1 /***********************************************************************
2 * *
3 * This software is part of the ast package *
4 * Copyright (c) 1985-2011 AT&T Intellectual Property *
5 * and is licensed under the *
6 * Eclipse Public License, Version 1.0 *
7 * by AT&T Intellectual Property *
8 * *
9 * A copy of the License is available at *
10 * http://www.eclipse.org/org/documents/epl-v10.html *
11 * (with md5 checksum b35adb5213ca9657e911e9befb180842) *
12 * *
13 * Information and Software Systems Research *
14 * AT&T Research *
15 * Florham Park NJ *
16 * *
17 * Glenn Fowler <gsf@research.att.com> *
18 * David Korn <dgk@research.att.com> *
19 * Phong Vo <kpv@research.att.com> *
20 * *
21 ***********************************************************************/
22 #include "sfhdr.h"
23
24 /* Seek function that knows discipline
25 **
26 ** Written by Kiem-Phong Vo.
27 */
28 #if __STD_C
sfsk(Sfio_t * f,Sfoff_t addr,int type,Sfdisc_t * disc)29 Sfoff_t sfsk(Sfio_t* f, Sfoff_t addr, int type, Sfdisc_t* disc)
30 #else
31 Sfoff_t sfsk(f,addr,type,disc)
32 Sfio_t* f;
33 Sfoff_t addr;
34 int type;
35 Sfdisc_t* disc;
36 #endif
37 {
38 Sfoff_t p;
39 reg Sfdisc_t* dc;
40 reg ssize_t s;
41 reg int local, mode;
42 SFMTXDECL(f);
43
44 SFMTXENTER(f, (Sfoff_t)(-1));
45
46 GETLOCAL(f,local);
47 if(!local && !(f->bits&SF_DCDOWN))
48 { if((mode = f->mode&SF_RDWR) != (int)f->mode && _sfmode(f,mode,0) < 0)
49 SFMTXRETURN(f, (Sfoff_t)(-1));
50 if(SFSYNC(f) < 0)
51 SFMTXRETURN(f, (Sfoff_t)(-1));
52 #ifdef MAP_TYPE
53 if(f->mode == SF_READ && (f->bits&SF_MMAP) && f->data)
54 { SFMUNMAP(f, f->data, f->endb-f->data);
55 f->data = NIL(uchar*);
56 }
57 #endif
58 f->next = f->endb = f->endr = f->endw = f->data;
59 }
60
61 if((type &= (SEEK_SET|SEEK_CUR|SEEK_END)) > SEEK_END)
62 SFMTXRETURN(f, (Sfoff_t)(-1));
63
64 for(;;)
65 { dc = disc;
66 if(f->flags&SF_STRING)
67 { SFSTRSIZE(f);
68 if(type == SEEK_SET)
69 s = (ssize_t)addr;
70 else if(type == SEEK_CUR)
71 s = (ssize_t)(addr + f->here);
72 else s = (ssize_t)(addr + f->extent);
73 }
74 else
75 { SFDISC(f,dc,seekf);
76 if(dc && dc->seekf)
77 { SFDCSK(f,addr,type,dc,p);
78 }
79 else
80 { p = syslseekf(f->file,(sfoff_t)addr,type);
81 }
82 if(p >= 0)
83 SFMTXRETURN(f,p);
84 s = -1;
85 }
86
87 if(local)
88 SETLOCAL(f);
89 switch(_sfexcept(f,SF_SEEK,s,dc))
90 {
91 case SF_EDISC:
92 case SF_ECONT:
93 if(f->flags&SF_STRING)
94 SFMTXRETURN(f, (Sfoff_t)s);
95 goto do_continue;
96 default:
97 SFMTXRETURN(f, (Sfoff_t)(-1));
98 }
99
100 do_continue:
101 for(dc = f->disc; dc; dc = dc->disc)
102 if(dc == disc)
103 break;
104 disc = dc;
105 }
106 }
107