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