When there are multiple screens worth of output and `history` is writing to the
pager, pressing Ctrl-C at the end of a screen doesn't exit the pager (`q` is
needed for that) but previously caused fish to emit an error ("write:
Interrupted system call) until we starting silently handling SIGINT in
`fd_output_stream_t::append()`.
This patch makes `history` detect when the `append()` call returns with an error
and causes it to end early rather than repeatedly trying (and failing) to write
to the output stream.
If EINTR caused by SIGINT is encountered while writing to the
`fd_output_stream_t` output fd, mark the output stream as errored and return
false to the caller but do not visibly complain.
Addressing the outstanding TODO notwithstanding, this is needed to avoid
littering the tty with spurious errors when the user hits Ctrl-C to abort a
long-running builtin's output (w/ the primary example being `history`).
Up to now, in normal locales \x was essentially the same as \X, except
that it errored if given a value > 0x7f.
That's kind of annoying and useless.
A subtle change is that `\xHH` now represents the character (if any)
encoded by the byte value "HH", so even for values <= 0x7f if that's
not the same as the ASCII value we would diverge.
I do not believe anyone has ever run fish on a system where that
distinction matters. It isn't a thing for UTF-8, it isn't a thing for
ASCII, it isn't a thing for UTF-16, it isn't a thing for any extended
ASCII scheme - ISO8859-X, it isn't a thing for SHIFT-JIS.
I am reasonably certain we are making that same assumption in other
places.
Fixes#1352
Closes#9240.
Squash of the following commits (in reverse-chronological order):
commit 03b5cab3dc40eca9d50a9df07a8a32524338a807
Author: Mahmoud Al-Qudsi <mqudsi@neosmart.net>
Date: Sun Sep 25 15:09:04 2022 -0500
Handle differently declared posix_spawnxxx_t on macOS
On macOS, posix_spawnattr_t and posix_spawn_file_actions_t are declared as void
pointers, so we can't use maybe_t's bool operator to test if it has a value.
commit aed83b8bb308120c0f287814d108b5914593630a
Author: Mahmoud Al-Qudsi <mqudsi@neosmart.net>
Date: Sun Sep 25 14:48:46 2022 -0500
Update maybe_t tests to reflect dynamic bool conversion
maybe_t<T> is now bool-convertible only if T _isn't_ already bool-convertible.
commit 2b5a12ca97b46f96b1c6b56a41aafcbdb0dfddd6
Author: Mahmoud Al-Qudsi <mqudsi@neosmart.net>
Date: Sun Sep 25 14:34:03 2022 -0500
Make maybe_t a little harder to misuse
We've had a few bugs over the years stemming from accidental misuse of maybe_t
with bool-convertible types. This patch disables maybe_t's bool operator if the
type T is already bool convertible, forcing the (barely worth mentioning) need
to use maybe_t::has_value() instead.
This patch both removes maybe_t's bool conversion for bool-convertible types and
updates the existing codebase to use the explicit `has_value()` method in place
of existing implicit bool conversions.
The parent commit made the destructor of the DIR* member close it if necessary
(i.e. only if it's not null). This means that we can use the same logic in
the move constructor (where the source DIR* is null) and for move assignment
(where it might not be).
No functional change.
dir_iter_t closes its DIR* member in two places: the move assignment and
the destructor. Simplify this by closing it in the destructor of the DIR*
member which is called in both places. Use std::unique_ptr, which is shorter
than a dedicated wrapper class. Conveniently, it calls the deleter only if
the pointer is not-null. Unfortunately, std::unique_ptr requires explicit
conversion to DIR* when interacting with C APIs but it's probably still
better than a wrapper class.
This means that the noncopyable_t annotation is now implied due to the
unique_ptr member.
Additionally, we could probably remove the user-declared move constructor
and move assignment (the compiler-generated ones should be good enough). To
be safe, keep them around since they also erase the fd (though I hope we
don't rely on that behavior anywhere).
We should perhaps remove the user-declared destructor entirely but
dir_iter_t::entry_t also has one, I'm not sure why. Maybe there's a good
reason, like code size.
No functional change.
This was recently converted to a while-loop. However, we only
loop in a specific case when (by hitting "continue") so a
loop condition is not necessary.
No functional change.
We forgot to decode (i.e. turn into nice wchar_t codepoints)
"byte_literal" escape sequences. This meant that e.g.
```fish
string match ö \Xc3\Xb6
math 5 \X2b 5
```
didn't work, but `math 5 \x2b 5` did, and would print the wonderful
error:
```
math: Error: Missing operator
'5 + 5'
^
```
So, instead, we decode eagerly.
descend_unique_hierarchy is used for the cd autosuggestion: if a directory
contains exactly one subdirectory and no other entries, then propose that
as part of the cd autosuggestion.
This had a bug: if the subdirectory is a symlink to the parent, we would
chase that, going around the loop suggesting a longer path until we hit
PATH_MAX.
Fix this by using the new API which provides the inode "for free," and
track whether we've seen this inode before. This is technically too
conservative since the inode may be for a directory on a different device,
but devices are not available for free so this would incur a cost. In
practice encountering the same inode twice with different devices in a
unique hierarchy is unlikely, and should it happen the consequences are
merely cosmetic: we fail to suggest a longer path.
This introduces dir_iter_t, a new class for iterating the contents of a
directory. dir_iter_t encapsulates the logic that tries to avoid using
stat() to determine the type of a file, when possible.
While we hardcode the return values for the rest of our builtins, the `return`
builtin bubbles up whatever the user returned in their fish script, allowing
invalid return values such as negative numbers to make it into our C++ side of
things.
In creating a `proc_status_t` from the return code of a builtin, we invoke
W_EXITCODE() which is a macro that shifts left the return code by some amount,
and left-shifting a negative integer is undefined behavior.
Aside from causing us to land in UB territory, it also can cause some negative
return values to map to a "successful" exit code of 0, which was probably not
the fish script author's intention.
This patch also adds error logging to help catch any inadvertent additions of
cases where a builtin returns a negative value (should one forget that unix
return codes are always positive) and an assertion protecting against UB.
This was always the case if HAVE_TEXT wasn't defined, but if it was then we were
coercing the result of `_C()` to a `const wchar_t *` pointer, because we were
returning the address of a constant zero-length wchar_t pointer. This reserves a
local static `wcstring` variable that we can return as the "no text" sentinel
and bubbles back the `wcstring` reference rather than decomposing it into a
pointer.
This is a prerequisite for a bigger change I'm working on.
It's gone from 136 bytes to a 128 bytes by rearranging the items in order of
decreasing alignment requirements. While this reduces the memory consumption
slightly (by around 6%) for each completion we have in-memory, that translates
to only around ~8KiB of savings for a command with 1000 possible completions,
which is nice but ultimately not that big of a deal.
The bigger benefit is that a single `complete_entry_t` might now fit in a cache
line, hopefully making the process of testing completions for matches more
cache friendly (and maybe even faster).
The impact here depends on the command and how much output it
produces.
It's possible to get up to 1.5x - `string upper` being a good example,
or a no-op `string match '*'`.
But the more the command actually needs to do, the less of an effect
this has.
This basically immediately issues a "write()" if it's to a pipe or the
terminal.
That means we can reduce syscalls and improve performance, even by
doing something like
```c++
streams.out.append(somewcstring + L"\n");
```
instead of
```c++
streams.out.append(somewcstring);
streams.out.push_back(L'\n');
```
Some benchmarks of the
```fish
for i in (string repeat -n 2000 \n)
$thing
end
```
variety:
1. `set` (printing variables) sped up 1.75x
2. `builtin -n` 1.60x
3. `jobs` 1.25x (with 3 jobs)
4. `functions` 1.20x
5. `math 1 + 1` 1.1x
6. `pwd` 1.1x
Piping yields similar results, there is no real difference when
outputting to a command substitution.
This writes the output once per argument instead of once per format or
escaped char.
An egregious case:
```fish
printf (string repeat -n 200 \\x7f)%s\n (string repeat -n 2000 aaa\n)
```
Has been sped up by ~20x by reducing write() calls from 40000 to 200.
Even a simple
```fish
printf %s\n (string repeat -n 2000 aaa\n)
```
should now be ~1.2x faster by issuing 2000 instead of 4000 write
calls (the `\n` was written separately!).
This at least halves the number of "write()" calls we do if it goes to
a pipe or the terminal, or reduces them by 75% if there is a
description.
This makes
```fish
complete -c foo -xa "(seq 50000)"
complete -C"foo "
```
faster by 1.33x.
This uses wreaddir_resolving, which tries to use the dirent d_type
field if it exists. In that way, it can skip the `stat` to determine
if the given file is a directory.
This allows `cd` completions to skip stat in most cases:
```fish
strace -Ce newfstatat fish --no-config -c 'complete -C"cd /tmp/completion_test/"' >/dev/null
```
prints before:
```
% time seconds usecs/call calls errors syscall
------ ----------- ----------- --------- --------- ----------------
100,00 0,002627 2 1033 4 newfstatat
```
after:
```
% time seconds usecs/call calls errors syscall
------ ----------- ----------- --------- --------- ----------------
100,00 0,000054 1 31 3 newfstatat
```
for a directory with 1000 subdirectories.
(just `fish --no-config -c exit` does 26 newfstatat)
This should improve the situation with slow filesystems like fuse or
network fsen.
In case we have no d_type, we use `stat`, which would yield about the
same results.
The worst case is that we need directories *and* descriptions or the
"executable" flag (which we don't currently check for cd, if I read
this right?).
This flag determines whether or not more shortopt switches will be offered up as
potential completions (vs only the payload for the last-parsed shortopt switch).
Previously, it was being stomped before it was determined whether or not two
`complete` rules with different `result_mode.requires_param` values were
actually resolved against the current command line or not, and the last
evaluated completion rule would win out.
There are two changes here:
* `last_option_requires_param` is only assigned if all associated conditions for
a potential completion are also met, and
* If already assigned by a conflicting rule (which can only be user/developer
error), `last_option_requires_param` is allowed to change from true to false
but not the other way around (i.e. in case of a conflict, generate both
payloads and other shortopt completions)
The first change is immediately noticeable and affects many of our own
completions, see the discussion in #9221 for an example regarding `git` where
`-c` has any of about a million different possible meanings depending on which
completion preconditions have been met. The second change should only happen if
a dev/user mistakenly enters a `complete -c ...` rule for the same shortopt more
than once, both with conditions matching, sometimes requiring an argument and
not sometimes not. It should be a rare occurence.
