## Summary
- Fix SSH `-L` port-forward arguments to wrap IPv6 addresses in brackets
(e.g. `-L[::1]:8080:[::1]:80`), so SSH can correctly parse them
- Rewrite `parse_port_forward_spec` to support bracket-wrapped IPv6
tokens like `[::1]:8080:[::1]:80`
- Add diagnostic logging for stdin read failures in the remote server to
aid debugging connection issues
Closes#49009
## Test plan
- [x] New unit tests: `test_parse_port_forward_spec_ipv6`,
`test_port_forward_ipv6_formatting`,
`test_build_command_with_ipv6_port_forward`
- [x] Existing tests pass: `cargo test -p remote --lib
transport::ssh::tests` (6/6)
- [ ] Manual verification: connect via SSH to an IPv6 host with port
forwarding configured
🤖 Generated with [Claude Code](https://claude.com/claude-code)
---------
Co-authored-by: Claude <noreply@anthropic.com>
We see a number of crashes in Sentry that appear to be crashes in
wasmtime.
This shouldn't happen, as wasmtime is designed to run untrusted code
"safely".
Looking into this, it seems likely that the problem is that we race with
wasmtime
when installing signal handlers. If wasmtime's handlers are installed
before ours,
then any signals that it intends to handle (like out of bounds memory
access) will
reach our handlers before its; which causes us to assume the app has
crashed.
This changes fixes our crash handler initialization to ensure we always
create
our signal handler first, and reverts a previous attempt to fix this
from #40883
Closes #ISSUE
Before you mark this PR as ready for review, make sure that you have:
- [ ] Added a solid test coverage and/or screenshots from doing manual
testing
- [ ] Done a self-review taking into account security and performance
aspects
- [ ] Aligned any UI changes with the [UI
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
Release Notes:
- Linux: Fixed crashes that could happen due to our crash handler
erroneously catching signals intended for wasmtime.
#2874 on steroids
Before you mark this PR as ready for review, make sure that you have:
- [ ] Added a solid test coverage and/or screenshots from doing manual
testing
- [ ] Done a self-review taking into account security and performance
aspects
- [ ] Aligned any UI changes with the [UI
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
Release Notes:
- N/A
---------
Co-authored-by: Eric Holk <eric@zed.dev>
Here's some backstory:
* on macOS, @cole-miller and I noticed that since roughly Oct 2025, due
to some changes to latest macOS Tahoe, for any spawned child process we
needed to reset Mach exception ports
(https://github.com/zed-industries/zed/issues/36754 +
https://github.com/RemiKalbe/zed/commit/6e8f2d2ebe5a93753625a3026aeb996de8cb436b)
* the changes in that PR achieve that via `pre_exec` hook on
`std::process::Command` which then abandons `posix_spawn` syscall for
`fork` + `execve` dance on macOS (we tracked it down in Rust's std
implementation)
* as it turns out, `fork` + `execve` is pretty expensive on macOS
(apparently way more so than on other OSes like Linux) and `fork` takes
a process-wide lock on the allocator which is bad
* however, since we wanna reset exception ports on the child, the only
official way supported by Rust's std is to use `pre_exec` hook
* posix_spawn on macOS exposes this tho via a macOS specific extension
to that syscall `posix_spawnattr_setexceptionports_np` but there is no
way to use that via any standard interfaces in `std::process::Command`
* thus, it seemed like a good idea to instead create our own custom
Command wrapper that on non-macOS hosts is a zero-cost wrapper of
`smol::process::Command`, while on macOS we reimplement the minimum to
achieve `smol::process::Command` with `posix_spawn` under-the-hood
Notably, this changeset improves git-blame in very large repos
significantly.
Release Notes:
- Fixed performance spawning child processes on macOS by always forcing
`posix_spawn` no matter what.
---------
Co-authored-by: Cole Miller <cole@zed.dev>
