From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 121090 invoked by alias); 13 Mar 2019 17:20:15 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Received: (qmail 121078 invoked by uid 89); 13 Mar 2019 17:20:15 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-11.0 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_NONE,SPF_PASS autolearn=ham version=3.3.1 spammy= X-HELO: rock.gnat.com Received: from rock.gnat.com (HELO rock.gnat.com) (205.232.38.15) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Wed, 13 Mar 2019 17:20:14 +0000 Received: from localhost (localhost.localdomain [127.0.0.1]) by filtered-rock.gnat.com (Postfix) with ESMTP id 37F725612C; Wed, 13 Mar 2019 13:20:12 -0400 (EDT) Received: from rock.gnat.com ([127.0.0.1]) by localhost (rock.gnat.com [127.0.0.1]) (amavisd-new, port 10024) with LMTP id KEP4hXVkLBTf; Wed, 13 Mar 2019 13:20:12 -0400 (EDT) Received: from murgatroyd (75-166-85-218.hlrn.qwest.net [75.166.85.218]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by rock.gnat.com (Postfix) with ESMTPSA id BD3615612A; Wed, 13 Mar 2019 13:20:11 -0400 (EDT) From: Tom Tromey To: Pedro Alves Cc: Tom Tromey , gdb-patches@sourceware.org Subject: Re: [RFC 8.3 3/3] Avoid a crash in source_cache::extract_lines References: <20190308210433.32683-1-tromey@adacore.com> <20190308210433.32683-4-tromey@adacore.com> Date: Wed, 13 Mar 2019 17:20:00 -0000 In-Reply-To: (Pedro Alves's message of "Wed, 13 Mar 2019 17:07:02 +0000") Message-ID: <87va0mpu7o.fsf@tromey.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-SW-Source: 2019-03/txt/msg00275.txt.bz2 >>>>> "Pedro" == Pedro Alves writes: Pedro> Can you clarify how can first_pos end up as npos? Is that a bug in the Pedro> caller, or is it normal? The documentation doesn't seem to allow for that: Pedro> /* Get the source text for the source file in symtab S. FIRST_LINE Pedro> and LAST_LINE are the first and last lines to return; line Pedro> numbers are 1-based. If the file cannot be read, false is Pedro> returned. Otherwise, LINES_OUT is set to the desired text. The Pedro> returned text may include ANSI terminal escapes. */ I think you're just confusing first_pos and first_line here. first_pos is a local variable that's used to track the position where the first line starts: std::string::size_type first_pos = std::string::npos; [...] if (lineno == first_line) first_pos = pos; It can still be npos if first_line is greater than the number of lines in the file. Tom