implement shm_open(2) and shm_unlink(2) in the kernel:
- Each shared memory file descriptor is associated with a swap-backed vm
object which provides the backing store. Each descriptor starts off with
a size of zero, but the size can be altered via ftruncate(2). The shared
memory file descriptors also support fstat(2). read(2), write(2),
ioctl(2), select(2), poll(2), and kevent(2) are not supported on shared
memory file descriptors.
- shm_open(2) and shm_unlink(2) are now implemented as system calls that
manage shared memory file descriptors. The virtual namespace that maps
pathnames to shared memory file descriptors is implemented as a hash
table where the hash key is generated via the 32-bit Fowler/Noll/Vo hash
of the pathname.
- As an extension, the constant 'SHM_ANON' may be specified in place of the
path argument to shm_open(2). In this case, an unnamed shared memory
file descriptor will be created similar to the IPC_PRIVATE key for
shmget(2). Note that the shared memory object can still be shared among
processes by sharing the file descriptor via fork(2) or sendmsg(2), but
it is unnamed. This effectively serves to implement the getmemfd() idea
bandied about the lists several times over the years.
- The backing store for shared memory file descriptors are garbage
collected when they are not referenced by any open file descriptors or
the shm_open(2) virtual namespace.
Submitted by: dillon, peter (previous versions)
Submitted by: rwatson (I based this on his version)
Reviewed by: alc (suggested converting getmemfd() to shm_open())
default. This has the disadvantage of rendering the datasize resource
limit irrelevant, but without this change, legitimate uses of more
memory than will fit in the data segment are thwarted by default.
Fix chunk_alloc_mmap() to work correctly if initial mapping is not
chunk-aligned and mapping extension fails.
the number of bytes read is actually not important as long as we have at
least what we ask for. Illustrate its benefits by using it throughout
the ZIP support code, except for the few cases where it doesn't apply.
Approved by: kientzle
exercises and verifies the libarchive APIs:
* Improved error reporting; hexdumps are now provided for
many file/memory content differences.
* Overall status more clearly counts "tests" and "assertions"
* Reference files can now be stored on disk instead of having
to be compiled into the test program itself. A couple of
tests have been converted to this more natural structure.
* Several memory leaks corrected so that leaks within libarchive
itself can be more easily detected and diagnosed.
* New test: GNU tar compatibility
* New test: Zip compatibility
* New test: Zero-byte writes to a compressed archive entry
* New test: archive_entry_strmode() format verification
* New test: mtree reader
* New test: write/read of large (2G - 1TB) entries to tar archives
(thanks to recent performance work, this test only requires a few seconds)
* New test: detailed format verification of cpio odc and newc writers
* Many minor additions/improvements to existing tests as well.
Clean up DSS-related locking and protect all pertinent variables with
dss_mtx (remove dss_chunks_mtx). This fixes race conditions that could
cause chunk leaks.
Reported by: [1] kris
This is a long-standing bug, but until recent changes it was difficult
to trigger, and even then its impact was non-catastrophic, with the
exception of revision 1.157.
Optimize chunk_alloc_mmap() to avoid the need for unmapping pages in the
common case. Thanks go to Kris Kennaway for a patch that inspired this
change.
Do not maintain a record of previously mmap'ed chunk address ranges.
The original intent was to avoid the extra system call overhead in
chunk_alloc_mmap(), which is no longer a concern. This also allows some
simplifications for the tree of unused DSS chunks.
Introduce huge_mtx and dss_chunks_mtx to replace chunks_mtx. There was
no compelling reason to use the same mutex for these disjoint purposes.
Avoid memset() for huge allocations when possible.
Maintain two trees instead of one for tracking unused DSS address
ranges. This allows scalable allocation of multi-chunk huge objects in
the DSS. Previously, multi-chunk huge allocation requests failed if the
DSS could not be extended.
that I've been working on but put off committing until after the
RELENG_7 branch, including:
* New manpages: cpio.5 mtree.5
* New archive_entry_strmode()
* New archive_entry_link_resolver()
* New read support: mtree format
* Internal API change: read format auction only runs once
* Running the auction only once allowed simplifying a lot of bid logic.
* Cpio robustness: search for next header after a sync error
* Support device nodes on ISO9660 images
* Eliminate a lot of unnecessary copies for uncompressed archives
* Corrected handling of new GNU --sparse --posix formats
* Correctly handle a zero-byte write to a compressed archive
* Fixed memory leaks
Many of these improvements were motivated by the upcoming bsdcpio
front-end.
There have also been extensive improvements to the libarchive_test
test harness, which I'll commit separately.
global list of all files.
- Mark kvm_getfiles() as broken since the live version exports struct xfile
with no filelist at the head and does so incorrectly and the deadfiles
version exports struct file with a filelist at the head. It is not known
if either version works or complies to the manpage.
order to support re-use of multi-chunk unused regions within the DSS for
huge allocations. This generalization is important to correct function
when mmap-based allocation is disabled.
Avoid zeroing re-used memory in the DSS unless it really needs to be
zeroed.
memory is acquired from the system via sbrk(2) and/or mmap(2). By default,
use sbrk(2) only, in order to support traditional use of resource limits.
Additionally, when both options are enabled, prefer the data segment to
anonymous mappings, in order to coexist better with large file mappings
in applications on 32-bit platforms. This change has the potential to
increase memory fragmentation due to the linear nature of the data
segment, but from a performance perspective this is mitigated by the use
of madvise(2). [1]
Add the ability to interpret integer prefixes in MALLOC_OPTIONS
processing. For example, MALLOC_OPTIONS=lllllllll can now be specified as
MALLOC_OPTIONS=9l.
Reported by: [1] rwatson
Design review: [1] alc, peter, rwatson
- Use PTY* for all pty(4) related constants.
- Use PTMX* for all pts(4) related constants.
- Consistently use _PATH_DEV PTMX rather than "/dev/ptmx".
- Revert 1.7 and properly fix it by using the correct prefix string for
pts(4) masters.
MFC after: 3 days
kick off any other users on the device line before using it since
openpty(3) is documented to do this. Note that grantpt(3) does not
call revoke(2), it only adjusts permissions and ownership.
MFC after: 3 days
my original implementation made both use the same code. Unfortunately,
this meant libm depended on a vendor header at compile time and previously-
unexposed vendor bits in libc at runtime.
Hence, I just wrote my own version of the relevant vendor routine. As it
turns out, mine has a factor of 8 fewer of lines of code, and is a bit more
readable anyway. The strtod() and *scanf() routines still use vendor code.
Reviewed by: bde
lynx, curl etc. Note that this patch differs significantly from that
in the PR, as the submitter refined it after submitting the PR.
PR: 110388
Submitted by: Alexander Pohoyda <alexander.pohoyda@gmx.net>
MFC after: 3 weeks
calculating run sizes. Use of the floating point unit was a potential
pessimization to context switching for applications that do not otherwise
use floating point math. [1]
Reformat cpp macro-related comments to improve consistency.
Submitted by: das
returned on a perfectly valid bzip2 stream whose decompressed size
is multiple of read-ahead buffer size. Reproduce the problem is easy:
create some power-of-two sized file (truncate -s 1m file will do),
bzip2 it and try to load it as md_image from loader. See how it fails.
The bug doesn't affect gzip code (which most of bzip2-reading code was
copied from) probably due to the fact that libgzip doesn't report
Z_STREAM_END with the last block, but requires extra call to inflate()
to retrieve it and has some extra data in the input stream at that time.
However, apply similar fix to gzipfs.c just in the case the API will
change in the future to do what bzip2 code does.
Add some ifdef'ed code to enable testing bzipfs.c from witin normal
FreeBSD environment as opposed to the restricted loader one, so that
one can use gdb and whatnot.
Sponsored by: Sippy Software, Inc., http://www.sippysoft.com/
MFC in: 7 days
someone thought it would be a good idea to copy z_abs() to libm in 1994.
However, it's never been declared or documented anywhere, and I'm
reasonably confident that nobody uses it.
Discussed with: bde, deischen, kan
I hope that this and the i386 version of it will not be needed, but
this is currently about 16 cycles or 36% faster than the C version,
and the i386 version is about 8 cycles or 19% faster than the C
version, due to poor optimization of the C version.
deallocation and dynamic load balancing via the MALLOC_LAZY_FREE and
MALLOC_BALANCE knobs. This is a non-functional change, since these
features are still enabled when possible.
Clean up a few things that more pedantic compiler settings would cause
complaints over.
