| 1 | //===-- Linux implementation of isatty ------------------------------------===// |
|---|---|
| 2 | // |
| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| 4 | // See https://llvm.org/LICENSE.txt for license information. |
| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| 6 | // |
| 7 | //===----------------------------------------------------------------------===// |
| 8 | |
| 9 | #include "src/unistd/isatty.h" |
| 10 | |
| 11 | #include "src/__support/OSUtil/syscall.h" // For internal syscall function. |
| 12 | #include "src/__support/common.h" |
| 13 | |
| 14 | #include "src/errno/libc_errno.h" |
| 15 | #include <sys/ioctl.h> // For ioctl numbers. |
| 16 | #include <sys/syscall.h> // For syscall numbers. |
| 17 | |
| 18 | namespace LIBC_NAMESPACE { |
| 19 | |
| 20 | LLVM_LIBC_FUNCTION(int, isatty, (int fd)) { |
| 21 | constexpr int INIT_VAL = 0x1234abcd; |
| 22 | int line_d_val = INIT_VAL; |
| 23 | // This gets the line dicipline of the terminal. When called on something that |
| 24 | // isn't a terminal it doesn't change line_d_val and returns -1. |
| 25 | int result = |
| 26 | LIBC_NAMESPACE::syscall_impl<int>(SYS_ioctl, ts: fd, TIOCGETD, ts: &line_d_val); |
| 27 | if (result == 0) |
| 28 | return 1; |
| 29 | |
| 30 | libc_errno = -result; |
| 31 | return 0; |
| 32 | } |
| 33 | |
| 34 | } // namespace LIBC_NAMESPACE |
| 35 |