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

fusl/src/stdio/open_wmemstream.c

Index: fusl/src/stdio/open_wmemstream.c
diff --git a/fusl/src/stdio/open_wmemstream.c b/fusl/src/stdio/open_wmemstream.c
new file mode 100644
index 0000000000000000000000000000000000000000..4d90cd971964f5f91f6dca091e2f2a0d82d4b934
--- /dev/null
+++ b/fusl/src/stdio/open_wmemstream.c
@@ -0,0 +1,92 @@
+#include "stdio_impl.h"
+#include <wchar.h>
+#include <errno.h>
+#include <limits.h>
+#include <string.h>
+
+struct cookie {
+	wchar_t **bufp;
+	size_t *sizep;
+	size_t pos;
+	wchar_t *buf;
+	size_t len;
+	size_t space;
+	mbstate_t mbs;
+};
+
+static off_t wms_seek(FILE *f, off_t off, int whence)
+{
+	ssize_t base;
+	struct cookie *c = f->cookie;
+	if (whence>2U) {
+fail:
+		errno = EINVAL;
+		return -1;
+	}
+	base = (size_t [3]){0, c->pos, c->len}[whence];
+	if (off < -base || off > SSIZE_MAX/4-base) goto fail;
+	memset(&c->mbs, 0, sizeof c->mbs);
+	return c->pos = base+off;
+}
+
+static size_t wms_write(FILE *f, const unsigned char *buf, size_t len)
+{
+	struct cookie *c = f->cookie;
+	size_t len2;
+	wchar_t *newbuf;
+	if (len + c->pos >= c->space) {
+		len2 = 2*c->space+1 | c->pos+len+1;
+		if (len2 > SSIZE_MAX/4) return 0;
+		newbuf = realloc(c->buf, len2*4);
+		if (!newbuf) return 0;
+		*c->bufp = c->buf = newbuf;
+		memset(c->buf + c->space, 0, 4*(len2 - c->space));
+		c->space = len2;
+	}
+	
+	len2 = mbsnrtowcs(c->buf+c->pos, (void *)&buf, len, c->space-c->pos, &c->mbs);
+	if (len2 == -1) return 0;
+	c->pos += len2;
+	if (c->pos >= c->len) c->len = c->pos;
+	*c->sizep = c->pos;
+	return len;
+}
+
+static int wms_close(FILE *f)
+{
+	return 0;
+}
+
+FILE *open_wmemstream(wchar_t **bufp, size_t *sizep)
+{
+	FILE *f;
+	struct cookie *c;
+	wchar_t *buf;
+
+	if (!(f=malloc(sizeof *f + sizeof *c))) return 0;
+	if (!(buf=malloc(sizeof *buf))) {
+		free(f);
+		return 0;
+	}
+	memset(f, 0, sizeof *f + sizeof *c);
+	f->cookie = c = (void *)(f+1);
+
+	c->bufp = bufp;
+	c->sizep = sizep;
+	c->pos = c->len = c->space = *sizep = 0;
+	c->buf = *bufp = buf;
+	*buf = 0;
+
+	f->flags = F_NORD;
+	f->fd = -1;
+	f->buf = (void *)(c+1);
+	f->buf_size = 0;
+	f->lbf = EOF;
+	f->write = wms_write;
+	f->seek = wms_seek;
+	f->close = wms_close;
+
+	if (!libc.threaded) f->lock = -1;
+
+	return __ofl_add(f);
+}