This repo contains sample code for my two blog posts: A Simple ELF and ELF Shenanigans (for the XMAS Special).
Let's have some fun with linker scripts, ANSI codes, and emojis!
The program works, and is loaded on address Dec25. And when you run objdump you get a fun surprise...
MEMORY {
XMAS (rx) : ORIGIN = 0xDEC25000, LENGTH = 0x1000
}
SECTIONS
{
"🎄 ^[[31;49m▓▒░^[[0m ^[[95;1;5m🌟^[[0m ^[[31m░▒▓^[[92;41;1mXMAS^[[31;49m▓▒░^[[0m ^[[95;1;5m🌟^[[0m ^[[31;49m░▒▓^[[0m 🎄" : {
*(.text*)
} > XMAS
}
ENTRY(xmas)
If you want to dig in to some more details about how all this works, my blog post "A Simple ELF" might be helpful.
What other fun things can you come up with? Multi-line (ie. multi segment) ASCII art? Or hiding text using other ANSI codes? Let me know!
These are a few examples of peeling away complexity from my blog post A Simple ELF:
$ make hello
$ make hello-nostd
$ make hello-nostd-nopie
$ make hello-data
In the end, we arrive at:
$ objdump -t -h ./build/hello-data
./build/hello-data: file format elf64-x86-64
Sections:
Idx Name Size VMA LMA File off Algn
0 📜 .text 0000005c 00000000c0de0000 00000000c0de0000 00001000 2**0
CONTENTS, ALLOC, LOAD, READONLY, CODE
1 📦 .data 00000008 00000000feed0000 00000000feed0000 00003000 2**3
CONTENTS, ALLOC, LOAD, DATA
2 📁 .bss 00000008 00000000feed0008 00000000feed0008 00003008 2**3
ALLOC
3 🧊 .rodata 00000013 00000000dead0000 00000000dead0000 00002000 2**4
CONTENTS, ALLOC, LOAD, READONLY, DATA
SYMBOL TABLE:
0000000000000000 l df *ABS* 0000000000000000 hello-data.c
00000000c0de002f g F 📜 .text 000000000000002d startup
00000000feed0000 g O 📦 .data 0000000000000008 length
00000000dead0000 g O 🧊 .rodata 0000000000000013 message
00000000c0de0000 g F 📜 .text 000000000000002f main
00000000feed0008 g O 📁 .bss 0000000000000008 status