POSIX: make readv() and writev() conform to IEEE Std 1003.1-2001

The standardized version of readv() and writev() take an int as the third
parameter. Arguably a size_t makes more sense, but the standardization bodies
decided otherwise.

The non-standard functions of readv_pos() and writev_pos() have been updated
for consistency. The corresponding _kern_readv() and _kern_writev() internal
functions continue to take the size_t parameter.

The ABI will not change, even though on 64 bit machines the size of the count
parameter will change from 8 to 4 bytes.

The actual use will be slightly different. Like with the size_t argument type,
it will not be possible to give a count lower than 0. If the value is less than
0, then the B_BAD_VALUE/EINVAL error will be set.

Change-Id: I949c8ed67dbc0b4e209768cbdee554c929fc242e
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3770
Reviewed-by: Jérôme Duval <jerome.duval@gmail.com>

s/Haiku License/MIT License/g.

They are the same thing.

libroot: More RETURN_AND_SET_ERRNO cleanup.

No functional change intended.

Introduce __set_errno() throughout libroot.

* add errno_private.h, which defines the __set_errno() macro with
and without tracing
* instead of setting errno manually, all libroot's code now invokes
__set_errno(), which makes it much easier to trace changes to errno
* redirect glibc's use of __set_errno() to our own version

Check the pos parameter before calling into kernel.
This does prevent the unwanted side effect of reading or writing at the current
file pointer position when the functions are called with a -1 position.
It's save to do this check in user space, because calling the _kern_* function
with -1 pos has the same effect as calling the normal read/write posix functions.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@21701 a95241bf-73f2-0310-859d-f6bbb57e9c96

Renamed src/kernel to src/system.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@12359 a95241bf-73f2-0310-859d-f6bbb57e9c96

Introduce __set_errno() throughout libroot.

* add errno_private.h, which defines the __set_errno() macro with
and without tracing
* instead of setting errno manually, all libroot's code now invokes
__set_errno(), which makes it much easier to trace changes to errno
* redirect glibc's use of __set_errno() to our own version

Check the pos parameter before calling into kernel.
This does prevent the unwanted side effect of reading or writing at the current
file pointer position when the functions are called with a -1 position.
It's save to do this check in user space, because calling the _kern_* function
with -1 pos has the same effect as calling the normal read/write posix functions.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@21701 a95241bf-73f2-0310-859d-f6bbb57e9c96

Renamed src/kernel to src/system.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@12359 a95241bf-73f2-0310-859d-f6bbb57e9c96