Libraries on Sandeep Kumar

Library Calling in C

Wed, 01 May 2019 00:00:00 +0530

In this post we are exploring how different types of binaries are generated, how function calls work when code is split across multiple files, and how the toolchain (compiler, linker, loader) helps. We’ll also cover how to build and install a custom libc for testing and debugging purposes.

File Types and High-Level Flow

Difference in types of files:

.c / .cpp: source files
.o: object files (compiled but not yet linked)
.a: static library (archive of .o files)
.so: shared library (dynamically linked at runtime)

Typical build pipeline:

Installing custom LibC

Mon, 09 Mar 2020 00:00:00 +0530

Glibc is the standard library that is linked against all the linux applications. It provides the necessary functionality like printf.

It also provides wrappers for most used system calls like open, read, write, close.

Manually building and installing libc.

Example from a StackOverflow answer

export glibc_install="$(pwd)/glibc/build/install"

git clone git://sourceware.org/git/glibc.git
cd glibc
git checkout glibc-2.28
mkdir build
cd build
../configure --prefix "$glibc_install"
make
make install

Followed by a test c code