Annotation of embedaddon/curl/lib/select.c, revision 1.1.1.1
1.1 misho 1: /***************************************************************************
2: * _ _ ____ _
3: * Project ___| | | | _ \| |
4: * / __| | | | |_) | |
5: * | (__| |_| | _ <| |___
6: * \___|\___/|_| \_\_____|
7: *
8: * Copyright (C) 1998 - 2020, Daniel Stenberg, <daniel@haxx.se>, et al.
9: *
10: * This software is licensed as described in the file COPYING, which
11: * you should have received as part of this distribution. The terms
12: * are also available at https://curl.haxx.se/docs/copyright.html.
13: *
14: * You may opt to use, copy, modify, merge, publish, distribute and/or sell
15: * copies of the Software, and permit persons to whom the Software is
16: * furnished to do so, under the terms of the COPYING file.
17: *
18: * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
19: * KIND, either express or implied.
20: *
21: ***************************************************************************/
22:
23: #include "curl_setup.h"
24:
25: #ifdef HAVE_SYS_SELECT_H
26: #include <sys/select.h>
27: #elif defined(HAVE_UNISTD_H)
28: #include <unistd.h>
29: #endif
30:
31: #if !defined(HAVE_SELECT) && !defined(HAVE_POLL_FINE)
32: #error "We can't compile without select() or poll() support."
33: #endif
34:
35: #if defined(__BEOS__) && !defined(__HAIKU__)
36: /* BeOS has FD_SET defined in socket.h */
37: #include <socket.h>
38: #endif
39:
40: #ifdef MSDOS
41: #include <dos.h> /* delay() */
42: #endif
43:
44: #ifdef __VXWORKS__
45: #include <strings.h> /* bzero() in FD_SET */
46: #endif
47:
48: #include <curl/curl.h>
49:
50: #include "urldata.h"
51: #include "connect.h"
52: #include "select.h"
53: #include "warnless.h"
54:
55: /* Convenience local macros */
56: #define ELAPSED_MS() (int)Curl_timediff(Curl_now(), initial_tv)
57:
58: /*
59: * Internal function used for waiting a specific amount of ms
60: * in Curl_socket_check() and Curl_poll() when no file descriptor
61: * is provided to wait on, just being used to delay execution.
62: * WinSock select() and poll() timeout mechanisms need a valid
63: * socket descriptor in a not null file descriptor set to work.
64: * Waiting indefinitely with this function is not allowed, a
65: * zero or negative timeout value will return immediately.
66: * Timeout resolution, accuracy, as well as maximum supported
67: * value is system dependent, neither factor is a citical issue
68: * for the intended use of this function in the library.
69: *
70: * Return values:
71: * -1 = system call error, invalid timeout value, or interrupted
72: * 0 = specified timeout has elapsed
73: */
74: int Curl_wait_ms(int timeout_ms)
75: {
76: int r = 0;
77:
78: if(!timeout_ms)
79: return 0;
80: if(timeout_ms < 0) {
81: SET_SOCKERRNO(EINVAL);
82: return -1;
83: }
84: #if defined(MSDOS)
85: delay(timeout_ms);
86: #elif defined(USE_WINSOCK)
87: Sleep(timeout_ms);
88: #else
89: #if defined(HAVE_POLL_FINE)
90: r = poll(NULL, 0, timeout_ms);
91: #else
92: {
93: struct timeval pending_tv;
94: pending_tv.tv_sec = timeout_ms / 1000;
95: pending_tv.tv_usec = (timeout_ms % 1000) * 1000;
96: r = select(0, NULL, NULL, NULL, &pending_tv);
97: }
98: #endif /* HAVE_POLL_FINE */
99: #endif /* USE_WINSOCK */
100: if(r)
101: r = -1;
102: return r;
103: }
104:
105: /*
106: * This is a wrapper around select() to aid in Windows compatibility.
107: * A negative timeout value makes this function wait indefinitely,
108: * unless no valid file descriptor is given, when this happens the
109: * negative timeout is ignored and the function times out immediately.
110: *
111: * Return values:
112: * -1 = system call error or fd >= FD_SETSIZE
113: * 0 = timeout
114: * N = number of signalled file descriptors
115: */
116: int Curl_select(curl_socket_t maxfd,
117: fd_set *fds_read,
118: fd_set *fds_write,
119: fd_set *fds_err,
120: time_t timeout_ms) /* milliseconds to wait */
121: {
122: struct timeval pending_tv;
123: struct timeval *ptimeout;
124: int pending_ms;
125: int r;
126:
127: #if SIZEOF_TIME_T != SIZEOF_INT
128: /* wrap-around precaution */
129: if(timeout_ms >= INT_MAX)
130: timeout_ms = INT_MAX;
131: #endif
132:
133: #ifdef USE_WINSOCK
134: /* WinSock select() can't handle zero events. See the comment below. */
135: if((!fds_read || fds_read->fd_count == 0) &&
136: (!fds_write || fds_write->fd_count == 0) &&
137: (!fds_err || fds_err->fd_count == 0)) {
138: r = Curl_wait_ms((int)timeout_ms);
139: return r;
140: }
141: #endif
142:
143: ptimeout = &pending_tv;
144:
145: if(timeout_ms < 0) {
146: ptimeout = NULL;
147: }
148: else if(timeout_ms > 0) {
149: pending_ms = (int)timeout_ms;
150: pending_tv.tv_sec = pending_ms / 1000;
151: pending_tv.tv_usec = (pending_ms % 1000) * 1000;
152: }
153: else if(!timeout_ms) {
154: pending_tv.tv_sec = 0;
155: pending_tv.tv_usec = 0;
156: }
157:
158: #ifdef USE_WINSOCK
159: /* WinSock select() must not be called with an fd_set that contains zero
160: fd flags, or it will return WSAEINVAL. But, it also can't be called
161: with no fd_sets at all! From the documentation:
162:
163: Any two of the parameters, readfds, writefds, or exceptfds, can be
164: given as null. At least one must be non-null, and any non-null
165: descriptor set must contain at least one handle to a socket.
166:
167: It is unclear why WinSock doesn't just handle this for us instead of
168: calling this an error.
169: */
170: r = select((int)maxfd + 1,
171: fds_read && fds_read->fd_count ? fds_read : NULL,
172: fds_write && fds_write->fd_count ? fds_write : NULL,
173: fds_err && fds_err->fd_count ? fds_err : NULL, ptimeout);
174: #else
175: r = select((int)maxfd + 1, fds_read, fds_write, fds_err, ptimeout);
176: #endif
177:
178: return r;
179: }
180:
181: /*
182: * Wait for read or write events on a set of file descriptors. It uses poll()
183: * when a fine poll() is available, in order to avoid limits with FD_SETSIZE,
184: * otherwise select() is used. An error is returned if select() is being used
185: * and a file descriptor is too large for FD_SETSIZE.
186: *
187: * A negative timeout value makes this function wait indefinitely,
188: * unless no valid file descriptor is given, when this happens the
189: * negative timeout is ignored and the function times out immediately.
190: *
191: * Return values:
192: * -1 = system call error or fd >= FD_SETSIZE
193: * 0 = timeout
194: * [bitmask] = action as described below
195: *
196: * CURL_CSELECT_IN - first socket is readable
197: * CURL_CSELECT_IN2 - second socket is readable
198: * CURL_CSELECT_OUT - write socket is writable
199: * CURL_CSELECT_ERR - an error condition occurred
200: */
201: int Curl_socket_check(curl_socket_t readfd0, /* two sockets to read from */
202: curl_socket_t readfd1,
203: curl_socket_t writefd, /* socket to write to */
204: timediff_t timeout_ms) /* milliseconds to wait */
205: {
206: #ifdef HAVE_POLL_FINE
207: struct pollfd pfd[3];
208: int pending_ms;
209: int num;
210: #else
211: fd_set fds_read;
212: fd_set fds_write;
213: fd_set fds_err;
214: curl_socket_t maxfd;
215: #endif
216: int r;
217: int ret;
218:
219: #if SIZEOF_TIME_T != SIZEOF_INT
220: /* wrap-around precaution */
221: if(timeout_ms >= INT_MAX)
222: timeout_ms = INT_MAX;
223: #endif
224:
225: if((readfd0 == CURL_SOCKET_BAD) && (readfd1 == CURL_SOCKET_BAD) &&
226: (writefd == CURL_SOCKET_BAD)) {
227: /* no sockets, just wait */
228: r = Curl_wait_ms((int)timeout_ms);
229: return r;
230: }
231:
232: /* Avoid initial timestamp, avoid Curl_now() call, when elapsed
233: time in this function does not need to be measured. This happens
234: when function is called with a zero timeout or a negative timeout
235: value indicating a blocking call should be performed. */
236:
237: #ifdef HAVE_POLL_FINE
238:
239: num = 0;
240: if(readfd0 != CURL_SOCKET_BAD) {
241: pfd[num].fd = readfd0;
242: pfd[num].events = POLLRDNORM|POLLIN|POLLRDBAND|POLLPRI;
243: pfd[num].revents = 0;
244: num++;
245: }
246: if(readfd1 != CURL_SOCKET_BAD) {
247: pfd[num].fd = readfd1;
248: pfd[num].events = POLLRDNORM|POLLIN|POLLRDBAND|POLLPRI;
249: pfd[num].revents = 0;
250: num++;
251: }
252: if(writefd != CURL_SOCKET_BAD) {
253: pfd[num].fd = writefd;
254: pfd[num].events = POLLWRNORM|POLLOUT;
255: pfd[num].revents = 0;
256: num++;
257: }
258:
259: if(timeout_ms > 0)
260: pending_ms = (int)timeout_ms;
261: else if(timeout_ms < 0)
262: pending_ms = -1;
263: else
264: pending_ms = 0;
265: r = poll(pfd, num, pending_ms);
266:
267: if(r < 0)
268: return -1;
269: if(r == 0)
270: return 0;
271:
272: ret = 0;
273: num = 0;
274: if(readfd0 != CURL_SOCKET_BAD) {
275: if(pfd[num].revents & (POLLRDNORM|POLLIN|POLLERR|POLLHUP))
276: ret |= CURL_CSELECT_IN;
277: if(pfd[num].revents & (POLLRDBAND|POLLPRI|POLLNVAL))
278: ret |= CURL_CSELECT_ERR;
279: num++;
280: }
281: if(readfd1 != CURL_SOCKET_BAD) {
282: if(pfd[num].revents & (POLLRDNORM|POLLIN|POLLERR|POLLHUP))
283: ret |= CURL_CSELECT_IN2;
284: if(pfd[num].revents & (POLLRDBAND|POLLPRI|POLLNVAL))
285: ret |= CURL_CSELECT_ERR;
286: num++;
287: }
288: if(writefd != CURL_SOCKET_BAD) {
289: if(pfd[num].revents & (POLLWRNORM|POLLOUT))
290: ret |= CURL_CSELECT_OUT;
291: if(pfd[num].revents & (POLLERR|POLLHUP|POLLNVAL))
292: ret |= CURL_CSELECT_ERR;
293: }
294:
295: return ret;
296:
297: #else /* HAVE_POLL_FINE */
298:
299: FD_ZERO(&fds_err);
300: maxfd = (curl_socket_t)-1;
301:
302: FD_ZERO(&fds_read);
303: if(readfd0 != CURL_SOCKET_BAD) {
304: VERIFY_SOCK(readfd0);
305: FD_SET(readfd0, &fds_read);
306: FD_SET(readfd0, &fds_err);
307: maxfd = readfd0;
308: }
309: if(readfd1 != CURL_SOCKET_BAD) {
310: VERIFY_SOCK(readfd1);
311: FD_SET(readfd1, &fds_read);
312: FD_SET(readfd1, &fds_err);
313: if(readfd1 > maxfd)
314: maxfd = readfd1;
315: }
316:
317: FD_ZERO(&fds_write);
318: if(writefd != CURL_SOCKET_BAD) {
319: VERIFY_SOCK(writefd);
320: FD_SET(writefd, &fds_write);
321: FD_SET(writefd, &fds_err);
322: if(writefd > maxfd)
323: maxfd = writefd;
324: }
325:
326: /* We know that we have at least one bit set in at least two fd_sets in
327: this case, but we may have no bits set in either fds_read or fd_write,
328: so check for that and handle it. Luckily, with WinSock, we can _also_
329: ask how many bits are set on an fd_set.
330:
331: Note also that WinSock ignores the first argument, so we don't worry
332: about the fact that maxfd is computed incorrectly with WinSock (since
333: curl_socket_t is unsigned in such cases and thus -1 is the largest
334: value).
335: */
336: r = Curl_select(maxfd, &fds_read, &fds_write, &fds_err, (time_t)timeout_ms);
337:
338: if(r < 0)
339: return -1;
340: if(r == 0)
341: return 0;
342:
343: ret = 0;
344: if(readfd0 != CURL_SOCKET_BAD) {
345: if(FD_ISSET(readfd0, &fds_read))
346: ret |= CURL_CSELECT_IN;
347: if(FD_ISSET(readfd0, &fds_err))
348: ret |= CURL_CSELECT_ERR;
349: }
350: if(readfd1 != CURL_SOCKET_BAD) {
351: if(FD_ISSET(readfd1, &fds_read))
352: ret |= CURL_CSELECT_IN2;
353: if(FD_ISSET(readfd1, &fds_err))
354: ret |= CURL_CSELECT_ERR;
355: }
356: if(writefd != CURL_SOCKET_BAD) {
357: if(FD_ISSET(writefd, &fds_write))
358: ret |= CURL_CSELECT_OUT;
359: if(FD_ISSET(writefd, &fds_err))
360: ret |= CURL_CSELECT_ERR;
361: }
362:
363: return ret;
364:
365: #endif /* HAVE_POLL_FINE */
366:
367: }
368:
369: /*
370: * This is a wrapper around poll(). If poll() does not exist, then
371: * select() is used instead. An error is returned if select() is
372: * being used and a file descriptor is too large for FD_SETSIZE.
373: * A negative timeout value makes this function wait indefinitely,
374: * unless no valid file descriptor is given, when this happens the
375: * negative timeout is ignored and the function times out immediately.
376: *
377: * Return values:
378: * -1 = system call error or fd >= FD_SETSIZE
379: * 0 = timeout
380: * N = number of structures with non zero revent fields
381: */
382: int Curl_poll(struct pollfd ufds[], unsigned int nfds, int timeout_ms)
383: {
384: #ifdef HAVE_POLL_FINE
385: int pending_ms;
386: #else
387: fd_set fds_read;
388: fd_set fds_write;
389: fd_set fds_err;
390: curl_socket_t maxfd;
391: #endif
392: bool fds_none = TRUE;
393: unsigned int i;
394: int r;
395:
396: if(ufds) {
397: for(i = 0; i < nfds; i++) {
398: if(ufds[i].fd != CURL_SOCKET_BAD) {
399: fds_none = FALSE;
400: break;
401: }
402: }
403: }
404: if(fds_none) {
405: r = Curl_wait_ms(timeout_ms);
406: return r;
407: }
408:
409: /* Avoid initial timestamp, avoid Curl_now() call, when elapsed
410: time in this function does not need to be measured. This happens
411: when function is called with a zero timeout or a negative timeout
412: value indicating a blocking call should be performed. */
413:
414: #ifdef HAVE_POLL_FINE
415:
416: if(timeout_ms > 0)
417: pending_ms = timeout_ms;
418: else if(timeout_ms < 0)
419: pending_ms = -1;
420: else
421: pending_ms = 0;
422: r = poll(ufds, nfds, pending_ms);
423:
424: if(r < 0)
425: return -1;
426: if(r == 0)
427: return 0;
428:
429: for(i = 0; i < nfds; i++) {
430: if(ufds[i].fd == CURL_SOCKET_BAD)
431: continue;
432: if(ufds[i].revents & POLLHUP)
433: ufds[i].revents |= POLLIN;
434: if(ufds[i].revents & POLLERR)
435: ufds[i].revents |= (POLLIN|POLLOUT);
436: }
437:
438: #else /* HAVE_POLL_FINE */
439:
440: FD_ZERO(&fds_read);
441: FD_ZERO(&fds_write);
442: FD_ZERO(&fds_err);
443: maxfd = (curl_socket_t)-1;
444:
445: for(i = 0; i < nfds; i++) {
446: ufds[i].revents = 0;
447: if(ufds[i].fd == CURL_SOCKET_BAD)
448: continue;
449: VERIFY_SOCK(ufds[i].fd);
450: if(ufds[i].events & (POLLIN|POLLOUT|POLLPRI|
451: POLLRDNORM|POLLWRNORM|POLLRDBAND)) {
452: if(ufds[i].fd > maxfd)
453: maxfd = ufds[i].fd;
454: if(ufds[i].events & (POLLRDNORM|POLLIN))
455: FD_SET(ufds[i].fd, &fds_read);
456: if(ufds[i].events & (POLLWRNORM|POLLOUT))
457: FD_SET(ufds[i].fd, &fds_write);
458: if(ufds[i].events & (POLLRDBAND|POLLPRI))
459: FD_SET(ufds[i].fd, &fds_err);
460: }
461: }
462:
463: r = Curl_select(maxfd, &fds_read, &fds_write, &fds_err, timeout_ms);
464:
465: if(r < 0)
466: return -1;
467: if(r == 0)
468: return 0;
469:
470: r = 0;
471: for(i = 0; i < nfds; i++) {
472: ufds[i].revents = 0;
473: if(ufds[i].fd == CURL_SOCKET_BAD)
474: continue;
475: if(FD_ISSET(ufds[i].fd, &fds_read))
476: ufds[i].revents |= POLLIN;
477: if(FD_ISSET(ufds[i].fd, &fds_write))
478: ufds[i].revents |= POLLOUT;
479: if(FD_ISSET(ufds[i].fd, &fds_err))
480: ufds[i].revents |= POLLPRI;
481: if(ufds[i].revents != 0)
482: r++;
483: }
484:
485: #endif /* HAVE_POLL_FINE */
486:
487: return r;
488: }
489:
490: #ifdef TPF
491: /*
492: * This is a replacement for select() on the TPF platform.
493: * It is used whenever libcurl calls select().
494: * The call below to tpf_process_signals() is required because
495: * TPF's select calls are not signal interruptible.
496: *
497: * Return values are the same as select's.
498: */
499: int tpf_select_libcurl(int maxfds, fd_set *reads, fd_set *writes,
500: fd_set *excepts, struct timeval *tv)
501: {
502: int rc;
503:
504: rc = tpf_select_bsd(maxfds, reads, writes, excepts, tv);
505: tpf_process_signals();
506: return rc;
507: }
508: #endif /* TPF */
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