1da2e3ebdSchin /***********************************************************************
2da2e3ebdSchin * *
3da2e3ebdSchin * This software is part of the ast package *
4*3e14f97fSRoger A. Faulkner * Copyright (c) 1985-2010 AT&T Intellectual Property *
5da2e3ebdSchin * and is licensed under the *
6da2e3ebdSchin * Common Public License, Version 1.0 *
77c2fbfb3SApril Chin * by AT&T Intellectual Property *
8da2e3ebdSchin * *
9da2e3ebdSchin * A copy of the License is available at *
10da2e3ebdSchin * http://www.opensource.org/licenses/cpl1.0.txt *
11da2e3ebdSchin * (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9) *
12da2e3ebdSchin * *
13da2e3ebdSchin * Information and Software Systems Research *
14da2e3ebdSchin * AT&T Research *
15da2e3ebdSchin * Florham Park NJ *
16da2e3ebdSchin * *
17da2e3ebdSchin * Glenn Fowler <gsf@research.att.com> *
18da2e3ebdSchin * David Korn <dgk@research.att.com> *
19da2e3ebdSchin * Phong Vo <kpv@research.att.com> *
20da2e3ebdSchin * *
21da2e3ebdSchin ***********************************************************************/
22da2e3ebdSchin #include "sfdchdr.h"
23da2e3ebdSchin
24da2e3ebdSchin /* Discipline to make an unseekable read stream seekable
25da2e3ebdSchin **
26da2e3ebdSchin ** sfraise(f,SFSK_DISCARD,0) discards previous seek data
27da2e3ebdSchin ** but seeks from current offset on still allowed
28da2e3ebdSchin **
29da2e3ebdSchin ** Written by Kiem-Phong Vo, kpv@research.att.com, 03/18/1998.
30da2e3ebdSchin */
31da2e3ebdSchin
32da2e3ebdSchin typedef struct _skable_s
33da2e3ebdSchin { Sfdisc_t disc; /* sfio discipline */
34da2e3ebdSchin Sfio_t* shadow; /* to shadow data */
35da2e3ebdSchin Sfoff_t discard;/* sfseek(f,-1,SEEK_SET) discarded data */
36da2e3ebdSchin Sfoff_t extent; /* shadow extent */
37da2e3ebdSchin int eof; /* if eof has been reached */
38da2e3ebdSchin } Seek_t;
39da2e3ebdSchin
40da2e3ebdSchin #if __STD_C
skwrite(Sfio_t * f,const Void_t * buf,size_t n,Sfdisc_t * disc)41da2e3ebdSchin static ssize_t skwrite(Sfio_t* f, const Void_t* buf, size_t n, Sfdisc_t* disc)
42da2e3ebdSchin #else
43da2e3ebdSchin static ssize_t skwrite(f, buf, n, disc)
44da2e3ebdSchin Sfio_t* f; /* stream involved */
45da2e3ebdSchin Void_t* buf; /* buffer to read into */
46da2e3ebdSchin size_t n; /* number of bytes to read */
47da2e3ebdSchin Sfdisc_t* disc; /* discipline */
48da2e3ebdSchin #endif
49da2e3ebdSchin {
50da2e3ebdSchin return (ssize_t)(-1);
51da2e3ebdSchin }
52da2e3ebdSchin
53da2e3ebdSchin #if __STD_C
skread(Sfio_t * f,Void_t * buf,size_t n,Sfdisc_t * disc)54da2e3ebdSchin static ssize_t skread(Sfio_t* f, Void_t* buf, size_t n, Sfdisc_t* disc)
55da2e3ebdSchin #else
56da2e3ebdSchin static ssize_t skread(f, buf, n, disc)
57da2e3ebdSchin Sfio_t* f; /* stream involved */
58da2e3ebdSchin Void_t* buf; /* buffer to read into */
59da2e3ebdSchin size_t n; /* number of bytes to read */
60da2e3ebdSchin Sfdisc_t* disc; /* discipline */
61da2e3ebdSchin #endif
62da2e3ebdSchin {
63da2e3ebdSchin Seek_t* sk;
64da2e3ebdSchin Sfio_t* sf;
65da2e3ebdSchin Sfoff_t addr;
66da2e3ebdSchin ssize_t r, w, p;
67da2e3ebdSchin
68da2e3ebdSchin sk = (Seek_t*)disc;
69da2e3ebdSchin sf = sk->shadow;
70da2e3ebdSchin if(sk->eof)
71da2e3ebdSchin return sfread(sf,buf,n);
72da2e3ebdSchin
73da2e3ebdSchin addr = sfseek(sf,(Sfoff_t)0,SEEK_CUR);
74da2e3ebdSchin
75da2e3ebdSchin if(addr+n <= sk->extent)
76da2e3ebdSchin return sfread(sf,buf,n);
77da2e3ebdSchin
78da2e3ebdSchin if((r = (ssize_t)(sk->extent-addr)) > 0)
79da2e3ebdSchin { if((w = sfread(sf,buf,r)) != r)
80da2e3ebdSchin return w;
81da2e3ebdSchin buf = (char*)buf + r;
82da2e3ebdSchin n -= r;
83da2e3ebdSchin }
84da2e3ebdSchin
85da2e3ebdSchin /* do a raw read */
86da2e3ebdSchin if((w = sfrd(f,buf,n,disc)) <= 0)
87da2e3ebdSchin { sk->eof = 1;
88da2e3ebdSchin w = 0;
89da2e3ebdSchin }
90da2e3ebdSchin else
91da2e3ebdSchin {
92da2e3ebdSchin if((p = sfwrite(sf,buf,w)) != w)
93da2e3ebdSchin sk->eof = 1;
94da2e3ebdSchin if(p > 0)
95da2e3ebdSchin sk->extent += p;
96da2e3ebdSchin }
97da2e3ebdSchin
98da2e3ebdSchin return r+w;
99da2e3ebdSchin }
100da2e3ebdSchin
101da2e3ebdSchin #if __STD_C
skseek(Sfio_t * f,Sfoff_t addr,int type,Sfdisc_t * disc)102da2e3ebdSchin static Sfoff_t skseek(Sfio_t* f, Sfoff_t addr, int type, Sfdisc_t* disc)
103da2e3ebdSchin #else
104da2e3ebdSchin static Sfoff_t skseek(f, addr, type, disc)
105da2e3ebdSchin Sfio_t* f;
106da2e3ebdSchin Sfoff_t addr;
107da2e3ebdSchin int type;
108da2e3ebdSchin Sfdisc_t* disc;
109da2e3ebdSchin #endif
110da2e3ebdSchin {
111da2e3ebdSchin Seek_t* sk;
112da2e3ebdSchin Sfio_t* sf;
113da2e3ebdSchin char buf[SF_BUFSIZE];
114da2e3ebdSchin ssize_t r, w;
115da2e3ebdSchin
116da2e3ebdSchin sk = (Seek_t*)disc;
117da2e3ebdSchin sf = sk->shadow;
118da2e3ebdSchin
119da2e3ebdSchin switch (type)
120da2e3ebdSchin {
121da2e3ebdSchin case SEEK_SET:
122da2e3ebdSchin addr -= sk->discard;
123da2e3ebdSchin break;
124da2e3ebdSchin case SEEK_CUR:
125da2e3ebdSchin addr += sftell(sf);
126da2e3ebdSchin break;
127da2e3ebdSchin case SEEK_END:
128da2e3ebdSchin addr += sk->extent;
129da2e3ebdSchin break;
130da2e3ebdSchin default:
131da2e3ebdSchin return -1;
132da2e3ebdSchin }
133da2e3ebdSchin
134da2e3ebdSchin if(addr < 0)
135da2e3ebdSchin return (Sfoff_t)(-1);
136da2e3ebdSchin else if(addr > sk->extent)
137da2e3ebdSchin { if(sk->eof)
138da2e3ebdSchin return (Sfoff_t)(-1);
139da2e3ebdSchin
140da2e3ebdSchin /* read enough to reach the seek point */
141da2e3ebdSchin while(addr > sk->extent)
142da2e3ebdSchin { if(addr > sk->extent+sizeof(buf) )
143da2e3ebdSchin w = sizeof(buf);
144da2e3ebdSchin else w = (int)(addr-sk->extent);
145da2e3ebdSchin if((r = sfrd(f,buf,w,disc)) <= 0)
146da2e3ebdSchin w = r-1;
147da2e3ebdSchin else if((w = sfwrite(sf,buf,r)) > 0)
148da2e3ebdSchin sk->extent += w;
149da2e3ebdSchin if(w != r)
150da2e3ebdSchin { sk->eof = 1;
151da2e3ebdSchin break;
152da2e3ebdSchin }
153da2e3ebdSchin }
154da2e3ebdSchin
155da2e3ebdSchin if(addr > sk->extent)
156da2e3ebdSchin return (Sfoff_t)(-1);
157da2e3ebdSchin }
158da2e3ebdSchin
159da2e3ebdSchin return sfseek(sf,addr,SEEK_SET) + sk->discard;
160da2e3ebdSchin }
161da2e3ebdSchin
162da2e3ebdSchin /* on close, remove the discipline */
163da2e3ebdSchin #if __STD_C
skexcept(Sfio_t * f,int type,Void_t * data,Sfdisc_t * disc)164da2e3ebdSchin static int skexcept(Sfio_t* f, int type, Void_t* data, Sfdisc_t* disc)
165da2e3ebdSchin #else
166da2e3ebdSchin static int skexcept(f,type,data,disc)
167da2e3ebdSchin Sfio_t* f;
168da2e3ebdSchin int type;
169da2e3ebdSchin Void_t* data;
170da2e3ebdSchin Sfdisc_t* disc;
171da2e3ebdSchin #endif
172da2e3ebdSchin {
173da2e3ebdSchin Seek_t* sk;
174da2e3ebdSchin
175da2e3ebdSchin sk = (Seek_t*)disc;
176da2e3ebdSchin
177da2e3ebdSchin switch (type)
178da2e3ebdSchin {
179da2e3ebdSchin case SF_FINAL:
180da2e3ebdSchin case SF_DPOP:
181da2e3ebdSchin sfclose(sk->shadow);
182da2e3ebdSchin free(disc);
183da2e3ebdSchin break;
184da2e3ebdSchin case SFSK_DISCARD:
185da2e3ebdSchin sk->eof = 0;
186da2e3ebdSchin sk->discard += sk->extent;
187da2e3ebdSchin sk->extent = 0;
188da2e3ebdSchin sfseek(sk->shadow,(Sfoff_t)0,SEEK_SET);
189da2e3ebdSchin break;
190da2e3ebdSchin }
191da2e3ebdSchin return 0;
192da2e3ebdSchin }
193da2e3ebdSchin
194da2e3ebdSchin #if __STD_C
sfdcseekable(Sfio_t * f)195da2e3ebdSchin int sfdcseekable(Sfio_t* f)
196da2e3ebdSchin #else
197da2e3ebdSchin int sfdcseekable(f)
198da2e3ebdSchin Sfio_t* f;
199da2e3ebdSchin #endif
200da2e3ebdSchin {
201da2e3ebdSchin reg Seek_t* sk;
202da2e3ebdSchin
203da2e3ebdSchin /* see if already seekable */
204da2e3ebdSchin if(sfseek(f,(Sfoff_t)0,SEEK_CUR) >= 0)
205da2e3ebdSchin return 0;
206da2e3ebdSchin
207da2e3ebdSchin if(!(sk = (Seek_t*)malloc(sizeof(Seek_t))) )
208da2e3ebdSchin return -1;
209da2e3ebdSchin memset(sk, 0, sizeof(*sk));
210da2e3ebdSchin
211da2e3ebdSchin sk->disc.readf = skread;
212da2e3ebdSchin sk->disc.writef = skwrite;
213da2e3ebdSchin sk->disc.seekf = skseek;
214da2e3ebdSchin sk->disc.exceptf = skexcept;
215da2e3ebdSchin sk->shadow = sftmp(SF_BUFSIZE);
216da2e3ebdSchin sk->discard = 0;
217da2e3ebdSchin sk->extent = 0;
218da2e3ebdSchin sk->eof = 0;
219da2e3ebdSchin
220da2e3ebdSchin if(sfdisc(f, (Sfdisc_t*)sk) != (Sfdisc_t*)sk)
221da2e3ebdSchin { sfclose(sk->shadow);
222da2e3ebdSchin free(sk);
223da2e3ebdSchin return -1;
224da2e3ebdSchin }
225da2e3ebdSchin
226da2e3ebdSchin return 0;
227da2e3ebdSchin }
228