linux - How does one link NASM program to libc via ld? -


i have following program nasm (archlinux i686)

section .data lc1: db "library call", 0  section .text extern exit extern printf  ;global main ;main: global _start _start: push    lc1 call    printf  push    0 call    exit

which assembled command: 

nasm -f elf libcall.asm

if comment 2 lines _start , uncomment 2 lines main, assemble , link command:

gcc libcall.o -o libcall

then program runs ok. if assemble code _start entry point , link command:

ld libcall.o -o libcall -lc

then after launching program in bash (via command ./libcall) following error message returned:

bash: ./libcall: no such file or directory

although libcall file exist. objdump shows following:

[al libcall ]$ objdump -d libcall  libcall:     file format elf32-i386   disassembly of section .plt:  08048190 <printf@plt-0x10>:  8048190:   ff 35 78 92 04 08       pushl  0x8049278  8048196:   ff 25 7c 92 04 08       jmp    *0x804927c  804819c:   00 00                   add    %al,(%eax)     ...  080481a0 <printf@plt>:  80481a0:   ff 25 80 92 04 08       jmp    *0x8049280  80481a6:   68 00 00 00 00          push   $0x0  80481ab:   e9 e0 ff ff ff          jmp    8048190 <printf@plt-0x10>  080481b0 <exit@plt>:  80481b0:   ff 25 84 92 04 08       jmp    *0x8049284  80481b6:   68 08 00 00 00          push   $0x8  80481bb:   e9 d0 ff ff ff          jmp    8048190 <printf@plt-0x10>  disassembly of section .text:  080481c0 <_start>:  80481c0:   68 88 92 04 08          push   $0x8049288  80481c5:   e8 d6 ff ff ff          call   80481a0 <printf@plt>  80481ca:   6a 00                   push   $0x0  80481cc:   e8 df ff ff ff          call   80481b0 <exit@plt>

how nasm assembly code should linked libc via ld?

there parts of libc/crt come in object files need link. additionally need specify options such dynamic loader (aka. interpreter) use (which reason issue.) use gcc right thing you. if interested can run gcc -v , see horrible command line uses link. have been warned ;)

ps: should use main entry point have commented out.


Comments

Post a Comment

Popular posts from this blog

javascript - jQuery: Add class depending on URL in the best way -

i have html progress meter: <div class="col-md-3" style="margin-left: -20px;"> <div class="progress-pos active" id="progess-1"> <div class="progress-pos-inner"> login </div> </div> </div> <div class="col-md-3 progress-pos-container"> <div class="progress-pos" id="progess-2"> <div class="progress-pos-inner"> scan items </div> </div> </div> <div class="col-md-3 progress-pos-container"> <div class="progress-pos" id="progess-3"> <div class="progress-pos-inner"> confirm address </div> </div> </div> <div class="col-md-3 progress-pos-container"> <div class="progress-pos" id="progess-4"> <div class="progress-pos-in...
Read more

caching - How to check if a url path exists in the service worker cache -

i need check if particular url path exists in service worker cache. example, suppose url is: /myserviceworker/service?a=110&b=70 this url exists in cache, there many of them different values of , b. now, suppose want refresh of these urls, how can that? i want know how access key values service worker cache. if know key, plan follows: var url = new url(key); if(url.pathname === "\/myserviceworker/service") refetch key but not sure how cache key , in format is. mean, string or url? cache api has match() method returns promise resolving in response object if match or undefined if no match exists. second parameter object can specify ignoresearch not take account url parameters. the ignoresearch option supported firefox ( chrome status here ). in other hand, retrieve cache entries, can use keys() method.
Read more

Redirect to a HTTPS version using .htaccess -

i need modify .htaccess file redirect urls https version without "www". http://example.com --> https://example.com http://www.example.com --> https://example.com https://www.example.com --> https://example.com this how .htaccess file looks like: rewriteengine on rewritecond %{request_filename} !-d rewritecond %{request_filename} !-f rewriterule ^(.*)$ redirect.php?id=$1&page=$2 [qsa,l] what modifications need make .htaccess in order forward https without "www"? it depends on doing current code. looks file called redirect trying display php page seo friendly url. think might confusing people. anyway, need , force https without www, need 1 more rule above. also second rule needs two capture groups in rewriterule test string because wanting 2 different values using $1 , $2 references. rewriteengine on #rediect www non www and/or http https --- combinations. rewritecond %{http_host} !^example\.com [nc,or] rewritecond %{https} !^...
Read more