newlib: vf[w]scanf: Drop width computation mixup

The width value keeps the maximum field width.  This is the maximum
field width of the *input*.  It's *never* to be used in conjunction
with the number of bytes or characters written to the output argument.

However, especially in vfwscanf, the code is partially taken from
NetBSD which erroneously subtracts the number of multibyte chars
written to the argument from the width variable, thus potentially
subtracting up to MB_CUR_MAX from width for a single character in
the input stream.

To make matters worse, the previous patch adding %m added basically
the same mistake for 'c' type input.

Fix it.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

2 files changed, 44 insertions, 70 deletions

diff --git a/newlib/libc/stdio/vfscanf.c b/newlib/libc/stdio/vfscanf.c
index 23d73916a..e8e4dab2e 100644
--- a/newlib/libc/stdio/vfscanf.c
+++ b/newlib/libc/stdio/vfscanf.c
@@ -945,7 +945,7 @@ _DEFUN(__SVFSCANF_R, (rptr, fp, fmt0, ap),
 #ifdef _WANT_IO_POSIX_EXTENSIONS
 	      wchar_t **wcp_p = NULL;
 	      wchar_t *wcp0 = NULL;
-	      size_t width0 = 0;
+	      size_t wcp_siz = 0;
 #endif
               mbstate_t state;
               memset (&state, 0, sizeof (mbstate_t));
@@ -953,12 +953,12 @@ _DEFUN(__SVFSCANF_R, (rptr, fp, fmt0, ap),
                 wcp = NULL;
 #ifdef _WANT_IO_POSIX_EXTENSIONS
 	      else if (flags & MALLOC)
-		width0 = alloc_m_ptr (wchar_t, wcp, wcp0, wcp_p, width);
+		wcp_siz = alloc_m_ptr (wchar_t, wcp, wcp0, wcp_p, 32);
 #endif
               else
                 wcp = GET_ARG (N, ap, wchar_t *);
               n = 0;
-              while (width != 0)
+              while (width-- != 0)
                 {
                   if (n == MB_CUR_MAX)
                     goto input_failure;
@@ -973,9 +973,14 @@ _DEFUN(__SVFSCANF_R, (rptr, fp, fmt0, ap),
                   if (mbslen != (size_t)-2) /* Incomplete sequence */
                     {
                       nread += n;
-                      width -= 1;
                       if (!(flags & SUPPRESS))
-                        wcp += 1;
+			{
+#ifdef _WANT_IO_POSIX_EXTENSIONS
+			  wcp_siz = realloc_m_ptr (wchar_t, wcp, wcp0, wcp_p,
+						   wcp_siz);
+#endif
+			  wcp++;
+			}
                       n = 0;
                     }
                   if (BufferEmpty)
@@ -986,7 +991,7 @@ _DEFUN(__SVFSCANF_R, (rptr, fp, fmt0, ap),
                     }
                 }
 #ifdef _WANT_IO_POSIX_EXTENSIONS
-	      shrink_m_ptr (wchar_t, wcp_p, width0 - width, width0);
+	      shrink_m_ptr (wchar_t, wcp_p, wcp - wcp0, wcp_siz);
 #endif
               if (!(flags & SUPPRESS))
                 nassigned++;
@@ -1134,6 +1139,7 @@ _DEFUN(__SVFSCANF_R, (rptr, fp, fmt0, ap),
                   buf[n++] = *fp->_p;
                   fp->_r -= 1;
                   fp->_p += 1;
+		  width--;
                   if ((mbslen = _mbrtowc_r (rptr, wcp, buf, n, &state))
                                                         == (size_t)-1)
                     goto input_failure;
@@ -1148,7 +1154,6 @@ _DEFUN(__SVFSCANF_R, (rptr, fp, fmt0, ap),
                           break;
                         }
                       nread += n;
-                      width -= 1;
                       if ((flags & SUPPRESS) == 0)
 			{
 			  wcp += 1;
diff --git a/newlib/libc/stdio/vfwscanf.c b/newlib/libc/stdio/vfwscanf.c
index 46c156694..a317eae44 100644
--- a/newlib/libc/stdio/vfwscanf.c
+++ b/newlib/libc/stdio/vfwscanf.c
@@ -376,7 +376,6 @@ _DEFUN(__SVFWSCANF_R, (rptr, fp, fmt0, ap),
   wint_t wi;                    /* handy wint_t */
   char *mbp = NULL;             /* multibyte string pointer for %c %s %[ */
   size_t nconv;                 /* number of bytes in mb. conversion */
-  char mbbuf[MB_LEN_MAX];       /* temporary mb. character buffer */
 
   char *cp;
   short *sp;
@@ -884,14 +883,14 @@ _DEFUN(__SVFWSCANF_R, (rptr, fp, fmt0, ap),
 #ifdef _WANT_IO_POSIX_EXTENSIONS
 	      wchar_t **p_p = NULL;
 	      wchar_t *p0 = NULL;
-	      size_t width0 = 0;
+	      size_t p_siz = 0;
 #endif
 
 	      if (flags & SUPPRESS)
 		;
 #ifdef _WANT_IO_POSIX_EXTENSIONS
 	      else if (flags & MALLOC)
-		width0 = alloc_m_ptr (wchar_t, p, p0, p_p, width);
+		p_siz = alloc_m_ptr (wchar_t, p, p0, p_p, 32);
 #endif
 	      else
 		p = GET_ARG(N, ap, wchar_t *);
@@ -899,14 +898,20 @@ _DEFUN(__SVFWSCANF_R, (rptr, fp, fmt0, ap),
 	      while (width-- != 0 && (wi = _fgetwc_r (rptr, fp)) != WEOF)
 		{
 		  if (!(flags & SUPPRESS))
-		    *p++ = (wchar_t) wi;
+		    {
+#ifdef _WANT_IO_POSIX_EXTENSIONS
+		      /* Check before ++ because we never add a \0 */
+		      p_siz = realloc_m_ptr (wchar_t, p, p0, p_p, p_siz);
+#endif
+		      *p++ = (wchar_t) wi;
+		    }
 		  n++;
 		}
 	      if (n == 0)
 		goto input_failure;
 	      nread += n;
 #ifdef _WANT_IO_POSIX_EXTENSIONS
-	      shrink_m_ptr (wchar_t, p_p, width0 - width, width0);
+	      shrink_m_ptr (wchar_t, p_p, p - p0, p_siz);
 #endif
 	      if (!(flags & SUPPRESS))
 		nassigned++;
@@ -916,50 +921,38 @@ _DEFUN(__SVFWSCANF_R, (rptr, fp, fmt0, ap),
 #ifdef _WANT_IO_POSIX_EXTENSIONS
 	      char **mbp_p = NULL;
 	      char *mbp0 = NULL;
-	      size_t width0 = 0;
+	      size_t mbp_siz = 0;
 #endif
 
 	      if (flags & SUPPRESS)
 		;
 #ifdef _WANT_IO_POSIX_EXTENSIONS
 	      else if (flags & MALLOC)
-		width0 = alloc_m_ptr (char, mbp, mbp0, mbp_p, width);
+		mbp_siz = alloc_m_ptr (char, mbp, mbp0, mbp_p, 32);
 #endif
 	      else
 		mbp = GET_ARG(N, ap, char *);
 	      n = 0;
 	      memset ((_PTR)&mbs, '\0', sizeof (mbstate_t));
-	      while (width != 0 && (wi = _fgetwc_r (rptr, fp)) != WEOF)
+	      while (width-- != 0 && (wi = _fgetwc_r (rptr, fp)) != WEOF)
 		{
-		  if (width >= MB_CUR_MAX && !(flags & SUPPRESS))
+#ifdef _WANT_IO_POSIX_EXTENSIONS
+		  mbp_siz = realloc_m_ptr (char, mbp, mbp0, mbp_p, mbp_siz);
+#endif
+		  if (!(flags & SUPPRESS))
 		    {
 		      nconv = _wcrtomb_r (rptr, mbp, wi, &mbs);
 		      if (nconv == (size_t) -1)
 			goto input_failure;
+		      mbp += nconv;
 		    }
-		  else
-		    {
-		      nconv = _wcrtomb_r (rptr, mbbuf, wi, &mbs);
-		      if (nconv == (size_t) -1)
-			goto input_failure;
-		      if (nconv > width)
-			{
-			  _ungetwc_r (rptr, wi, fp);
-			  break;
-			}
-		      if (!(flags & SUPPRESS))
-			memcpy(mbp, mbbuf, nconv);
-		    }
-		  if (!(flags & SUPPRESS))
-		    mbp += nconv;
-		  width -= nconv;
 		  n++;
 		}
 	      if (n == 0)
 		goto input_failure;
 	      nread += n;
 #ifdef _WANT_IO_POSIX_EXTENSIONS
-	      shrink_m_ptr (char, mbp_p, width0 - width, width0);
+	      shrink_m_ptr (char, mbp_p, mbp - mbp0, mbp_siz);
 #endif
 	      if (!(flags & SUPPRESS))
 		nassigned++;
@@ -1031,30 +1024,18 @@ _DEFUN(__SVFWSCANF_R, (rptr, fp, fmt0, ap),
 	      n = 0;
 	      memset ((_PTR) &mbs, '\0', sizeof (mbstate_t));
 	      while ((wi = _fgetwc_r (rptr, fp)) != WEOF
-		     && width != 0 && INCCL (wi))
+		     && width-- != 0 && INCCL (wi))
 		{
-#ifdef _WANT_IO_POSIX_EXTENSIONS
-		  mbp_siz = realloc_m_ptr (char, mbp, mbp0, mbp_p, mbp_siz);
-#endif
-		  if (width >= MB_CUR_MAX && !(flags & SUPPRESS))
+		  if (!(flags & SUPPRESS))
 		    {
 		      nconv = _wcrtomb_r (rptr, mbp, wi, &mbs);
 		      if (nconv == (size_t) -1)
 			goto input_failure;
+		      mbp += nconv;
+#ifdef _WANT_IO_POSIX_EXTENSIONS
+		      mbp_siz = realloc_m_ptr (char, mbp, mbp0, mbp_p, mbp_siz);
+#endif
 		    }
-		  else
-		    {
-		      nconv = wcrtomb(mbbuf, wi, &mbs);
-		      if (nconv == (size_t) -1)
-			goto input_failure;
-		      if (nconv > width)
-			break;
-		      if (!(flags & SUPPRESS))
-			memcpy(mbp, mbbuf, nconv);
-		    }
-		  if (!(flags & SUPPRESS))
-		    mbp += nconv;
-		  width -= nconv;
 		  n++;
 		}
 	      if (wi != WEOF)
@@ -1098,10 +1079,10 @@ _DEFUN(__SVFWSCANF_R, (rptr, fp, fmt0, ap),
 		     && width-- != 0 && !iswspace (wi))
 		{
 		  *p++ = (wchar_t) wi;
-		  nread++;
 #ifdef _WANT_IO_POSIX_EXTENSIONS
 		  p_siz = realloc_m_ptr (wchar_t, p, p0, p_p, p_siz);
 #endif
+		  nread++;
 		}
 	      if (wi != WEOF)
 		_ungetwc_r (rptr, wi, fp);
@@ -1129,30 +1110,18 @@ _DEFUN(__SVFWSCANF_R, (rptr, fp, fmt0, ap),
 		mbp = GET_ARG(N, ap, char *);
 	      memset ((_PTR) &mbs, '\0', sizeof (mbstate_t));
 	      while ((wi = _fgetwc_r (rptr, fp)) != WEOF
-		     && width != 0 && !iswspace (wi))
+		     && width-- != 0 && !iswspace (wi))
 		{
-#ifdef _WANT_IO_POSIX_EXTENSIONS
-		  mbp_siz = realloc_m_ptr (char, mbp, mbp0, mbp_p, mbp_siz);
-#endif
-		  if (width >= MB_CUR_MAX && !(flags & SUPPRESS))
+		  if (!(flags & SUPPRESS))
 		    {
 		      nconv = wcrtomb(mbp, wi, &mbs);
 		      if (nconv == (size_t)-1)
 			goto input_failure;
+		      mbp += nconv;
+#ifdef _WANT_IO_POSIX_EXTENSIONS
+		      mbp_siz = realloc_m_ptr (char, mbp, mbp0, mbp_p, mbp_siz);
+#endif
 		    }
-		  else
-		    {
-		      nconv = wcrtomb(mbbuf, wi, &mbs);
-		      if (nconv == (size_t)-1)
-			goto input_failure;
-		      if (nconv > width)
-			break;
-		      if (!(flags & SUPPRESS))
-			memcpy(mbp, mbbuf, nconv);
-		    }
-		  if (!(flags & SUPPRESS))
-		    mbp += nconv;
-		  width -= nconv;
 		  nread++;
 		}
 	      if (wi != WEOF)