This rather large commit adds/fixes missing WASI functionality
in `libstd` needed to pass the `libstd` tests. As such, now by
default tests targeting `wasm32-wasi` target are enabled in
`test/tests.zig` module. However, they can be disabled by passing
the `-Dskip-wasi=true` flag when invoking the `zig build test`
command. When the flag is set to `false`, i.e., when WASI tests are
included, `wasmtime` with `--dir=.` is used as the default testing
command.
Since the majority of `libstd` tests were relying on `fs.cwd()`
call to get current working directory handle wrapped in `Dir`
struct, in order to make the tests WASI-friendly, `fs.cwd()`
call was replaced with `testing.getTestDir()` function which
resolved to either `fs.cwd()` for non-WASI targets, or tries to
fetch the preopen list from the WASI runtime and extract a
preopen for '.' path.
The summary of changes introduced by this commit:
* implement `Dir.makeDir` and `Dir.openDir` targeting WASI
* implement `Dir.deleteFile` and `Dir.deleteDir` targeting WASI
* fix `os.close` and map errors in `unlinkat`
* move WASI-specific `mkdirat` and `unlinkat` from `std.fs.wasi`
to `std.os` module
* implement `lseek_{SET, CUR, END}` targeting WASI
* implement `futimens` targeting WASI
* implement `ftruncate` targeting WASI
* implement `readv`, `writev`, `pread{v}`, `pwrite{v}` targeting WASI
* make sure ANSI escape codes are _not_ used in stderr or stdout
in WASI, as WASI always sanitizes stderr, and sanitizes stdout if
fd is a TTY
* fix specifying WASI rights when opening/creating files/dirs
* tweak `AtomicFile` to be WASI-compatible
* implement `os.renameatWasi` for WASI-compliant `os.renameat` function
* implement sleep() targeting WASI
* fix `process.getEnvMap` targeting WASI
Previously, the path and preopens helpers were prototyped in `std.os.wasi`
module, but since they are higher-level abstraction over wasi, they belong in
`std.fs.wasi` module.
This commit removes `std.os.openatWasi` function, and renames it to
`std.os.wasi.openat`. Additionally, the added `PreopenList.findByPath`
method allows querying the list for a matching preopen by path.
This commit refactors `std.os.wasi.resolve_preopen` into a (higher-level)
`std.os.wasi.getPreopens` funtion which returns a slice with _all_
preopens at any given time. This fn allows the WASI module to
inquire at any given time for all preopens provided by the runtime.
This commit also makes `cwd()` a compile error on WASI.
This commit adds WASI specific impl of `std.fs.cwd()` in which we
emulate the `cwd` behaviour by inquiring the runtime for a "."
preopen if available. This is OK for simple relative ops, but will
not work for any ops which require absolute paths.
It seems that `std.os.openZ` is too POSIX-specific, so I think it
should not be a point of entry for WASI `open` call. I figure
WASI should be treated as a separate "os" that's _not_ POSIX
especially given the incoming changes in the ephemeral snapshot.
The tests were put into a deadlock, and it seems that darwin doesn't
support `O_SYNC`, though it supports `O_NONBLOCK`. It shouldn't block
even with that, but I'm not sure why else it would fail.
`flock` locks based on the file handle, instead of the process id.
This brings the file locking on unix based systems closer to file
locking on Windows.
This new name (and the fact that it is a function returning a type) will
make it more clear which use cases are better suited for ArrayList and
which are better suited for ArrayListSentineled.
Also for consistency with ArrayList,
* `append` => `appendSlice`
* `appendByte` => `append`
Thanks daurnimator for pointing out the confusion of std.Buffer.
