When a function is encountered by exec_job, a new context is created for
its execution from the ground up, with a new job and all, ultimately
resulting in a recursive call to exec_job from the same (main) thread.
Since each time exec_job encounters a new job with external commands
that needs terminal control it creates a new pgrp and gives it control
of the terminal (tcsetpgrp & co), this effectively takes control away
from the previously spawned external commands which may be (and likely
are) expecting to still have terminal access.
This commit attempts to detect when such a situation arises by handling
recursive calls to exec_job (which can only happen if the pipeline
included a function) by borrowing the pgrp from the (necessarily still
active) parent job and spawning new external commands into it.
When a parent job spawns new jobs due to the evaluation of a new
function (which shouldn't be the case in the first place), we end up
with two distinct jobs sharing one pgrp (to fix#3952). This can lead to
early termination of a pgrp if finished parent job children are reaped
before future processes in either the parent or future child jobs can
join it.
While the parent job is under construction, require that waitpid(2)
calls for the child job be done by process id and not job pgrp.
Closes#3952.
* Convert JOB_* enums to scoped enums
* Convert standalone job_is_* functions to member functions
* Convert standalone job_{promote, signal, continue} to member functions
* Convert standolen job_get{,_from_pid} to `job_t` static functions
* Reduce usage of JOB_* enums outside of proc.cpp by using new
`job_t::is_foo()` const helper methods instead.
This patch is only a refactor and should not change any functionality or
behavior (both observed and unobserved).
* Debug level 3: describe all commands being executed (this is, after all,
a shell and one can argue that this is the most important debug
information avaliable)
* Debug level 4: details of execution, mainly fork vs no-fork and io
handling
Also introduced j->preview() to print a short descriptor of the job
based on the head of the first process so we don't overwhelm with
needless repitition, but also so that we don't have to rely on
distinguishing between repeated, non-unique/non-monotonic job ids that
are often recycled within a single "execution cycle" (pressing enter
once).
* Instead of reaping all child processes when we receive a SIGCHLD, try
reaping only processes belonging to process groups from fully-
constructed jobs, which should eliminate the need for the keepalive
process entirely (WSL's lack of zombies not withstanding) as now
completed processes are not reaped until the job has been fully
constructed (i.e. all processes launched), which means their process
group should still be around for new processes to join.
* When `tcgetpgrp()` calls return 0, attempt to `tcsetpgrp()` before
invoking failure handling code.
* When forking a builtin and not running interactively, do not bail if
unable to set/restore terminal attributes.
Fixes#4178. Fixes#3805. Fixes#5210.
This reverts commit 8c14f0f30f.
This list is not reliable - there are many ways for fish to quit that does not
invoke these functions. It's also not necessary since the history is correctly
saved on exec.
Fix#5133 changed builtins to acquire the terminal, but this regressed
caused fish to be stopped when running in background via `sudo fish`.
Fix this by only acquiring the terminal if the terminal was owned by the
builtin's pgroup.
Fixes#5147
This adds a new string command split0, which splits on zero bytes.
split0 has superpowers because its output is not further split on
newlines when used in command substitutions.
separated_buffer_t encapsulates the logic around discarding (which
was previously duplicated between output_stream_t and io_buffer_t),
and will also encapsulate the logic around explicitly separated
output.
This should speed things up on slower PCs given that the vast majority
of shell commands are simple jobs consisting of a single command without
any pipelines, in which case there's no need for a keepalive process at
all. Applies to WSL only.
As a temporary workaround for the behavior described in
Microsoft/WSL#2997 wherein WSL does not correctly assign the spawned
child its own PID as its PGID, explicitly set the PGID for the newly
spawned process.
The job control functions were a bit messy, in particular
`set_child_group`'s name would imply that all it does is set the child
group, but in reality it used to set the child group (via `setpgid`),
set the job's pgrp if it hasn't been set, and possibly assign control of
the terminal to the newly-created job.
These have been split into separate functions. Now `set_child_group`
does just (and only) that, `maybe_assign_terminal` might assign the
terminal to the new pgrp, and `on_process_created` is used to set the
job properties the first time an external process is created. This might
also speed things up (but probably not noticeably) as there are no more
repeated calls to `getpgrp()` if JOB_CONTROL is not set.
Additionally, this closes#4715 by no longer unconditionally calling
`setpgid` on all new processes, including those created by `posix_spawn`
which does not need this since the child's pgrep is set at in the
arguments to that API call.
This switches function execution from the function's source code to
its stored node and pstree. This means we no longer have to re-parse
the function every time we execute it.
This concerns block nodes with redirections, like
begin ... end | grep ...
Prior to this fix, we passed in a pointer to the node. Switch to passing
in the tnode and parsed source ref. This improves type safety and better
aligns with the function-node plans.
keepalive processes are typically killed by the main shell process.
However if the main shell exits the keepalive may linger. In WSL
keepalives are used more often, and the lingering keepalives are both
leaks and prevent the tests from finishing.
Have keepalives poll for their parent process ID and exit when it
changes, so they can clean themselves up. The polling frequency can be
low.
Have WSL use a keepalive whenever the first process is external.
This works around the fact that WSL prohibits setting an exited
process as the group leader.
We had pid_status defined as a pid_t instance, which was fine since on
most platforms pid_t is an alias for int. However, that is not
universally the case and waitpid takes an int *, not a pid_t *.
This eliminates the "missing" notion of env_var_t. Instead
env_get returns a maybe_t<env_var_t>, which forces callers to
handle the possibility that the variable is missing.
Internally fish should store vars as a vector of elements. The current
flat string representation is a holdover from when the code was written
in C.
Fixes#4200
It's bugged me forever that the scope is the second arg to `env_get()`
but not `env_set()`. And since I'll be introducing some helper functions
that wrap `env_set()` now is a good time to change the order of its
arguments.
