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