From 87701a58e291bd7ac3b407d10a829dac52c9c16e Mon Sep 17 00:00:00 2001 From: Carlos O'Donell Date: Thu, 8 Oct 2015 16:34:53 -0400 Subject: strcoll: Remove incorrect STRDIFF-based optimization (Bug 18589). The optimization introduced in commit f13c2a8dff2329c6692a80176262ceaaf8a6f74e, causes regressions in sorting for languages that have digraphs that change sort order, like cs_CZ which sorts ch between h and i. My analysis shows the fast-forwarding optimization in STRCOLL advances through a digraph while possibly stopping in the middle which results in a subsequent skipping of the digraph and incorrect sorting. The optimization is incorrect as implemented and because of that I'm removing it for 2.23, and I will also commit this fix for 2.22 where it was originally introduced. This patch reverts the optimization, introduces a new bug-strcoll2.c regression test that tests both cs_CZ.UTF-8 and da_DK.ISO-8859-1 and ensures they sort one digraph each correctly. The optimization can't be applied without regressing this test. Checked on x86_64, bug-strcoll2.c fails without this patch and passes after. This will also get a fix on 2.22 which has the same bug. --- string/strcoll_l.c | 38 +------------------------------------- 1 file changed, 1 insertion(+), 37 deletions(-) (limited to 'string/strcoll_l.c') diff --git a/string/strcoll_l.c b/string/strcoll_l.c index 8f1225fc7a..35bc0e42a2 100644 --- a/string/strcoll_l.c +++ b/string/strcoll_l.c @@ -29,7 +29,6 @@ # define STRING_TYPE char # define USTRING_TYPE unsigned char # define STRCOLL __strcoll_l -# define STRDIFF __strdiff # define STRCMP strcmp # define WEIGHT_H "../locale/weight.h" # define SUFFIX MB @@ -42,20 +41,6 @@ #include "../locale/localeinfo.h" #include WEIGHT_H -#define MASK_UTF8_7BIT (1 << 7) -#define MASK_UTF8_START (3 << 6) - -size_t -STRDIFF (const STRING_TYPE *s, const STRING_TYPE *t) -{ - size_t n; - - for (n = 0; *s != '\0' && *s++ == *t++; ++n) - continue; - - return n; -} - /* Track status while looking for sequences in a string. */ typedef struct { @@ -269,29 +254,9 @@ STRCOLL (const STRING_TYPE *s1, const STRING_TYPE *s2, __locale_t l) const USTRING_TYPE *extra; const int32_t *indirect; - /* In case there is no locale specific sort order (C / POSIX). */ if (nrules == 0) return STRCMP (s1, s2); - /* Fast forward to the position of the first difference. Needs to be - encoding aware as the byte-by-byte comparison can stop in the middle - of a char sequence for multibyte encodings like UTF-8. */ - uint_fast32_t encoding = - current->values[_NL_ITEM_INDEX (_NL_COLLATE_ENCODING_TYPE)].word; - if (encoding != __cet_other) - { - size_t diff = STRDIFF (s1, s2); - if (diff > 0) - { - if (encoding == __cet_utf8 && (*(s1 + diff) & MASK_UTF8_7BIT) != 0) - do - diff--; - while (diff > 0 && (*(s1 + diff) & MASK_UTF8_START) != MASK_UTF8_START); - s1 += diff; - s2 += diff; - } - } - /* Catch empty strings. */ if (__glibc_unlikely (*s1 == '\0') || __glibc_unlikely (*s2 == '\0')) return (*s1 != '\0') - (*s2 != '\0'); @@ -358,8 +323,7 @@ STRCOLL (const STRING_TYPE *s1, const STRING_TYPE *s2, __locale_t l) byte-level comparison to ensure that we don't waste time going through multiple passes for totally equal strings before proceeding to subsequent passes. */ - if (pass == 0 && encoding == __cet_other && - STRCMP (s1, s2) == 0) + if (pass == 0 && STRCMP (s1, s2) == 0) return result; else break; -- cgit v1.2.1