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Tue, 28 Nov 2023 06:01:50 -0800 (PST) Received: from localhost.localdomain ([2001:448a:20a0:8364:1de5:f731:fb48:6e20]) by smtp.gmail.com with ESMTPSA id du22-20020a056a002b5600b006cbaf63d14bsm8950471pfb.75.2023.11.28.06.01.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Nov 2023 06:01:49 -0800 (PST) From: James Tirta Halim To: wilco.dijkstra@arm.com Cc: libc-alpha@sourceware.org, tirtajames45@gmail.com Subject: [PATCH] strcasestr: try to find non-alpha char in NEEDLE Date: Tue, 28 Nov 2023 21:01:37 +0700 Message-ID: <20231128140137.81955-1-tirtajames45@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: References: MIME-Version: 1.0 X-Spam-Status: No, score=-12.0 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_ENVFROM_END_DIGIT, FREEMAIL_FROM, GIT_PATCH_0, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.30 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: libc-alpha-bounces+patchwork=sourceware.org@sourceware.org --- string/strcasestr.c | 37 ++++++++++++++++++++++++++++++------- 1 file changed, 30 insertions(+), 7 deletions(-) diff --git a/string/strcasestr.c b/string/strcasestr.c index 2f6b4f8641..65eae2f047 100644 --- a/string/strcasestr.c +++ b/string/strcasestr.c @@ -54,7 +54,6 @@ #define STRCASESTR __strcasestr #endif - /* Find the first occurrence of NEEDLE in HAYSTACK, using case-insensitive comparison. This function gives unspecified results in multibyte locales. */ @@ -63,18 +62,42 @@ STRCASESTR (const char *haystack, const char *needle) { size_t needle_len; /* Length of NEEDLE. */ size_t haystack_len; /* Known minimum length of HAYSTACK. */ + const char *h, *n; /* Handle empty NEEDLE special case. */ if (needle[0] == '\0') return (char *) haystack; - /* Ensure HAYSTACK length is at least as long as NEEDLE length. - Since a match may occur early on in a huge HAYSTACK, use strnlen - and read ahead a few cachelines for improved performance. */ - needle_len = strlen (needle); - haystack_len = __strnlen (haystack, needle_len + 256); - if (haystack_len < needle_len) + /* Try to find a non-alphanumeric character in NEEDLE to pass to + strchr() while checking if HAYSTACK is as long as NEEDLE. */ + for (h = haystack, n = needle; *h && isalpha (*n); ++h, ++n); + if (__glibc_unlikely (*h == '\0')) return NULL; + if (*n) { + size_t shift; + shift = n - needle; + haystack = strchr (h + shift, *n); + if (__glibc_unlikely (haystack == NULL)) + return NULL; + haystack -= shift; + /* Check if we have an early match. */ + for (h = haystack, n = needle; TOLOWER (*h) == TOLOWER (*n) && *h; ++h, ++n); + if (*n == '\0') + return (char *)haystack; + if (__glibc_unlikely (*h == '\0')) + return NULL; + if ((size_t) (n - needle) > shift) + shift = n - needle; + /* Since a match may occur early on in a huge HAYSTACK, use strnlen + and read ahead a few cachelines for improved performance. */ + needle_len = shift + strlen (needle + shift); + haystack_len = shift + __strnlen (h + shift, 256); + if (__glibc_unlikely (haystack_len < needle_len)) + return NULL; + } else { + needle_len = n - needle; + haystack_len = needle_len + __strnlen (haystack + needle_len, 256); + } /* Perform the search. Abstract memory is considered to be an array of 'unsigned char' values, not an array of 'char' values. See