__vfscanf_internal: fix aliasing violation (bug 26690)

As noted in <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97264>, the cast
in the call to the read_int function is an aliasing violation.  Change the
type of local variable f to a pointer to unsigned, which allows to
eliminate most casts while only adding three new ones.

diff --git a/stdio-common/vfscanf-internal.c b/stdio-common/vfscanf-internal.c
index 95b46dc..3a32354 100644 (file)
--- a/stdio-common/vfscanf-internal.c
+++ b/stdio-common/vfscanf-internal.c
@@ -277,7 +277,7 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr,
 #endif
 {
   va_list arg;
-  const CHAR_T *f = format;
+  const UCHAR_T *f = (const UCHAR_T *) format;
   UCHAR_T fc;  /* Current character of the format.  */
   WINT_T done = 0;     /* Assignments done.  */
   size_t read_in = 0;  /* Chars read in.  */
@@ -415,10 +415,11 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr,
 #endif
 
 #ifndef COMPILE_WSCANF
-      if (!isascii ((unsigned char) *f))
+      if (!isascii (*f))
        {
          /* Non-ASCII, may be a multibyte.  */
-         int len = __mbrlen (f, strlen (f), &state);
+         int len = __mbrlen ((const char *) f, strlen ((const char *) f),
+                             &state);
          if (len > 0)
            {
              do
@@ -426,7 +427,7 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr,
                  c = inchar ();
                  if (__glibc_unlikely (c == EOF))
                    input_error ();
-                 else if (c != (unsigned char) *f++)
+                 else if (c != *f++)
                    {
                      ungetc_not_eof (c, s);
                      conv_error ();
@@ -484,9 +485,9 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr,
       char_buffer_rewind (&charbuf);
 
       /* Check for a positional parameter specification.  */
-      if (ISDIGIT ((UCHAR_T) *f))
+      if (ISDIGIT (*f))
        {
-         argpos = read_int ((const UCHAR_T **) &f);
+         argpos = read_int (&f);
          if (*f == L_('$'))
            ++f;
          else
@@ -521,8 +522,8 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr,
 
       /* Find the maximum field width.  */
       width = 0;
-      if (ISDIGIT ((UCHAR_T) *f))
-       width = read_int ((const UCHAR_T **) &f);
+      if (ISDIGIT (*f))
+       width = read_int (&f);
     got_width:
       if (width == 0)
        width = -1;
@@ -2522,12 +2523,11 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr,
            }
 
          while ((fc = *f++) != '\0' && fc != ']')
-           if (fc == '-' && *f != '\0' && *f != ']'
-               && (unsigned char) f[-2] <= (unsigned char) *f)
+           if (fc == '-' && *f != '\0' && *f != ']' && f[-2] <= *f)
              {
                /* Add all characters from the one before the '-'
                   up to (but not including) the next format char.  */
-               for (fc = (unsigned char) f[-2]; fc < (unsigned char) *f; ++fc)
+               for (fc = f[-2]; fc < *f; ++fc)
                  ((char *)charbuf.scratch.data)[fc] = 1;
              }
            else