Improve isatty on POSIX (#1904)

Author: BCSharp

src/core/IronPython.Modules/nt.cs

@@ -526,8 +526,12 @@ static void linkWindows(string src, string dst) {
         }
 
         public static bool isatty(CodeContext context, int fd) {
-            if (context.LanguageContext.FileManager.TryGetStreams(fd, out var streams))
+            if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux) || RuntimeInformation.IsOSPlatform(OSPlatform.OSX)) {
+                return isattyUnix(fd);
+            }
+            if (context.LanguageContext.FileManager.TryGetStreams(fd, out var streams)) {
                 return streams.IsConsoleStream();
+            }
             return false;
         }
 

src/core/IronPython.Modules/posix.cs

@@ -206,14 +206,16 @@ public static BigInteger geteuid() {
         [SupportedOSPlatform("linux")]
         [SupportedOSPlatform("macos")]
         private static void utimeUnix(string path, long atime_ns, long utime_ns) {
-            var atime = new Timespec();
-            atime.tv_sec = atime_ns / 1_000_000_000;
-            atime.tv_nsec = atime_ns % 1_000_000_000;
-            var utime = new Timespec();
-            utime.tv_sec = utime_ns / 1_000_000_000;
-            utime.tv_nsec = utime_ns % 1_000_000_000;
-
-            if (Syscall.utimensat(Syscall.AT_FDCWD, path, new[] { atime, utime }, 0) == 0) return;
+            var atime = new Timespec {
+                tv_sec = atime_ns / 1_000_000_000,
+                tv_nsec = atime_ns % 1_000_000_000
+            };
+            var utime = new Timespec {
+                tv_sec = utime_ns / 1_000_000_000,
+                tv_nsec = utime_ns % 1_000_000_000
+            };
+
+            if (Syscall.utimensat(Syscall.AT_FDCWD, path, [atime, utime], 0) == 0) return;
             throw GetLastUnixError(path);
         }
 
@@ -225,6 +227,13 @@ private static void killUnix(int pid, int sig) {
             throw GetLastUnixError();
         }
 
+
+        [SupportedOSPlatform("linux")]
+        [SupportedOSPlatform("macos")]
+        private static bool isattyUnix(int fd) {
+            return Syscall.isatty(fd);
+        }
+
 #endif
     }
 }