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Diffstat (limited to 'Utilities/cmcurl/lib/select.c')
| -rw-r--r-- | Utilities/cmcurl/lib/select.c | 398 |
1 files changed, 398 insertions, 0 deletions
diff --git a/Utilities/cmcurl/lib/select.c b/Utilities/cmcurl/lib/select.c new file mode 100644 index 0000000000..61cce619b4 --- /dev/null +++ b/Utilities/cmcurl/lib/select.c @@ -0,0 +1,398 @@ +/*************************************************************************** + * _ _ ____ _ + * Project ___| | | | _ \| | + * / __| | | | |_) | | + * | (__| |_| | _ <| |___ + * \___|\___/|_| \_\_____| + * + * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al. + * + * This software is licensed as described in the file COPYING, which + * you should have received as part of this distribution. The terms + * are also available at https://curl.se/docs/copyright.html. + * + * You may opt to use, copy, modify, merge, publish, distribute and/or sell + * copies of the Software, and permit persons to whom the Software is + * furnished to do so, under the terms of the COPYING file. + * + * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY + * KIND, either express or implied. + * + * SPDX-License-Identifier: curl + * + ***************************************************************************/ + +#include "curl_setup.h" + +#include <limits.h> + +#ifdef HAVE_SYS_SELECT_H +#include <sys/select.h> +#elif defined(HAVE_UNISTD_H) +#include <unistd.h> +#endif + +#if !defined(HAVE_SELECT) && !defined(HAVE_POLL_FINE) +#error "We can't compile without select() or poll() support." +#endif + +#ifdef MSDOS +#include <dos.h> /* delay() */ +#endif + +#include <curl/curl.h> + +#include "urldata.h" +#include "connect.h" +#include "select.h" +#include "timediff.h" +#include "warnless.h" + +/* + * Internal function used for waiting a specific amount of ms + * in Curl_socket_check() and Curl_poll() when no file descriptor + * is provided to wait on, just being used to delay execution. + * WinSock select() and poll() timeout mechanisms need a valid + * socket descriptor in a not null file descriptor set to work. + * Waiting indefinitely with this function is not allowed, a + * zero or negative timeout value will return immediately. + * Timeout resolution, accuracy, as well as maximum supported + * value is system dependent, neither factor is a critical issue + * for the intended use of this function in the library. + * + * Return values: + * -1 = system call error, invalid timeout value, or interrupted + * 0 = specified timeout has elapsed + */ +int Curl_wait_ms(timediff_t timeout_ms) +{ + int r = 0; + + if(!timeout_ms) + return 0; + if(timeout_ms < 0) { + SET_SOCKERRNO(EINVAL); + return -1; + } +#if defined(MSDOS) + delay(timeout_ms); +#elif defined(WIN32) + /* prevent overflow, timeout_ms is typecast to ULONG/DWORD. */ +#if TIMEDIFF_T_MAX >= ULONG_MAX + if(timeout_ms >= ULONG_MAX) + timeout_ms = ULONG_MAX-1; + /* don't use ULONG_MAX, because that is equal to INFINITE */ +#endif + Sleep((ULONG)timeout_ms); +#else +#if defined(HAVE_POLL_FINE) + /* prevent overflow, timeout_ms is typecast to int. */ +#if TIMEDIFF_T_MAX > INT_MAX + if(timeout_ms > INT_MAX) + timeout_ms = INT_MAX; +#endif + r = poll(NULL, 0, (int)timeout_ms); +#else + { + struct timeval pending_tv; + r = select(0, NULL, NULL, NULL, curlx_mstotv(&pending_tv, timeout_ms)); + } +#endif /* HAVE_POLL_FINE */ +#endif /* USE_WINSOCK */ + if(r) + r = -1; + return r; +} + +#ifndef HAVE_POLL_FINE +/* + * This is a wrapper around select() to aid in Windows compatibility. + * A negative timeout value makes this function wait indefinitely, + * unless no valid file descriptor is given, when this happens the + * negative timeout is ignored and the function times out immediately. + * + * Return values: + * -1 = system call error or fd >= FD_SETSIZE + * 0 = timeout + * N = number of signalled file descriptors + */ +static int our_select(curl_socket_t maxfd, /* highest socket number */ + fd_set *fds_read, /* sockets ready for reading */ + fd_set *fds_write, /* sockets ready for writing */ + fd_set *fds_err, /* sockets with errors */ + timediff_t timeout_ms) /* milliseconds to wait */ +{ + struct timeval pending_tv; + struct timeval *ptimeout; + +#ifdef USE_WINSOCK + /* WinSock select() can't handle zero events. See the comment below. */ + if((!fds_read || fds_read->fd_count == 0) && + (!fds_write || fds_write->fd_count == 0) && + (!fds_err || fds_err->fd_count == 0)) { + /* no sockets, just wait */ + return Curl_wait_ms(timeout_ms); + } +#endif + + ptimeout = curlx_mstotv(&pending_tv, timeout_ms); + +#ifdef USE_WINSOCK + /* WinSock select() must not be called with an fd_set that contains zero + fd flags, or it will return WSAEINVAL. But, it also can't be called + with no fd_sets at all! From the documentation: + + Any two of the parameters, readfds, writefds, or exceptfds, can be + given as null. At least one must be non-null, and any non-null + descriptor set must contain at least one handle to a socket. + + It is unclear why WinSock doesn't just handle this for us instead of + calling this an error. Luckily, with WinSock, we can _also_ ask how + many bits are set on an fd_set. So, let's just check it beforehand. + */ + return select((int)maxfd + 1, + fds_read && fds_read->fd_count ? fds_read : NULL, + fds_write && fds_write->fd_count ? fds_write : NULL, + fds_err && fds_err->fd_count ? fds_err : NULL, ptimeout); +#else + return select((int)maxfd + 1, fds_read, fds_write, fds_err, ptimeout); +#endif +} + +#endif + +/* + * Wait for read or write events on a set of file descriptors. It uses poll() + * when a fine poll() is available, in order to avoid limits with FD_SETSIZE, + * otherwise select() is used. An error is returned if select() is being used + * and a file descriptor is too large for FD_SETSIZE. + * + * A negative timeout value makes this function wait indefinitely, + * unless no valid file descriptor is given, when this happens the + * negative timeout is ignored and the function times out immediately. + * + * Return values: + * -1 = system call error or fd >= FD_SETSIZE + * 0 = timeout + * [bitmask] = action as described below + * + * CURL_CSELECT_IN - first socket is readable + * CURL_CSELECT_IN2 - second socket is readable + * CURL_CSELECT_OUT - write socket is writable + * CURL_CSELECT_ERR - an error condition occurred + */ +int Curl_socket_check(curl_socket_t readfd0, /* two sockets to read from */ + curl_socket_t readfd1, + curl_socket_t writefd, /* socket to write to */ + timediff_t timeout_ms) /* milliseconds to wait */ +{ + struct pollfd pfd[3]; + int num; + int r; + + if((readfd0 == CURL_SOCKET_BAD) && (readfd1 == CURL_SOCKET_BAD) && + (writefd == CURL_SOCKET_BAD)) { + /* no sockets, just wait */ + return Curl_wait_ms(timeout_ms); + } + + /* Avoid initial timestamp, avoid Curl_now() call, when elapsed + time in this function does not need to be measured. This happens + when function is called with a zero timeout or a negative timeout + value indicating a blocking call should be performed. */ + + num = 0; + if(readfd0 != CURL_SOCKET_BAD) { + pfd[num].fd = readfd0; + pfd[num].events = POLLRDNORM|POLLIN|POLLRDBAND|POLLPRI; + pfd[num].revents = 0; + num++; + } + if(readfd1 != CURL_SOCKET_BAD) { + pfd[num].fd = readfd1; + pfd[num].events = POLLRDNORM|POLLIN|POLLRDBAND|POLLPRI; + pfd[num].revents = 0; + num++; + } + if(writefd != CURL_SOCKET_BAD) { + pfd[num].fd = writefd; + pfd[num].events = POLLWRNORM|POLLOUT|POLLPRI; + pfd[num].revents = 0; + num++; + } + + r = Curl_poll(pfd, num, timeout_ms); + if(r <= 0) + return r; + + r = 0; + num = 0; + if(readfd0 != CURL_SOCKET_BAD) { + if(pfd[num].revents & (POLLRDNORM|POLLIN|POLLERR|POLLHUP)) + r |= CURL_CSELECT_IN; + if(pfd[num].revents & (POLLPRI|POLLNVAL)) + r |= CURL_CSELECT_ERR; + num++; + } + if(readfd1 != CURL_SOCKET_BAD) { + if(pfd[num].revents & (POLLRDNORM|POLLIN|POLLERR|POLLHUP)) + r |= CURL_CSELECT_IN2; + if(pfd[num].revents & (POLLPRI|POLLNVAL)) + r |= CURL_CSELECT_ERR; + num++; + } + if(writefd != CURL_SOCKET_BAD) { + if(pfd[num].revents & (POLLWRNORM|POLLOUT)) + r |= CURL_CSELECT_OUT; + if(pfd[num].revents & (POLLERR|POLLHUP|POLLPRI|POLLNVAL)) + r |= CURL_CSELECT_ERR; + } + + return r; +} + +/* + * This is a wrapper around poll(). If poll() does not exist, then + * select() is used instead. An error is returned if select() is + * being used and a file descriptor is too large for FD_SETSIZE. + * A negative timeout value makes this function wait indefinitely, + * unless no valid file descriptor is given, when this happens the + * negative timeout is ignored and the function times out immediately. + * + * Return values: + * -1 = system call error or fd >= FD_SETSIZE + * 0 = timeout + * N = number of structures with non zero revent fields + */ +int Curl_poll(struct pollfd ufds[], unsigned int nfds, timediff_t timeout_ms) +{ +#ifdef HAVE_POLL_FINE + int pending_ms; +#else + fd_set fds_read; + fd_set fds_write; + fd_set fds_err; + curl_socket_t maxfd; +#endif + bool fds_none = TRUE; + unsigned int i; + int r; + + if(ufds) { + for(i = 0; i < nfds; i++) { + if(ufds[i].fd != CURL_SOCKET_BAD) { + fds_none = FALSE; + break; + } + } + } + if(fds_none) { + /* no sockets, just wait */ + return Curl_wait_ms(timeout_ms); + } + + /* Avoid initial timestamp, avoid Curl_now() call, when elapsed + time in this function does not need to be measured. This happens + when function is called with a zero timeout or a negative timeout + value indicating a blocking call should be performed. */ + +#ifdef HAVE_POLL_FINE + + /* prevent overflow, timeout_ms is typecast to int. */ +#if TIMEDIFF_T_MAX > INT_MAX + if(timeout_ms > INT_MAX) + timeout_ms = INT_MAX; +#endif + if(timeout_ms > 0) + pending_ms = (int)timeout_ms; + else if(timeout_ms < 0) + pending_ms = -1; + else + pending_ms = 0; + r = poll(ufds, nfds, pending_ms); + if(r <= 0) { + if((r == -1) && (SOCKERRNO == EINTR)) + /* make EINTR from select or poll not a "lethal" error */ + r = 0; + return r; + } + + for(i = 0; i < nfds; i++) { + if(ufds[i].fd == CURL_SOCKET_BAD) + continue; + if(ufds[i].revents & POLLHUP) + ufds[i].revents |= POLLIN; + if(ufds[i].revents & POLLERR) + ufds[i].revents |= POLLIN|POLLOUT; + } + +#else /* HAVE_POLL_FINE */ + + FD_ZERO(&fds_read); + FD_ZERO(&fds_write); + FD_ZERO(&fds_err); + maxfd = (curl_socket_t)-1; + + for(i = 0; i < nfds; i++) { + ufds[i].revents = 0; + if(ufds[i].fd == CURL_SOCKET_BAD) + continue; + VERIFY_SOCK(ufds[i].fd); + if(ufds[i].events & (POLLIN|POLLOUT|POLLPRI| + POLLRDNORM|POLLWRNORM|POLLRDBAND)) { + if(ufds[i].fd > maxfd) + maxfd = ufds[i].fd; + if(ufds[i].events & (POLLRDNORM|POLLIN)) + FD_SET(ufds[i].fd, &fds_read); + if(ufds[i].events & (POLLWRNORM|POLLOUT)) + FD_SET(ufds[i].fd, &fds_write); + if(ufds[i].events & (POLLRDBAND|POLLPRI)) + FD_SET(ufds[i].fd, &fds_err); + } + } + + /* + Note also that WinSock ignores the first argument, so we don't worry + about the fact that maxfd is computed incorrectly with WinSock (since + curl_socket_t is unsigned in such cases and thus -1 is the largest + value). + */ + r = our_select(maxfd, &fds_read, &fds_write, &fds_err, timeout_ms); + if(r <= 0) { + if((r == -1) && (SOCKERRNO == EINTR)) + /* make EINTR from select or poll not a "lethal" error */ + r = 0; + return r; + } + + r = 0; + for(i = 0; i < nfds; i++) { + ufds[i].revents = 0; + if(ufds[i].fd == CURL_SOCKET_BAD) + continue; + if(FD_ISSET(ufds[i].fd, &fds_read)) { + if(ufds[i].events & POLLRDNORM) + ufds[i].revents |= POLLRDNORM; + if(ufds[i].events & POLLIN) + ufds[i].revents |= POLLIN; + } + if(FD_ISSET(ufds[i].fd, &fds_write)) { + if(ufds[i].events & POLLWRNORM) + ufds[i].revents |= POLLWRNORM; + if(ufds[i].events & POLLOUT) + ufds[i].revents |= POLLOUT; + } + if(FD_ISSET(ufds[i].fd, &fds_err)) { + if(ufds[i].events & POLLRDBAND) + ufds[i].revents |= POLLRDBAND; + if(ufds[i].events & POLLPRI) + ufds[i].revents |= POLLPRI; + } + if(ufds[i].revents) + r++; + } + +#endif /* HAVE_POLL_FINE */ + + return r; +} |