public inbox for gcc-prs@sourceware.org help / color / mirror / Atom feed
From: john.carter@tait.co.nz To: gcc-gnats@gcc.gnu.org Subject: libstdc++/7961: compare( char *) implemented incorrectly. Date: Tue, 17 Sep 2002 20:36:00 -0000 [thread overview] Message-ID: <20020918033536.25448.qmail@sources.redhat.com> (raw) >Number: 7961 >Category: libstdc++ >Synopsis: compare( char *) implemented incorrectly. >Confidential: no >Severity: non-critical >Priority: medium >Responsible: unassigned >State: open >Class: sw-bug >Submitter-Id: net >Arrival-Date: Tue Sep 17 20:36:00 PDT 2002 >Closed-Date: >Last-Modified: >Originator: john.carter@tait.co.nz >Release: gcc-3.1.1 >Organization: >Environment: All. >Description: In bits/basic_string.h template<typename _CharT, typename _Traits, typename _Alloc> inline bool operator==(const basic_string<_CharT, _Traits, _Alloc>& __lhs, const _CharT* __rhs) { return __lhs.compare(__rhs) == 0; } Which invokes in bits/basic_string.tc.... template<typename _CharT, typename _Traits, typename _Alloc> int basic_string<_CharT, _Traits, _Alloc>:: compare(const _CharT* __s) const { size_type __size = this->size(); int __r = traits_type::compare(_M_data(), __s, __size); if (!__r) __r = __size - traits_type::length(__s); return __r; } Which invokes ... bits/char_traits.h static int compare(const char_type* __s1, const char_type* __s2, size_t __n) { return memcmp(__s1, __s2, __n); } >How-To-Repeat: So this bit of code can possibly segviolate if it happens to be in the wrong place at the wrong time.... string lhs( "abc"); lhs.append( '\0', 1); lhs += "def"; lhs == "abc" >Fix: A correct implementation would be... template<typename _CharT, typename _Traits, typename _Alloc> int basic_string<_CharT, _Traits, _Alloc>:: compare(const _CharT* __s) const { size_type __size = this->size(); size_type __s_size = traits_types::length(__s); size_type __min = __size; if ( __size > __s_size) __min = __s_size; int __r = traits_type::compare(_M_data(), __s, __min); if (!__r) __r = __size - _s_size; return __r; } I haven't checked, but I suspect other code using the mem* functions in char_traits.h may suffer from the same problem. >Release-Note: >Audit-Trail: >Unformatted:
next reply other threads:[~2002-09-18 3:36 UTC|newest] Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top 2002-09-17 20:36 john.carter [this message] 2002-09-18 1:46 Andreas Schwab 2002-09-18 14:36 John Carter 2002-09-18 14:46 John Carter 2002-11-01 2:23 paolo 2002-11-01 2:36 paolo 2002-11-01 2:55 paolo 2002-11-01 7:27 paolo
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20020918033536.25448.qmail@sources.redhat.com \ --to=john.carter@tait.co.nz \ --cc=gcc-gnats@gcc.gnu.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).