scoutos / prex-0.9.0 / usr / lib / libc / stdio / fseek.c @ 03e9c04a
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/*-
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* Copyright (c) 1990, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Chris Torek.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/types.h> |
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#include <sys/stat.h> |
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#include <fcntl.h> |
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#include <stdio.h> |
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#include <stdlib.h> |
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#include <errno.h> |
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#include "local.h" |
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#define POS_ERR (-(fpos_t)1) |
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/*
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* Seek the given file to the given offset.
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* `Whence' must be one of the three SEEK_* macros.
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*/
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int
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fseek(fp, offset, whence) |
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FILE *fp; |
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long offset;
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int whence;
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{ |
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fpos_t curoff; |
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int havepos;
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/* make sure stdio is set up */
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if (!__sdidinit)
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__sinit(); |
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/*
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* Change any SEEK_CUR to SEEK_SET, and check `whence' argument.
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* After this, whence is either SEEK_SET or SEEK_END.
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*/
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switch (whence) {
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case SEEK_CUR:
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/*
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* In order to seek relative to the current stream offset,
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* we have to first find the current stream offset a la
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* ftell (see ftell for details).
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*/
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curoff = __sseek(fp, (fpos_t)0, SEEK_CUR);
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if (curoff == POS_ERR)
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return (EOF); |
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if (fp->_flags & __SRD) {
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curoff -= fp->_r; |
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if (HASUB(fp))
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curoff -= fp->_ur; |
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} else if (fp->_flags & __SWR && fp->_p != NULL) |
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curoff += fp->_p - fp->_bf._base; |
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offset += curoff; |
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whence = SEEK_SET; |
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havepos = 1;
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break;
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case SEEK_SET:
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case SEEK_END:
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curoff = 0; /* XXX just to keep gcc quiet */ |
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havepos = 0;
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break;
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default:
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errno = EINVAL; |
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return (EOF); |
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} |
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if (fp->_bf._base == NULL) |
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__smakebuf(fp); |
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if (__sflush(fp) ||
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__sseek(fp, (fpos_t)offset, whence) == POS_ERR) { |
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return (EOF); |
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} |
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/* success: clear EOF indicator and discard ungetc() data */
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if (HASUB(fp))
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FREEUB(fp); |
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fp->_p = fp->_bf._base; |
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fp->_r = 0;
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/* fp->_w = 0; */ /* unnecessary (I think...) */ |
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fp->_flags &= ~__SEOF; |
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return (0); |
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} |