/no_libc

libc from scratch

Primary LanguageC

nolibc

Warning

Still a work in progress

My poor attempt of re-writting a small portion of libc without libc but syscalls
This is not intended for any use.
Purely written out of fun and for demo purposes.

Compile

Edit src/main.c

Install dependencies

sudo pacman -S make gcc     # Archlinux
sudo apt install make gcc   # Debian based 
sudo dnf install make gcc   # Red Hat based

Compile

make        # compiles binary
make run    # run's binary

Run tests

make test

Targets in Makefile

  • test = compile lib in all formats (.so,.a,.c) for testing
  • static_lib = creates static lib no_libc.a in static_lib/ dir
  • shared_lib = creates shared objects (.so) in shared_lib/ ( it is the default target )
  • all = uses raw c files in include/src/ and links them to src/main.c

Note

  • The default make compiles the header files to .so files in lib/ which are then used to link src/main.c
  • compiled binary is located in bin/

DIRECTORIES

libc source codes

  • include/ = header include files
  • include/src/ = source include files for the header include files
  • src/ = source file(s), that's where main.c is located ( Program Entry )

Compiled source codes

  • shared_iib/ = compiled shared object files ( .so files )
  • static_lib/ = contains no_libc.a for static linking
  • bin = ouput binary is placed

others

  • scripts/ ( no longer in use ) = scripts to compile shared files and check shared files ( used in old makefile )

Available Functions

  • _read
  • _write
  • _print
  • _println
  • _scanline
  • _scan
  • _printf
  • _scanf
  • _exit
  • _free
  • _malloc
  • _memset
  • _brk
  • _sbrk
  • _strlen
  • _reverse
  • _itoa
  • _stoa
  • _memcpy
  • _memcmp
  • _format
  • _sprintf
  • _snprintf
  • _open
  • _creat
  • _close
  • _mmap
  • _munmap