Commit Graph

2290 Commits

Author SHA1 Message Date
Konstantin Belousov
724f4b62b0 Remove sv_prepsyscall, sv_sigsize and sv_sigtbl members of the struct
sysent.

sv_prepsyscall is unused.

sv_sigsize and sv_sigtbl translate signal number from the FreeBSD
namespace into the ABI domain.  It is only utilized on i386 for iBCS2
binaries.  The issue with this approach is that signals for iBCS2 were
delivered with the FreeBSD signal frame layout, which does not follow
iBCS2.  The same note is true for any other potential user if
sv_sigtbl.  In other words, if ABI needs signal number translation, it
really needs custom sv_sendsig method instead.

Sponsored by:	The FreeBSD Foundation
2015-11-28 08:49:07 +00:00
Konstantin Belousov
5e27d79314 Split kerne timekeep ABI structure vdso_sv_tk out of the struct
sysentvec.  This allows the timekeep data to be shared between similar
ABIs which cannot share sysentvec.

Make the timekeep_push_vdso() tick callback to the timekeep structures
instead of sysentvecs.  If several sysentvec share the vdso_sv_tk
structure, we would update the userspace data several times on each
tick, without the change.

Only allocate vdso_sv_tk in the exec_sysvec_init() sysinit when
sysentvec is marked with the new SV_TIMEKEEP flag.  This saves
allocation and update of unneeded vdso_sv_tk for ABIs which do not
provide userspace gettimeofday yet, which are PowerPCs arches right
now.

Make vdso_sv_tk allocator public, namely split out and export
alloc_sv_tk() and alloc_sv_tk_compat32().  ABIs which share timekeep
data now can allocate it manually and share as appropriate.

Requested by:	nwhitehorn
Tested by:	nwhitehorn, pho
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
2015-11-23 07:09:35 +00:00
Hans Petter Selasky
f727a767e9 Add assert and note about the size of "unsigned long" inside the
LinuxKPI for the future.

Sponsored by:	Mellanox Technologies
2015-11-13 09:00:39 +00:00
Hans Petter Selasky
86845417d1 Build fixes:
- Add some missing I/O functions for non-i386 and amd64 platforms.
- Stub ioremap() to NULL using a macro to ensure non-existing memory
  attributes are not referred when they do not exist.
- Add more header files to linux/list.h to resolve driver compilation
  issues on Sparc64 and PowerPC platforms.

Sponsored by:	Mellanox Technologies
2015-11-12 09:18:22 +00:00
Conrad Meyer
3b383c9ede linuxkpi/sysfs.h: Cast arg2 through intptr_t to avoid GCC warning
The code compiles fine under Clang, but GCC on PPC is less permissive about
integer and pointer sizes.  (An intmax_t is clearly *large enough* to hold a
pointer value.)

Another follow-up to r290475.

Reported by:	jhibbits
Sponsored by:	EMC / Isilon Storage Division
2015-11-09 16:50:42 +00:00
Hans Petter Selasky
8e7baabc9f Make all the LinuxKPI include files compile standalone.
Sponsored by:	Mellanox Technologies
2015-11-03 12:37:55 +00:00
Hans Petter Selasky
8d59ecb214 Finish process of moving the LinuxKPI module into the default kernel build.
- Move all files related to the LinuxKPI into sys/compat/linuxkpi and
  its subfolders.
- Update sys/conf/files and some Makefiles to use new file locations.
- Added description of COMPAT_LINUXKPI to sys/conf/NOTES which in turn
  adds the LinuxKPI to all LINT builds.
- The LinuxKPI can be added to the kernel by setting the
  COMPAT_LINUXKPI option. The OFED kernel option no longer builds the
  LinuxKPI into the kernel. This was done to keep the build rules for
  the LinuxKPI in sys/conf/files simple.
- Extend the LinuxKPI module to include support for USB by moving the
  Linux USB compat from usb.ko to linuxkpi.ko.
- Bump the FreeBSD_version.
- A universe kernel build has been done.

Reviewed by:	np @ (cxgb and cxgbe related changes only)
Sponsored by:	Mellanox Technologies
2015-10-29 08:28:39 +00:00
Konstantin Belousov
cd0a26c53f Fix build for the KTR-enabled kernels.
Sponsored by:	The FreeBSD Foundation
2015-10-23 11:41:55 +00:00
Ed Schouten
b78ef4bd86 Refactoring: move out generic bits from cloudabi64_sysvec.c.
In order to make it easier to support CloudABI on ARM64, move out all of
the bits from the AMD64 cloudabi_sysvec.c into a new file
cloudabi_module.c that would otherwise remain identical. This reduces
the AMD64 specific code to just ~160 lines.

Reviewed by:	kib
Differential Revision:	https://reviews.freebsd.org/D3974
2015-10-22 09:07:53 +00:00
Ed Schouten
808d980506 Properly format pointer size independent CloudABI system calls.
CloudABI has approximately 50 system calls that do not depend on the
pointer size of the system. As the ABI is pretty compact, it takes
little effort to each truss(8) the formatting rules for these system
calls. Start off by formatting pointer size independent system calls.

Changes:

- Make it possible to include the CloudABI system call definitions in
  FreeBSD userspace builds. Add ${root}/sys to the truss(8) Makefile so
  we can pull in <compat/cloudabi/cloudabi_syscalldefs.h>.
- Refactoring: patch up amd64-cloudabi64.c to use the CLOUDABI_*
  constants instead of rolling our own table.
- Add table entries for all of the system calls.
- Add new generic formatting types (UInt, IntArray) that we'll be using
  to format unsigned integers and arrays of integers.
- Add CloudABI specific formatting types.

Approved by:	jhb
Differential Revision:	https://reviews.freebsd.org/D3836
2015-10-08 05:27:45 +00:00
Bryan Drewery
a730673058 Remove redundant RFFPWAIT/vfork(2) handling in Linux fork(2) and clone(2) wrappers.
r161611 added some of the code from sys_vfork() directly into the Linux
module wrappers since they use RFSTOPPED.  In r232240, the RFFPWAIT handling
was moved to syscallret(), thus this code in the Linux module is no longer
needed as it will be called later.

This also allows the Linux wrappers to benefit from the fix in r275616 for
threads not getting suspended if their vforked child is stopped while they
wait on them.

Reviewed by:	jhb, kib
MFC after:	2 weeks
Differential Revision:	https://reviews.freebsd.org/D3828
2015-10-07 19:10:38 +00:00
Andriy Gapon
2f2f522b5d save some bytes by using more concise SDT_PROBE<n> instead of SDT_PROBE
SDT_PROBE requires 5 parameters whereas SDT_PROBE<n> requires n parameters
where n is typically smaller than 5.

Perhaps SDT_PROBE should be made a private implementation detail.

MFC after:	20 days
2015-09-28 12:14:16 +00:00
Edward Tomasz Napierala
089d32934a Fixes a panic triggered by threaded Linux applications when running
with RACCT/RCTL enabled.

Reviewed by:	ngie@, ed@
Tested by:	Larry Rosenman <ler@lerctr.org>
MFC after:	1 month
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D3470
2015-09-02 14:04:13 +00:00
Ed Schouten
bc1ace0b96 Decompose linkat()/renameat() rights to source and target.
To make it easier to understand how Capsicum interacts with linkat() and
renameat(), rename the rights to CAP_{LINK,RENAME}AT_{SOURCE,TARGET}.

This also addresses a shortcoming in Capsicum, where it isn't possible
to disable linking to files stored in a directory. Creating hardlinks
essentially makes it possible to access files with additional rights.

Reviewed by:	rwatson, wblock
Differential Revision:	https://reviews.freebsd.org/D3411
2015-08-27 15:16:41 +00:00
Ed Schouten
edcf7fbf59 Don't forget to invoke pre_execve() and post_execve().
CloudABI's proc_exec() was implemented before r282708 introduced
pre_execve() and post_execve(). Sync up by adding these missing calls.
2015-08-17 13:07:12 +00:00
Ed Schouten
fbb624e76f Add the last remaining system calls: send() and recv().
There is still one TODO item for these calls: add file descriptor
passing. The data structures are already prepared for this. It's just
the translation that's missing.

Obtained from:	http://github.com/NuxiNL/freebsd
2015-08-12 17:42:20 +00:00
Ed Schouten
2c20fbe43a Use CAP_EVENT instead of CAP_PDWAIT.
The cloudlibc pdwait() function ends up using FreeBSD's kqueue() in
combination with EVFILT_PROCDESC. This depends on CAP_EVENT -- not
CAP_PDWAIT.

Obtained from:	https://github.com/NuxiNL/freebsd
2015-08-12 11:07:03 +00:00
Ed Schouten
18528470cb Make blocking CloudABI futex operations work.
Blocking on locks and condition variables can be accomplished by polling
and using the special filters CONDVAR, LOCK_RDLOCK and LOCK_WRLOCK.

For now it wouldn't make sense to implement this functionality into
kqueue() itself, for the reason that they are CloudABI specific and
would require us to resize 'struct kevent' to hold all of the parameters
of interest.

Add a bandaid to the CloudABI poll system call to call into the futex
code directly if it detects specific combinations of events that are
used by the C library.

Obtained from:	https://github.com/NuxiNL/freebsd
2015-08-12 08:41:48 +00:00
Ed Schouten
322e16e87e Make poll() and kqueue() on CloudABI work.
This change implements two functions, cloudabi64_kevent_copyin() and
cloudabi64_kevent_copyout(), that convert CloudABI structures to
FreeBSD's struct kevent. CloudABI uses two structures: subscription_t
and event_t. The former is used for input, whereas the latter is used
for output. Unlike struct kevent, fields aren't overloaded for multiple
purposes or for separate event types.

For poll() we call into the newly introduced kern_kevent_anonymous()
function that allows us to poll without a file descriptor. This function
is not only used by poll(), but also by functions such as
sleep() and clock_nanosleep().

Reviewed by:	jmg
Obtained from:	https://github.com/NuxiNL/freebsd
Differential Revision:	https://reviews.freebsd.org/D3308
2015-08-12 07:59:00 +00:00
Ed Schouten
55a224afa2 Fall back to O_RDONLY -- not O_WRONLY.
If CloudABI processes open files with a set of requested rights that do
not match any of the privileges granted by O_RDONLY, O_WRONLY or O_RDWR,
we'd better fall back to O_RDONLY -- not O_WRONLY.
2015-08-11 14:08:46 +00:00
Ed Schouten
9d9123a80d Properly convert the error number to CloudABI's indexing.
We currently return FreeBSD's errno value directly, which is of course
not correct.
2015-08-11 14:07:04 +00:00
Ed Schouten
65c17fe451 Make cap_rights_limit() work for CloudABI processes.
Call into the recently introduced kern_cap_rights_limit() function to
restrict rights.
2015-08-11 08:44:19 +00:00
Ed Schouten
0f85ff377b Add file_open(): the underlying system call of openat().
CloudABI purely operates on file descriptor rights (CAP_*). File
descriptor access modes (O_ACCMODE) are emulated on top of rights.

Instead of accepting the traditional flags argument, file_open() copies
in an fdstat_t object that contains the initial rights the descriptor
should have, but also file descriptor flags that should persist after
opening (APPEND, NONBLOCK, *SYNC). Only flags that don't persist (EXCL,
TRUNC, CREAT, DIRECTORY) are passed in as an argument.

file_open() first converts the rights, the persistent flags and the
non-persistent flags to fflags. It then calls into vn_open(). If
successful, it installs the file descriptor with the requested
rights, trimming off rights that don't apply to the type of
the file that has been opened.

Unlike kern_openat(), this function does not support /dev/fd/*. I can't
think of a reason why we need to support this for CloudABI.

Obtained from:	https://github.com/NuxiNL/freebsd
Differential Revision:	https://reviews.freebsd.org/D3235
2015-08-06 06:47:28 +00:00
Ed Schouten
aaf53ab2aa Correct the previous commit: remove the DECLARE_MODULE().
It looks like a MODULE_VERSION() can also appear on its own -- there is
no need to use explicitly use DECLARE_MODULE(). Looking at other
modules, this seems common practice.
2015-08-05 16:53:49 +00:00
Ed Schouten
b6efa27589 Add DECLARE_MODULE() to the "cloudabi" kernel module.
This kernel module does not require any explicit initialization, but a
module declaration is needed to let the "cloudabi64" kernel module
automatically pull this in.

Obtained from:	https://github.com/NuxiNL/freebsd
2015-08-05 16:45:47 +00:00
Ed Schouten
36310bcd1d Make fcntl(F_SETFL) work.
The stat_put() system call can be used to modify file descriptor
attributes, such as flags, but also Capsicum permission bits. Support
for changing Capsicum bits will be added as soon as its dependent
changes have been pushed through code review.

Obtained from:	https://github.com/NuxiNL/freebsd
2015-08-05 16:15:43 +00:00
Ed Schouten
2412ae2b8e Regenerate the system call table. 2015-08-05 13:10:13 +00:00
Ed Schouten
2837d9ed43 Import the latest CloudABI system call definitions and table.
We're going to need these for next code I'm going to send out for
review: support for poll() and kqueue() on CloudABI.
2015-08-05 13:09:46 +00:00
Ed Schouten
db1c8ee585 Add the remaining pointer size independent CloudABI socket system calls.
CloudABI uses a structure called cloudabi_sockstat_t. Think of it as
'struct stat' for sockets. It is used by functions such as
getsockname(), getpeername(), some of the getsockopt() values, etc.

This change implements the sock_stat_get() system call that returns a
copy of this structure. The accept() system call should also return a
full copy of this structure eventually, but for now we're only
interested in the peer address. Add a TODO() to make sure this is
patched up later on.

Differential Revision:	https://reviews.freebsd.org/D3218
2015-08-05 08:18:05 +00:00
Ed Schouten
4958fab8cd Allow the creation of polling descriptors (kqueues) on CloudABI. 2015-08-05 07:37:06 +00:00
Ed Schouten
a2034cc98a Allow the creation of kqueues with a restricted set of Capsicum rights.
On CloudABI we want to create file descriptors with just the minimal set
of Capsicum rights in place. The reason for this is that it makes it
easier to obtain uniform behaviour across different operating systems.

By explicitly whitelisting the operations, we can return consistent
error codes, but also prevent applications from depending OS-specific
behaviour.

Extend kern_kqueue() to take an additional struct filecaps that is
passed on to falloc_caps(). Update the existing consumers to pass in
NULL.

Differential Revision:	https://reviews.freebsd.org/D3259
2015-08-05 07:36:50 +00:00
Ed Schouten
0c0964844e Let the CloudABI futex code use umtx_keys.
The CloudABI kernel still passes all of the cloudlibc unit tests.

Reviewed by:	vangyzen
Differential Revision:	https://reviews.freebsd.org/D3286
2015-08-04 06:02:03 +00:00
Ed Schouten
f52c3dd415 Allow CloudABI processes to create shared memory objects.
Summary:
Use the newly created `kern_shm_open()` function to create objects with
just the rights that are actually needed.

Reviewers: jhb, kib

Subscribers: imp

Differential Revision: https://reviews.freebsd.org/D3260
2015-08-01 07:51:48 +00:00
Ed Schouten
367a13f905 Limit rights on process descriptors.
On CloudABI, the rights bits returned by cap_rights_get() match up with
the operations that you can actually perform on the file descriptor.

Limiting the rights is good, because it makes it easier to get uniform
behaviour across different operating systems. If process descriptors on
FreeBSD would suddenly gain support for any new file operation, this
wouldn't become exposed to CloudABI processes without first extending
the rights.

Extend fork1() to gain a 'struct filecaps' argument that allows you to
construct process descriptors with custom rights. Use this in
cloudabi_sys_proc_fork() to limit the rights to just fstat() and
pdwait().

Obtained from:	https://github.com/NuxiNL/freebsd
2015-07-31 10:21:58 +00:00
Ed Schouten
8328babdd0 Make pipes in CloudABI work.
Summary:
Pipes in CloudABI are unidirectional. The reason for this is that
CloudABI attempts to provide a uniform runtime environment across
different flavours of UNIX.

Instead of implementing a custom pipe that is unidirectional, we can
simply reuse Capsicum permission bits to support this. This is nice,
because CloudABI already attempts to restrict permission bits to
correspond with the operations that apply to a certain file descriptor.

Replace kern_pipe() and kern_pipe2() by a single kern_pipe() that takes
a pair of filecaps. These filecaps are passed to the newly introduced
falloc_caps() function that creates the descriptors with rights in
place.

Test Plan:
CloudABI pipes seem to be created with proper rights in place:

https://github.com/NuxiNL/cloudlibc/blob/master/src/libc/unistd/pipe_test.c#L44

Reviewers: jilles, mjg

Reviewed By: mjg

Subscribers: imp

Differential Revision: https://reviews.freebsd.org/D3236
2015-07-29 17:18:27 +00:00
Ed Schouten
9d2332c9ee Split up Capsicum to CloudABI rights conversion into two separate routines.
CloudABI's openat() ensures that files are opened with the smallest set
of relevant rights. For example, when opening a FIFO, unrelated rights
like CAP_RECV are automatically removed. To remove unrelated rights, we
can just reuse the code for this that was already present in the rights
conversion function.
2015-07-29 12:42:45 +00:00
Ed Schouten
3720b82fa8 Implement CloudABI's readdir().
Summary:
CloudABI's readdir() system call could be thought of as a mixture
between FreeBSD's getdents(2) and pread(). Instead of using the file
descriptor offset, userspace provides a 64-bit cloudabi_dircookie_t
continue reading at a given point. CLOUDABI_DIRCOOKIE_START, having
value 0, can be used to return entries at the start of the directory.

The file descriptor offset is not used to store the cookie for the
reason that in a file descriptor centric environment, it would make
sense to allow concurrent use of a single file descriptor.

The remaining space returned by the system call should be filled with a
partially truncated copy of the next entry. The advantage of doing this
is that it gracefully deals with long filenames. If the C library
provides a buffer that is too small to hold a single entry, it can still
extract the directory entry header, meaning that it can retry the read
with a larger buffer or skip it using the cookie.

Test Plan:
This implementation passes the cloudlibc unit tests at:

	https://github.com/NuxiNL/cloudlibc/tree/master/src/libc/dirent

Reviewers: marcel, kib

Reviewed By: kib

Subscribers: imp

Differential Revision: https://reviews.freebsd.org/D3226
2015-07-29 06:31:44 +00:00
Ed Schouten
1d96fd8d9f Implement file attribute modification system calls for CloudABI.
CloudABI uses a system call interface to modify file attributes that is
more similar to KPI's/FUSE, namely where a stat structure is passed back
to the kernel, together with a bitmask of attributes that should be
changed. This would allow us to update any set of attributes atomically.

That said, I'd rather not go as far as to actually implement it that
way, as it would require us to duplicate more code than strictly needed.
Let's just stick to the combinations that are actually used by
cloudlibc.

Obtained from:	https://github.com/NuxiNL/freebsd
2015-07-28 12:57:19 +00:00
Ed Schouten
29515a68a5 Implement directory and FIFO creation.
The file_create() system call can be used to create files of a given
type. Right now it can only be used to create directories and FIFOs. As
CloudABI does not expose filesystem permissions, this system call lacks
a mode argument. Simply use 0777 or 0666 depending on the file type.
2015-07-28 06:50:47 +00:00
Ed Schouten
cec575201a Make fstat() and friends work.
Summary:
CloudABI provides access to two different stat structures:

- fdstat, containing file descriptor level status: oflags, file
  descriptor type and Capsicum rights, used by cap_rights_get(),
  fcntl(F_GETFL), getsockopt(SO_TYPE).
- filestat, containing your regular file status: timestamps, inode
  number, used by fstat().

Unlike FreeBSD's stat::st_mode, CloudABI file descriptor types don't
have overloaded meanings (e.g., returning S_ISCHR() for kqueues). Add a
utility function to extract the type of a file descriptor accurately.

CloudABI does not work with O_ACCMODEs. File descriptors have two sets
of Capsicum-style rights: rights that apply to the file descriptor
itself ('base') and rights that apply to any new file descriptors
yielded through openat() ('inheriting'). Though not perfect, we can
pretty safely decompose Capsicum rights to such a pair. This is done in
convert_capabilities().

Test Plan: Tests for these system calls are fairly extensive in cloudlibc.

Reviewers: jonathan, mjg, #manpages

Reviewed By: mjg

Subscribers: imp

Differential Revision: https://reviews.freebsd.org/D3171
2015-07-28 06:36:49 +00:00
Ed Schouten
af7e75f59d Add a futex implementation for CloudABI.
Summary:
CloudABI provides two different types of futex objects: read-write locks
and condition variables. There is no need to provide separate support
for once objects and thread joining, as these are efficiently simulated
by blocking on a read-write lock. Mutexes simply use read-write locks.

Condition variables always have a lock object associated to them. They
always know to which lock a thread needs to be migrated if woken up.
This allows us to implement requeueing. A broadcast on a condition
variable will never cause multiple threads to be woken up at once. They
will be woken up iteratively.

This implementation still has lots of room for improvement. Locking is
coarse and right now we use linked lists to store all of the locks and
condition variables, instead of using a hash table. The primary goal of
this implementation was to behave correctly. Performance will be
improved as we go.

Test Plan:
This futex implementation has been in use for the last couple of months
and seems to work pretty well. All of the cloudlibc and libc++ unit
tests seem to pass.

Reviewers: dchagin, kib, vangyzen

Subscribers: imp

Differential Revision: https://reviews.freebsd.org/D3148
2015-07-27 10:07:29 +00:00
Ed Schouten
533c8a29da Regenerate system call table. 2015-07-27 10:04:28 +00:00
Ed Schouten
f4c06d124f Sync in latest upstream system call definitions.
Futex object scopes have been renamed from using their own constants to
simply reusing the existing CLOUDABI_MAP_{PRIVATE,SHARED} flags, as they
are more accurate in this context.
2015-07-27 10:04:06 +00:00
Ed Schouten
4615998165 Implement the basic system calls that operate on pathnames.
Summary:
Unlike FreeBSD, CloudABI does not use null terminated strings for its
pathnames. Introduce a function called copyin_path() that can be used by
all of the filesystem system calls that use pathnames. This change
already implements the system calls that don't depend on any additional
functionality (e.g., conversion of struct stat).

Also implement the socket system calls that operate on pathnames, namely
the ones used by the C library functions bindat() and connectat(). These
don't receive a 'struct sockaddr_un', but just the pathname, meaning
they could be implemented in such a way that they don't depend on the
size of sun_path. For now, just use the existing interfaces.

Add a missing #include to cloudabi_syscalldefs.h to get this code to
build, as one of its macros depends on UINT64_C().

Test Plan:
These implementations have already been tested in the CloudABI branch on
GitHub. They pass all of the tests.

Reviewers: kib, pjd

Subscribers: imp

Differential Revision: https://reviews.freebsd.org/D3097
2015-07-24 07:46:02 +00:00
Ed Schouten
fef97e09d9 Allow us to create UNIX sockets and socketpairs in CloudABI processes. 2015-07-23 13:52:53 +00:00
Ed Schouten
c989441af6 Regenerate system call table. 2015-07-22 10:05:46 +00:00
Ed Schouten
73dcd7db56 Import upstream changes to the system call definitions.
Support has been added for providing the scope of a futex operation,
whether the futex is local to the process or shared between processes.
2015-07-22 10:04:53 +00:00
Ed Schouten
072cb63ddc Make clock_gettime() and clock_getres() work for CloudABI programs.
Though the standard C library uses a 'struct timespec' using a 64-bit
'time_t', there is no need to use such a type at the system call level.
CloudABI uses a simple 64-bit unsigned timestamp in nanoseconds. This is
sufficient to express any time value from 1970 to 2554.

The CloudABI low-level interface also supports fetching timestamp values
with a lower precision. Instead of overloading the clock ID argument for
this purpose, the system call provides a precision argument that may be
used to specify the maximum slack. The current system call
implementation does not use this information, but it's good to already
have this available.

Expose cloudabi_convert_timespec(), as we're going to need this for
fstat() as well.

Obtained from:	https://github.com/NuxiNL/freebsd
2015-07-21 15:08:13 +00:00
Ed Schouten
21d30b29d5 Make thread creation work for CloudABI processes.
Summary:
Remove the stub system call that was put in place during the system call
import and replace it by a target-dependent version stored in sys/amd64.
Initialize the thread in a way similar to cpu_set_upcall_kse(). We
provide the entry point with two arguments: the thread ID and the
argument pointer.

Test Plan:
Thread creation still seems to work, both for FreeBSD and CloudABI
binaries.

Reviewers: dchagin, mjg, kib

Reviewed By: kib

Subscribers: imp

Differential Revision: https://reviews.freebsd.org/D3110
2015-07-21 12:47:15 +00:00
Ed Schouten
62c31cffae Make forking of CloudABI processes work.
Just like FreeBSD+Capsicum, CloudABI uses process descriptors. Return
the file descriptor number to the parent process.

To the child process we both return a special value for the file
descriptor number (CLOUDABI_PROCESS_CHILD). We also return the thread ID
of the new thread in the copied process, so the threading library can
reinitialize itself.

Obtained from:	https://github.com/NuxiNL/freebsd
2015-07-20 13:46:22 +00:00