From sacadmin Fri Oct 26 17:30:32 2007 Received: from sac.sfbay.sun.com (localhost [127.0.0.1]) by sac.sfbay.sun.com (8.13.8+Sun/8.13.8) with ESMTP id l9R0UWM9028512; Fri, 26 Oct 2007 17:30:32 -0700 (PDT) Received: (from ab196087@localhost) by sac.sfbay.sun.com (8.13.8+Sun/8.13.8/Submit) id l9R0UWGm028508; Fri, 26 Oct 2007 17:30:32 -0700 (PDT) Date: Fri, 26 Oct 2007 17:30:32 -0700 (PDT) From: Ali Bahrami Message-Id: <200710270030.l9R0UWGm028508@sac.sfbay.sun.com> To: PSARC-record@sac.sfbay.sun.com Subject: elfdump -T, and simplified matching [PSARC/2007/620 Self Review] Status: RO Content-Length: 570 Template Version: @(#)sac_nextcase 1.64 07/13/07 SMI This information is Copyright 2007 Sun Microsystems 1. Introduction 1.1. Project/Component Working Name: elfdump -T, and simplified matching 1.2. Name of Document Author/Supplier: Author: Ali Bahrami 1.3 Date of This Document: 26 October, 2007 4. Technical Description See the case directory for more detail 6. Resources and Schedule 6.4. Steering Committee requested information 6.4.1. Consolidation C-team Name: ON 6.5. ARC review type: Automatic 6.6. ARC Exposure: open From Ali.Bahrami@Sun.COM Fri Oct 26 17:36:25 2007 Received: from sunmail5.uk.sun.com (sunmail5.UK.Sun.COM [129.156.85.165]) by sac.sfbay.sun.com (8.13.8+Sun/8.13.8) with ESMTP id l9R0aOki028555 for ; Fri, 26 Oct 2007 17:36:25 -0700 (PDT) Received: from nwk-avmta-2.sfbay.sun.com (nwk-avmta-2.SFBay.Sun.COM [129.145.155.6]) by sunmail5.uk.sun.com (8.13.8+Sun/8.13.7/ENSMAIL,v2.2) with ESMTP id l9R0WqrE028975 for <@sunmail2sca.sfbay.sun.com:psarc-ext@sun.com>; Sat, 27 Oct 2007 01:32:53 +0100 (BST) Received: from pmxchannel-daemon.nwk-avmta-2.sfbay.sun.com by nwk-avmta-2.sfbay.sun.com (Sun Java System Messaging Server 6.2-3.04 (built Jul 15 2005)) id <0JQJ00205O6S4L00@nwk-avmta-2.sfbay.sun.com> for psarc-ext@sun.com (ORCPT psarc-ext@sun.com); Fri, 26 Oct 2007 17:32:52 -0700 (PDT) Received: from brmea-mail-2.sun.com ([192.18.98.43]) by nwk-avmta-2.sfbay.sun.com (Sun Java System Messaging Server 6.2-3.04 (built Jul 15 2005)) with ESMTP id <0JQJ00MNVO6LOA10@nwk-avmta-2.sfbay.sun.com> for psarc-ext@sun.com (ORCPT psarc-ext@sun.com); Fri, 26 Oct 2007 17:32:45 -0700 (PDT) Received: from fe-amer-10.sun.com ([192.18.109.80]) by brmea-mail-2.sun.com (8.13.6+Sun/8.12.9) with ESMTP id l9R0Wjnh021141 for ; Sat, 27 Oct 2007 00:32:45 +0000 (GMT) Received: from conversion-daemon.mail-amer.sun.com by mail-amer.sun.com (Sun Java System Messaging Server 6.2-8.04 (built Feb 28 2007)) id <0JQJ00I01O6IST00@mail-amer.sun.com> (original mail from Ali.Bahrami@Sun.COM) for psarc-ext@sun.com (ORCPT psarc-ext@sun.com); Fri, 26 Oct 2007 18:32:45 -0600 (MDT) Received: from [172.20.25.67] by mail-amer.sun.com (Sun Java System Messaging Server 6.2-8.04 (built Feb 28 2007)) with ESMTPSA id <0JQJ00D1GO6KIZ20@mail-amer.sun.com> for psarc-ext@sun.com (ORCPT psarc-ext@sun.com); Fri, 26 Oct 2007 18:32:45 -0600 (MDT) Date: Fri, 26 Oct 2007 18:32:44 -0600 From: Ali Bahrami Subject: PSARC/2007/620 elfdump -T, and simplified matching Sender: Ali.Bahrami@Sun.COM To: psarc-ext@Sun.COM Message-id: <4722872C.5000002@Sun.COM> MIME-version: 1.0 Content-type: text/plain; format=flowed; charset=ISO-8859-1 Content-transfer-encoding: 7BIT X-PMX-Version: 5.2.0.264296 User-Agent: Thunderbird 2.0.0.6 (X11/20070802) Status: RO Content-Length: 5584 I am sponsoring the following self-reviewed case for myself. I belive it qualifies for self review: The changes have limited scope, are similar to existing features, and preserve backward compatibility. I will promote it to a fastrack if an objection is raised. Release Binding: Patch/Micro -T elfdump option: Committed Behavior of (-I, -N, -T) when used without another selection option: Committed --------------------------------------------------------------------------- This case extends the command interface to the elfdump utility in two ways: 1) Adds the -T option, to allow for the selection of section and program headers by type. elfdump already has the -I option for selecting by index, and -N for selecting by name. -T will be accepted in any context where -I and -N are allowed. These three options (-I, -N, and -T) will be collectively referred to as the "match options". 2) In the case where a match option (-I, -N, -T) is used, and no other option specifying the information to be displayed is provided, elfdump will examine the object for matching sections, and will display them. The combination of these changes is expected to yield the following benefits: - Simplifies elfdump use in the common case where the user wants to display a single section. - Makes it possible to add support in elfdump for displaying new section types without necessarily requiring the addition of a new command line option to select it. - Completeness / Convenience I have placed an updated elfdump(1) manpage, documenting these features, in the case materials directory. Simplification -------------- Consider the common case where the user wishes to display the contents of the dynamic symbol table without showing any other symbol tables. Prior to this change, the syntax for that would be: % elfdump -s -N .dynsym file This is redundant. The user is required to specify that symbol tables are being dumped, something that elfdump can easily determine given the name. Furthermore, elfdump has to independently determine this anyway, so no work is saved. After this change, it suffices to simply say % elfdump -N .dynsym file It should be noted that the '-s' option is still useful in the case where the user wants to dump all symbol tables. Also, this change only takes effect in a case that was previously a usage error, so backward compatibility is preserved. Slowing Down Command Line Option Growth --------------------------------------- Prior to this change, every time we added the ability to display a new section type, we also added a new command line option for selecting it. In the early days, this made intuitive sense, and the option letters were reasonable (-s for symbol tables, etc). However, as elfdump has grown, we have ended up with a large number of options, some of which have little or no mnemonic value (e.g. -y for SHT_SUNW_syminfo). Furthermore, some of these options are rarely used, and provide little incremental value to elfdump. The change proposed by this case makes it possible to add support for new sections without adding an elfdump command line option, while allowing the user to specify that only those sections should be displayed. For example, we have an outstanding request to add dumping of ELF signature sections to elfdump: 6608612 elfdump should display .SUNW_signature section We are not planning to add a command line option for this. Instead, the user will be able to display signature sections using one of the following: % elfdump -N .SUNW_signature file % elfdump -T SHT_SUNW_SIGNATURE file The -T option does case insensitive matching, and allows the omission of the SHT_ prefix, so the second version might also be written as % elfdump -T sunw_signature file Convenience / Completeness -------------------------- Given the ability to match by index and by name, the ability to match by type is an obvious missing feature. These are the three ways in which sections and program headers are commonly specified. They are equivalent ways of specifying the same thing, but one of them will often be notably more convenient for the user than the others, depending on the particular query being made. It is usually true that well known section types have "standard" names. For instance, sections of type SHT_DYNSYM are usually named ".dynsym". However, this name is simply a convention, and not a formal requirement. The -T option allows the caller to specify the desired section more precisely. Beyond that, the ability to match based on type can be useful in the situation where sections of different type have the same name. An example of this occurs with our versioning sections. Solaris ELF objects give both version definition and version needed sections the same name (.SUNW_version): % elfdump -c -N .SUNW_version /bin/elfedit Section Header[8]: sh_name: .SUNW_version sh_addr: 0x80532cc sh_flags: [ SHF_ALLOC ] sh_size: 0x90 sh_type: [ SHT_SUNW_verneed ] sh_offset: 0x32cc sh_entsize: 0x1 (144 entries) sh_link: 7 sh_info: 4 sh_addralign: 0x4 Section Header[9]: sh_name: .SUNW_version sh_addr: 0x805335c sh_flags: [ SHF_ALLOC ] sh_size: 0x1c sh_type: [ SHT_SUNW_verdef ] sh_offset: 0x335c sh_entsize: 0x1 (28 entries) sh_link: 7 sh_info: 1 sh_addralign: 0x4 The -T option allows either one of these sections to be matched unambiguously.