From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [63.128.21.124]) by sourceware.org (Postfix) with ESMTP id 956903846078 for ; Wed, 17 Mar 2021 21:03:55 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 956903846078 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-522-phVYj8oqNtmUY6nmw6OsAg-1; Wed, 17 Mar 2021 17:03:53 -0400 X-MC-Unique: phVYj8oqNtmUY6nmw6OsAg-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 45D6B800D53; Wed, 17 Mar 2021 21:03:52 +0000 (UTC) Received: from oldenburg.str.redhat.com (ovpn-115-121.ams2.redhat.com [10.36.115.121]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 50EE62B1A1; Wed, 17 Mar 2021 21:03:51 +0000 (UTC) From: Florian Weimer To: Godmar Back Cc: Ian Pilcher via Libc-help , Ian Pilcher Subject: Re: Bug or not? printf allocates buffer & never frees it References: <87h7l91xnu.fsf@oldenburg.str.redhat.com> Date: Wed, 17 Mar 2021 22:03:57 +0100 In-Reply-To: (Godmar Back's message of "Wed, 17 Mar 2021 16:47:31 -0400") Message-ID: <87a6r1wkzm.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-6.6 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H4, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-help@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-help mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 17 Mar 2021 21:03:56 -0000 * Godmar Back: > Is GNU libc designed to be used in environments that do not deallocate > all memory upon exit(), i.e., environments that can call exit() > multiple times without being provided with a fresh heap each time? I > understand ISO C allows this and POSIX is quiet on this specific > issue. Is complete deallocation of one-time buffers before exit() a > design goal of GNU libc? Not really. None of the currently supported targets behave in that way. We have __libc_freeres to clean up *after* exit (and atexit handlers etc.), but it only exists for leak debuggers. valgrind can call it, for example, and we also call it in mtrace mode. It's also a bit of a reasonable effort thing: there are allocations we currently do not free, particularly around dlopen. Thanks, Florian