Task: Standard C Library

Enter the labs/lab-02/tasks/libc/ folder, then enter support/. Now go through the practice items below.

1. Use malloc() and free() functions in the memory.c program. Make your own use of the allocated memory.

   It’s very easy to use memory management functions with the libc. The alternative (without the libc) would be more cumbersome.

   Use different values for malloc(), i.e. the allocation size. Use strace to check the system calls invoked by malloc() and free(). You’ll see that, depending on the size, the brk() or mmap() / munmap() system calls are invoked. And for certain calls to malloc() / free() no syscall is happening. You’ll find more about them in the Data chapter.

   Quiz

2. Create your own C program with calls to the standard C library in vendetta.c. Be as creative as you can about the types of functions being made.

   Quiz

3. Inside the vendetta.c file make a call open("a.txt", O_RDWR | O_CREAT, 0644) to open / create the a.txt file. Make sure you include all required headers. Check the system call being made.

   Make an fopen() with the proper arguments that gets as close as possible to the open() call, i.e. the system call arguments are as close as possible.

4. Inside the vendetta.c file make a call to sin() function (for sine). Compute sin(0) and sin(PI/2).

If you’re having difficulties solving this exercise, go through this reading material.