libc/bionic/poll.cpp

/*
 * Copyright (C) 2013 The Android Open Source Project
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *  * Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *  * Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <errno.h>
#include <sys/poll.h>
#include <sys/select.h>

#include <platform/bionic/reserved_signals.h>

#include "private/bionic_time_conversions.h"
#include "private/SigSetConverter.h"

extern "C" int __ppoll(pollfd*, unsigned int, timespec*, const sigset64_t*, size_t);
extern "C" int __pselect6(int, fd_set*, fd_set*, fd_set*, timespec*, void*);

int poll(pollfd* fds, nfds_t fd_count, int ms) {
  timespec ts;
  timespec* ts_ptr = nullptr;
  if (ms >= 0) {
    timespec_from_ms(ts, ms);
    ts_ptr = &ts;
  }
  return __ppoll(fds, fd_count, ts_ptr, nullptr, 0);
}

// The underlying ppoll(2) system call only takes `sigset64_t`.
#if defined(__LP64__)
// That's fine for LP64 where `sigset_t` and `sigset64_t` are the same.
__strong_alias(ppoll, ppoll64);
#else
// ILP32 needs a shim.
int ppoll(pollfd* fds, nfds_t fd_count, const timespec* ts, const sigset_t* ss) {
  SigSetConverter set{ss};
  return ppoll64(fds, fd_count, ts, set.ptr);
}
#endif

int ppoll64(pollfd* fds, nfds_t fd_count, const timespec* ts, const sigset64_t* ss) {
  // The underlying __ppoll system call modifies its `struct timespec` argument.
  timespec mutable_ts;
  timespec* mutable_ts_ptr = nullptr;
  if (ts != nullptr) {
    mutable_ts = *ts;
    mutable_ts_ptr = &mutable_ts;
  }

  sigset64_t mutable_ss;
  sigset64_t* mutable_ss_ptr = nullptr;
  if (ss != nullptr) {
    mutable_ss = filter_reserved_signals(*ss, SIG_SETMASK);
    mutable_ss_ptr = &mutable_ss;
  }

  return __ppoll(fds, fd_count, mutable_ts_ptr, mutable_ss_ptr, sizeof(*mutable_ss_ptr));
}

int select(int fd_count, fd_set* read_fds, fd_set* write_fds, fd_set* error_fds, timeval* tv) {
  timespec ts;
  timespec* ts_ptr = nullptr;
  if (tv != nullptr) {
    if (!timespec_from_timeval(ts, *tv)) {
      errno = EINVAL;
      return -1;
    }
    ts_ptr = &ts;
  }
  int result = __pselect6(fd_count, read_fds, write_fds, error_fds, ts_ptr, nullptr);
  if (tv != nullptr) {
    timeval_from_timespec(*tv, ts);
  }
  return result;
}

// The underlying pselect6(2) system call only takes `sigset64_t`.
#if defined(__LP64__)
// That's fine for LP64 where `sigset_t` and `sigset64_t` are the same.
__strong_alias(pselect, pselect64);
#else
// ILP32 needs a shim.
int pselect(int fd_count, fd_set* read_fds, fd_set* write_fds, fd_set* error_fds,
            const timespec* ts, const sigset_t* ss) {
  // The underlying `__pselect6` system call only takes `sigset64_t`.
  SigSetConverter set{ss};
  return pselect64(fd_count, read_fds, write_fds, error_fds, ts, set.ptr);
}
#endif

int pselect64(int fd_count, fd_set* read_fds, fd_set* write_fds, fd_set* error_fds,
              const timespec* ts, const sigset64_t* ss) {
  // The underlying __pselect6 system call modifies its `struct timespec` argument.
  timespec mutable_ts;
  timespec* mutable_ts_ptr = nullptr;
  if (ts != nullptr) {
    mutable_ts = *ts;
    mutable_ts_ptr = &mutable_ts;
  }

  sigset64_t mutable_ss;
  sigset64_t* mutable_ss_ptr = nullptr;
  if (ss != nullptr) {
    mutable_ss = filter_reserved_signals(*ss, SIG_SETMASK);
    mutable_ss_ptr = &mutable_ss;
  }

  // The Linux kernel only handles 6 arguments and this system call really needs 7,
  // so the last argument is a void* pointing to:
  struct pselect6_extra_data_t {
    uintptr_t ss_addr;
    size_t ss_len;
  };
  pselect6_extra_data_t extra_data;
  extra_data.ss_addr = reinterpret_cast<uintptr_t>(mutable_ss_ptr);
  extra_data.ss_len = sizeof(*mutable_ss_ptr);

  return __pselect6(fd_count, read_fds, write_fds, error_fds, mutable_ts_ptr, &extra_data);
}