IPC and lib Functions
Inter-Process Communication and library functions have two small directories dedicated to them.
The ipc directory includes a generic file called
util.c and one source file for each communication facility:
sem.c, shm.c, and msg.c. msg.c is
in charge of message queues and the kerneld engine,
kerneld_send. If IPC is not enabled at compile time,
util.c exports empty functions that implement
IPC-related system calls by returning -ENOSYS.
The library functions are like the utilities and variables that you
usually use in C
programs: sprintf, vsprintf, the errno integer
variable, and the _ctype array used by the various
<linux/ctype.h> macros. The file string.c
contains portable implementations of the string functions, but
they are compiled only if the architecture-specific code
does not include optimized inline functions. If the inline functions are
defined in the header, the implementations in string.c are
left out of the game by #ifdef statements.
The most ``interesting'' file in lib is inflate.c, which
is the ``gunzip'' part of gzip, extracted from gzip itself
to allow using a compressed RAM disk at boot time. This technique is used
whenever the needed data wouldn’t fit on a floppy unless compressed.
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