Fix SEEK_END seeking twice as far as requested. Centralize lseek handling in
one place and avoid overflow bugs. Inode lseek handlers now only need to
handle SEEK_END with offset 0. Prevent the file offset from ever going below
zero or overflowing.
Character devices are now not seekable, but lseek will pretend they are, yet
always stay at the file offset 0. pread/pwrite on character devices will now
ignore the file offset and call read/write.
This change prevents character devices from being memory mapped, notably
/dev/zero can no longer be memory mapped. None of the current ports seem
to rely on this behavior and will work with just MAP_ANONYMOUS.
Refactor read and write system calls to have a shared return statement for
both seekable and non-seekable IO.
Fix file offset overflow bugs in read and write system calls.
Fix system calls returning EPERM instead of properly returning EBADF when
the file has not been opened in the right mode.
Truncate IO counts and total vector IO length so the IO operation does not
do any IO beyond OFF_MAX. Truncate also total vector IO length for recvmsg
and sendmsg. Fail with EINVAL if total vector IO length exceeds SSIZE_MAX.
Don't stop early if the total IO length is zero, so zero length IO now block
on any locks internal to the inode.
Handle reads at the maximum file offset with an end of file condition and
handle writes of at least one byte at the maximum file offset by failing
with EFBIG.
Refactor UtilMemoryBuffer to store the file size using off_t instead of
size_t to avoid casts and keep file sizes in the off_t type. Properly
handle errors in the code, such as failing with EROFS instead of EBADF if
the backing memory is not writeable, and failing with EFBIG if writing
beyond the end of the file.
Fix mkpartition not rejecting invalid partition start offsets and lengths.
Strictly enforce partition start and length checks in the partition code.
Enforce partitions exist within regular files or block devices.
Fix a few indention issues.
I hereby relicense all my work on Sortix under the ISC license as below.
All Sortix contributions by other people are already under this license,
are not substantial enough to be copyrightable, or have been removed.
All imported code from other projects is compatible with this license.
All GPL licensed code from other projects had previously been removed.
Copyright 2011-2016 Jonas 'Sortie' Termansen and contributors.
Permission to use, copy, modify, and distribute this software for any
purpose with or without fee is hereby granted, provided that the above
copyright notice and this permission notice appear in all copies.
THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
Enable the NX bit on x86_64 and set if not PROT_EXEC and enable the write
protection mode (CR0.WP) that disables the default behavior where the kernel
is able to write to read-only memory. Fix kernel broken assumptions it can
access read-only memory and take care to never set PROT_KWRITE on user-space
pages unless PROT_WRITE is also set, otherwise user-space will be able to
write to read-only memory.
This achieves X^W in the whole system except for the core kernel itself as
it is currently don't know the purpose of pages when identity mapping the
first 4 MiB.
This fixes a rather nasty issue where gcc's garbage collection triggered a
munmap call with the effect that it began unmapping huge amounts of kernel
data until the system triple faulted.
