{"id":767,"date":"2025-04-18T00:35:46","date_gmt":"2025-04-18T04:35:46","guid":{"rendered":"https:\/\/www.fitzsim.org\/blog\/?p=767"},"modified":"2025-04-18T00:35:46","modified_gmt":"2025-04-18T04:35:46","slug":"lisp-elf-toolkit","status":"publish","type":"post","link":"https:\/\/www.fitzsim.org\/blog\/?p=767","title":{"rendered":"Lisp ELF toolkit"},"content":{"rendered":"\n

I recently needed to generate an ELF<\/code> binary with both RPATH<\/code> and RUNPATH<\/code> entries. I could not figure out how to produce this using linker command line arguments.<\/p>\n\n\n\n

I was considering attempting a linker script, but first I switched to my Lisp<\/code> REPL<\/code> buffer 1<\/sup> and found that (ql:quickload \"elf\")<\/code> loaded a promising-looking Common Lisp ELF<\/code> library<\/a>.<\/p>\n\n\n\n

I created a stub library with RPATH<\/code> using gcc<\/code> and an empty C<\/code> file, then loaded it with (elf:read-elf)<\/code>.<\/p>\n\n\n\n

With the SLIME<\/code> inspector (M-x slime-inspect<\/code>) I could traverse the structure of the ELF<\/code> headers. I eventually found the RPATH<\/code> entry.<\/p>\n\n\n\n

In the REPL<\/code> I built up a function to search for RPATH<\/code> then push<\/code> a new RUNPATH<\/code> entry alongside it.<\/p>\n\n\n\n

It turned out the ELF<\/code> library had no support for the RUNPATH<\/code> entry, so I redefined its dyn-tag<\/code> dictionary to include it.<\/p>\n\n\n\n

After adding RUNPATH<\/code>, I wrote the modified ELF<\/code> structures to a file using (elf:write-elf)<\/code>. The generated ELF<\/code> file sufficed for the test case.<\/p>\n\n\n\n

I thought this was an interesting use case to share, demonstrating unique properties of the Lisp<\/code> environment. I published the result<\/a> (I realize now I should have written generate-example-library.sh<\/code> in Lisp<\/code> instead of shell!; oh well).<\/p>\n\n\n\n

  1. Which I have been trying to keep open lately, inspired by this post<\/a>.<\/li><\/ol>\n\n\n\n

    <\/p>\n","protected":false},"excerpt":{"rendered":"

    I recently needed to generate an ELF binary with both RPATH and RUNPATH entries. I could not figure out how to produce this using linker command line arguments. I was considering attempting a linker script, but first I switched to my Lisp REPL buffer 1 and found that (ql:quickload “elf”) loaded a promising-looking Common Lisp … <\/p>\n

    Continue reading “Lisp ELF toolkit”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6],"tags":[],"class_list":["post-767","post","type-post","status-publish","format-standard","hentry","category-lisp","entry"],"_links":{"self":[{"href":"https:\/\/www.fitzsim.org\/blog\/index.php?rest_route=\/wp\/v2\/posts\/767","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.fitzsim.org\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.fitzsim.org\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.fitzsim.org\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.fitzsim.org\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=767"}],"version-history":[{"count":12,"href":"https:\/\/www.fitzsim.org\/blog\/index.php?rest_route=\/wp\/v2\/posts\/767\/revisions"}],"predecessor-version":[{"id":779,"href":"https:\/\/www.fitzsim.org\/blog\/index.php?rest_route=\/wp\/v2\/posts\/767\/revisions\/779"}],"wp:attachment":[{"href":"https:\/\/www.fitzsim.org\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=767"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.fitzsim.org\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=767"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.fitzsim.org\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=767"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}