The last half year I've been working on a replacement TTY layer for the
FreeBSD kernel. The new TTY layer was designed to improve the following:
- Improved driver model:
The old TTY layer has a driver model that is not abstract enough to
make it friendly to use. A good example is the output path, where the
device drivers directly access the output buffers. This means that an
in-kernel PPP implementation must always convert network buffers into
TTY buffers.
If a PPP implementation would be built on top of the new TTY layer
(still needs a hooks layer, though), it would allow the PPP
implementation to directly hand the data to the TTY driver.
- Improved hotplugging:
With the old TTY layer, it isn't entirely safe to destroy TTY's from
the system. This implementation has a two-step destructing design,
where the driver first abandons the TTY. After all threads have left
the TTY, the TTY layer calls a routine in the driver, which can be
used to free resources (unit numbers, etc).
The pts(4) driver also implements this feature, which means
posix_openpt() will now return PTY's that are created on the fly.
- Improved performance:
One of the major improvements is the per-TTY mutex, which is expected
to improve scalability when compared to the old Giant locking.
Another change is the unbuffered copying to userspace, which is both
used on TTY device nodes and PTY masters.
Upgrading should be quite straightforward. Unlike previous versions,
existing kernel configuration files do not need to be changed, except
when they reference device drivers that are listed in UPDATING.
Obtained from: //depot/projects/mpsafetty/...
Approved by: philip (ex-mentor)
Discussed: on the lists, at BSDCan, at the DevSummit
Sponsored by: Snow B.V., the Netherlands
dcons(4) fixed by: kan
ckrealloc and ckfree (added), respectively. sh jumps out of the signal handler
using longjmp which is obviously a bad idea during malloc calls.
Note: I think there is still a small race here because volatile sig_atomic_t
only guarantees atomic reads and writes while we're doing increments and
decrements.
Protect a setmode call with INT{ON,OFF} as it calls malloc internally.
PR: 45478
Patch from: Nate Eldredge
and linting procedure:
1. Remove useless sub-expression:
- if (*start || (!ifsspc && start > string && (nulonly || 1))) {
+ if (*start || (!ifsspc && start > string)) {
The sub-expression "(nulonly || 1)" always evaluates to true and
according to CVS logs seems to be just a left-over from some
debugging and introduced by accident. Removing the sub-expression
doesn't change semantics and a code inspection showed that the
variable "nulonly" is also not necessary here in any way (and the
expression would require fixing instead of removing).
2. Remove dead code:
- if (backslash && c == '\\') {
- if (read(STDIN_FILENO, &c, 1) != 1) {
- status = 1;
- break;
- }
- STPUTC(c, p);
- } else if (ap[1] != NULL && strchr(ifs, c) != NULL) {
+ if (ap[1] != NULL && strchr(ifs, c) != NULL) {
Inspection of the control and data flow showed that variable
"backslash" is always false (0) when the "if"-expression is
evaluated, hence the whole block is effectively dead code.
Additionally, the skipping of characters after a backslash is already
performed correctly a few lines above, so this code is also not
needed at all. According to the CVS logs and the ASH 0.2 sources,
this code existed in this way already since its early days.
3. Cleanup Style:
- ! trap[signo][0] == '\0' &&
+ ! (trap[signo][0] == '\0') &&
The expression wants to ensure the trap is not assigned the empty
string. But the "!" operator has higher precedence than "==", so the
comparison should be put into parenthesis to form the intended way of
expression. Nevertheless the code was effectively not really broken
as both particular NUL comparisons are semantically equal, of course.
But the parenthesized version is a lot more intuitive.
4. Remove shadowing variable declaration:
- char *q;
The declaration of symbol "q" hides another identical declaration of
"q" in the same context. As the other "q" is already reused multiple
times and also can be reused again without negative side-effects,
just remove the shadowing declaration.
5. Just small cosmetics:
- if (ifsset() != 0)
+ if (ifsset())
The ifsset() macro is already coded by returning the boolean result
of a comparison operator, so no need to compare this boolean result
again against a numerical value. This also aligns the macros usage to
the remaining existing code.
Reviewed by: stefanf@
o Old-style K&R declarations have been converted to new C89 style
o register has been removed
o prototype for main() has been removed (gcc3 makes it an error)
o int main(int argc, char *argv[]) is the preferred main definition.
o Attempt to not break style(9) conformance for declarations more than
they already are.
o Change
int
foo() {
...
to
int
foo(void)
{
...
spaces reserved by the header files it includes.
mkinit.c still produces C code with redundant declarations, although
they are more harmless since they automatically derived from the right
places.
i.e. this makes emacs usable from system(3). Programs called from
shellscripts are now required to exit with proper signal status. That
means, they have to kill themself. Exiting with faked numerical exit
code is not sufficient.
Exit with proper signal status if script exits on signal.
Make the wait builtin interruptable, both with and without traps set.
Use volatile sig_atomic_t where (and only where) appropriate.
(Almost) fix printing of newlines on SIGINT.
Make traps setable from trap handlers. This is needed for shellscripts
that catch SIGINT for cleanup work but intend to exit on it, hance
have to kill themself from a trap handler. I.e. mkdep.
While I'm at it, make it -Wall clean. -Wall is not enabled in
Makefile, since vararg warnx() macro calls in usr.bin/printf/printf.c
are not -Wall-able.
PR: 1206
Obtained from: Basic SIGINT fix from Bruce Evans
'read' command to return an error if the user fails to supply any
input withink a given time period. The behaviour of this option is
similar to that of the like-named option in ksh93.
Reviewed by: joerg
This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.
Boy, I'm glad we're not using sup anymore. This update would have been
insane otherwise.
face of aliases. Note, bash doesn't do aliases while running scripts, but
"real" ksh does..
Also:
Reduce redundant .Nm macros in (unused) bltin/echo.1
nuke error2, it's hardly used.
More -Wall cleanups
dont do certain history operations if NO_HISTORY defined
handle quad_t's from resource limits
Submitted by: Steve Price <sprice@hiwaay.net> (minor tweaks by me)
- don't put \n on error() calls, error adds it already.
- don't prepend "ulimit" on error() calls in miscbltin.c.
- getopt typo on ulimit -p -> -u conversion
- get/setrlimit() calls were not being error checked
ulimit formatting cleanup from me, use same wording as bash on Bruce's
suggestion. Add ulimit arg to output on Joerg's suggestion.
merge of parallel duplicate work by Steve Price and myself. :-]
There are some changes to the build that are my fault... mkinit.c was
trying (poorly) to duplicate some of the work that make(1) is designed to
do. The Makefile hackery is my fault too, the depend list was incomplete
because of some explicit OBJS+= entries, so mkdep wasn't picking up their
source file #includes.
This closes a pile of /bin/sh PR's, but not all of them..
Submitted by: Steve Price <steve@bonsai.hiwaay.net>, peter
o fix brokeness for 1>&5 redirection, where `5' was an invalid file
descriptor, but no error message has been generated
o fix brokeness for redirect to/from myself case
command and badly needed in sh(1) for everybody who wants to modify
the system-wide limits from inside /etc/rc.
The options are similar to other system's implemantations of this
command, with the FreeBSD additions for -m (memoryuse) and -p (max
processes) that are not available on other systems.
