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 [170.10.133.124]) by sourceware.org (Postfix) with ESMTP id 89853384842A for ; Tue, 25 May 2021 08:41:48 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 89853384842A 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-580-foBbqjRjPV60UXgLCmwiVQ-1; Tue, 25 May 2021 04:41:46 -0400 X-MC-Unique: foBbqjRjPV60UXgLCmwiVQ-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 DF0F41883522; Tue, 25 May 2021 08:41:45 +0000 (UTC) Received: from oldenburg.str.redhat.com (ovpn-113-228.ams2.redhat.com [10.36.113.228]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 12D8C60BF1; Tue, 25 May 2021 08:41:44 +0000 (UTC) From: Florian Weimer To: Fengkai Sun via Libc-help Cc: Fengkai Sun Subject: Re: Can LD_PRELOAD set different symbol definitions for shared objects and executable? References: Date: Tue, 25 May 2021 10:41:43 +0200 In-Reply-To: (Fengkai Sun via Libc-help's message of "Tue, 25 May 2021 10:35:20 +0800") Message-ID: <87eedv19yw.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (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=-6.7 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: Tue, 25 May 2021 08:41:49 -0000 * Fengkai Sun via Libc-help: > For example, if I set LD_PRELOAD="./mymalloc.so", then all references to > malloc will be interposed. There is no way to specify a custom allocator > only for shared objects(maybe I can make a difference in the source code of > custom malloc, but that's off topic). Yes, LD_* variables are captured at startup, and changing their values later using setenv etc. does not have an impact on the current process. > I wonder if there is any way to do this, or if I missed out some > fundamental ideas. It is possible to do this using the LD_AUDIT framework. Thanks, Florian