1*71db0c75SAndroid Build Coastguard Worker //===-- Linux implementation of isatty ------------------------------------===// 2*71db0c75SAndroid Build Coastguard Worker // 3*71db0c75SAndroid Build Coastguard Worker // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4*71db0c75SAndroid Build Coastguard Worker // See https://llvm.org/LICENSE.txt for license information. 5*71db0c75SAndroid Build Coastguard Worker // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6*71db0c75SAndroid Build Coastguard Worker // 7*71db0c75SAndroid Build Coastguard Worker //===----------------------------------------------------------------------===// 8*71db0c75SAndroid Build Coastguard Worker 9*71db0c75SAndroid Build Coastguard Worker #include "src/unistd/isatty.h" 10*71db0c75SAndroid Build Coastguard Worker 11*71db0c75SAndroid Build Coastguard Worker #include "src/__support/OSUtil/syscall.h" // For internal syscall function. 12*71db0c75SAndroid Build Coastguard Worker #include "src/__support/common.h" 13*71db0c75SAndroid Build Coastguard Worker 14*71db0c75SAndroid Build Coastguard Worker #include "src/__support/macros/config.h" 15*71db0c75SAndroid Build Coastguard Worker #include "src/errno/libc_errno.h" 16*71db0c75SAndroid Build Coastguard Worker #include <sys/ioctl.h> // For ioctl numbers. 17*71db0c75SAndroid Build Coastguard Worker #include <sys/syscall.h> // For syscall numbers. 18*71db0c75SAndroid Build Coastguard Worker 19*71db0c75SAndroid Build Coastguard Worker namespace LIBC_NAMESPACE_DECL { 20*71db0c75SAndroid Build Coastguard Worker 21*71db0c75SAndroid Build Coastguard Worker LLVM_LIBC_FUNCTION(int, isatty, (int fd)) { 22*71db0c75SAndroid Build Coastguard Worker constexpr int INIT_VAL = 0x1234abcd; 23*71db0c75SAndroid Build Coastguard Worker int line_d_val = INIT_VAL; 24*71db0c75SAndroid Build Coastguard Worker // This gets the line dicipline of the terminal. When called on something that 25*71db0c75SAndroid Build Coastguard Worker // isn't a terminal it doesn't change line_d_val and returns -1. 26*71db0c75SAndroid Build Coastguard Worker int result = 27*71db0c75SAndroid Build Coastguard Worker LIBC_NAMESPACE::syscall_impl<int>(SYS_ioctl, fd, TIOCGETD, &line_d_val); 28*71db0c75SAndroid Build Coastguard Worker if (result == 0) 29*71db0c75SAndroid Build Coastguard Worker return 1; 30*71db0c75SAndroid Build Coastguard Worker 31*71db0c75SAndroid Build Coastguard Worker libc_errno = -result; 32*71db0c75SAndroid Build Coastguard Worker return 0; 33*71db0c75SAndroid Build Coastguard Worker } 34*71db0c75SAndroid Build Coastguard Worker 35*71db0c75SAndroid Build Coastguard Worker } // namespace LIBC_NAMESPACE_DECL 36