This commit adds support for custom stream via fopencookie function.
The function allows the programmer the create his own custom stream
for IO operations and hook his custom functions to it.
This is a non POSIX interface defined in Standard C library and implemented
according to it. The only difference is in usage of off_t instead of
off64_t. Programmer can use 64 bits offset if CONFIG_FS_LARGEFILE is
enabled. In that case off_t is defined as int64_t (int32_t otherwise).
Field fs_fd is removed from file_struct and fs_cookie is used instead
as a shared variable for file descriptor or user defined cookie.
The interface will be useful for future fmemopen implementation.
Signed-off-by: Michal Lenc <michallenc@seznam.cz>
FD (file descriptor) is widely used in system software development,
and almost all implementations of posix os (including nuttx) use FD as an index.
the value of fd needs to be allocated starting from the minimum available value of 3, and each process has a copy,
so the same fd value is very easy to reuse in the program.
In multi threaded or multi process environments without address isolation,
If the ownership, global variables, and competition relationships of fd are not properly handled,
there may be issues with fd duplication or accidental closure.
Further leading to the following issues, which are difficult to troubleshoot.
1. Security vulnerability: the fd we wrote is not the expected fd and will be accessed by hackers to obtain data
2. Program exceptions or crashes: write or read fd failures, and program logic errors
3. The structured file XML or database is damaged: the data format written to the database is not the expected format.
The implementation principle of fdsan is based on the implementation of Android
https://android.googlesource.com/platform/bionic/+/master/docs/fdsan.md
Signed-off-by: hujun5 <hujun5@xiaomi.com>
This is preparation for flushing streams from user space, like it should
be done.
- Move tg_streamlist (group, kernel space) ->
ta_streamlist (TLS, user space)
- Access stream list via tg_info in kernel
- Access stream list via TLS in user space
- Remove / rename nxsched_get_streams -> lib_getstreams
- Remove system call for nxsched_get_streams
1.Reduce the default size of task_group_s(~512B each task)
2.Scale better between simple and complex application
Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
Change-Id: Ia872137504fddcf64d89c48d6f0593d76d582710
Squashed commit of the following:
libs/libxx: Fix some confusing in naming. If the directory is called libxx, then the library must be libxx.a (unless perhaps LIBCXX is selected).
libs/: Fix paths in moved library directories.
libs: Brute force move of libc, libnx, and libxx to libs. Cannot yet build it in that configuration.
Xiang Xiao