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Hi! As the testcase shows, if length passed to memchr is above half of address space length, memchr will return NULL instead of the correct result. 2009-06-16 Jakub Jelinek <jakub@redhat.com> * sysdeps/x86_64/memchr.S (memchr): Use unsigned instead of signed comparisons. * string/test-memchr.c (do_random_tests): Test very large lengths as well. --- libc/sysdeps/x86_64/memchr.S.jj 2009-05-16 19:23:47.000000000 +0200 +++ libc/sysdeps/x86_64/memchr.S 2009-06-16 19:04:08.000000000 +0200 @@ -41,7 +41,7 @@ ENTRY (memchr) movl $16, %esi jnz 1f cmpq %rsi, %rdx - jle 3f + jbe 3f 2: movdqa (%rdi,%rsi), %xmm0 leaq 16(%rsi), %rsi @@ -50,7 +50,7 @@ ENTRY (memchr) testl %ecx, %ecx jnz 1f cmpq %rsi, %rdx - jg 2b + ja 2b 3: xorl %eax, %eax ret @@ -60,7 +60,7 @@ ENTRY (memchr) addq %rcx, %rax leaq -16(%rsi,%rcx), %rsi cmpq %rsi, %rdx - jle 3b + jbe 3b ret END (memchr) --- libc/string/test-memchr.c.jj 2009-05-16 19:23:37.000000000 +0200 +++ libc/string/test-memchr.c 2009-06-16 18:48:34.000000000 +0200 @@ -1,5 +1,5 @@ /* Test and measure memchr functions. - Copyright (C) 1999, 2002, 2003, 2005 Free Software Foundation, Inc. + Copyright (C) 1999, 2002, 2003, 2005, 2009 Free Software Foundation, Inc. This file is part of the GNU C Library. Written by Jakub Jelinek <jakub@redhat.com>, 1999. @@ -144,7 +144,12 @@ do_random_tests (void) } if (pos < len) - result = (char *) (p + pos + align); + { + size_t r = random (); + if ((r & 31) == 0) + len = ~(uintptr_t) (p + align) - ((r >> 5) & 31); + result = (char *) (p + pos + align); + } else result = NULL; Jakub
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