On 12/20/16 02:00, Markus Trippelsdorf wrote: > On 2016.12.20 at 01:30 -0800, H. Peter Anvin wrote: >> I'd strongly prefer a non-data-dependent solution, specifically adding >> at the top of sort_relocs(): >> >> if (!r->count) >> return; >> >> However, by my reading of the C and POSIX standards, this is a gcc >> error: qsort() should do nothing if the count is zero. > > No, it is invoking undefined behavior. H > Notice the nonnull attribute in /usr/include/stdlib.h: > > 739 /* Sort NMEMB elements of BASE, of SIZE bytes each, > 740 using COMPAR to perform the comparisons. */ > 741 extern void qsort (void *__base, size_t __nmemb, size_t __size, > 742 __compar_fn_t __compar) __nonnull ((1, 4)); > > But feel free to revert my patch and add your solution. Well, s/gcc/glibc/ then. > The qsort() function shall sort an array of nel objects, the > initial element of which is pointed to by base. The size of > each object, in bytes, is specified by the width argument. If > the nel argument has the value zero, the comparison function > pointed to by compar shall not be called and no rearrangement > shall take place. -hpa -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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