Now that our interactive signal handlers are a strict superset of
non-interactive ones, there is no reason to "reset" signals or take action
when becoming non-interactive. Clean up how signal handlers get installed.
The signal handlers for interactive and non-interactive SIGINT were distinct
and talked to the reader. This wasn't really justified and will complicate
having multiple threads. Unify these into a single signal handler.
This runs build_tools/style.fish, which runs clang-format on C++, fish_indent on fish and (new) black on python.
If anything is wrong with the formatting, we should fix the tools, but automated formatting is worth it.
fish's signal handlers are now sufficiently innocuous that there should
be no reason to block signals (outside of temporarily, when creating a
thread and we need to manipulate the signal mask).
Prior to this fix, fish had a signal_list_t that accumulated signals.
Signals were added to an array of integers, with an overflow flag.
The event machinery would attempt to atomically "swap in" the other list.
After this fix, there is a single list of pending signal events, as an array
of atomic booleans. The signal handler sets the boolean corresponding to its
signal.
This is a big change to how process reaping works, reimplenting it using
topics. The idea is to simplify the logic in
process_mark_finished_children around blocking, and also prepare for
"internal processes" which do not correspond to real processes.
Before this change, fish would use waitpid() to wait for a process group,
OR would individually poll processes if the process group leader was
unreapable.
After this change, fish no longer ever calls blocking waitpid(). Instead
fish uses the topic mechanism. For each reapable process, fish checks if
it has received a SIGCHLD since last poll; if not it waits until the next
SIGCHLD, and then polls them all.
topic_monitor allows for querying changes posted to one or more topics,
initially sigchld. This will eventually replace the waitpid logic in
process_mark_finished_children().
Comment from the new header:
Topic monitoring support. Topics are conceptually "a thing that can
happen." For example, delivery of a SIGINT, a child process exits, etc. It
is possible to post to a topic, which means that that thing happened.
Associated with each topic is a current generation, which is a 64 bit
value. When you query a topic, you get back a generation. If on the next
query the generation has increased, then it indicates someone posted to
the topic.
For example, if you are monitoring a child process, you can query the
sigchld topic. If it has increased since your last query, it is possible
that your child process has exited.
Topic postings may be coalesced. That is there may be two posts to a given
topic, yet the generation only increases by 1. The only guarantee is that
after a topic post, the current generation value is larger than any value
previously queried.
Tying this all together is the topic_monitor_t. This provides the current
topic generations, and also provides the ability to perform a blocking
wait for any topic to change in a particular topic set. This is the real
power of topics: you can wait for a sigchld signal OR a thread exit.
fish forks child processes when (for example) writing out builtin output.
After fork it resets signal handlers, but if a signal is delivered before
the signal handlers are reset, it will inherit fish's default handlers,
which do things like swallow SIGINT. Teach fish's default signal handlers
to detect this case and re-raise signals with default handlers.
This improves the reliability of control-C in the face of builtins.
Prior to this fix, fish would swallow SIGINT in non-interactive mode. This
meant that scripts could only be Ctrl-C'd if fish was executing an external
command.
Unblock SIGINT in non-interactive mode.
Fixes#5253
Valgrind warns that the sometimes uninitialized sigaction.sa_flags field
is sometimes used when passed to the signal handler.
This patch explicitly zeros out the sigaction.sa_flags field at creation
time.
PR #3691 made most calls to `signal_block()` and `signal_unblock()`
no-ops unless a magic env var is set when fish starts running. It's
been seven months since that change was made and no problems have been
reported. This finishes that work by removing those no-op function calls
and support for the magic env var in our next major release (which won't
happen till at least six months from now).
Working on a related problem caused me to notice that if a fish script
was run via `nohup` it would die when receiving SIGHUP. This fixes the
code to handle that correctly so that fish scripts can be nohup'd.
Fixes#4007
This is the next step in determining whether we can disable blocking
signals without a good reason to do so. This makes not blocking signals
the default behavior. If someone finds a problem they can add this to
their ~/config/fish/config.fish file:
set FISH_NO_SIGNAL_BLOCK 0
Alternatively set that env var before starting fish. I won't be surprised
if people report problems. Till now we have relied on people opting in
to this behavior to tell us whether it causes problems. This makes the
experimental behavior the default that has to be opted out of. This will
give us a lot more confidence this change doesn't cause problems before
the next minor release.
Note that there are still a few places where we force blocking of
signals. Primarily to keep SIGTSTP from interfering with the shell in
response to manipulating the controlling tty. Bash is more selective
in the signals it blocks around the problematic syscalls (c.f., its
`git_terminal_to()` function). However, I don't see any value in that
refinement.
There should be just one place that calls `setupterm()`. While refactoring
the code I also decided to not make initializing the curses subsystem a
fatal error. We now try two fallback terminal names ("ansi" and "dumb")
and if those can't be used we still end up with a usable shell.
Fixes#3850
This reverts commit e30f3fee88.
Not sure why I didn't notice this before merging it but the change I'm
reverting makes it impossible to start a login shell.
This is the next step in determining whether we can disable blocking
signals without a good reason to do so. This makes not blocking signals
the default behavior. If someone finds a problem they can add this to
their ~/config/fish/config.fish file:
set FISH_NO_SIGNAL_BLOCK 0
Alternatively set that env var before starting fish. I won't be surprised
if people report problems. Till now we have relied on people opting in
to this behavior to tell us whether it causes problems. This makes the
experimental behavior the default that has to be opted out of. This will
give is a lot more confidence this change doesn't cause major problems
prior to the next minor release.
The shell was doing a log of signal blocking/unblocking that hurts
performance and can be avoided. This reduced the elapsed time for a
simple benchmark by 25%.
Partial fix for #2007
The existing code is inconsistent, and in a couple of cases wrong, about
dealing with strings that are not valid ints. For example, there are
locations that call wcstol() and check errno without first setting errno
to zero. Normalize the code to a consistent pattern. This is mostly to
deal with inconsistencies between BSD, GNU, and other UNIXes.
This does make some syntax more liberal. For example `echo $PATH[1 .. 3]`
is now valid due to uniformly allowing leading and trailing whitespace
around numbers. Whereas prior to this change you would get a "Invalid
index value" error. Contrast this with `echo $PATH[ 1.. 3 ]` which was
valid and still is.
This fixes some of the IWYU and cppcheck lint warnings. And only on
macOS (formerly OS X). Fixing these types of warnings on a broader set
of platforms should be done but this is a baby step to making `make
lint-all` have few, if any, warnings. This reduces the number of lines
in the `make lint-all` output on macOS by over 500 lines.
The use of wcstoimax causes certain out-of-range values
to be silently truncated (e.g. when converted to a pid),
and is incompatible with FreeBSD (see #626)
This reverts commit 6faa2f9866.
Fixes various spots throughout fish where broken strtoi checks
were converting empty strings to zero. Zero is not a valid pid and
this was causing breakage as well when input.
Nix fish_wcstoi - wcstoimax does the same thing.
Improve comments and some general cleanup.
This only eliminates errors reported by `make lint`. It shouldn't cause any
functional changes.
This change does remove several functions that are unused. It also removes the
`desc_arr` variable which is both unused and out of date with reality.
The autoconf-generated config.h contains a number of directives which
may alter the behaviour of system headers on certain platforms. Always
include it in every C++ file as the first include.
Closes#2993.
I'm doing this as part of fixing issue #2980. The code for managing tty modes
and job control is a horrible mess. This is a very tiny step towards improving
the situation.
Remove the "make iwyu" build target. Move the functionality into the
recently introduced lint.fish script. Fix a lot, but not all, of the
include-what-you-use errors. Specifically, it fixes all of the IWYU errors
on my OS X server but only removes some of them on my Ubuntu 14.04 server.
Fixes#2957
This change moves source files into a src/ directory,
and puts object files into an obj/ directory. The Makefile
and xcode project are updated accordingly.
Fixes#1866
