Before considering to execute a command substitution in the same process,
check if any of the expansions may have a side effect; if so, execute it in
a new process just like happens if it is not a single simple command.
Although the check happens at run time, it is a static check that does not
depend on current state. It is triggered by:
- expanding $! (which may cause the job to be remembered)
- ${var=value} default value assignment
- assignment operators in arithmetic
- parameter substitutions in arithmetic except ${#param}, $$, $# and $?
- command substitutions in arithmetic
This means that $((v+1)) does not prevent optimized command substitution,
whereas $(($v+1)) does, because $v might expand to something containing
assignment operators.
Scripts should not depend on these exact details for correctness. It is also
imaginable to have the shell fork if and when a side effect is encountered
or to create a new temporary namespace for variables.
Due to the $! change, the construct $(jobs $!) no longer works. The value of
$! should be stored in a variable outside command substitution first.
has device mem in it almost everywhere, we get warnings about
duplicated device almost everywhere. Comment it out, with a note
about why, so that we don't get those warnings.
so turn off UFS-specific hack that assumes so in ZFS case.
Before the change we can miss returning some directory entries to a
NFS client.
I believe that the hack should be moved to ufs_readdir(), but until we find
somebody who will do it, turn it off for ZFS in NFS server code.
Submitted by: rmacklem
Discussed with: rmacklem, mckusick
MFC after: 3 days
2MB of memory in the bootmem allocator for the SDK to use internally at a later
point. It'd be nice if there were some functions we could call before
allocating memory to let various facilities reserve some memory, but for now
this seems sufficient. Previously some unfortunate systems could give up all
(or at least most) of their memory to the kernel from bootmem, and then
allocating command queues for packet output and the like would fail later in
the boot process (which in turn would lead to crashes even later.)
Reported by: kan
table. The 'locked' attribute is used to circumvent the regular page table
locking for some special pages, with the result that including locked pages
here causes races when updating the stats.
This test verifies that certain expansions without side effects do not
cause the command substitution to be executed in a child process.
This is not a correctness requirement, but it involves a nontrivial amount
of code and it would be unfortunate if it stopped working.
Command substitutions consisting of a single simple command are executed in
the main shell process but this should be invisible apart from performance
and very few exceptions such as $(trap).
access inbound/outbound events and associated data for established TCP
connections. The hooks only run if at least one hook function is registered
for the hook point, ensuring the impact on the stack is effectively nil when
no TCP Khelp modules are loaded. struct tcp_hhook_data is passed as contextual
data to any registered Khelp module hook functions.
- Add an OSD (Object Specific Data) pointer to struct tcpcb to allow Khelp
modules to associate per-connection data with the TCP control block.
- Bump __FreeBSD_version and add a note to UPDATING regarding to ABI changes
introduced by this commit and r216753.
In collaboration with: David Hayes <dahayes at swin edu au> and
Grenville Armitage <garmitage at swin edu au>
Sponsored by: FreeBSD Foundation
Reviewed by: bz, others along the way
MFC after: 3 months
small non fatal inconsistency. EBR may contain boot loader and sometimes
it just has some garbage data. Now this does not prevent FreeBSD to use
extended partitions. But since we do not support bootcode for EBR we mark
tables which have non empty boot area as corrupt. This does make them
readonly and we can not damage this data.
PR: kern/141235
MFC after: 1 month
This will be used by the incoming Enhanced RTT Khelp module.
Sponsored by: FreeBSD Foundation
Submitted by: David Hayes <dahayes at swin edu au>
Reviewed by: bz and others (as part of a larger patch)
MFC after: 3 months
categories: Those which can't build with PAE because they attempt to cast
a pointer to a bus_addr_t (mostly scsi drivers); and those which can't be
built with XEN because they conflict with something in xen-os.h (e.g., in
cxgb there is a conflicting definition of test_and_clear_bit).
MFC after: 1 week
If a command substitution consists of one special builtin and there is a
redirection error, this should not abort the outer shell.
It was fixed in r201366 by ignoring special builtin properties for command
substitutions consisting of one builtin.
While I'm here, don't run the sysctl frob unconditionally, and
s/sysctl/$SYSCTL/
PR: conf/153460 [1]
Submitted by: Grigory Rechistov <ggg_mail@inbox.ru>
Maintain a pointer to the end of the stack string area instead of how much
space is left. This simplifies the macros in memalloc.h. The places where
the new variable must be updated are only where the memory area is created,
destroyed or resized.
more useful information. Instead of:
hastd: remote address not configured for resource foo
Print the following:
No resource foo configuration for this node (acceptable node names: freefall, freefall.freebsd.org, 44333332-4c44-4e31-4a30-313920202020).
MFC after: 3 days
section.
* Document the `-l`, `-M` and `-S` options.
* Improve the text describing the behavior of the `-r` option.
* Start a section on standard compliance.
* Indicate in the synopsis that the `-S` and `-s` options are mutually
exclusive.
Obtained from: elftoolchain
to PMAP_SET_VA; this fixes a mutex-not-held panic when a process
which called mlock(2) exits, and parallels a change made in
pmap_pte 10 months ago (svn r204160).
Note: The locking in this code is utterly broken. We should not
be using the VM page queue mutex to protect the queue of pending
Xen page mapping hypervisor calls. Even if it made sense to do
so, this commit and r204160 introduce LORs between the vm page
queue mutex and PMAP2mutex.
(However, a possible deadlock is better than a guaranteed panic,
and this change will hopefully make life easier for whoever fixes
the Xen pmap locking in the future.)
PR: kern/140313
MFC after: 3 days
for RPC operations when it can. Since VFS_FHTOVP() currently
always gets an exclusively locked vnode and is usually called
at the beginning of each RPC, the RPCs for a given vnode will
still be serialized. As such, passing a lock type argument to
VFS_FHTOVP() would be preferable to doing the vn_lock() with
LK_DOWNGRADE after the VFS_FHTOVP() call.
Reviewed by: kib
MFC after: 2 weeks
filters are implemented.
Filtees are loaded on demand, unless LD_LOADFLTR environment variable
is set or -z loadfltr was specified during the linking. This forces
rtld to upgrade read-locked rtld_bind_lock to write lock when it
encounters an object with filter during symbol lookup.
Consolidate common arguments of the symbol lookup functions in the
SymLook structure. Track the state of the rtld locks in the
RtldLockState structure. Pass local RtldLockState through the rtld
symbol lookup calls to allow lock upgrades.
Reviewed by: kan
Tested by: Mykola Dzham <i levsha me>, nwhitehorn (powerpc)
