implement open_wmemstream

not heavily tested, but it seems to be correct, including the odd
behavior that seeking is in terms of wide character count. this
precludes any simple buffering, so we just make the stream unbuffered.

1 files changed, 95 insertions, 0 deletions

diff --git a/src/stdio/open_wmemstream.c b/src/stdio/open_wmemstream.c
new file mode 100644
index 00000000..5402ca1a
--- /dev/null
+++ b/src/stdio/open_wmemstream.c
@@ -0,0 +1,95 @@
+#include "stdio_impl.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;
+	switch (whence) {
+	case SEEK_SET:
+		base = 0;
+		break;
+	case SEEK_CUR:
+		base = c->pos;
+		break;
+	case SEEK_END:
+		base = c->len;
+		break;
+	default:
+	fail:
+		errno = EINVAL;
+		return -1;
+	}
+	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->space - c->pos) {
+		len2 = 2*c->space+1 | c->space+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, 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;
+	if (!(f=malloc(sizeof *f + sizeof *c))) 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 = 0;
+	c->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;
+		f->next = libc.ofl_head;
+		if (libc.ofl_head) libc.ofl_head->prev = f;
+		libc.ofl_head = f;
+	}
+
+	return f;
+}