1 files changed, 22 insertions, 0 deletions
diff --git a/libc-bottom-half/sources/isatty.c b/libc-bottom-half/sources/isatty.c
new file mode 100644
index 0000000..c6f8662
--- /dev/null
+++ b/libc-bottom-half/sources/isatty.c
@@ -0,0 +1,22 @@
+#include <wasi/api.h>
+#include <__errno.h>
+#include <__function___isatty.h>
+
+int __isatty(int fd) {
+    __wasi_fdstat_t statbuf;
+    int r = __wasi_fd_fdstat_get(fd, &statbuf);
+    if (r != 0) {
+        errno = r;
+        return 0;
+    }
+
+    // A tty is a character device that we can't seek or tell on.
+    if (statbuf.fs_filetype != __WASI_FILETYPE_CHARACTER_DEVICE ||
+        (statbuf.fs_rights_base & (__WASI_RIGHTS_FD_SEEK | __WASI_RIGHTS_FD_TELL)) != 0) {
+        errno = __WASI_ERRNO_NOTTY;
+        return 0;
+    }
+
+    return 1;
+}
+extern __typeof(__isatty) isatty __attribute__((weak, alias("__isatty")));