xref: /titanic_41/usr/src/lib/libast/common/sfio/sfrd.c (revision 3e14f97f673e8a630f076077de35afdd43dc1587)
1 /***********************************************************************
2 *                                                                      *
3 *               This software is part of the ast package               *
4 *          Copyright (c) 1985-2010 AT&T Intellectual Property          *
5 *                      and is licensed under the                       *
6 *                  Common Public License, Version 1.0                  *
7 *                    by AT&T Intellectual Property                     *
8 *                                                                      *
9 *                A copy of the License is available at                 *
10 *            http://www.opensource.org/licenses/cpl1.0.txt             *
11 *         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
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 /*	Internal function to do a hard read.
25 **	This knows about discipline and memory mapping, peek read.
26 **
27 **	Written by Kiem-Phong Vo.
28 */
29 
30 /* synchronize unseekable write streams */
31 #if __STD_C
_sfwrsync(void)32 static void _sfwrsync(void)
33 #else
34 static void _sfwrsync()
35 #endif
36 {	reg Sfpool_t*	p;
37 	reg Sfio_t*	f;
38 	reg int		n;
39 
40 	/* sync all pool heads */
41 	for(p = _Sfpool.next; p; p = p->next)
42 	{	if(p->n_sf <= 0)
43 			continue;
44 		f = p->sf[0];
45 		if(!SFFROZEN(f) && f->next > f->data &&
46 		   (f->mode&SF_WRITE) && f->extent < 0 )
47 			(void)_sfflsbuf(f,-1);
48 	}
49 
50 	/* and all the ones in the discrete pool */
51 	for(n = 0; n < _Sfpool.n_sf; ++n)
52 	{	f = _Sfpool.sf[n];
53 
54 		if(!SFFROZEN(f) && f->next > f->data &&
55 		   (f->mode&SF_WRITE) && f->extent < 0 )
56 			(void)_sfflsbuf(f,-1);
57 	}
58 }
59 
60 #if __STD_C
sfrd(Sfio_t * f,Void_t * buf,size_t n,Sfdisc_t * disc)61 ssize_t sfrd(Sfio_t* f, Void_t* buf, size_t n, Sfdisc_t* disc)
62 #else
63 ssize_t sfrd(f,buf,n,disc)
64 Sfio_t*		f;
65 Void_t*		buf;
66 size_t		n;
67 Sfdisc_t*	disc;
68 #endif
69 {
70 	Sfoff_t		r;
71 	reg Sfdisc_t*	dc;
72 	reg int		local, rcrv, dosync, oerrno;
73 	SFMTXDECL(f);
74 
75 	SFMTXENTER(f,-1);
76 
77 	GETLOCAL(f,local);
78 	if((rcrv = f->mode & (SF_RC|SF_RV)) )
79 		f->mode &= ~(SF_RC|SF_RV);
80 	f->bits &= ~SF_JUSTSEEK;
81 
82 	if(f->mode&SF_PKRD)
83 		SFMTXRETURN(f, -1);
84 
85 	if(!local && !(f->bits&SF_DCDOWN)) /* an external user's call */
86 	{	if(f->mode != SF_READ && _sfmode(f,SF_READ,0) < 0)
87 			SFMTXRETURN(f, -1);
88 		if(f->next < f->endb)
89 		{	if(SFSYNC(f) < 0)
90 				SFMTXRETURN(f, -1);
91 			if((f->mode&(SF_SYNCED|SF_READ)) == (SF_SYNCED|SF_READ) )
92 			{	f->endb = f->next = f->endr = f->data;
93 				f->mode &= ~SF_SYNCED;
94 			}
95 #ifdef MAP_TYPE
96 			if((f->bits&SF_MMAP) && f->data)
97 			{	SFMUNMAP(f, f->data, f->endb-f->data);
98 				f->data = NIL(uchar*);
99 			}
100 #endif
101 			f->next = f->endb = f->endr = f->endw = f->data;
102 		}
103 	}
104 
105 	for(dosync = 0;;)
106 	{	/* stream locked by sfsetfd() */
107 		if(!(f->flags&SF_STRING) && f->file < 0)
108 			SFMTXRETURN(f, 0);
109 
110 		f->flags &= ~(SF_EOF|SF_ERROR);
111 
112 		dc = disc;
113 		if(f->flags&SF_STRING)
114 		{	if((r = (f->data+f->extent) - f->next) < 0)
115 				r = 0;
116 			if(r <= 0)
117 				goto do_except;
118 			SFMTXRETURN(f, (ssize_t)r);
119 		}
120 
121 		/* warn that a read is about to happen */
122 		SFDISC(f,dc,readf);
123 		if(dc && dc->exceptf && (f->flags&SF_IOCHECK) )
124 		{	reg int	rv;
125 			if(local)
126 				SETLOCAL(f);
127 			if((rv = _sfexcept(f,SF_READ,n,dc)) > 0)
128 				n = rv;
129 			else if(rv < 0)
130 			{	f->flags |= SF_ERROR;
131 				SFMTXRETURN(f, (ssize_t)rv);
132 			}
133 		}
134 
135 #ifdef MAP_TYPE
136 		if(f->bits&SF_MMAP)
137 		{	reg ssize_t	a, round;
138 			sfstat_t	st;
139 
140 			/* determine if we have to copy data to buffer */
141 			if((uchar*)buf >= f->data && (uchar*)buf <= f->endb)
142 			{	n += f->endb - f->next;
143 				buf = NIL(char*);
144 			}
145 
146 			/* actual seek location */
147 			if((f->flags&(SF_SHARE|SF_PUBLIC)) == (SF_SHARE|SF_PUBLIC) &&
148 			   (r = SFSK(f,(Sfoff_t)0,SEEK_CUR,dc)) != f->here)
149 				f->here = r;
150 			else	f->here -= f->endb-f->next;
151 
152 			/* before mapping, make sure we have data to map */
153 			if((f->flags&SF_SHARE) || (size_t)(r = f->extent-f->here) < n)
154 			{	if((r = sysfstatf(f->file,&st)) < 0)
155 					goto do_except;
156 				if((r = (f->extent = st.st_size) - f->here) <= 0 )
157 				{	r = 0;	/* eof */
158 					goto do_except;
159 				}
160 			}
161 
162 			/* make sure current position is page aligned */
163 			if((a = (size_t)(f->here%_Sfpage)) != 0)
164 			{	f->here -= a;
165 				r += a;
166 			}
167 
168 			/* map minimal requirement */
169 			if(r > (round = (1 + (n+a)/f->size)*f->size) )
170 				r = round;
171 
172 			if(f->data)
173 				SFMUNMAP(f, f->data, f->endb-f->data);
174 
175 			for(;;)
176 			{	f->data = (uchar*) sysmmapf((caddr_t)0, (size_t)r,
177 							(PROT_READ|PROT_WRITE),
178 							MAP_PRIVATE,
179 							f->file, (sfoff_t)f->here);
180 				if(f->data && (caddr_t)f->data != (caddr_t)(-1))
181 					break;
182 				else
183 				{	f->data = NIL(uchar*);
184 					if((r >>= 1) < (_Sfpage*SF_NMAP) ||
185 					   (errno != EAGAIN && errno != ENOMEM) )
186 						break;
187 				}
188 			}
189 
190 			if(f->data)
191 			{	if(f->bits&SF_SEQUENTIAL)
192 					SFMMSEQON(f,f->data,r);
193 				f->next = f->data+a;
194 				f->endr = f->endb = f->data+r;
195 				f->endw = f->data;
196 				f->here += r;
197 
198 				/* make known our seek location */
199 				(void)SFSK(f,f->here,SEEK_SET,dc);
200 
201 				if(buf)
202 				{	if(n > (size_t)(r-a))
203 						n = (ssize_t)(r-a);
204 					memcpy(buf,f->next,n);
205 					f->next += n;
206 				}
207 				else	n = f->endb - f->next;
208 
209 				SFMTXRETURN(f, n);
210 			}
211 			else
212 			{	r = -1;
213 				f->here += a;
214 
215 				/* reset seek pointer to its physical location */
216 				(void)SFSK(f,f->here,SEEK_SET,dc);
217 
218 				/* make a buffer */
219 				(void)SFSETBUF(f,(Void_t*)f->tiny,(size_t)SF_UNBOUND);
220 
221 				if(!buf)
222 				{	buf = (Void_t*)f->data;
223 					n = f->size;
224 				}
225 			}
226 		}
227 #endif
228 
229 		/* sync unseekable write streams to prevent deadlock */
230 		if(!dosync && f->extent < 0)
231 		{	dosync = 1;
232 			_sfwrsync();
233 		}
234 
235 		/* make sure file pointer is right */
236 		if(f->extent >= 0 && (f->flags&SF_SHARE) )
237 		{	if(!(f->flags&SF_PUBLIC) )
238 				f->here = SFSK(f,f->here,SEEK_SET,dc);
239 			else	f->here = SFSK(f,(Sfoff_t)0,SEEK_CUR,dc);
240 		}
241 
242 		oerrno = errno;
243 		errno = 0;
244 
245 		if(dc && dc->readf)
246 		{	int	share = f->flags&SF_SHARE;
247 
248 			if(rcrv) /* pass on rcrv for possible continuations */
249 				f->mode |= rcrv;
250 				/* tell readf that no peeking necessary */
251 			else	f->flags &= ~SF_SHARE;
252 
253 			SFDCRD(f,buf,n,dc,r);
254 
255 			/* reset flags */
256 			if(rcrv)
257 				f->mode &= ~rcrv;
258 			else	f->flags |= share;
259 		}
260 		else if(SFISNULL(f))
261 			r = 0;
262 		else if(f->extent < 0 && (f->flags&SF_SHARE) && rcrv)
263 		{	/* try peek read */
264 			r = sfpkrd(f->file, (char*)buf, n,
265 				    (rcrv&SF_RC) ? (int)f->getr : -1,
266 				    -1L, (rcrv&SF_RV) ? 1 : 0);
267 			if(r > 0)
268 			{	if(rcrv&SF_RV)
269 					f->mode |= SF_PKRD;
270 				else	f->mode |= SF_RC;
271 			}
272 		}
273 		else	r = sysreadf(f->file,buf,n);
274 
275 		if(errno == 0 )
276 			errno = oerrno;
277 
278 		if(r > 0 )
279 		{	if(!(f->bits&SF_DCDOWN) )	/* not a continuation call */
280 			{	if(!(f->mode&SF_PKRD) )
281 				{	f->here += r;
282 					if(f->extent >= 0 && f->extent < f->here)
283 						f->extent = f->here;
284 				}
285 				if((uchar*)buf >= f->data &&
286 				   (uchar*)buf < f->data+f->size)
287 					f->endb = f->endr = ((uchar*)buf) + r;
288 			}
289 
290 			SFMTXRETURN(f, (ssize_t)r);
291 		}
292 
293 	do_except:
294 		if(local)
295 			SETLOCAL(f);
296 		switch(_sfexcept(f,SF_READ,(ssize_t)r,dc))
297 		{
298 		case SF_ECONT :
299 			goto do_continue;
300 		case SF_EDONE :
301 			n = local ? 0 : (ssize_t)r;
302 			SFMTXRETURN(f,n);
303 		case SF_EDISC :
304 			if(!local && !(f->flags&SF_STRING))
305 				goto do_continue;
306 			/* else fall thru */
307 		case SF_ESTACK :
308 			SFMTXRETURN(f, -1);
309 		}
310 
311 	do_continue:
312 		for(dc = f->disc; dc; dc = dc->disc)
313 			if(dc == disc)
314 				break;
315 		disc = dc;
316 	}
317 }
318