14887Schin /***********************************************************************
24887Schin * *
34887Schin * This software is part of the ast package *
4*12068SRoger.Faulkner@Oracle.COM * Copyright (c) 1985-2010 AT&T Intellectual Property *
54887Schin * and is licensed under the *
64887Schin * Common Public License, Version 1.0 *
78462SApril.Chin@Sun.COM * by AT&T Intellectual Property *
84887Schin * *
94887Schin * A copy of the License is available at *
104887Schin * http://www.opensource.org/licenses/cpl1.0.txt *
114887Schin * (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9) *
124887Schin * *
134887Schin * Information and Software Systems Research *
144887Schin * AT&T Research *
154887Schin * Florham Park NJ *
164887Schin * *
174887Schin * Glenn Fowler <gsf@research.att.com> *
184887Schin * David Korn <dgk@research.att.com> *
194887Schin * Phong Vo <kpv@research.att.com> *
204887Schin * *
214887Schin ***********************************************************************/
224887Schin #include "sfdchdr.h"
234887Schin
244887Schin
254887Schin /* Discipline to treat a contiguous segment of a stream as a stream
264887Schin ** in its own right. The hard part in all this is to allow multiple
274887Schin ** segments of the stream to be used as substreams at the same time.
284887Schin **
294887Schin ** Written by David G. Korn and Kiem-Phong Vo (03/18/1998)
304887Schin */
314887Schin
324887Schin typedef struct _subfile_s
334887Schin {
344887Schin Sfdisc_t disc; /* sfio discipline */
354887Schin Sfio_t* parent; /* parent stream */
364887Schin Sfoff_t offset; /* starting offset */
374887Schin Sfoff_t extent; /* size wanted */
384887Schin Sfoff_t here; /* current seek location */
394887Schin } Subfile_t;
404887Schin
414887Schin #if __STD_C
streamio(Sfio_t * f,Void_t * buf,size_t n,Sfdisc_t * disc,int type)424887Schin static ssize_t streamio(Sfio_t* f, Void_t* buf, size_t n, Sfdisc_t* disc, int type)
434887Schin #else
444887Schin static ssize_t streamio(f, buf, n, disc, type)
454887Schin Sfio_t* f;
464887Schin Void_t* buf;
474887Schin size_t n;
484887Schin Sfdisc_t* disc;
494887Schin int type;
504887Schin #endif
514887Schin {
524887Schin reg Subfile_t *su;
534887Schin reg Sfoff_t here, parent;
544887Schin reg ssize_t io;
554887Schin
564887Schin su = (Subfile_t*)disc;
574887Schin
584887Schin /* read just what we need */
594887Schin if(su->extent >= 0 && (ssize_t)n > (io = (ssize_t)(su->extent - su->here)) )
604887Schin n = io;
614887Schin if(n <= 0)
624887Schin return n;
634887Schin
644887Schin /* save current location in parent stream */
654887Schin parent = sfsk(f,(Sfoff_t)0,SEEK_CUR,disc);
664887Schin
674887Schin /* read data */
684887Schin here = su->here + su->offset;
694887Schin if(sfsk(f,here,SEEK_SET,disc) != here)
704887Schin io = 0;
714887Schin else
724887Schin { if(type == SF_WRITE)
734887Schin io = sfwr(f,buf,n,disc);
744887Schin else io = sfrd(f,buf,n,disc);
754887Schin if(io > 0)
764887Schin su->here += io;
774887Schin }
784887Schin
794887Schin /* restore parent current position */
804887Schin sfsk(f,parent,SEEK_SET,disc);
814887Schin
824887Schin return io;
834887Schin }
844887Schin
854887Schin #if __STD_C
streamwrite(Sfio_t * f,const Void_t * buf,size_t n,Sfdisc_t * disc)864887Schin static ssize_t streamwrite(Sfio_t* f, const Void_t* buf, size_t n, Sfdisc_t* disc)
874887Schin #else
884887Schin static ssize_t streamwrite(f, buf, n, disc)
894887Schin Sfio_t* f;
904887Schin Void_t* buf;
914887Schin size_t n;
924887Schin Sfdisc_t* disc;
934887Schin #endif
944887Schin {
954887Schin return streamio(f,(Void_t*)buf,n,disc,SF_WRITE);
964887Schin }
974887Schin
984887Schin #if __STD_C
streamread(Sfio_t * f,Void_t * buf,size_t n,Sfdisc_t * disc)994887Schin static ssize_t streamread(Sfio_t* f, Void_t* buf, size_t n, Sfdisc_t* disc)
1004887Schin #else
1014887Schin static ssize_t streamread(f, buf, n, disc)
1024887Schin Sfio_t* f;
1034887Schin Void_t* buf;
1044887Schin size_t n;
1054887Schin Sfdisc_t* disc;
1064887Schin #endif
1074887Schin {
1084887Schin return streamio(f,buf,n,disc,SF_READ);
1094887Schin }
1104887Schin
1114887Schin #if __STD_C
streamseek(Sfio_t * f,Sfoff_t pos,int type,Sfdisc_t * disc)1124887Schin static Sfoff_t streamseek(Sfio_t* f, Sfoff_t pos, int type, Sfdisc_t* disc)
1134887Schin #else
1144887Schin static Sfoff_t streamseek(f, pos, type, disc)
1154887Schin Sfio_t* f;
1164887Schin Sfoff_t pos;
1174887Schin int type;
1184887Schin Sfdisc_t* disc;
1194887Schin #endif
1204887Schin {
1214887Schin reg Subfile_t* su;
1224887Schin reg Sfoff_t here, parent;
1234887Schin
1244887Schin su = (Subfile_t*)disc;
1254887Schin
1264887Schin switch(type)
1274887Schin {
1284887Schin case SEEK_SET:
1294887Schin here = 0;
1304887Schin break;
1314887Schin case SEEK_CUR:
1324887Schin here = su->here;
1334887Schin break;
1344887Schin case SEEK_END:
1354887Schin if(su->extent >= 0)
1364887Schin here = su->extent;
1374887Schin else
1384887Schin { parent = sfsk(f,(Sfoff_t)0,SEEK_CUR,disc);
1394887Schin if((here = sfsk(f,(Sfoff_t)0,SEEK_END,disc)) < 0)
1404887Schin return -1;
1414887Schin else here -= su->offset;
1424887Schin sfsk(f,parent,SEEK_SET,disc);
1434887Schin }
1444887Schin break;
1454887Schin default:
1464887Schin return -1;
1474887Schin }
1484887Schin
1494887Schin pos += here;
1504887Schin if(pos < 0 || (su->extent >= 0 && pos >= su->extent))
1514887Schin return -1;
1524887Schin
1534887Schin return (su->here = pos);
1544887Schin }
1554887Schin
1564887Schin #if __STD_C
streamexcept(Sfio_t * f,int type,Void_t * data,Sfdisc_t * disc)1574887Schin static int streamexcept(Sfio_t* f, int type, Void_t* data, Sfdisc_t* disc)
1584887Schin #else
1594887Schin static int streamexcept(f, type, data, disc)
1604887Schin Sfio_t* f;
1614887Schin int type;
1624887Schin Void_t* data;
1634887Schin Sfdisc_t* disc;
1644887Schin #endif
1654887Schin {
1664887Schin if(type == SF_FINAL || type == SF_DPOP)
1674887Schin free(disc);
1684887Schin return 0;
1694887Schin }
1704887Schin
1714887Schin #if __STD_C
sfdcsubstream(Sfio_t * f,Sfio_t * parent,Sfoff_t offset,Sfoff_t extent)1724887Schin Sfio_t* sfdcsubstream(Sfio_t* f, Sfio_t* parent, Sfoff_t offset, Sfoff_t extent)
1734887Schin #else
1744887Schin Sfio_t* sfdcsubstream(f, parent, offset, extent)
1754887Schin Sfio_t* f; /* stream */
1764887Schin Sfio_t* parent; /* parent stream */
1774887Schin Sfoff_t offset; /* offset in f */
1784887Schin Sfoff_t extent; /* desired size */
1794887Schin #endif
1804887Schin {
1814887Schin reg Sfio_t* sp;
1824887Schin reg Subfile_t* su;
1834887Schin reg Sfoff_t here;
1844887Schin
1854887Schin /* establish that we can seek to offset */
1864887Schin if((here = sfseek(parent,(Sfoff_t)0,SEEK_CUR)) < 0 || sfseek(parent,offset,SEEK_SET) < 0)
1874887Schin return 0;
1884887Schin else sfseek(parent,here,SEEK_SET);
1894887Schin sfpurge(parent);
1904887Schin
1914887Schin if (!(sp = f) && !(sp = sfnew(NIL(Sfio_t*), NIL(Void_t*), (size_t)SF_UNBOUND, dup(sffileno(parent)), parent->flags)))
1924887Schin return 0;
1934887Schin
1944887Schin if(!(su = (Subfile_t*)malloc(sizeof(Subfile_t))))
1954887Schin { if(sp != f)
1964887Schin sfclose(sp);
1974887Schin return 0;
1984887Schin }
1994887Schin memset(su, 0, sizeof(*su));
2004887Schin
2014887Schin su->disc.readf = streamread;
2024887Schin su->disc.writef = streamwrite;
2034887Schin su->disc.seekf = streamseek;
2044887Schin su->disc.exceptf = streamexcept;
2054887Schin su->parent = parent;
2064887Schin su->offset = offset;
2074887Schin su->extent = extent;
2084887Schin
2094887Schin if(sfdisc(sp, (Sfdisc_t*)su) != (Sfdisc_t*)su)
2104887Schin { free(su);
2114887Schin if(sp != f)
2124887Schin sfclose(sp);
2134887Schin return 0;
2144887Schin }
2154887Schin
2164887Schin return sp;
2174887Schin }
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