
| 92 | ␊ |
| 93 | /*␊ |
| 94 | * Seek the given file to the given offset.␊ |
| 95 | * `Whence' must be one of the three SEEK_* macros.␊ |
| 96 | */␊ |
| 97 | int␊ |
| 98 | _fseeko(fp, offset, whence, ltest)␊ |
| 99 | ␉FILE *fp;␊ |
| 100 | ␉off_t offset;␊ |
| 101 | ␉int whence;␊ |
| 102 | ␉int ltest;␊ |
| 103 | {␊ |
| 104 | ␉fpos_t (*seekfn)(void *, fpos_t, int);␊ |
| 105 | ␉fpos_t target, curoff, ret;␊ |
| 106 | ␉size_t n;␊ |
| 107 | ␉struct stat st;␊ |
| 108 | ␉int havepos;␊ |
| 109 | ␊ |
| 110 | ␉/*␊ |
| 111 | ␉ * Have to be able to seek.␊ |
| 112 | ␉ */␊ |
| 113 | ␉if ((seekfn = fp->_seek) == NULL) {␊ |
| 114 | ␉␉errno = ESPIPE;␊ |
| 115 | return (-1);␊ |
| 116 | ␉}␊ |
| 117 | ␊ |
| 118 | ␉/*␊ |
| 119 | ␉ * Change any SEEK_CUR to SEEK_SET, and check `whence' argument.␊ |
| 120 | ␉ * After this, whence is either SEEK_SET or SEEK_END.␊ |
| 121 | ␉ */␊ |
| 122 | ␉switch (whence) {␊ |
| 123 | ␊ |
| 124 | ␉case SEEK_CUR:␊ |
| 125 | ␉␉/*␊ |
| 126 | ␉␉ * In order to seek relative to the current stream offset,␊ |
| 127 | ␉␉ * we have to first find the current stream offset via␊ |
| 128 | ␉␉ * ftell (see ftell for details).␊ |
| 129 | ␉␉ */␊ |
| 130 | ␉␉if (_ftello(fp, &curoff))␊ |
| 131 | ␉␉␉return (-1);␊ |
| 132 | ␉␉if (curoff < 0) {␊ |
| 133 | ␉␉␉/* Unspecified position because of ungetc() at 0 */␊ |
| 134 | errno = ESPIPE;␊ |
| 135 | ␉␉␉return (-1);␊ |
| 136 | ␉␉}␊ |
| 137 | ␉␉if (offset > 0 && curoff > OFF_MAX - offset) {␊ |
| 138 | errno = EOVERFLOW;␊ |
| 139 | ␉␉␉return (-1);␊ |
| 140 | ␉␉}␊ |
| 141 | ␉␉offset += curoff;␊ |
| 142 | ␉␉if (offset < 0) {␊ |
| 143 | errno = EINVAL;␊ |
| 144 | ␉␉␉return (-1);␊ |
| 145 | ␉␉}␊ |
| 146 | ␉␉if (ltest && offset > LONG_MAX) {␊ |
| 147 | errno = EOVERFLOW;␊ |
| 148 | ␉␉␉return (-1);␊ |
| 149 | ␉␉}␊ |
| 150 | ␉␉whence = SEEK_SET;␊ |
| 151 | ␉␉havepos = 1;␊ |
| 152 | ␉␉break;␊ |
| 153 | ␊ |
| 154 | ␉case SEEK_SET:␊ |
| 155 | ␉␉if (offset < 0) {␊ |
| 156 | errno = EINVAL;␊ |
| 157 | ␉␉␉return (-1);␊ |
| 158 | ␉␉}␊ |
| 159 | ␉case SEEK_END:␊ |
| 160 | ␉␉curoff = 0;␉␉/* XXX just to keep gcc quiet */␊ |
| 161 | ␉␉havepos = 0;␊ |
| 162 | ␉␉break;␊ |
| 163 | ␊ |
| 164 | ␉default: ␊ |
| 165 | errno = EINVAL;␊ |
| 166 | ␉␉return (-1);␊ |
| 167 | ␉}␊ |
| 168 | ␊ |
| 169 | ␉/*␊ |
| 170 | ␉ * Can only optimise if:␊ |
| 171 | ␉ *␉reading (and not reading-and-writing);␊ |
| 172 | ␉ *␉not unbuffered; and␊ |
| 173 | ␉ *␉this is a `regular' Unix file (and hence seekfn==__sseek).␊ |
| 174 | ␉ * We must check __NBF first, because it is possible to have __NBF␊ |
| 175 | ␉ * and __SOPT both set.␊ |
| 176 | ␉ */␊ |
| 177 | ␉if (fp->_bf._base == NULL)␊ |
| 178 | ␉␉__smakebuf(fp);␊ |
| 179 | ␉if (fp->_flags & (__SWR | __SRW | __SNBF | __SNPT))␊ |
| 180 | ␉␉goto dumb;␊ |
| 181 | #if 0␊ |
| 182 | ␉if ((fp->_flags & __SOPT) == 0) {␊ |
| 183 | ␉␉if (seekfn != __sseek ||␊ |
| 184 | ␉␉ fp->_file < 0 || _fstat(fp->_file, &st) ||␊ |
| 185 | ␉␉ (st.st_mode & S_IFMT) != S_IFREG) {␊ |
| 186 | ␉␉␉fp->_flags |= __SNPT;␊ |
| 187 | ␉␉␉goto dumb;␊ |
| 188 | ␉␉}␊ |
| 189 | ␉␉fp->_blksize = st.st_blksize;␊ |
| 190 | ␉␉fp->_flags |= __SOPT;␊ |
| 191 | ␉}␊ |
| 192 | #else␊ |
| 193 | fp->_flags |= __SNPT;␊ |
| 194 | goto dumb;␊ |
| 195 | #endif␊ |
| 196 | ␊ |
| 197 | ␉/*␊ |
| 198 | ␉ * We are reading; we can try to optimise.␊ |
| 199 | ␉ * Figure out where we are going and where we are now.␊ |
| 200 | ␉ */␊ |
| 201 | ␉if (whence == SEEK_SET)␊ |
| 202 | ␉␉target = offset;␊ |
| 203 | ␉else {␊ |
| 204 | ␉␉if (_fstat(fp->_file, &st))␊ |
| 205 | ␉␉␉goto dumb;␊ |
| 206 | ␉␉if (offset > 0 && st.st_size > OFF_MAX - offset) {␊ |
| 207 | errno = EOVERFLOW;␊ |
| 208 | ␉␉␉return (-1);␊ |
| 209 | ␉␉}␊ |
| 210 | ␉␉target = st.st_size + offset;␊ |
| 211 | ␉␉if ((off_t)target < 0) {␊ |
| 212 | errno = EINVAL;␊ |
| 213 | ␉␉␉return (-1);␊ |
| 214 | ␉␉}␊ |
| 215 | ␉␉if (ltest && (off_t)target > LONG_MAX) {␊ |
| 216 | errno = EOVERFLOW;␊ |
| 217 | ␉␉␉return (-1);␊ |
| 218 | ␉␉}␊ |
| 219 | ␉}␊ |
| 220 | ␊ |
| 221 | ␉if (!havepos && _ftello(fp, &curoff))␊ |
| 222 | ␉␉goto dumb;␊ |
| 223 | ␊ |
| 224 | ␉/*␊ |
| 225 | ␉ * (If the buffer was modified, we have to␊ |
| 226 | ␉ * skip this; see fgetln.c.)␊ |
| 227 | ␉ */␊ |
| 228 | ␉if (fp->_flags & __SMOD)␊ |
| 229 | ␉␉goto abspos;␊ |
| 230 | ␊ |
| 231 | ␉/*␊ |
| 232 | ␉ * Compute the number of bytes in the input buffer (pretending␊ |
| 233 | ␉ * that any ungetc() input has been discarded). Adjust current␊ |
| 234 | ␉ * offset backwards by this count so that it represents the␊ |
| 235 | ␉ * file offset for the first byte in the current input buffer.␊ |
| 236 | ␉ */␊ |
| 237 | ␉if (HASUB(fp)) {␊ |
| 238 | ␉␉curoff += fp->_r;␉/* kill off ungetc */␊ |
| 239 | ␉␉n = fp->_up - fp->_bf._base;␊ |
| 240 | ␉␉curoff -= n;␊ |
| 241 | ␉␉n += fp->_ur;␊ |
| 242 | ␉} else {␊ |
| 243 | ␉␉n = fp->_p - fp->_bf._base;␊ |
| 244 | ␉␉curoff -= n;␊ |
| 245 | ␉␉n += fp->_r;␊ |
| 246 | ␉}␊ |
| 247 | ␊ |
| 248 | ␉/*␊ |
| 249 | ␉ * If the target offset is within the current buffer,␊ |
| 250 | ␉ * simply adjust the pointers, clear EOF, undo ungetc(),␊ |
| 251 | ␉ * and return.␊ |
| 252 | ␉ */␊ |
| 253 | ␉if (target >= curoff && target < curoff + n) {␊ |
| 254 | ␉␉size_t o = target - curoff;␊ |
| 255 | ␊ |
| 256 | ␉␉fp->_p = fp->_bf._base + o;␊ |
| 257 | ␉␉fp->_r = n - o;␊ |
| 258 | ␉␉if (HASUB(fp))␊ |
| 259 | ␉␉␉FREEUB(fp);␊ |
| 260 | ␉␉fp->_flags &= ~__SEOF;␊ |
| 261 | ␉␉memset(&fp->_mbstate, 0, sizeof(mbstate_t));␊ |
| 262 | ␉␉return (0);␊ |
| 263 | ␉}␊ |
| 264 | ␊ |
| 265 | abspos:␊ |
| 266 | ␉/*␊ |
| 267 | ␉ * The place we want to get to is not within the current buffer,␊ |
| 268 | ␉ * but we can still be kind to the kernel copyout mechanism.␊ |
| 269 | ␉ * By aligning the file offset to a block boundary, we can let␊ |
| 270 | ␉ * the kernel use the VM hardware to map pages instead of␊ |
| 271 | ␉ * copying bytes laboriously. Using a block boundary also␊ |
| 272 | ␉ * ensures that we only read one block, rather than two.␊ |
| 273 | ␉ */␊ |
| 274 | ␉curoff = target & ~(fp->_blksize - 1);␊ |
| 275 | ␉if (_sseek(fp, curoff, SEEK_SET) == POS_ERR)␊ |
| 276 | ␉␉goto dumb;␊ |
| 277 | ␉fp->_r = 0;␊ |
| 278 | ␉fp->_p = fp->_bf._base;␊ |
| 279 | ␉if (HASUB(fp))␊ |
| 280 | ␉␉FREEUB(fp);␊ |
| 281 | ␉n = target - curoff;␊ |
| 282 | ␉if (n) {␊ |
| 283 | ␉␉if (__srefill(fp) || fp->_r < n)␊ |
| 284 | ␉␉␉goto dumb;␊ |
| 285 | ␉␉fp->_p += n;␊ |
| 286 | ␉␉fp->_r -= n;␊ |
| 287 | ␉}␊ |
| 288 | ␉fp->_flags &= ~__SEOF;␊ |
| 289 | ␉memset(&fp->_mbstate, 0, sizeof(mbstate_t));␊ |
| 290 | ␉return (0);␊ |
| 291 | ␊ |
| 292 | ␉/*␊ |
| 293 | ␉ * We get here if we cannot optimise the seek ... just␊ |
| 294 | ␉ * do it. Allow the seek function to change fp->_bf._base.␊ |
| 295 | ␉ */␊ |
| 296 | dumb:␊ |
| 297 | ␉if (__sflush(fp) ||␊ |
| 298 | ␉ (ret = _sseek(fp, (fpos_t)offset, whence)) == POS_ERR)␊ |
| 299 | ␉␉return (-1);␊ |
| 300 | ␉if (ltest && ret > LONG_MAX) {␊ |
| 301 | ␉␉fp->_flags |= __SERR;␊ |
| 302 | errno = EOVERFLOW;␊ |
| 303 | ␉␉return (-1);␊ |
| 304 | ␉}␊ |
| 305 | ␉/* success: clear EOF indicator and discard ungetc() data */␊ |
| 306 | ␉if (HASUB(fp))␊ |
| 307 | ␉␉FREEUB(fp);␊ |
| 308 | ␉fp->_p = fp->_bf._base;␊ |
| 309 | ␉fp->_r = 0;␊ |
| 310 | ␉/* fp->_w = 0; */␉/* unnecessary (I think...) */␊ |
| 311 | ␉fp->_flags &= ~__SEOF;␊ |
| 312 | ␉memset(&fp->_mbstate, 0, sizeof(mbstate_t));␊ |
| 313 | ␉return (0);␊ |
| 314 | }␊ |
| 315 | |
