path: root/contrib/libs/curl/lib/select.c

/*************************************************************************** 
 *                                  _   _ ____  _ 
 *  Project                     ___| | | |  _ \| | 
 *                             / __| | | | |_) | | 
 *                            | (__| |_| |  _ <| |___ 
 *                             \___|\___/|_| \_\_____| 
 * 
 * Copyright (C) 1998 - 2020, 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. 
 * 
 ***************************************************************************/ 
 
#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 
 
#if defined(__BEOS__) && !defined(__HAIKU__) 
/* BeOS has FD_SET defined in socket.h */ 
#include <socket.h> 
#endif 
 
#ifdef MSDOS 
#include <dos.h>  /* delay() */ 
#endif 
 
#ifdef __VXWORKS__
#include <strings.h>  /* bzero() in FD_SET */
#endif

#include <curl/curl.h> 
 
#include "urldata.h" 
#include "connect.h" 
#include "select.h" 
#include "timeval.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 citical 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;
    timediff_t tv_sec = timeout_ms / 1000;
    timediff_t tv_usec = (timeout_ms % 1000) * 1000; /* max=999999 */
#ifdef HAVE_SUSECONDS_T
#if TIMEDIFF_T_MAX > TIME_T_MAX
    /* tv_sec overflow check in case time_t is signed */
    if(tv_sec > TIME_T_MAX)
      tv_sec = TIME_T_MAX;
#endif
    pending_tv.tv_sec = (time_t)tv_sec;
    pending_tv.tv_usec = (suseconds_t)tv_usec;
#else
#if TIMEDIFF_T_MAX > INT_MAX
    /* tv_sec overflow check in case time_t is signed */
    if(tv_sec > INT_MAX)
      tv_sec = INT_MAX;
#endif
    pending_tv.tv_sec = (int)tv_sec;
    pending_tv.tv_usec = (int)tv_usec;
#endif
    r = select(0, NULL, NULL, NULL, &pending_tv); 
  }
#endif /* HAVE_POLL_FINE */ 
#endif /* USE_WINSOCK */ 
  if(r) 
    r = -1; 
  return r; 
} 
 
/* 
 * 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
 */
int Curl_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 = &pending_tv;
  if(timeout_ms < 0) {
    ptimeout = NULL;
  }
  else if(timeout_ms > 0) {
    timediff_t tv_sec = timeout_ms / 1000;
    timediff_t tv_usec = (timeout_ms % 1000) * 1000; /* max=999999 */
#ifdef HAVE_SUSECONDS_T
#if TIMEDIFF_T_MAX > TIME_T_MAX
    /* tv_sec overflow check in case time_t is signed */
    if(tv_sec > TIME_T_MAX)
      tv_sec = TIME_T_MAX;
#endif
    pending_tv.tv_sec = (time_t)tv_sec;
    pending_tv.tv_usec = (suseconds_t)tv_usec;
#elif defined(WIN32) /* maybe also others in the future */
#if TIMEDIFF_T_MAX > LONG_MAX
    /* tv_sec overflow check on Windows there we know it is long */
    if(tv_sec > LONG_MAX)
      tv_sec = LONG_MAX;
#endif
    pending_tv.tv_sec = (long)tv_sec;
    pending_tv.tv_usec = (long)tv_usec;
#else
#if TIMEDIFF_T_MAX > INT_MAX
    /* tv_sec overflow check in case time_t is signed */
    if(tv_sec > INT_MAX)
      tv_sec = INT_MAX;
#endif
    pending_tv.tv_sec = (int)tv_sec;
    pending_tv.tv_usec = (int)tv_usec;
#endif
  }
  else {
    pending_tv.tv_sec = 0;
    pending_tv.tv_usec = 0;
  }

#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
}

/*
 * 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 & (POLLRDBAND|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 & (POLLRDBAND|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)
    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 = Curl_select(maxfd, &fds_read, &fds_write, &fds_err, timeout_ms);
  if(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 != 0) 
      r++; 
  } 
 
#endif  /* HAVE_POLL_FINE */ 
 
  return r; 
} 
 
#ifdef TPF 
/* 
 * This is a replacement for select() on the TPF platform. 
 * It is used whenever libcurl calls select(). 
 * The call below to tpf_process_signals() is required because 
 * TPF's select calls are not signal interruptible. 
 * 
 * Return values are the same as select's. 
 */ 
int tpf_select_libcurl(int maxfds, fd_set *reads, fd_set *writes,
                       fd_set *excepts, struct timeval *tv)
{ 
   int rc; 
 
   rc = tpf_select_bsd(maxfds, reads, writes, excepts, tv); 
   tpf_process_signals(); 
   return rc;
} 
#endif /* TPF */