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-rw-r--r--src/stdio/vswprintf.c46
1 files changed, 46 insertions, 0 deletions
diff --git a/src/stdio/vswprintf.c b/src/stdio/vswprintf.c
new file mode 100644
index 00000000..4ad581fb
--- /dev/null
+++ b/src/stdio/vswprintf.c
@@ -0,0 +1,46 @@
+#include "stdio_impl.h"
+
+struct cookie {
+ wchar_t *ws;
+ size_t l;
+};
+
+static size_t sw_write(FILE *f, const unsigned char *s, size_t l)
+{
+ size_t l0 = l;
+ int i = 0;
+ struct cookie *c = f->cookie;
+ while (c->l && l && (i=mbtowc(c->ws, s, l))>=0) {
+ s+=i;
+ l-=i;
+ c->l--;
+ c->ws++;
+ }
+ *c->ws = 0;
+ return i<0 ? i : l0;
+}
+
+int vswprintf(wchar_t *s, size_t n, const wchar_t *fmt, va_list ap)
+{
+ int r;
+ FILE f;
+ unsigned char buf[256];
+ struct cookie c = { s, n-1 };
+
+ memset(&f, 0, sizeof(FILE));
+ f.lbf = EOF;
+ f.write = sw_write;
+ f.buf_size = sizeof buf;
+ f.buf = buf;
+ f.owner = -1;
+ f.cookie = &c;
+ if (!n) {
+ return -1;
+ } else if (n > INT_MAX) {
+ errno = EOVERFLOW;
+ return -1;
+ }
+ r = vfwprintf(&f, fmt, ap);
+ __oflow(&f);
+ return r>=n ? -1 : r;
+}