xref: /titanic_50/usr/src/lib/libast/common/sfio/sfpoll.c (revision 257ece65b709e4f1ef13631685422aab6fad85cf)
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 /*	Poll a set of streams to see if any is available for I/O.
25 **	Ready streams are moved to front of array but retain the
26 **	same relative order.
27 **
28 **	Written by Kiem-Phong Vo.
29 */
30 
31 #if __STD_C
32 int sfpoll(Sfio_t** fa, reg int n, int tm)
33 #else
34 int sfpoll(fa, n, tm)
35 Sfio_t**	fa;	/* array of streams to poll		*/
36 reg int		n;	/* number of streams in array		*/
37 int		tm;	/* time in millisecs for select/poll	*/
38 #endif
39 {
40 	reg int		r, c, m, np;
41 	reg Sfio_t*	f;
42 	reg int		*status, *check;
43 
44 	if(n <= 0 || !fa)
45 		return -1;
46 
47 	if(!(status = (int*)malloc(2*n*sizeof(int))) )
48 		return -1;
49 	check = status+n; /* streams that need polling */
50 
51 	/* a SF_READ stream is ready if there is buffered read data */
52 #define RDREADY(f)	(((f->mode&SF_READ) && f->next < f->endb) || \
53 			 ((f->mode&SF_WRITE) && f->proc && f->proc->ndata > 0) )
54 
55 	/* a SF_WRITE stream is ready if there is no write data */
56 #define WRREADY(f)	(!(f->mode&SF_WRITE) || f->next == f->data)
57 
58 #define HASAUXFD(f)	(f->proc && f->proc->file >= 0 && f->proc->file != f->file)
59 
60 	for(r = c = 0; r < n; ++r) /* compute streams that must be checked */
61 	{	f = fa[r];
62 		status[r] = 0;
63 
64 		/* check accessibility */
65 		m = f->mode&SF_RDWR;
66 		if((int)f->mode != m && _sfmode(f,m,0) < 0)
67 			continue;
68 
69 		if((f->flags&SF_READ) && RDREADY(f))
70 			status[r] |= SF_READ;
71 
72 		if((f->flags&SF_WRITE) && WRREADY(f))
73 			status[r] |= SF_WRITE;
74 
75 		if((f->flags&SF_RDWR) == status[r])
76 			continue;
77 
78 		/* has discipline, ask its opinion */
79 		if(f->disc && f->disc->exceptf)
80 		{	if((m = (*f->disc->exceptf)(f,SF_DPOLL,&tm,f->disc)) < 0)
81 				continue;
82 			else if(m > 0)
83 			{	status[r] = m&SF_RDWR;
84 				continue;
85 			}
86 		}
87 
88 		if(f->extent < 0) /* unseekable stream, must poll/select */
89 			check[c++] = r;
90 		else /* seekable streams are always ready */
91 		{	if(f->flags&SF_READ)
92 				status[r] |= SF_READ;
93 			if(f->flags&SF_WRITE)
94 				status[r] |= SF_WRITE;
95 		}
96 	}
97 
98 	np = -1;
99 #if _lib_poll
100 	if(c > 0)
101 	{	struct pollfd*	fds;
102 
103 		/* construct the poll array */
104 		for(m = 0, r = 0; r < c; ++r, ++m)
105 		{	f = fa[check[r]];
106 			if(HASAUXFD(f))
107 				m += 1;
108 		}
109 		if(!(fds = (struct pollfd*)malloc(m*sizeof(struct pollfd))) )
110 			return -1;
111 
112 		for(m = 0, r = 0; r < c; ++r, ++m)
113 		{	f = fa[check[r]];
114 
115 			fds[m].fd = f->file;
116 			fds[m].events = fds[m].revents = 0;
117 
118 			if((f->flags&SF_WRITE) && !WRREADY(f) )
119 				fds[m].events |= POLLOUT;
120 
121 			if((f->flags&SF_READ)  && !RDREADY(f) )
122 			{	/* a sfpopen situation with two file descriptors */
123 				if((f->mode&SF_WRITE) && HASAUXFD(f))
124 				{	m += 1;
125 					fds[m].fd = f->proc->file;
126 					fds[m].revents = 0;
127 				}
128 
129 				fds[m].events |= POLLIN;
130 			}
131 		}
132 
133 		while((np = SFPOLL(fds,m,tm)) < 0 )
134 		{	if(errno == EINTR || errno == EAGAIN)
135 				errno = 0;
136 			else	break;
137 		}
138 		if(np > 0) /* poll succeeded */
139 			np = c;
140 
141 		for(m = 0, r = 0; r < np; ++r, ++m)
142 		{	f = fa[check[r]];
143 
144 			if((f->flags&SF_WRITE) && !WRREADY(f) )
145 			{	if(fds[m].revents&POLLOUT)
146 					status[check[r]] |= SF_WRITE;
147 			}
148 
149 			if((f->flags&SF_READ)  && !RDREADY(f))
150 			{	if((f->mode&SF_WRITE) && HASAUXFD(f))
151 					m += 1;
152 				if(fds[m].revents&POLLIN)
153 					status[check[r]] |= SF_READ;
154 			}
155 		}
156 
157 		free((Void_t*)fds);
158 	}
159 #endif /*_lib_poll*/
160 
161 #if _lib_select
162 	if(np < 0 && c > 0)
163 	{	fd_set		rd, wr;
164 		struct timeval	tmb, *tmp;
165 
166 		FD_ZERO(&rd);
167 		FD_ZERO(&wr);
168 		m = 0;
169 		for(r = 0; r < c; ++r)
170 		{	f = fa[check[r]];
171 
172 			if(f->file > m)
173 				m = f->file;
174 
175 			if((f->flags&SF_WRITE) && !WRREADY(f))
176 				FD_SET(f->file,&wr);
177 
178 			if((f->flags&SF_READ)  && !RDREADY(f))
179 			{	if((f->mode&SF_WRITE) && HASAUXFD(f))
180 				{	if(f->proc->file > m)
181 						m = f->proc->file;
182 					FD_SET(f->proc->file, &rd);
183 				}
184 				else	FD_SET(f->file,&rd);
185 			}
186 		}
187 		if(tm < 0)
188 			tmp = NIL(struct timeval*);
189 		else
190 		{	tmp = &tmb;
191 			tmb.tv_sec = tm/SECOND;
192 			tmb.tv_usec = (tm%SECOND)*SECOND;
193 		}
194 
195 		while((np = select(m+1,&rd,&wr,NIL(fd_set*),tmp)) < 0 )
196 		{	if(errno == EINTR)
197 				errno = 0;
198 			else	break;
199 		}
200 		if(np > 0)
201 			np = c;
202 
203 		for(r = 0; r < np; ++r)
204 		{	f = fa[check[r]];
205 
206 			if((f->flags&SF_WRITE) && !WRREADY(f) )
207 			{	if(FD_ISSET(f->file,&wr) )
208 					status[check[r]] |= SF_WRITE;
209 			}
210 
211 			if((f->flags&SF_READ) && !RDREADY(f) )
212 			{	if((f->mode&SF_WRITE) && HASAUXFD(f) )
213 				{	if(FD_ISSET(f->proc->file, &rd) )
214 						status[check[r]] |= SF_READ;
215 				}
216 				else
217 				{	if(FD_ISSET(f->file,&rd) )
218 						status[check[r]] |= SF_READ;
219 				}
220 			}
221 		}
222 	}
223 #endif /*_lib_select*/
224 
225 	for(r = c = 0; c < n; ++c)
226 	{	if(status[c] == 0)
227 			continue;
228 
229 		f = fa[c];
230 		f->val = (ssize_t)status[c];
231 
232 		/* announce status */
233 		if(f->disc && f->disc->exceptf)
234 			(*f->disc->exceptf)(f,SF_READY,(Void_t*)(long)status[c],f->disc);
235 
236 		if(c > r) /* move to front of list */
237 		{	fa[c] = fa[r];
238 			fa[r] = f;
239 		}
240 		r += 1;
241 	}
242 
243 	free((Void_t*)status);
244 	return r;
245 }
246