Document behavior of `create_dir_all` wrt. empty path
The behavior makes sense because `Path::new("one_component").parent() == Some(Path::new(""))`, so if one naively wants to create the parent directory for a file to be written, it simply works.
Closes#105108 by documenting the current behavior.
These changes bring it closer to other standard library documentation
and, in particular, `std::fs::canonicalize`, which it will often be
compared with.
* Add `# Platform-specific behavior` section, with content moved from
Examples section.
* Create `# Errors` section.
* Phrase error description to allow future platforms to have new
syntactic errors, rather than only emptiness.
* Add missing commas.
* Indent example code 4 spaces.
The behavior makes sense because `Path::new("one_component").parent() ==
Some(Path::new(""))`, so if one naively wants to create the parent
directory for a file to be written, it simply works.
Closes#105108 by documenting the current behavior.
impl From<TryReserveError> for io::Error
There's an obvious mapping between these two errors, and it makes I/O code less noisy.
I've chosen to use simple `ErrorKind::OutOfMemory` `io::Error`, without keeping `TryReserveError` for the `source()`, because:
* It matches current uses in libstd,
* `ErrorData::Custom` allocates, which is a risky proposition for handling OOM errors specifically.
* Currently `TryReserveError` has no public fields/methods, so it's usefulness is limited. How allocators should report errors, especially custom and verbose ones is still an open question.
Just in case I've added note in the doccomment that this may change.
The compiler forced me to declare stability of this impl. I think this implementation is simple enough that it doesn't need full-blown stabilization period, and I've marked it for the next release, but of course I can adjust the attribute if needed.
Improve std::fs::read_to_string example
Resolves [#118621](https://github.com/rust-lang/rust/issues/118621)
For the original code to succeed it requires address.txt to contain a socketaddress, however it is much easier to follow if this is just any strong - eg address could be a street address or just text.
Also changed the variable name from "foo" to something more meaningful as cargo clippy warns you against using foo as a placeholder.
```
$ cat main.rs
use std::fs;
use std::error::Error;
fn main() -> Result<(), Box<dyn Error>> {
let addr: String = fs::read_to_string("address.txt")?.parse()?;
println!("{}", addr);
Ok(())
}
$ cat address.txt
123 rusty lane
san francisco 94999
$ cargo run
Finished dev [unoptimized + debuginfo] target(s) in 0.00s
Running `/home/haydon/workspace/rust-test-pr/tester/target/debug/tester`
123 rusty lane
san francisco 94999
```
fix typo in documentation for std::fs::Permissions
Please check and re-check this PR carefully to see if I got this right.
But by my logic, if the `read_only` function returns `true`, I would not expect be able to write to the file (it being read only); so this text is meant to clarify that `read_only` being `false` doesn't mean *you* can actually write to the file, just that "in general" someone is able to.
Document that File does not buffer reads/writes
...and refer to `BufReader`/`BufWriter`.
This is a common source of efficiency issues in Rust programs written naively. Including this information with the `File` docs, and adding a link to the wrapper types, will help discoverability.
Add initial libstd support for Xous
This patchset adds some minimal support to the tier-3 target `riscv32imac-unknown-xous-elf`. The following features are supported:
* alloc
* thread creation and joining
* thread sleeping
* thread_local
* panic_abort
* mutex
* condvar
* stdout
Additionally, internal support for the various Xous primitives surrounding IPC have been added as part of the Xous FFI. These may be exposed as part of `std::os::xous::ffi` in the future, however for now they are not public.
This represents the minimum viable product. A future patchset will add support for networking and filesystem support.
docs: improve std::fs::read doc
#### What does this PR do
1. Rephrase a confusing sentence in the document of `std::fs::read()`
-----
Closes#114432
cc `@Dexus0` `@saethlin`
Add `Read`, `Write` and `Seek` impls for `Arc<File>` where appropriate
If `&T` implements these traits, `Arc<T>` has no reason not to do so
either. This is useful for operating system handles like `File` or
`TcpStream` which don't need a mutable reference to implement these
traits.
CC #53835.
CC #94744.
If `&T` implements these traits, `Arc<T>` has no reason not to do so
either. This is useful for operating system handles like `File` or
`TcpStream` which don't need a mutable reference to implement these
traits.
CC #53835.
CC #94744.
Add creation time support to `FileTimes` on apple and windows
Adds support for setting file creation times on platforms which support changing it directly (currently only Apple and Windows). Based on top of #110093 (which was split from this PR).
ACP: rust-lang/libs-team#199 (currently still in progress)
Tracking issue: #98245
`@rustbot` label +T-libs-api -T-libs
Update documentation wording on path 'try_exists' functions
Just eliminate the quadruple negation in `doesn't silently ignore errors unrelated to ... not existing.`
This documents the very surprising behaviour that `set_readonly(false)` will make a file *world writable* on Unix. I would go so far as to say that this function should be deprecated on Unix, or maybe even entirely. But documenting the bad behaviour is a good first step.
Add a `File::create_new` constructor
We have `File::create` for creating a file or opening an existing file,
but the secure way to guarantee creating a new file requires a longhand
invocation via `OpenOptions`.
Add `File::create_new` to handle this case, to make it easier for people
to do secure file creation.
Support setting file accessed/modified timestamps
Add `struct FileTimes` to contain the relevant file timestamps, since
most platforms require setting all of them at once. (This also allows
for future platform-specific extensions such as setting creation time.)
Add `File::set_file_time` to set the timestamps for a `File`.
Implement the `sys` backends for UNIX, macOS (which needs to fall back
to `futimes` before macOS 10.13 because it lacks `futimens`), Windows,
and WASI.
Add `struct FileTimes` to contain the relevant file timestamps, since
most platforms require setting all of them at once. (This also allows
for future platform-specific extensions such as setting creation time.)
Add `File::set_file_time` to set the timestamps for a `File`.
Implement the `sys` backends for UNIX, macOS (which needs to fall back
to `futimes` before macOS 10.13 because it lacks `futimens`), Windows,
and WASI.
We have `File::create` for creating a file or opening an existing file,
but the secure way to guarantee creating a new file requires a longhand
invocation via `OpenOptions`.
Add `File::create_new` to handle this case, to make it easier for people
to do secure file creation.
This stabilizes the `Path::try_exists()` method which returns
`Result<bool, io::Error>` instead of `bool` allowing handling of errors
unrelated to the file not existing. (e.g permission errors)
Along with the stabilization it also:
* Warns that the `exists()` method is error-prone and suggests to use
the newly stabilized one.
* Suggests it instead of `metadata()` to handle errors.
* Mentions TOCTOU bugs to avoid false assumption that `try_exists()` is
completely safe fixed version of `exists()`.
* Renames the feature of still-unstable `std::fs::try_exists()` to
`fs_try_exists` to avoid name conflict.
The tracking issue #83186 remains open to track `fs_try_exists`.
Remove `#[rustc_deprecated]`
This removes `#[rustc_deprecated]` and introduces diagnostics to help users to the right direction (that being `#[deprecated]`). All uses of `#[rustc_deprecated]` have been converted. CI is expected to fail initially; this requires #95958, which includes converting `stdarch`.
I plan on following up in a short while (maybe a bootstrap cycle?) removing the diagnostics, as they're only intended to be short-term.
remove_dir_all: use fallback implementation on Miri
Fixes https://github.com/rust-lang/miri/issues/1966
The new implementation requires `openat`, `unlinkat`, and `fdopendir`. These cannot easily be shimmed in Miri since libstd does not expose APIs corresponding to them. So for now it is probably easiest to just use the fallback code in Miri. Nobody should run Miri as root anyway...
This updates the standard library's documentation to use the new syntax. The
documentation is worthwhile to update as it should be more idiomatic
(particularly for features like this, which are nice for users to get acquainted
with). The general codebase is likely more hassle than benefit to update: it'll
hurt git blame, and generally updates can be done by folks updating the code if
(and when) that makes things more readable with the new format.
A few places in the compiler and library code are updated (mostly just due to
already having been done when this commit was first authored).
Use `NtCreateFile` instead of `NtOpenFile` to open a file
Generally the internal `Nt*` functions should be avoided but when we do need to use one we should stick to the most commonly used for the job. To that end, this PR replaces `NtOpenFile` with `NtCreateFile`.
NOTE: The initial version of this comment hypothesised that this may help with some recent false positives from malware scanners. This hypothesis proved wrong. Sorry for the distraction.
