libc/src/termios/linux/tcgetattr.cpp

//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
///
/// \file
/// Linux implementation of tcgetattr.
///
//===----------------------------------------------------------------------===//

#include "src/termios/tcgetattr.h"
#include "hdr/termios_macros.h"
#include "hdr/types/struct_termios.h"
#include "src/__support/CPP/algorithm.h"
#include "src/__support/OSUtil/linux/syscall_wrappers/ioctl.h"
#include "src/__support/common.h"
#include "src/__support/libc_errno.h"
#include "src/__support/macros/null_check.h"
#include "src/termios/linux/kernel_termios.h"
#include "src/termios/linux/speed_utils.h"

#include <asm/ioctls.h> // Safe to include without the risk of name pollution.

namespace LIBC_NAMESPACE_DECL {

LLVM_LIBC_FUNCTION(int, tcgetattr, (int fd, termios *t)) {
  LIBC_CRASH_ON_NULLPTR(t);
  LIBC_NAMESPACE::kernel_termios kt;
  auto ret = linux_syscalls::ioctl(fd, TCGETS, &kt);
  if (!ret.has_value()) {
    libc_errno = ret.error();
    return -1;
  }
  t->c_iflag = kt.c_iflag;
  t->c_oflag = kt.c_oflag;
  t->c_cflag = kt.c_cflag;
  t->c_lflag = kt.c_lflag;
  t->c_line = kt.c_line;

  speed_t ospeed_mask = kt.c_cflag & CBAUD;
  speed_t ispeed_mask = (kt.c_cflag & CIBAUD) >> 16;
  if (ispeed_mask == 0)
    ispeed_mask = ospeed_mask;

  t->c_ospeed = decode_speed(ospeed_mask);
  t->c_ispeed = decode_speed(ispeed_mask);

  size_t nccs = cpp::min(KERNEL_NCCS, static_cast<size_t>(NCCS));
  for (size_t i = 0; i < nccs; ++i)
    t->c_cc[i] = kt.c_cc[i];
  if (NCCS > nccs) {
    for (size_t i = nccs; i < NCCS; ++i)
      t->c_cc[i] = 0;
  }
  return 0;
}

} // namespace LIBC_NAMESPACE_DECL