Bug 81859 points out that my fix for bug 81586 wasn't quite
right (or complete): the argument of a %.*s directive need
not be a nul-terminated string when the precision is less
than the initialized size of the array the argument points
to. The attached tweak uses strnlen to avoid reading past
the end of a non-nul terminated array.
The patch has been tested on x86_64-linux and by running
self tests under Valgrind. I'll go ahead and commit it as
obvious sometime later today if there are no objections in
the meantime.
Martin
PR c/81859 - [8 Regression] valgrind error from warn_about_normalization
gcc/ChangeLog:
PR c/81859
* pretty-print.c (pp_format): Use strnlen in %.*s to avoid reading
past the end of an array.
(test_pp_format): Add test cases.
Index: gcc/pretty-print.c
===================================================================
--- gcc/pretty-print.c (revision 251100)
+++ gcc/pretty-print.c (working copy)
@@ -668,15 +668,11 @@ pp_format (pretty_printer *pp, text_info *text)
s = va_arg (*text->args_ptr, const char *);
- /* Negative precision is treated as if it were omitted. */
- if (n < 0)
- n = INT_MAX;
+ /* Append the lesser of precision and strlen (s) characters
+ from the array (which need not be a nul-terminated string).
+ Negative precision is treated as if it were omitted. */
+ size_t len = n < 0 ? strlen (s) : strnlen (s, n);
- /* Append the lesser of precision and strlen (s) characters. */
- size_t len = strlen (s);
- if ((unsigned) n < len)
- len = n;
-
pp_append_text (pp, s, s + len);
}
break;
@@ -1438,6 +1434,13 @@ test_pp_format ()
ASSERT_PP_FORMAT_2 ("A 12345678", "%c %x", 'A', 0x12345678);
ASSERT_PP_FORMAT_2 ("hello world 12345678", "%s %x", "hello world",
0x12345678);
+
+ /* Not nul-terminated. */
+ char arr[5] = { '1', '2', '3', '4', '5' };
+ ASSERT_PP_FORMAT_2 ("123", "%.*s", 3, arr);
+ ASSERT_PP_FORMAT_2 ("1234", "%.*s", -1, "1234");
+ ASSERT_PP_FORMAT_2 ("12345", "%.*s", 7, "12345");
+
/* We can't test for %p; the pointer is printed in an implementation-defined
manner. */
ASSERT_PP_FORMAT_2 ("normal colored normal 12345678",
