From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-2.9 required=5.0 tests=BAYES_00,FREEMAIL_FROM, MAILING_LIST_MULTI autolearn=unavailable autolearn_force=no version=3.4.4 X-Google-Thread: 103376,892f841b317b302e X-Google-Attributes: gid103376,public X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news1.google.com!news2.google.com!proxad.net!usenet-fr.net!enst.fr!melchior!cuivre.fr.eu.org!melchior.frmug.org!not-for-mail From: Marius Amado Alves Newsgroups: comp.lang.ada Subject: Re: Format string bugs & race conditions Date: Sun, 17 Oct 2004 13:28:20 +0100 Organization: Cuivre, Argent, Or Message-ID: References: <1c2f5137.0410160128.7ef88436@posting.google.com> <1097990937.246146@yasure> NNTP-Posting-Host: lovelace.ada-france.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-Trace: melchior.cuivre.fr.eu.org 1098016134 28879 212.85.156.195 (17 Oct 2004 12:28:54 GMT) X-Complaints-To: usenet@melchior.cuivre.fr.eu.org NNTP-Posting-Date: Sun, 17 Oct 2004 12:28:54 +0000 (UTC) To: comp.lang.ada@ada-france.org Return-Path: User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.4) Gecko/20030624 Netscape/7.1 (ax) X-Accept-Language: en-us, en In-Reply-To: <1097990937.246146@yasure> X-OriginalArrivalTime: 17 Oct 2004 12:28:20.0929 (UTC) FILETIME=[C9C78B10:01C4B444] X-Virus-Scanned: by amavisd-new-20030616-p10 (Debian) at ada-france.org X-BeenThere: comp.lang.ada@ada-france.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "Gateway to the comp.lang.ada Usenet newsgroup" List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Xref: g2news1.google.com comp.lang.ada:5358 Date: 2004-10-17T13:28:20+01:00 > /* If lockfile already exists, wait until it goes away. */ > while((p = fopen("lockfile", "r"))) { > fclose(p); > sleep(1); > } > /* (race) */ > p = fopen("lockfile", "w"); > /* Access the stuff which lockfile is supposed to protect from > * multiple access. But of course it doesn't. */ > fclose(p); > remove("lockfile"); > > Ada just makes it easier to implement this bug within a single > instance of the executable. No. Using files for locks is equally easy to implement and equally buggy in any language. But in Ada you would implement a lock as a protected object and be safe from race conditions by definition. Regarding format strings my experience confirms that the C approach is buggy and Ada is not. In Ada you can format even better than in C and very safely even without leaving the standard. Resources include: Put and Get procedures for all scalar types, all bases; actual format strings, COBOL picture strings, in Annex F; the 'Image attribute, handy for quick instrumentation. Happy formating :-)