Notes on the Linux Programming Interface

How To Call a Syscall

• Use syscall():

syscall(SYS_kill, pid, signum);

• Use inline asm:

//
// 57 is the syscall number for fork()
// the return value is stored in the pid variable
//
int pid;
asm("mov    $57, %%eax\n syscall\n" : "=r" (pid));

File System

filename -> inode identifier -> inode reference
                                 / | \
                                /  |  \
                               /   |   \
                        [data0] [data1] [data2] ...

inode

• Unique identifier for a file object.
• File metadata

dentry

Translates between file name and inode. There is a cache for both dentries and inodes.

select() vs. poll()

TL;DR: Use poll() instead of select() Reasons: - select() has poor performances (for-loop from FD 0 to target FD). - select() can destroy your stack, if checking for a FD larger than FD_SETSIZE.

More info: https://beesbuzz.biz/code/5739-The-problem-with-select-vs-poll