xref: /illumos-gate/usr/src/lib/libresolv2/common/isc/ev_files.c (revision 458f44a49dc56cd17a39815122214e7a1b4793e3)
1 /*
2  * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
3  * Copyright (c) 1995-1999 by Internet Software Consortium
4  *
5  * Permission to use, copy, modify, and distribute this software for any
6  * purpose with or without fee is hereby granted, provided that the above
7  * copyright notice and this permission notice appear in all copies.
8  *
9  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11  * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
15  * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16  */
17 
18 /* ev_files.c - implement asynch file IO for the eventlib
19  * vix 11sep95 [initial]
20  */
21 
22 #include "port_before.h"
23 #include "fd_setsize.h"
24 
25 #include <sys/types.h>
26 #include <sys/time.h>
27 #include <sys/ioctl.h>
28 
29 #include <errno.h>
30 #include <fcntl.h>
31 #include <unistd.h>
32 
33 #include <isc/eventlib.h>
34 #include "eventlib_p.h"
35 
36 #include "port_after.h"
37 
38 static evFile *FindFD(const evContext_p *ctx, int fd, int eventmask);
39 
40 int
evSelectFD(evContext opaqueCtx,int fd,int eventmask,evFileFunc func,void * uap,evFileID * opaqueID)41 evSelectFD(evContext opaqueCtx,
42 	   int fd,
43 	   int eventmask,
44 	   evFileFunc func,
45 	   void *uap,
46 	   evFileID *opaqueID
47 ) {
48 	evContext_p *ctx = opaqueCtx.opaque;
49 	evFile *id;
50 	int mode;
51 
52 	evPrintf(ctx, 1,
53 		 "evSelectFD(ctx %p, fd %d, mask 0x%x, func %p, uap %p)\n",
54 		 ctx, fd, eventmask, func, uap);
55 	if (eventmask == 0 || (eventmask & ~EV_MASK_ALL) != 0)
56 		EV_ERR(EINVAL);
57 #ifndef USE_POLL
58 	if (fd > ctx->highestFD)
59 		EV_ERR(EINVAL);
60 #endif
61 	OK(mode = fcntl(fd, F_GETFL, NULL));	/*%< side effect: validate fd. */
62 	/*
63 	 * The first time we touch a file descriptor, we need to check to see
64 	 * if the application already had it in O_NONBLOCK mode and if so, all
65 	 * of our deselect()'s have to leave it in O_NONBLOCK.  If not, then
66 	 * all but our last deselect() has to leave it in O_NONBLOCK.
67 	 */
68 #ifdef USE_POLL
69 	/* Make sure both ctx->pollfds[] and ctx->fdTable[] are large enough */
70 	if (fd >= ctx->maxnfds && evPollfdRealloc(ctx, 1, fd) != 0)
71 		EV_ERR(ENOMEM);
72 #endif /* USE_POLL */
73 	id = FindFD(ctx, fd, EV_MASK_ALL);
74 	if (id == NULL) {
75 		if (mode & PORT_NONBLOCK)
76 			FD_SET(fd, &ctx->nonblockBefore);
77 		else {
78 #ifdef USE_FIONBIO_IOCTL
79 			int on = 1;
80 			OK(ioctl(fd, FIONBIO, (char *)&on));
81 #else
82 			OK(fcntl(fd, F_SETFL, mode | PORT_NONBLOCK));
83 #endif
84 			FD_CLR(fd, &ctx->nonblockBefore);
85 		}
86 	}
87 
88 	/*
89 	 * If this descriptor is already in use, search for it again to see
90 	 * if any of the eventmask bits we want to set are already captured.
91 	 * We cannot usefully capture the same fd event more than once in the
92 	 * same context.
93 	 */
94 	if (id != NULL && FindFD(ctx, fd, eventmask) != NULL)
95 		EV_ERR(ETOOMANYREFS);
96 
97 	/* Allocate and fill. */
98 	OKNEW(id);
99 	id->func = func;
100 	id->uap = uap;
101 	id->fd = fd;
102 	id->eventmask = eventmask;
103 
104 	/*
105 	 * Insert at head.  Order could be important for performance if we
106 	 * believe that evGetNext()'s accesses to the fd_sets will be more
107 	 * serial and therefore more cache-lucky if the list is ordered by
108 	 * ``fd.''  We do not believe these things, so we don't do it.
109 	 *
110 	 * The interesting sequence is where GetNext() has cached a select()
111 	 * result and the caller decides to evSelectFD() on some descriptor.
112 	 * Since GetNext() starts at the head, it can miss new entries we add
113 	 * at the head.  This is not a serious problem since the event being
114 	 * evSelectFD()'d for has to occur before evSelectFD() is called for
115 	 * the file event to be considered "missed" -- a real corner case.
116 	 * Maintaining a "tail" pointer for ctx->files would fix this, but I'm
117 	 * not sure it would be ``more correct.''
118 	 */
119 	if (ctx->files != NULL)
120 		ctx->files->prev = id;
121 	id->prev = NULL;
122 	id->next = ctx->files;
123 	ctx->files = id;
124 
125 	/* Insert into fd table. */
126 	if (ctx->fdTable[fd] != NULL)
127 		ctx->fdTable[fd]->fdprev = id;
128 	id->fdprev = NULL;
129 	id->fdnext = ctx->fdTable[fd];
130 	ctx->fdTable[fd] = id;
131 
132 	/* Turn on the appropriate bits in the {rd,wr,ex}Next fd_set's. */
133 	if (eventmask & EV_READ)
134 		FD_SET(fd, &ctx->rdNext);
135 	if (eventmask & EV_WRITE)
136 		FD_SET(fd, &ctx->wrNext);
137 	if (eventmask & EV_EXCEPT)
138 		FD_SET(fd, &ctx->exNext);
139 
140 	/* Update fdMax. */
141 	if (fd > ctx->fdMax)
142 		ctx->fdMax = fd;
143 
144 	/* Remember the ID if the caller provided us a place for it. */
145 	if (opaqueID)
146 		opaqueID->opaque = id;
147 
148 	return (0);
149 }
150 
151 int
evDeselectFD(evContext opaqueCtx,evFileID opaqueID)152 evDeselectFD(evContext opaqueCtx, evFileID opaqueID) {
153 	evContext_p *ctx = opaqueCtx.opaque;
154 	evFile *del = opaqueID.opaque;
155 	evFile *cur;
156 	int mode, eventmask;
157 
158 	if (!del) {
159 		evPrintf(ctx, 11, "evDeselectFD(NULL) ignored\n");
160 		errno = EINVAL;
161 		return (-1);
162 	}
163 
164 	evPrintf(ctx, 1, "evDeselectFD(fd %d, mask 0x%x)\n",
165 		 del->fd, del->eventmask);
166 
167 	/* Get the mode.  Unless the file has been closed, errors are bad. */
168 	mode = fcntl(del->fd, F_GETFL, NULL);
169 	if (mode == -1 && errno != EBADF)
170 		EV_ERR(errno);
171 
172 	/* Remove from the list of files. */
173 	if (del->prev != NULL)
174 		del->prev->next = del->next;
175 	else
176 		ctx->files = del->next;
177 	if (del->next != NULL)
178 		del->next->prev = del->prev;
179 
180 	/* Remove from the fd table. */
181 	if (del->fdprev != NULL)
182 		del->fdprev->fdnext = del->fdnext;
183 	else
184 		ctx->fdTable[del->fd] = del->fdnext;
185 	if (del->fdnext != NULL)
186 		del->fdnext->fdprev = del->fdprev;
187 
188 	/*
189 	 * If the file descriptor does not appear in any other select() entry,
190 	 * and if !EV_WASNONBLOCK, and if we got no EBADF when we got the mode
191 	 * earlier, then: restore the fd to blocking status.
192 	 */
193 	if (!(cur = FindFD(ctx, del->fd, EV_MASK_ALL)) &&
194 	    !FD_ISSET(del->fd, &ctx->nonblockBefore) &&
195 	    mode != -1) {
196 		/*
197 		 * Note that we won't return an error status to the caller if
198 		 * this fcntl() fails since (a) we've already done the work
199 		 * and (b) the caller didn't ask us anything about O_NONBLOCK.
200 		 */
201 #ifdef USE_FIONBIO_IOCTL
202 		int off = 0;
203 		(void) ioctl(del->fd, FIONBIO, (char *)&off);
204 #else
205 		(void) fcntl(del->fd, F_SETFL, mode & ~PORT_NONBLOCK);
206 #endif
207 	}
208 
209 	/*
210 	 * Now find all other uses of this descriptor and OR together an event
211 	 * mask so that we don't turn off {rd,wr,ex}Next bits that some other
212 	 * file event is using.  As an optimization, stop if the event mask
213 	 * fills.
214 	 */
215 	eventmask = 0;
216 	for ((void)NULL;
217 	     cur != NULL && eventmask != EV_MASK_ALL;
218 	     cur = cur->next)
219 		if (cur->fd == del->fd)
220 			eventmask |= cur->eventmask;
221 
222 	/* OK, now we know which bits we can clear out. */
223 	if (!(eventmask & EV_READ)) {
224 		FD_CLR(del->fd, &ctx->rdNext);
225 		if (FD_ISSET(del->fd, &ctx->rdLast)) {
226 			FD_CLR(del->fd, &ctx->rdLast);
227 			ctx->fdCount--;
228 		}
229 	}
230 	if (!(eventmask & EV_WRITE)) {
231 		FD_CLR(del->fd, &ctx->wrNext);
232 		if (FD_ISSET(del->fd, &ctx->wrLast)) {
233 			FD_CLR(del->fd, &ctx->wrLast);
234 			ctx->fdCount--;
235 		}
236 	}
237 	if (!(eventmask & EV_EXCEPT)) {
238 		FD_CLR(del->fd, &ctx->exNext);
239 		if (FD_ISSET(del->fd, &ctx->exLast)) {
240 			FD_CLR(del->fd, &ctx->exLast);
241 			ctx->fdCount--;
242 		}
243 	}
244 
245 	/* If this was the maxFD, find the new one. */
246 	if (del->fd == ctx->fdMax) {
247 		ctx->fdMax = -1;
248 		for (cur = ctx->files; cur; cur = cur->next)
249 			if (cur->fd > ctx->fdMax)
250 				ctx->fdMax = cur->fd;
251 	}
252 
253 	/* If this was the fdNext, cycle that to the next entry. */
254 	if (del == ctx->fdNext)
255 		ctx->fdNext = del->next;
256 
257 	/* Couldn't free it before now since we were using fields out of it. */
258 	FREE(del);
259 
260 	return (0);
261 }
262 
263 static evFile *
FindFD(const evContext_p * ctx,int fd,int eventmask)264 FindFD(const evContext_p *ctx, int fd, int eventmask) {
265 	evFile *id;
266 
267 	for (id = ctx->fdTable[fd]; id != NULL; id = id->fdnext)
268 		if (id->fd == fd && (id->eventmask & eventmask) != 0)
269 			break;
270 	return (id);
271 }
272 
273 /*! \file */
274