1N/A/***********************************************************************
1N/A* *
1N/A* This software is part of the ast package *
1N/A* Copyright (c) 1985-2011 AT&T Intellectual Property *
1N/A* and is licensed under the *
1N/A* Common Public License, Version 1.0 *
1N/A* by AT&T Intellectual Property *
1N/A* *
1N/A* A copy of the License is available at *
1N/A* http://www.opensource.org/licenses/cpl1.0.txt *
1N/A* (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9) *
1N/A* *
1N/A* Information and Software Systems Research *
1N/A* AT&T Research *
1N/A* Florham Park NJ *
1N/A* *
1N/A* Glenn Fowler <gsf@research.att.com> *
1N/A* David Korn <dgk@research.att.com> *
1N/A* Phong Vo <kpv@research.att.com> *
1N/A* *
1N/A***********************************************************************/
1N/A#include "sfhdr.h"
1N/A
1N/A/* Set the IO pointer to a specific location in the stream
1N/A**
1N/A** Written by Kiem-Phong Vo.
1N/A*/
1N/A
1N/A#if __STD_C
1N/Astatic void newpos(Sfio_t* f, Sfoff_t p)
1N/A#else
1N/Astatic void newpos(f, p)
1N/ASfio_t* f;
1N/ASfoff_t p;
1N/A#endif
1N/A{
1N/A#ifdef MAP_TYPE
1N/A if((f->bits&SF_MMAP) && f->data)
1N/A { SFMUNMAP(f, f->data, f->endb-f->data);
1N/A f->data = NIL(uchar*);
1N/A }
1N/A#endif
1N/A f->next = f->endr = f->endw = f->data;
1N/A f->endb = (f->mode&SF_WRITE) ? f->data+f->size : f->data;
1N/A if((f->here = p) < 0)
1N/A { f->extent = -1;
1N/A f->here = 0;
1N/A }
1N/A}
1N/A
1N/A#if __STD_C
1N/ASfoff_t sfseek(Sfio_t* f, Sfoff_t p, int type)
1N/A#else
1N/ASfoff_t sfseek(f,p,type)
1N/ASfio_t* f; /* seek to a new location in this stream */
1N/ASfoff_t p; /* place to seek to */
1N/Aint type; /* 0: from org, 1: from here, 2: from end */
1N/A#endif
1N/A{
1N/A Sfoff_t r, s;
1N/A int mode, local, hardseek, mustsync;
1N/A SFMTXDECL(f);
1N/A
1N/A SFMTXENTER(f, (Sfoff_t)(-1));
1N/A
1N/A GETLOCAL(f,local);
1N/A
1N/A hardseek = (type|f->flags)&(SF_SHARE|SF_PUBLIC);
1N/A
1N/A if(hardseek && f->mode == (SF_READ|SF_SYNCED) )
1N/A { newpos(f,f->here);
1N/A f->mode = SF_READ;
1N/A }
1N/A
1N/A /* set and initialize the stream to a definite mode */
1N/A if((int)SFMODE(f,local) != (mode = f->mode&SF_RDWR))
1N/A { int flags = f->flags;
1N/A
1N/A if(hardseek&SF_PUBLIC) /* seek ptr must follow file descriptor */
1N/A f->flags |= SF_SHARE|SF_PUBLIC;
1N/A mode = _sfmode(f,mode,local);
1N/A if(hardseek&SF_PUBLIC)
1N/A f->flags = flags;
1N/A
1N/A if(mode < 0)
1N/A SFMTXRETURN(f, (Sfoff_t)(-1));
1N/A }
1N/A
1N/A mustsync = (type&SF_SHARE) && !(type&SF_PUBLIC) &&
1N/A (f->mode&SF_READ) && !(f->flags&SF_STRING);
1N/A
1N/A /* Xopen-compliant */
1N/A if((type &= (SEEK_SET|SEEK_CUR|SEEK_END)) != SEEK_SET &&
1N/A type != SEEK_CUR && type != SEEK_END )
1N/A { errno = EINVAL;
1N/A SFMTXRETURN(f, (Sfoff_t)(-1));
1N/A }
1N/A
1N/A if(f->extent < 0)
1N/A { /* let system call set errno */
1N/A (void)SFSK(f,(Sfoff_t)0,SEEK_CUR,f->disc);
1N/A SFMTXRETURN(f, (Sfoff_t)(-1));
1N/A }
1N/A
1N/A /* throw away ungetc data */
1N/A if(f->disc == _Sfudisc)
1N/A (void)sfclose((*_Sfstack)(f,NIL(Sfio_t*)));
1N/A
1N/A /* lock the stream for internal manipulations */
1N/A SFLOCK(f,local);
1N/A
1N/A /* clear error and eof bits */
1N/A f->flags &= ~(SF_EOF|SF_ERROR);
1N/A
1N/A while(f->flags&SF_STRING)
1N/A { SFSTRSIZE(f);
1N/A
1N/A if(type == SEEK_CUR)
1N/A r = p + (f->next - f->data);
1N/A else if(type == SEEK_END)
1N/A r = p + f->extent;
1N/A else r = p;
1N/A
1N/A if(r >= 0 && r <= f->size)
1N/A { p = r;
1N/A f->next = f->data+p;
1N/A f->here = p;
1N/A if(p > f->extent)
1N/A memclear((char*)(f->data+f->extent),(int)(p-f->extent));
1N/A goto done;
1N/A }
1N/A
1N/A /* check exception handler, note that this may pop stream */
1N/A if(SFSK(f,r,SEEK_SET,f->disc) != r)
1N/A { p = -1;
1N/A goto done;
1N/A }
1N/A else if(!(f->flags&SF_STRING))
1N/A { p = r;
1N/A goto done;
1N/A }
1N/A }
1N/A
1N/A if(f->mode&SF_WRITE)
1N/A { /* see if we can avoid flushing buffer */
1N/A if(!hardseek && type < SEEK_END && !(f->flags&SF_APPENDWR) )
1N/A { s = f->here + (f->next - f->data);
1N/A r = p + (type == SEEK_SET ? 0 : s);
1N/A if(r == s)
1N/A { p = r;
1N/A goto done;
1N/A }
1N/A }
1N/A
1N/A if(f->next > f->data && SFSYNC(f) < 0)
1N/A { p = -1;
1N/A goto done;
1N/A }
1N/A }
1N/A
1N/A if(type == SEEK_END || (f->mode&SF_WRITE) )
1N/A { if((hardseek&SF_PUBLIC) || type == SEEK_END)
1N/A p = SFSK(f, p, type, f->disc);
1N/A else
1N/A { r = p + (type == SEEK_CUR ? f->here : 0);
1N/A p = (hardseek || r != f->here) ? SFSK(f,r,SEEK_SET,f->disc) : r;
1N/A }
1N/A if(p >= 0)
1N/A newpos(f,p);
1N/A
1N/A goto done;
1N/A }
1N/A
1N/A /* if get here, must be a read stream */
1N/A s = f->here - (f->endb - f->next);
1N/A r = p + (type == SEEK_CUR ? s : 0);
1N/A if(r <= f->here && r >= (f->here - (f->endb-f->data)) )
1N/A { if((hardseek || (type == SEEK_CUR && p == 0)) )
1N/A { if((s = SFSK(f, (Sfoff_t)0, SEEK_CUR, f->disc)) == f->here ||
1N/A (s >= 0 && !(hardseek&SF_PUBLIC) &&
1N/A (s = SFSK(f, f->here, SEEK_SET, f->disc)) == f->here) )
1N/A goto near_done;
1N/A else if(s < 0)
1N/A { p = -1;
1N/A goto done;
1N/A }
1N/A else
1N/A { newpos(f,s);
1N/A hardseek = 0;
1N/A }
1N/A }
1N/A else
1N/A { near_done:
1N/A f->next = f->endb - (f->here - r);
1N/A p = r;
1N/A goto done;
1N/A }
1N/A }
1N/A
1N/A /* desired position */
1N/A if((p += type == SEEK_CUR ? s : 0) < 0)
1N/A goto done;
1N/A
1N/A#ifdef MAP_TYPE
1N/A if(f->bits&SF_MMAP)
1N/A { /* if mmap is not great, stop mmaping if moving around too much */
1N/A#if _mmap_worthy < 2
1N/A if((f->next - f->data) < ((f->endb - f->data)/4) )
1N/A { SFSETBUF(f,(Void_t*)f->tiny,(size_t)SF_UNBOUND);
1N/A hardseek = 1; /* this forces a hard seek below */
1N/A }
1N/A else
1N/A#endif
1N/A { /* for mmap, f->here can be virtual except for hardseek */
1N/A newpos(f,p);
1N/A if(!hardseek)
1N/A goto done;
1N/A }
1N/A }
1N/A#endif
1N/A
1N/A if(f->endb > f->next)
1N/A { /* reduce wastage in future buffer fillings */
1N/A f->iosz = (f->next - f->data) + (f->endb - f->next)/2;
1N/A f->iosz = ((f->iosz + f->blksz-1)/f->blksz)*f->blksz;
1N/A }
1N/A if(f->iosz >= f->size)
1N/A f->iosz = 0;
1N/A
1N/A /* buffer is now considered empty */
1N/A f->next = f->endr = f->endb = f->data;
1N/A
1N/A /* small backseeks often come in bunches, so seek back as far as possible */
1N/A if(p < f->lpos && f->size > f->blksz && (p + f->blksz) > s)
1N/A { if((r = s - f->size) < 0)
1N/A r = 0;
1N/A }
1N/A /* try to align buffer to block boundary to enhance I/O speed */
1N/A else if(f->blksz > 0 && f->size >= 2*f->blksz)
1N/A r = p - (p%f->blksz);
1N/A else
1N/A { r = p;
1N/A
1N/A /* seeking around and wasting data, be conservative */
1N/A if(f->iosz > 0 && (p > f->lpos || p < f->lpos-f->size) )
1N/A f->bits |= SF_JUSTSEEK;
1N/A }
1N/A
1N/A if((hardseek || r != f->here) && (f->here = SFSK(f,r,SEEK_SET,f->disc)) != r)
1N/A { if(r < p) /* now try to just get to p */
1N/A f->here = SFSK(f,p,SEEK_SET,f->disc);
1N/A if(f->here != p)
1N/A p = -1;
1N/A goto done;
1N/A }
1N/A
1N/A if(r < p) /* read to cover p */
1N/A { (void)SFRD(f, f->data, f->size, f->disc);
1N/A if(p <= f->here && p >= (f->here - (f->endb - f->data)) )
1N/A f->next = f->endb - (size_t)(f->here-p);
1N/A else /* recover from read failure by just seeking to p */
1N/A { f->next = f->endb = f->data;
1N/A if((f->here = SFSK(f,p,SEEK_SET,f->disc)) != p)
1N/A p = -1;
1N/A }
1N/A }
1N/A
1N/Adone :
1N/A if(f->here < 0) /* hasn't been the best of time */
1N/A { f->extent = -1;
1N/A f->here = 0;
1N/A }
1N/A
1N/A f->lpos = p;
1N/A
1N/A SFOPEN(f,local);
1N/A
1N/A if(mustsync)
1N/A sfsync(f);
1N/A SFMTXRETURN(f, p);
1N/A}