problem in swscanf

[Shoichi Sakon]

Hi,

It seems there is a problem in swscanf.

Here is a test program.
----------------------------------------------------------
#include <stdio.h>
#include <wchar.h>
#define SIZE 100

main() {
        const wchar_t *ws = L"ab cd ef";
        wchar_t x[SIZE],y[SIZE],z[SIZE];
        int ret;

        ret = swscanf(ws, L"%3$l[ab] %2$ls %1$lc",x,y,z);
        wprintf(L"ret=%d x=%lc y=%ls z=%ls\n",ret,*x,y,z);
}
-----------------------------------------------------------

In case of l[], ls or lc format, it does not handle %n$ properly,
null character is not add, and/or return value is not correct.

I made an experimental patch to try to correct them.
Please take a look.

diff -u newlib/libc/stdio/vfwscanf.c.orig newlib/libc/stdio/vfwscanf.c
--- newlib/libc/stdio/vfwscanf.c.orig   2013-12-20 03:50:00.000000000 +0900
+++ newlib/libc/stdio/vfwscanf.c        2015-08-03 18:53:04.548889253 +0900
@@ -777,7 +777,7 @@
           if (flags & LONG)
            {
              if (!(flags & SUPPRESS))
-               p = va_arg(ap, wchar_t *);
+               p = GET_ARG(N, ap, wchar_t *);
              n = 0;
              while (width-- != 0 && (wi = _fgetwc_r (rptr, fp)) != WEOF)
                {
@@ -794,7 +794,7 @@
          else
            {
              if (!(flags & SUPPRESS))
-               mbp = va_arg(ap, char *);
+               mbp = GET_ARG(N, ap, char *);
              n = 0;
              memset ((_PTR)&mbs, '\0', sizeof (mbstate_t));
              while (width != 0 && (wi = _fgetwc_r (rptr, fp)) != WEOF)
@@ -849,7 +849,7 @@
            }
          else if (flags & LONG)
            {
-             p0 = p = va_arg(ap, wchar_t *);
+             p0 = p = GET_ARG(N, ap, wchar_t *);
              while ((wi = _fgetwc_r (rptr, fp)) != WEOF
                     && width-- != 0 && INCCL (wi))
                *p++ = (wchar_t) wi;
@@ -858,11 +858,13 @@
              n = p - p0;
              if (n == 0)
                goto match_failure;
+             *p = L'\0';
+             nassigned++;
            }
          else
            {
              if (!(flags & SUPPRESS))
-               mbp = va_arg(ap, char *);
+               mbp = GET_ARG(N, ap, char *);
              n = 0;
              memset ((_PTR) &mbs, '\0', sizeof (mbstate_t));
              while ((wi = _fgetwc_r (rptr, fp)) != WEOF
@@ -914,7 +916,7 @@
            }
          else if (flags & LONG)
            {
-             p0 = p = va_arg(ap, wchar_t *);
+             p0 = p = GET_ARG(N, ap, wchar_t *);
              while ((wi = _fgetwc_r (rptr, fp)) != WEOF
                     && width-- != 0 && !iswspace (wi))
                {
@@ -923,13 +925,13 @@
                }
              if (wi != WEOF)
                _ungetwc_r (rptr, wi, fp);
-             *p = '\0';
+             *p = L'\0';
              nassigned++;
            }
          else
            {
              if (!(flags & SUPPRESS))
-               mbp = va_arg(ap, char *);
+               mbp = GET_ARG(N, ap, char *);
              memset ((_PTR) &mbs, '\0', sizeof (mbstate_t));
              while ((wi = _fgetwc_r (rptr, fp)) != WEOF
                     && width != 0 && !iswspace (wi))

---

Shoichi Sakon
NEC Corp.