[PATCH] Fix strtod on 0x. [BZ #3855]

[Jakub Jelinek <jakub at redhat dot com>]

Hi!

0x needs to be followed by non-empty sequence of hex digits optionally
containing the radix character to form a valid hexadecimal number for
strtod, similarly how a valid decimal float number needs to start with
non-empty sequence of decimal digits optionally containing the
radix character.
So, 0x.X should be parsed just accept just the initial 0.
For base != 16 this is handled early:
  /* Return 0.0 if no legal string is found.
     No character is used even if a sign was found.  */
#ifdef USE_WIDE_CHAR
  if (c == (wint_t) decimal
      && (wint_t) cp[1] >= L'0' && (wint_t) cp[1] <= L'9')
    {
      /* We accept it.  This funny construct is here only to indent
         the code directly.  */
    }
#else
  for (cnt = 0; decimal[cnt] != '\0'; ++cnt)
    if (cp[cnt] != decimal[cnt])
      break;
  if (decimal[cnt] == '\0' && cp[cnt] >= '0' && cp[cnt] <= '9')
    {
      /* We accept it.  This funny construct is here only to indent
         the code directly.  */
    }
#endif

Either we can handle this early too for 0x (in the if which sets
base == 16), or IMHO better just to extend the check later on,
as done in this patch.

2007-01-11  Jakub Jelinek  <jakub@redhat.com>

	[BZ #3855]
	* stdlib/strtod_l.c (____STRTOF_INTERNAL): 0x. not followed by
	hexadecimal digit should accept just the initial 0.
	* stdlib/tst-strtod2.c (tests): New variable.
	(do_test): Run several tests rather than just one.

--- libc/stdlib/strtod_l.c.jj	2007-01-11 15:43:07.000000000 +0100
+++ libc/stdlib/strtod_l.c	2007-01-11 17:10:27.000000000 +0100
@@ -1,5 +1,6 @@
 /* Convert string representing a number to float value, using given locale.
-   Copyright (C) 1997,1998,2002,2004,2005,2006 Free Software Foundation, Inc.
+   Copyright (C) 1997,1998,2002,2004,2005,2006,2007
+   Free Software Foundation, Inc.
    This file is part of the GNU C Library.
    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
 
@@ -665,14 +666,23 @@ ____STRTOF_INTERNAL (nptr, endptr, group
   if (!((c >= L_('0') && c <= L_('9'))
 	|| (base == 16 && ((CHAR_TYPE) TOLOWER (c) >= L_('a')
 			   && (CHAR_TYPE) TOLOWER (c) <= L_('f')))
+	|| (
 #ifdef USE_WIDE_CHAR
-	|| c == (wint_t) decimal
+	    c == (wint_t) decimal
 #else
-	|| ({ for (cnt = 0; decimal[cnt] != '\0'; ++cnt)
-	      if (decimal[cnt] != cp[cnt])
-		break;
-	      decimal[cnt] == '\0'; })
-#endif
+	    ({ for (cnt = 0; decimal[cnt] != '\0'; ++cnt)
+		 if (decimal[cnt] != cp[cnt])
+		   break;
+	       decimal[cnt] == '\0'; })
+#endif
+	    /* '0x.' alone is not a valid hexadecimal number.
+	       '.' alone is not valid either, but that has been checked
+	       already earlier.  */
+	    && (base != 16
+		|| cp != start_of_digits
+		|| (cp[decimal_len] >= L_('0') && cp[decimal_len] <= L_('9'))
+		|| ((CHAR_TYPE) TOLOWER (cp[decimal_len]) >= L_('a')
+		    && (CHAR_TYPE) TOLOWER (cp[decimal_len]) <= L_('f'))))
 	|| (base == 16 && (cp != start_of_digits
 			   && (CHAR_TYPE) TOLOWER (c) == L_('p')))
 	|| (base != 16 && (CHAR_TYPE) TOLOWER (c) == L_('e'))))
--- libc/stdlib/tst-strtod2.c.jj	2007-01-03 10:59:42.000000000 +0100
+++ libc/stdlib/tst-strtod2.c	2007-01-11 14:57:13.000000000 +0100
@@ -1,22 +1,41 @@
 #include <stdio.h>
 #include <stdlib.h>
 
+struct test
+{
+  const char *str;
+  double result;
+  size_t offset;
+} tests[] =
+{
+  { "0xy", 0.0, 1 },
+  { "0x.y", 0.0, 1 },
+  { "0x0.y", 0.0, 4 },
+  { "0x.0y", 0.0, 4 },
+  { ".y", 0.0, 0 },
+  { "0.y", 0.0, 2 },
+  { ".0y", 0.0, 2 }
+};
+
 static int
 do_test (void)
 {
   int status = 0;
-  const char s[] = "0x";
-  char *ep;
-  double r = strtod (s, &ep);
-  if (r != 0)
-    {
-      printf ("r = %g, expect 0\n", r);
-      status = 1;
-    }
-  if (ep != s + 1)
+  for (size_t i = 0; i < sizeof (tests) / sizeof (tests[0]); ++i)
     {
-      printf ("strtod parsed %ju characters, expected 1\n", ep - s);
-      status = 1;
+      char *ep;
+      double r = strtod (tests[i].str, &ep);
+      if (r != tests[i].result)
+	{
+	  printf ("test %zu r = %g, expect %g\n", i, r, tests[i].result);
+	  status = 1;
+	}
+      if (ep != tests[i].str + tests[i].offset)
+	{
+	  printf ("test %zu strtod parsed %ju characters, expected %zu\n",
+		  i, ep - tests[i].str, tests[i].offset);
+	  status = 1;
+	}
     }
   return status;
 }

	Jakub