[libc] Add termios.h and the implementation of functions declared in it.

Reviewed By: lntue, michaelrj

Differential Revision: https://reviews.llvm.org/D136143

1 files changed, 31 insertions, 0 deletions

diff --git a/libc/src/termios/linux/tcgetsid.cpp b/libc/src/termios/linux/tcgetsid.cpp
new file mode 100644
index 000000000000..8f0923431a42
--- /dev/null
+++ b/libc/src/termios/linux/tcgetsid.cpp
@@ -0,0 +1,31 @@
+//===-- Linux implementation of tcgetsid ----------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/termios/tcgetsid.h"
+
+#include "src/__support/OSUtil/syscall.h"
+#include "src/__support/common.h"
+
+#include <asm/ioctls.h> // Safe to include without the risk of name pollution.
+#include <errno.h>
+#include <sys/syscall.h> // For syscall numbers
+#include <termios.h>
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(pid_t, tcgetsid, (int fd)) {
+  pid_t sid;
+  long ret = __llvm_libc::syscall_impl(SYS_ioctl, fd, TIOCGSID, &sid);
+  if (ret < 0) {
+    errno = -ret;
+    return -1;
+  }
+  return sid;
+}
+
+} // namespace __llvm_libc