This commit sketches an idea for how to deal with detection of file
streams as being terminals.
When a File stream is a terminal, writes through the stream should have
their escapes stripped unless the programmer explicitly enables terminal
escapes. Furthermore, the programmer needs a convenient API for
intentionally outputting escapes into the stream. In particular it
should be possible to set colors that are silently discarded when the
stream is not a terminal.
This commit makes `Io.File.Writer` track the terminal mode in the
already-existing `mode` field, making it the appropriate place to
implement escape stripping.
`Io.lockStderrWriter` returns a `*Io.File.Writer` with terminal
detection already done by default. This is a higher-level application
layer stream for writing to stderr.
Meanwhile, `std.debug.lockStderrWriter` also returns a `*Io.File.Writer`
but a lower-level one that is hard-coded to use a static single-threaded
`std.Io.Threaded` instance. This is the same instance that is used for
collecting debug information and iterating the unwind info.
This decision should be audited and discussed.
Some factors:
* Passing an Io instance into start.
* Avoiding reference to global static instance if it won't be used, so
that it doesn't bloat the executable.
* Being able to use std.debug.print, and related functionality when
debugging std.Io instances and std.Progress.
instead, allow the user to set it as a field.
this fixes a bug where leak printing and error printing would run tty
config detection for stderr, and then emit a log, which is not necessary
going to print to stderr.
however, the nice defaults are gone; the user must explicitly assign the
tty_config field during initialization or else the logging will not have
color.
related: https://github.com/ziglang/zig/issues/24510
The 6.17 kernel added[1] syscalls for getting/setting certain file flags
and attributes. It's meant to be a more extensible replacement for these
ioctl's:
- `FS_IOC_GETFLAGS`/`FS_IOC_SETFLAGS`.
- `FS_IOC_FSGETXATTR`/`FS_IOC_FSSETXATTR`.
The definitions of these calls are as follows:
```zig
const file_attr = extern struct {
/// Extended flags that apply to this file. (get/set).
xflags: u64,
/// Preferred extent allocation size, in bytes. (get/set).
extsize: u32,
/// One of:
/// - The number of data extents in this file.
/// - If `FS_IOC_FSGETXATTRA` is set, the number of extended attribute events in the file.
/// (get)
nextents: u32,
/// Project Identifier (get/set).
projid: u32,
/// Preferred extent allocation size for CoW operations, in bytes (get/set).
cowextsize: u32,
};
// size=@sizeOf(file_attr)
fn file_getattr(dirfd: fd_t, path: [*:0], fattr: *file_attr, size: usize, at_flags: u32) {}
fn file_setattr(dirfd: fd_t, path: [*:0], fattr: *file_attr, size: usize, at_flags: u32) {}
```
Users need to set/check `xflags` with the `FS_XFLAG` flags defined in
`linux/fs.h`. `ioctl_xfs_fsgetxattr(2)` has more information about the
type of information one can retrieve.
[1]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=57fcb7d930d8f00f383e995aeebdcd2b416a187a
Eliminate the `std.Thread.Pool` used in the compiler for concurrency and
asynchrony, in favour of the new `std.Io.async` and `std.Io.concurrent`
primitives.
This removes the last usage of `std.Thread.Pool` in the Zig repository.
More tasks could be added to the group at any time before it completes,
so it's not valid to look at the `token` passed in here.
There's also a related bug in `Threaded`, which is that tasks spawned in
a group after it is canceled will not observe that cancelation, but that
is a more complex bug which needs some deeper design changes.
Andrew Kelley