ITT: we try to COMPILE a non-bloated program

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Anonymous
ITT: we try to COMPILE a non-bloated program 2017-06-12 06:59:38 Post No. 60865834
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ITT: we try to COMPILE a non-bloated program Anonymous 2017-06-12 06:59:38 Post No. 60865834 [Report]

I'll start:

void _start(void) {
    __asm__("mov $60, %rax\n" // SYS_EXIT
            "mov $0, %rdi\n" // exit code
            "syscall");
}

Result: 824 bytes.

$ gcc -static -nostdlib -nostartfiles -Os -s main.c
$ ./a.out
$ echo $?
99
$ wc -c a.out
824 a.out

Why is GCC so shit?

Anonymous 2017-06-12 07:00:44 Post No.60865839
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Anonymous 2017-06-12 07:00:44 Post No.60865839 [Report]

>>60865834
sorry, forgot to change
mov $0, %rdi
to
mov $99, %rdi

Anonymous 2017-06-12 07:08:32 Post No.60865883
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Anonymous 2017-06-12 07:08:32 Post No.60865883 [Report]

use objdump and have a look, GCC is including more than you think.

Anonymous 2017-06-12 07:15:45 Post No.60865924
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Anonymous 2017-06-12 07:15:45 Post No.60865924 [Report]

>>60865883
You mean
readelf -a a.out
?

Anonymous 2017-06-12 07:19:44 Post No.60865953
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Anonymous 2017-06-12 07:19:44 Post No.60865953 [Report]

How do I remove build-id for starters?
--build-id=none
doesn't work.

Anonymous 2017-06-12 07:24:09 Post No.60865974
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Anonymous 2017-06-12 07:24:09 Post No.60865974 [Report]

>>60865883
>>60865924
No, I think you meant
objdump -x

Anonymous 2017-06-12 07:25:12 Post No.60865980
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Anonymous 2017-06-12 07:25:12 Post No.60865980 [Report]

>>60865834
There's a lot of boilerplate that gets loaded in on binaries compiled for memory managed platforms, because memory isn't an issue, and neither is disk space.

The ELF format probably has more boilerplate stuff in it than the code you're executing.

Anonymous 2017-06-12 07:29:07 Post No.60865998
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Anonymous 2017-06-12 07:29:07 Post No.60865998 [Report]

>>60865980
Yeah, I think I need to remove 3 sections out of 4:

.note.gnu.build-id
.eh_frame
.comment

And only leave .text - I'll come back when I figure out how to do that

Anonymous 2017-06-12 07:29:16 Post No.60866000
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Anonymous 2017-06-12 07:29:16 Post No.60866000 [Report]

https://developer.xamarin.com/guides/android/advanced_topics/application_package_sizes/

why is xamarin so shit?

Anonymous 2017-06-12 07:34:05 Post No.60866015
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Anonymous 2017-06-12 07:34:05 Post No.60866015 [Report]

>>60865998
Executed these:
$ objcopy --remove-section .comment a.out
$ objcopy --remove-section .note.gnu.build-id a.out
$ objcopy --remove-section .eh_frame a.out
Down to 496 bytes. Any more suggestions?

Anonymous 2017-06-12 07:38:39 Post No.60866042
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Anonymous 2017-06-12 07:38:39 Post No.60866042 [Report]

>>60866015
-Os
strip

Anonymous 2017-06-12 07:42:52 Post No.60866075
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Anonymous 2017-06-12 07:42:52 Post No.60866075 [Report]

>>60866015
-fvisibility=hidden -fno-stack-protector -fdata-sections -ffunction-sections -Wl,--gc-sections

Anonymous 2017-06-12 08:52:37 Post No.60866494
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Anonymous 2017-06-12 08:52:37 Post No.60866494 [Report]

>>60866015
use gas instead of gcc, or yasm if you like a non shit tier asm syntax

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