Add a "fork" of musl as //fusl.

fusl/src/stdio/__stdio_read.c

Index: fusl/src/stdio/__stdio_read.c
diff --git a/fusl/src/stdio/__stdio_read.c b/fusl/src/stdio/__stdio_read.c
new file mode 100644
index 0000000000000000000000000000000000000000..f8fa6d3bf381bd5356e0f3c7bac33286f828ea25
--- /dev/null
+++ b/fusl/src/stdio/__stdio_read.c
@@ -0,0 +1,23 @@
+#include "stdio_impl.h"
+#include <sys/uio.h>
+
+size_t __stdio_read(FILE *f, unsigned char *buf, size_t len)
+{
+	struct iovec iov[2] = {
+		{ .iov_base = buf, .iov_len = len - !!f->buf_size },
+		{ .iov_base = f->buf, .iov_len = f->buf_size }
+	};
+	ssize_t cnt;
+
+	cnt = syscall(SYS_readv, f->fd, iov, 2);
+	if (cnt <= 0) {
+		f->flags |= F_EOF ^ ((F_ERR^F_EOF) & cnt);
+		return cnt;
+	}
+	if (cnt <= iov[0].iov_len) return cnt;
+	cnt -= iov[0].iov_len;
+	f->rpos = f->buf;
+	f->rend = f->buf + cnt;
+	if (f->buf_size) buf[len-1] = *f->rpos++;
+	return len;
+}