expansion of embedded variables in the left-hand-side of an assignment
expression, using the simplest case - hiding recursion using nil-expanded
variables.
seen (somewhat) in NetBSD. This catches a few extra recursion cases that
could be hidden by expanding a NIL variable causing an existing variable to
be returned (which caused infinite looping and climbing memory usage in at
least one case).
Obtained from: NetBSD (in principle)
the second buildworld environment is fully isolated from parent's
environment variables.
Tested virtually on: snapshots.jp.FreeBSD.org
Approved by: arch@ (silently)
MFC after: 2 weeks
reality (and POSIX): current directory isn't searched unless CDPATH has
a "." element or is unset.
PR: 38442
Submitted by: oleg dashevskii <be9@be9.ru>
MFC after: 1 week
in a user process gaining visibility into the 'old' contents of a filesystem
block. There were two cases: (1) when uiomove() fails (user process issues
illegal write), and (2) when uiomove() overlaps a mmap() of the same file at
the same offset (fault -> recursive buffer I/O reads contents of old block).
Unfortunately 1.72 also had the unintended effect of forcing the filesystem
to do a read-before-write in the case of a full-block-write (non append case),
e.g. 'dd if=/dev/zero of=test.dat bs=1m count=256 conv=notrunc'. This
destroys performance.. not only is a read forced for every write, but
clustering breaks as well.
The solution is to clear the buffer manually in the full-block case rather
then asking BALLOC to do it (BALLOC issues the read-before-write). In the
partial-block case we want BALLOC to do it because the read-before-write
is necessary. This patch should greatly improve database and news-feed
server performance.
Found by: MKI <mki@mozone.net>
MFC after: 3 days
executes in the usage() message and manual page. Use "utility" instead of
"command" in both places to emphasise that shell builtins etc. will not work,
and to be consistent with the terminology used by POSIX.
PR: 39210
Submitted by: Danny J. Zerkel <dzerkel@columbus.rr.com>
MFC after: 1 week
uifind() with a proc lock held.
change_ruid() and change_euid() have been modified to take a uidinfo
structure which will be pre-allocated by callers, they will then
call uihold() on the uidinfo structure so that the caller's logic
is simplified.
This allows one to call uifind() before locking the proc struct and
thereby avoid a potential blocking allocation with the proc lock
held.
This may need revisiting, perhaps keeping a spare uidinfo allocated
per process to handle this situation or re-examining if the proc
lock needs to be held over the entire operation of changing real
or effective user id.
Submitted by: Don Lewis <dl-freebsd@catspoiler.org>
release of Giant.
o Reduce the scope of GIANT_REQUIRED in vm_map_insert().
These changes will enable us to remove the acquisition and release
of Giant from obreak().
so that /dev/mumble can be the entrypoint to some networking graph,
e.g. a tunnel or a remote tape drive or whatever...
Not fully tested (by me) yet.
Submitted by: Mark Santcroos <marks@ripe.net>
MFC after: 3 weeks
This facilitates the use in circumstances where you are using a serial
console as well. GDB doesn't support anything higher than 9600 baud (19k2
if you are lucky), but the console does.
