64bit - Program in x64 assembly modifying array passed from a C++ procedure in Linux does not work, though analogous solution worked for x86 -

-

i wrote program in x64 assembly replace string's lower-case letters stars. assembly procedure called c++ program , receives array of chars. similar logic applied x86 worked (the difference being registers used etc.), string remains unaltered when built x64. use debian linux , nasm.

section .text global  func  func:     push    rbp     mov rbp, rsp  ; zadanie jako takie     mov rax, qword [rbp+8]     loop:         cmp byte [rax], 97         jl increment         cmp byte [rax], 122         jg increment         mov byte [rax], 42         increment:         add rax, 1         cmp byte [rax], 0         jne loop       exit:     mov rax, 0          ;return 0     mov rsp, rbp     pop rbp     ret

it called following c++ program:

#include <stdio.h> #define length 1024  extern "c" int func(char *a);  int main(void) {   int result;    char text[length];   printf( "write string\n" );   fgets( text, length -1, stdin );     printf("string: %s\n", text);   result=func(text);   printf("string: %s\n", text);    return 0; }

if necessary, here's makefile:

cc=gcc asmbin=nasm  : asm cc link asm :      $(asmbin) -o func.o -f elf64 -l func.lst func.asm cc :     $(cc) -m64 -c -g -o0 main.cc link :     $(cc) -m64 -o test -lstdc++ main.o func.o clean :     rm *.o     rm test     rm errors.txt        rm func.lst

additionally, resources porting x86 x64 appreciated.

the reason program not work different calling convention in x64. see: link reference. address of string array wasn't passed on stack, case of x86, stored in rdi register. therefore solution change instruction loading array address into:

mov rax, rdi

Comments

Post a Comment

Popular posts from this blog

C# random value from dictionary and tuple -

-
i have following code, , need random item contains string "region_1" dictionary. public static dictionary<int, tuple<string, int, currencytype>> itemarray = new dictionary<int, tuple<string, int, currencytype>>() { { 0xb3e, new tuple<string, int, currencytype>("region_1", 1500, currencytype.fame) } }; public static int generateitemid(string shopid) { var generateditem = itemarray.elementat(new random().next(0, itemarray.count)).key; } how select this? it's not possible efficiently... first create static random @ class level... prevent non-random behaviour if run query on short period of time... (it's seeded discrete clock) static random rnd = new random(); then: var item = itemarray.values .where(t => t.item1 == shopid) .orderby(_ => rnd.next()) .firstordefault()
Read more

cgi - How do I interpret URLs without extension as files rather than missing directories in nginx? -

-
so i'm trying install zoneminder , have run under nginx, has few compiled files need run using fast-cgi. these files lack extension. if file has extension, there no issue , nginx interprets file , return 404 if can't find it. if has no extension, assume it's directory , return 404 when can't find sort of index page. here have now: # security camera domain. server { listen 888; server_name mydomain.com; root /srv/http/zm; # enable php support. include php.conf; location / { index index.html index.htm index.php; } # enable cgi support. location ~ ^/cgi-bin/(.+)$ { alias /srv/cgi-bin/zm/; fastcgi_pass unix:/run/fcgiwrap.sock; fastcgi_param script_filename $document_root/$1; include fastcgi.conf; } } the idea is, under cgi-bin directory goes through fastcgi pipe. any idea on howi can fix this? upon closer inspection, realized zoneminder has 2 cgi sc...
Read more

.htaccess - htaccess convert request to clean url and add slash at the end of the url -

-
ok , searched more 4 days , more 20 posts here in stach or in websites without kind of success first here htaccess file rewriteengine on rewriterule ^([a-za-z0-9_]+)/?$ index.php?page=$1 [nc] rewriterule ^([a-za-z0-9_]+)\/([a-za-z0-9_]+)\/?$ index.php?page=$1&action=$2 [nc] i tried many codes 1 worked me can call request , works me www.example.com/pagename => www.example.com/index.php?page=pagename here questions , please provide me information "in detail" understand code well 1- how convert request automatically www.example.com/index.php?page=pagename www.example.com/pagename 2- if tried add slash @ end shows me page without images or styling mean www.example.com/pagename => works www.example.com/pagename/ => doesn't work that's :) for first part need 301 rule this: rewritecond %{the_request} /index\.php\?page=([^\s&]+) [nc] rewriterule ^ /%1? [r=301,l] for second part use absolute path in css, js, images files r...
Read more