nuttx

History

hujun5 8fe8417ffb libc/fdcheck: add fdcheck module In embedded development environments, due to the lack of address isolation between processes, fd may be passed between processes and lead to misuse, We have designed an fd cross-process automatic detection tool, fdcheck_protect returns the fd containing the pid information, indicating that the ownership of the current fd belongs to the pid and is not allowed to be used by other processes. fdcheck_restore will obtain the true fd and check if the ownership of the fd is legal For ease of understanding, let's give an example where the following information is represented in 32-bit binary format fd 00000000 00000000 00000000 10001010 pid 00000000 00000000 00000011 01010101 ret 00000000 00000011 01010101 10001010 Signed-off-by: hujun5 <hujun5@xiaomi.com>		2023-06-10 02:19:58 +08:00
..
libc	libc/fdcheck: add fdcheck module	2023-06-10 02:19:58 +08:00
libdsp	nuttx: unify MIN, MAX and ABS macro definition across the code	2022-12-21 09:31:28 +08:00
libm	Indent the define statement by two spaces	2023-05-21 09:52:08 -03:00
libnx	Indent the define statement by two spaces	2023-05-21 09:52:08 -03:00
libxx	libs/libxx: remove redundant code	2023-05-03 19:54:19 +08:00
README.txt

README.txt

README
======

This directory holds NuttX libraries.  Libraries in NuttX are very special
creatures.  They have these properties:

1. They can be shared by both application logic and logic within the OS when
   using the FLAT build.

2. But in PROTECTED and KERNEL modes, they must be built differently:  The
   copies used by applications and the OS cannot be the same.  Rather,
   separate versions of libraries must be built for the kernel and for
   applications.

3. When used by the OS, some special care must be taken to assure that the
   OS logic does not disrupt the user's errno value and that the OS does
   not create inappropriate cancellation points.

   For example, sem_wait() is both a cancellation point and modifies the
   errno value.  So within the FLAT build and without kernel version for
   the PROTECTED and KERNEL builds, the special internal OS interface
   nxsem_wait() must be used.  Within libraries, the macro _SEM_WAIT()
   (as defined in include/nuttx/semaphore.h) is used instead.  The
   definition of this macro accounts for the different usage environments.

NOTE:  The libraries under libs/ build differently from other NuttX
components:  There are no build-related files in the libs/ directory; it
is simply a container for other well-known, individual library directories.
The upper level Makefile logic is aware of the libraries within the libs/
container.

The only real function of the libs/ directory is to prevent the top-level
directory from becoming cluttered with individual libraries.