From owner-freebsd-hackers@freebsd.org Tue Jul 2 02:54:31 2019 Return-Path: Delivered-To: freebsd-hackers@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 46E2415C1AC7 for ; Tue, 2 Jul 2019 02:54:31 +0000 (UTC) (envelope-from yuri@rawbw.com) Received: from shell1.rawbw.com (shell1.rawbw.com [198.144.192.42]) by mx1.freebsd.org (Postfix) with ESMTP id 4BC3B6A228 for ; Tue, 2 Jul 2019 02:54:30 +0000 (UTC) (envelope-from yuri@rawbw.com) Received: from yv.noip.me (c-67-180-169-236.hsd1.ca.comcast.net [67.180.169.236]) (authenticated bits=0) by shell1.rawbw.com (8.15.1/8.15.1) with ESMTPSA id x622sSFv093517 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NO) for ; Mon, 1 Jul 2019 19:54:28 -0700 (PDT) (envelope-from yuri@rawbw.com) X-Authentication-Warning: shell1.rawbw.com: Host c-67-180-169-236.hsd1.ca.comcast.net [67.180.169.236] claimed to be yv.noip.me To: Freebsd hackers list From: Yuri Subject: Question: Is there a way to get the list of all dynamic libraries needed by a given elf through API? Message-ID: Date: Mon, 1 Jul 2019 19:54:27 -0700 User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Rspamd-Queue-Id: 4BC3B6A228 X-Spamd-Bar: ---- Authentication-Results: mx1.freebsd.org; spf=pass (mx1.freebsd.org: domain of yuri@rawbw.com designates 198.144.192.42 as permitted sender) smtp.mailfrom=yuri@rawbw.com X-Spamd-Result: default: False [-4.87 / 15.00]; RCVD_VIA_SMTP_AUTH(0.00)[]; R_SPF_ALLOW(-0.20)[+ip4:198.144.192.32/27]; HAS_XAW(0.00)[]; TO_DN_ALL(0.00)[]; MX_GOOD(-0.01)[cached: mx.rawbw.net]; NEURAL_HAM_SHORT(-0.84)[-0.835,0]; RCVD_NO_TLS_LAST(0.10)[]; RECEIVED_SPAMHAUS_PBL(0.00)[236.169.180.67.zen.spamhaus.org : 127.0.0.10]; FROM_EQ_ENVFROM(0.00)[]; R_DKIM_NA(0.00)[]; ASN(0.00)[asn:7961, ipnet:198.144.192.0/20, country:US]; MIME_TRACE(0.00)[0:+]; MID_RHS_MATCH_FROM(0.00)[]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-1.00)[-1.000,0]; FROM_HAS_DN(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000,0]; MIME_GOOD(-0.10)[text/plain]; DMARC_NA(0.00)[rawbw.com]; PREVIOUSLY_DELIVERED(0.00)[freebsd-hackers@freebsd.org]; RCPT_COUNT_ONE(0.00)[1]; SUBJECT_ENDS_QUESTION(1.00)[]; RCVD_IN_DNSWL_NONE(0.00)[42.192.144.198.list.dnswl.org : 127.0.10.0]; IP_SCORE(-2.82)[ip: (-6.28), ipnet: 198.144.192.0/20(-4.04), asn: 7961(-3.73), country: US(-0.06)]; RCVD_COUNT_TWO(0.00)[2] X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 02 Jul 2019 02:54:31 -0000 I want to get the same information that 'ldd ' returns, but from a C/C++ program without launching external processes. It is possible to find the list of elf's shared library dependencies using libelf. But I couldn't find how to map library names to full library paths. ldd(1) sets a certain environment variable, forks and calls execl(3), and the "ld.so magic" does the rest. Obviously, if one needs to do the same from their own C program, forking is a much less attractive option compared to the API way. Is there an API to find such mappings? If no, why doesn't it exist? Thank you, Yuri