Struct otter_nodejs_tests::otter_support::imports::fs::OpenOptions
1.0.0 · source · [−]pub struct OpenOptions(_);
Expand description
Options and flags which can be used to configure how a file is opened.
This builder exposes the ability to configure how a File
is opened and
what operations are permitted on the open file. The File::open
and
File::create
methods are aliases for commonly used options using this
builder.
Generally speaking, when using OpenOptions
, you’ll first call
OpenOptions::new
, then chain calls to methods to set each option, then
call OpenOptions::open
, passing the path of the file you’re trying to
open. This will give you a io::Result
with a File
inside that you
can further operate on.
Examples
Opening a file to read:
use std::fs::OpenOptions;
let file = OpenOptions::new().read(true).open("foo.txt");
Opening a file for both reading and writing, as well as creating it if it doesn’t exist:
use std::fs::OpenOptions;
let file = OpenOptions::new()
.read(true)
.write(true)
.create(true)
.open("foo.txt");
Implementations
sourceimpl OpenOptions
impl OpenOptions
sourcepub fn new() -> OpenOptions
pub fn new() -> OpenOptions
Creates a blank new set of options ready for configuration.
All options are initially set to false
.
Examples
use std::fs::OpenOptions;
let mut options = OpenOptions::new();
let file = options.read(true).open("foo.txt");
sourcepub fn read(&mut self, read: bool) -> &mut OpenOptions
pub fn read(&mut self, read: bool) -> &mut OpenOptions
Sets the option for read access.
This option, when true, will indicate that the file should be
read
-able if opened.
Examples
use std::fs::OpenOptions;
let file = OpenOptions::new().read(true).open("foo.txt");
sourcepub fn write(&mut self, write: bool) -> &mut OpenOptions
pub fn write(&mut self, write: bool) -> &mut OpenOptions
Sets the option for write access.
This option, when true, will indicate that the file should be
write
-able if opened.
If the file already exists, any write calls on it will overwrite its contents, without truncating it.
Examples
use std::fs::OpenOptions;
let file = OpenOptions::new().write(true).open("foo.txt");
sourcepub fn append(&mut self, append: bool) -> &mut OpenOptions
pub fn append(&mut self, append: bool) -> &mut OpenOptions
Sets the option for the append mode.
This option, when true, means that writes will append to a file instead
of overwriting previous contents.
Note that setting .write(true).append(true)
has the same effect as
setting only .append(true)
.
For most filesystems, the operating system guarantees that all writes are atomic: no writes get mangled because another process writes at the same time.
One maybe obvious note when using append-mode: make sure that all data
that belongs together is written to the file in one operation. This
can be done by concatenating strings before passing them to write()
,
or using a buffered writer (with a buffer of adequate size),
and calling flush()
when the message is complete.
If a file is opened with both read and append access, beware that after
opening, and after every write, the position for reading may be set at the
end of the file. So, before writing, save the current position (using
seek(SeekFrom::Current(0))
), and restore it before the next read.
Note
This function doesn’t create the file if it doesn’t exist. Use the
OpenOptions::create
method to do so.
Examples
use std::fs::OpenOptions;
let file = OpenOptions::new().append(true).open("foo.txt");
sourcepub fn truncate(&mut self, truncate: bool) -> &mut OpenOptions
pub fn truncate(&mut self, truncate: bool) -> &mut OpenOptions
Sets the option for truncating a previous file.
If a file is successfully opened with this option set it will truncate the file to 0 length if it already exists.
The file must be opened with write access for truncate to work.
Examples
use std::fs::OpenOptions;
let file = OpenOptions::new().write(true).truncate(true).open("foo.txt");
sourcepub fn create(&mut self, create: bool) -> &mut OpenOptions
pub fn create(&mut self, create: bool) -> &mut OpenOptions
Sets the option to create a new file, or open it if it already exists.
In order for the file to be created, OpenOptions::write
or
OpenOptions::append
access must be used.
Examples
use std::fs::OpenOptions;
let file = OpenOptions::new().write(true).create(true).open("foo.txt");
1.9.0 · sourcepub fn create_new(&mut self, create_new: bool) -> &mut OpenOptions
pub fn create_new(&mut self, create_new: bool) -> &mut OpenOptions
Sets the option to create a new file, failing if it already exists.
No file is allowed to exist at the target location, also no (dangling) symlink. In this way, if the call succeeds, the file returned is guaranteed to be new.
This option is useful because it is atomic. Otherwise between checking whether a file exists and creating a new one, the file may have been created by another process (a TOCTOU race condition / attack).
If .create_new(true)
is set, .create()
and .truncate()
are
ignored.
The file must be opened with write or append access in order to create a new file.
Examples
use std::fs::OpenOptions;
let file = OpenOptions::new().write(true)
.create_new(true)
.open("foo.txt");
sourcepub fn open<P>(&self, path: P) -> Result<File, Error> where
P: AsRef<Path>,
pub fn open<P>(&self, path: P) -> Result<File, Error> where
P: AsRef<Path>,
Opens a file at path
with the options specified by self
.
Errors
This function will return an error under a number of different
circumstances. Some of these error conditions are listed here, together
with their io::ErrorKind
. The mapping to io::ErrorKind
s is not
part of the compatibility contract of the function.
NotFound
: The specified file does not exist and neithercreate
orcreate_new
is set.NotFound
: One of the directory components of the file path does not exist.PermissionDenied
: The user lacks permission to get the specified access rights for the file.PermissionDenied
: The user lacks permission to open one of the directory components of the specified path.AlreadyExists
:create_new
was specified and the file already exists.InvalidInput
: Invalid combinations of open options (truncate without write access, no access mode set, etc.).
The following errors don’t match any existing io::ErrorKind
at the moment:
- One of the directory components of the specified file path was not, in fact, a directory.
- Filesystem-level errors: full disk, write permission requested on a read-only file system, exceeded disk quota, too many open files, too long filename, too many symbolic links in the specified path (Unix-like systems only), etc.
Examples
use std::fs::OpenOptions;
let file = OpenOptions::new().read(true).open("foo.txt");
Trait Implementations
sourceimpl Clone for OpenOptions
impl Clone for OpenOptions
sourcefn clone(&self) -> OpenOptions
fn clone(&self) -> OpenOptions
Returns a copy of the value. Read more
sourcefn clone_from(&mut self, source: &Self)
fn clone_from(&mut self, source: &Self)
Performs copy-assignment from source
. Read more
sourceimpl Debug for OpenOptions
impl Debug for OpenOptions
impl From<OpenOptions> for OpenOptions
impl From<OpenOptions> for OpenOptions
fn from(options: OpenOptions) -> OpenOptions
fn from(options: OpenOptions) -> OpenOptions
Converts to this type from the input type.
1.1.0 · sourceimpl OpenOptionsExt for OpenOptions
impl OpenOptionsExt for OpenOptions
sourcefn mode(&mut self, mode: u32) -> &mut OpenOptions
fn mode(&mut self, mode: u32) -> &mut OpenOptions
Sets the mode bits that a new file will be created with. Read more
sourcefn custom_flags(&mut self, flags: i32) -> &mut OpenOptions
fn custom_flags(&mut self, flags: i32) -> &mut OpenOptions
Pass custom flags to the flags
argument of open
. Read more
Auto Trait Implementations
impl RefUnwindSafe for OpenOptions
impl Send for OpenOptions
impl Sync for OpenOptions
impl Unpin for OpenOptions
impl UnwindSafe for OpenOptions
Blanket Implementations
sourceimpl<T> BorrowMut<T> for T where
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
const: unstable · sourcefn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more
impl<T> Downcast for T where
T: Any,
impl<T> Downcast for T where
T: Any,
fn into_any(self: Box<T, Global>) -> Box<dyn Any + 'static, Global>ⓘNotable traits for Box<W, Global>impl<W> Write for Box<W, Global> where
W: Write + ?Sized, impl<R> Read for Box<R, Global> where
R: Read + ?Sized, impl<F, A> Future for Box<F, A> where
F: Future + Unpin + ?Sized,
A: Allocator + 'static, type Output = <F as Future>::Output;impl<I, A> Iterator for Box<I, A> where
I: Iterator + ?Sized,
A: Allocator, type Item = <I as Iterator>::Item;
fn into_any(self: Box<T, Global>) -> Box<dyn Any + 'static, Global>ⓘNotable traits for Box<W, Global>impl<W> Write for Box<W, Global> where
W: Write + ?Sized, impl<R> Read for Box<R, Global> where
R: Read + ?Sized, impl<F, A> Future for Box<F, A> where
F: Future + Unpin + ?Sized,
A: Allocator + 'static, type Output = <F as Future>::Output;impl<I, A> Iterator for Box<I, A> where
I: Iterator + ?Sized,
A: Allocator, type Item = <I as Iterator>::Item;
W: Write + ?Sized, impl<R> Read for Box<R, Global> where
R: Read + ?Sized, impl<F, A> Future for Box<F, A> where
F: Future + Unpin + ?Sized,
A: Allocator + 'static, type Output = <F as Future>::Output;impl<I, A> Iterator for Box<I, A> where
I: Iterator + ?Sized,
A: Allocator, type Item = <I as Iterator>::Item;
Convert Box<dyn Trait>
(where Trait: Downcast
) to Box<dyn Any>
. Box<dyn Any>
can
then be further downcast
into Box<ConcreteType>
where ConcreteType
implements Trait
. Read more
fn into_any_rc(self: Rc<T>) -> Rc<dyn Any + 'static>
fn into_any_rc(self: Rc<T>) -> Rc<dyn Any + 'static>
Convert Rc<Trait>
(where Trait: Downcast
) to Rc<Any>
. Rc<Any>
can then be
further downcast
into Rc<ConcreteType>
where ConcreteType
implements Trait
. Read more
fn as_any(&self) -> &(dyn Any + 'static)
fn as_any(&self) -> &(dyn Any + 'static)
Convert &Trait
(where Trait: Downcast
) to &Any
. This is needed since Rust cannot
generate &Any
’s vtable from &Trait
’s. Read more
fn as_any_mut(&mut self) -> &mut (dyn Any + 'static)
fn as_any_mut(&mut self) -> &mut (dyn Any + 'static)
Convert &mut Trait
(where Trait: Downcast
) to &Any
. This is needed since Rust cannot
generate &mut Any
’s vtable from &mut Trait
’s. Read more
impl<A> DynCastExt for A
impl<A> DynCastExt for A
fn dyn_cast<T>(
self
) -> Result<<A as DynCastExtHelper<T>>::Target, <A as DynCastExtHelper<T>>::Source> where
A: DynCastExtHelper<T>,
T: ?Sized,
fn dyn_cast<T>(
self
) -> Result<<A as DynCastExtHelper<T>>::Target, <A as DynCastExtHelper<T>>::Source> where
A: DynCastExtHelper<T>,
T: ?Sized,
Use this to cast from one trait object type to another. Read more
fn dyn_upcast<T>(self) -> <A as DynCastExtAdvHelper<T, T>>::Target where
A: DynCastExtAdvHelper<T, T, Source = <A as DynCastExtAdvHelper<T, T>>::Target>,
T: ?Sized,
fn dyn_upcast<T>(self) -> <A as DynCastExtAdvHelper<T, T>>::Target where
A: DynCastExtAdvHelper<T, T, Source = <A as DynCastExtAdvHelper<T, T>>::Target>,
T: ?Sized,
Use this to upcast a trait to one of its supertraits. Read more
fn dyn_cast_adv<F, T>(
self
) -> Result<<A as DynCastExtAdvHelper<F, T>>::Target, <A as DynCastExtAdvHelper<F, T>>::Source> where
A: DynCastExtAdvHelper<F, T>,
F: ?Sized,
T: ?Sized,
fn dyn_cast_adv<F, T>(
self
) -> Result<<A as DynCastExtAdvHelper<F, T>>::Target, <A as DynCastExtAdvHelper<F, T>>::Source> where
A: DynCastExtAdvHelper<F, T>,
F: ?Sized,
T: ?Sized,
fn dyn_cast_with_config<C>(
self
) -> Result<<A as DynCastExtAdvHelper<<C as DynCastConfig>::Source, <C as DynCastConfig>::Target>>::Target, <A as DynCastExtAdvHelper<<C as DynCastConfig>::Source, <C as DynCastConfig>::Target>>::Source> where
C: DynCastConfig,
A: DynCastExtAdvHelper<<C as DynCastConfig>::Source, <C as DynCastConfig>::Target>,
fn dyn_cast_with_config<C>(
self
) -> Result<<A as DynCastExtAdvHelper<<C as DynCastConfig>::Source, <C as DynCastConfig>::Target>>::Target, <A as DynCastExtAdvHelper<<C as DynCastConfig>::Source, <C as DynCastConfig>::Target>>::Source> where
C: DynCastConfig,
A: DynCastExtAdvHelper<<C as DynCastConfig>::Source, <C as DynCastConfig>::Target>,
Use this to cast from one trait object type to another. With this method the type parameter is a config type that uniquely specifies which cast should be preformed. Read more
sourceimpl<T> Instrument for T
impl<T> Instrument for T
sourcefn instrument(self, span: Span) -> Instrumented<Self>ⓘNotable traits for Instrumented<T>impl<T> Future for Instrumented<T> where
T: Future, type Output = <T as Future>::Output;
fn instrument(self, span: Span) -> Instrumented<Self>ⓘNotable traits for Instrumented<T>impl<T> Future for Instrumented<T> where
T: Future, type Output = <T as Future>::Output;
T: Future, type Output = <T as Future>::Output;
sourcefn in_current_span(self) -> Instrumented<Self>ⓘNotable traits for Instrumented<T>impl<T> Future for Instrumented<T> where
T: Future, type Output = <T as Future>::Output;
fn in_current_span(self) -> Instrumented<Self>ⓘNotable traits for Instrumented<T>impl<T> Future for Instrumented<T> where
T: Future, type Output = <T as Future>::Output;
T: Future, type Output = <T as Future>::Output;
impl<V, T> VZip<V> for T where
V: MultiLane<T>,
impl<V, T> VZip<V> for T where
V: MultiLane<T>,
fn vzip(self) -> V
sourceimpl<T> WithSubscriber for T
impl<T> WithSubscriber for T
sourcefn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>ⓘNotable traits for WithDispatch<T>impl<T> Future for WithDispatch<T> where
T: Future, type Output = <T as Future>::Output;
where
S: Into<Dispatch>,
fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>ⓘNotable traits for WithDispatch<T>impl<T> Future for WithDispatch<T> where
T: Future, type Output = <T as Future>::Output;
where
S: Into<Dispatch>,
T: Future, type Output = <T as Future>::Output;
Attaches the provided Subscriber
to this type, returning a
WithDispatch
wrapper. Read more
sourcefn with_current_subscriber(self) -> WithDispatch<Self>ⓘNotable traits for WithDispatch<T>impl<T> Future for WithDispatch<T> where
T: Future, type Output = <T as Future>::Output;
fn with_current_subscriber(self) -> WithDispatch<Self>ⓘNotable traits for WithDispatch<T>impl<T> Future for WithDispatch<T> where
T: Future, type Output = <T as Future>::Output;
T: Future, type Output = <T as Future>::Output;
Attaches the current default Subscriber
to this type, returning a
WithDispatch
wrapper. Read more