StdLib/LibC/Stdio/fseeko.c

   1 /*
   2     Copyright (c) 2010 - 2011, Intel Corporation. All rights reserved.<BR>
   3     This program and the accompanying materials are licensed and made available
   4     under the terms and conditions of the BSD License that accompanies this
   5     distribution.  The full text of the license may be found at
   6     http://opensource.org/licenses/bsd-license.
   7
   8     THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
   9     WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  10
  11  * Copyright (c) 1990, 1993
  12  *  The Regents of the University of California.  All rights reserved.
  13  *
  14  * This code is derived from software contributed to Berkeley by
  15  * Chris Torek.
  16  *
  17  * Redistribution and use in source and binary forms, with or without
  18  * modification, are permitted provided that the following conditions
  19  * are met:
  20  * 1. Redistributions of source code must retain the above copyright
  21  *    notice, this list of conditions and the following disclaimer.
  22  * 2. Redistributions in binary form must reproduce the above copyright
  23  *    notice, this list of conditions and the following disclaimer in the
  24  *    documentation and/or other materials provided with the distribution.
  25  * 3. Neither the name of the University nor the names of its contributors
  26  *    may be used to endorse or promote products derived from this software
  27  *    without specific prior written permission.
  28  *
  29  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  30  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  31  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  32  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  33  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  34  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  35  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  36  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  37  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  38  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  39  * SUCH DAMAGE.
  40
  41     NetBSD: fseeko.c,v 1.5 2005/03/04 16:04:58 dsl Exp
  42  */
  43 //#include <Uefi.h>               // REMOVE, For DEBUG only
  44 //#include <Library/UefiLib.h>    // REMOVE, For DEBUG only
  45
  46 #include  <LibConfig.h>
  47 #include <sys/EfiCdefs.h>
  48
  49 #include "namespace.h"
  50 #include <sys/types.h>
  51 #include <sys/stat.h>
  52
  53 #include <assert.h>
  54 #include <errno.h>
  55 #include <fcntl.h>
  56 #include <stdio.h>
  57 #include <stdlib.h>
  58 #include "reentrant.h"
  59 #include "local.h"
  60
  61 #ifdef __weak_alias
  62 __weak_alias(fseeko, _fseeko)
  63 #endif
  64
  65 #define POS_ERR (-(fpos_t)1)
  66
  67 /*
  68  * Seek the given file to the given offset.
  69  * `Whence' must be one of the three SEEK_* macros.
  70  */
  71 int
  72 fseeko(FILE *fp, off_t offset, int whence)
  73 {
  74   fpos_t (*seekfn)(void *, fpos_t, int);
  75   fpos_t target, curoff;
  76   size_t n;
  77   struct stat st;
  78   int havepos;
  79
  80   _DIAGASSERT(fp != NULL);
  81   if(fp == NULL) {
  82     errno = EINVAL;
  83     return -1;
  84   }
  85
  86 #ifdef __GNUC__
  87   /* This outrageous construct just to shut up a GCC warning. */
  88   (void) &curoff;
  89 #endif
  90
  91   /* make sure stdio is set up */
  92   if (!__sdidinit)
  93     __sinit();
  94
  95 //Print(L"%a( %d, %Ld, %d)\n", __func__, fp->_file, offset, whence);
  96   FLOCKFILE(fp);
  97
  98   /*
  99    * Have to be able to seek.
 100    */
 101   if ((seekfn = fp->_seek) == NULL) {
 102     errno = ESPIPE;     /* historic practice */
 103     FUNLOCKFILE(fp);
 104 //Print(L"%a: %d\n", __func__, __LINE__);
 105     return (-1);
 106   }
 107
 108   /*
 109    * Change any SEEK_CUR to SEEK_SET, and check `whence' argument.
 110    * After this, whence is either SEEK_SET or SEEK_END.
 111    */
 112   switch (whence) {
 113
 114   case SEEK_CUR:
 115     /*
 116      * In order to seek relative to the current stream offset,
 117      * we have to first find the current stream offset a la
 118      * ftell (see ftell for details).
 119      */
 120     __sflush(fp); /* may adjust seek offset on append stream */
 121     if (fp->_flags & __SOFF)
 122       curoff = fp->_offset;
 123     else {
 124       curoff = (*seekfn)(fp->_cookie, (fpos_t)0, SEEK_CUR);
 125       if (curoff == POS_ERR) {
 126         FUNLOCKFILE(fp);
 127 //Print(L"%a: %d\n", __func__, __LINE__);
 128         return (-1);
 129       }
 130     }
 131     if (fp->_flags & __SRD) {
 132       curoff -= fp->_r;
 133       if (HASUB(fp))
 134         curoff -= fp->_ur;
 135     } else if (fp->_flags & __SWR && fp->_p != NULL)
 136       curoff += fp->_p - fp->_bf._base;
 137
 138     offset += curoff;
 139     whence = SEEK_SET;
 140     havepos = 1;
 141     break;
 142
 143   case SEEK_SET:
 144   case SEEK_END:
 145     curoff = 0;   /* XXX just to keep gcc quiet */
 146     havepos = 0;
 147     break;
 148
 149   default:
 150     errno = EINVAL;
 151     FUNLOCKFILE(fp);
 152 //Print(L"%a: %d\n", __func__, __LINE__);
 153     return (-1);
 154   }
 155
 156   /*
 157    * Can only optimise if:
 158    *  reading (and not reading-and-writing);
 159    *  not unbuffered; and
 160    *  this is a `regular' Unix file (and hence seekfn==__sseek).
 161    * We must check __NBF first, because it is possible to have __NBF
 162    * and __SOPT both set.
 163    */
 164   if (fp->_bf._base == NULL)
 165     __smakebuf(fp);
 166   if (fp->_flags & (__SWR | __SRW | __SNBF | __SNPT))
 167     goto dumb;
 168   if ((fp->_flags & __SOPT) == 0) {
 169     if (seekfn != __sseek ||
 170         fp->_file < 0 || fstat(fp->_file, &st) ||
 171         !S_ISREG(st.st_mode)) {
 172       fp->_flags |= __SNPT;
 173       goto dumb;
 174     }
 175     fp->_blksize = st.st_blksize;
 176     fp->_flags |= __SOPT;
 177   }
 178
 179   /*
 180    * We are reading; we can try to optimise.
 181    * Figure out where we are going and where we are now.
 182    */
 183   if (whence == SEEK_SET)
 184     target = offset;
 185   else {
 186     if (fstat(fp->_file, &st))
 187     {
 188 //Print(L"%a: %d\n", __func__, __LINE__);
 189       goto dumb;
 190     }
 191     target = st.st_size + offset;
 192   }
 193
 194   if (!havepos) {
 195     if (fp->_flags & __SOFF)
 196       curoff = fp->_offset;
 197     else {
 198       curoff = (*seekfn)(fp->_cookie, (fpos_t)0, SEEK_CUR);
 199       if (curoff == POS_ERR)
 200       {
 201 //Print(L"%a: %d\n", __func__, __LINE__);
 202         goto dumb;
 203       }
 204     }
 205     curoff -= fp->_r;
 206     if (HASUB(fp))
 207       curoff -= fp->_ur;
 208   }
 209
 210   /*
 211    * Compute the number of bytes in the input buffer (pretending
 212    * that any ungetc() input has been discarded).  Adjust current
 213    * offset backwards by this count so that it represents the
 214    * file offset for the first byte in the current input buffer.
 215    */
 216   if (HASUB(fp)) {
 217     curoff += fp->_r; /* kill off ungetc */
 218     n = fp->_up - fp->_bf._base;
 219     curoff -= n;
 220     n += fp->_ur;
 221   } else {
 222     n = fp->_p - fp->_bf._base;
 223     curoff -= n;
 224     n += fp->_r;
 225   }
 226
 227   /*
 228    * If the target offset is within the current buffer,
 229    * simply adjust the pointers, clear EOF, undo ungetc(),
 230    * and return.  (If the buffer was modified, we have to
 231    * skip this; see fgetln.c.)
 232    */
 233   if ((fp->_flags & __SMOD) == 0 &&
 234       target >= curoff && target < (fpos_t)(curoff + n)) {
 235     int o = (int)(target - curoff);
 236
 237     fp->_p = fp->_bf._base + o;
 238     fp->_r = (int)(n - o);
 239     if (HASUB(fp))
 240       FREEUB(fp);
 241     WCIO_FREE(fp);    /* Should this really be unconditional??? */
 242     fp->_flags &= ~__SEOF;
 243     FUNLOCKFILE(fp);
 244     return (0);
 245   }
 246
 247   /*
 248    * The place we want to get to is not within the current buffer,
 249    * but we can still be kind to the kernel copyout mechanism.
 250    * By aligning the file offset to a block boundary, we can let
 251    * the kernel use the VM hardware to map pages instead of
 252    * copying bytes laboriously.  Using a block boundary also
 253    * ensures that we only read one block, rather than two.
 254    */
 255   curoff = target & ~(fp->_blksize - 1);
 256   if ((*seekfn)(fp->_cookie, curoff, SEEK_SET) == POS_ERR)
 257   {
 258 //Print(L"%a: %d\n", __func__, __LINE__);
 259     goto dumb;
 260   }
 261   fp->_r = 0;
 262   fp->_p = fp->_bf._base;
 263   if (HASUB(fp))
 264     FREEUB(fp);
 265   WCIO_FREE(fp);    /* Should this really be unconditional??? */
 266   fp->_flags &= ~__SEOF;
 267   n = (int)(target - curoff);
 268   if (n) {
 269     if (__srefill(fp) || fp->_r < (int)n)
 270     {
 271 //Print(L"%a: %d\n", __func__, __LINE__);
 272       goto dumb;
 273     }
 274     fp->_p += n;
 275     fp->_r -= (int)n;
 276   }
 277   FUNLOCKFILE(fp);
 278   return (0);
 279
 280   /*
 281    * We get here if we cannot optimise the seek ... just
 282    * do it.  Allow the seek function to change fp->_bf._base.
 283    */
 284 dumb:
 285 //Print(L"%a: %d\n", __func__, __LINE__);
 286   if (__sflush(fp) ||
 287       (*seekfn)(fp->_cookie, (fpos_t)offset, whence) == POS_ERR) {
 288     FUNLOCKFILE(fp);
 289 //Print(L"%a: %d\n", __func__, __LINE__);
 290     return (-1);
 291   }
 292   /* success: clear EOF indicator and discard ungetc() data */
 293   if (HASUB(fp))
 294     FREEUB(fp);
 295   WCIO_FREE(fp);    /* Should this really be unconditional??? */
 296   fp->_p = fp->_bf._base;
 297   fp->_r = 0;
 298   fp->_w = 0;
 299   fp->_flags &= ~__SEOF;
 300   FUNLOCKFILE(fp);
 301 //Print(L"%a: %d\n", __func__, __LINE__);
 302   return (0);
 303 }