bottom part of serial port support on Unix

src/Common/src/Interop/Unix/Interop.Libraries.cs

@@ -12,6 +12,7 @@ internal static partial class Libraries
         internal const string NetSecurityNative = "System.Net.Security.Native";
         internal const string CryptoNative = "System.Security.Cryptography.Native.OpenSsl";
         internal const string CompressionNative = "System.IO.Compression.Native";
+        internal const string IOPortsNative = "System.IO.Ports.Native";
         internal const string Libdl = "libdl";
     }
 }

src/Native/Unix/CMakeLists.txt

@@ -256,6 +256,7 @@ endfunction()
 include(configure.cmake)
 
 add_subdirectory(System.IO.Compression.Native)
+add_subdirectory(System.IO.Ports.Native)
 
 add_compile_options(-Weverything)
 add_compile_options(-Wno-c++98-compat-pedantic)

src/Native/Unix/System.IO.Ports.Native/CMakeLists.txt

@@ -0,0 +1,22 @@
+project(System.IO.Ports.Native)
+
+add_library(System.IO.Ports.Native
+    SHARED
+    pal_termios.c
+    pal_serial.c
+    ${VERSION_FILE_PATH}
+)
+
+add_library(System.IO.Ports.Native-Static
+    STATIC
+    pal_termios.c
+    pal_serial.c
+    ${VERSION_FILE_PATH}
+)
+
+# Disable the "lib" prefix and override default name
+set_target_properties(System.IO.Ports.Native-Static PROPERTIES PREFIX "")
+set_target_properties(System.IO.Ports.Native-Static PROPERTIES OUTPUT_NAME System.IO.Ports.Native  CLEAN_DIRECT_OUTPUT 1)
+
+install_library_and_symbols (System.IO.Ports.Native)
+install (TARGETS System.IO.Ports.Native-Static DESTINATION .)

src/Native/Unix/System.IO.Ports.Native/pal_serial.c

@@ -0,0 +1,18 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+#include "pal_types.h"
+#include <fcntl.h>
+#include <errno.h>
+#include <pal_serial.h>
+
+
+/* Open device file in non-blocking mode and without controlling terminal */
+int SerialPortOpen(const char * name)
+{
+    int result;
+    while ((result = open(name, O_RDWR | O_NOCTTY | O_CLOEXEC | O_NONBLOCK)) < 0 && errno == EINTR);
+    return result;
+}
+

src/Native/Unix/System.IO.Ports.Native/pal_serial.h

@@ -0,0 +1,12 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+#include "pal_types.h"
+#include "pal_compiler.h"
+
+BEGIN_EXTERN_C
+
+int SerialPortOpen(const char * name);
+
+END_EXTERN_C