1//! Buffering wrappers for I/O traits
2
3mod bufreader;
4mod bufwriter;
5mod linewriter;
6mod linewritershim;
7
8#[cfg(test)]
9mod tests;
10
11#[stable(feature = "bufwriter_into_parts", since = "1.56.0")]
12pub use bufwriter::WriterPanicked;
13use linewritershim::LineWriterShim;
14
15#[stable(feature = "rust1", since = "1.0.0")]
16pub use self::{bufreader::BufReader, bufwriter::BufWriter, linewriter::LineWriter};
17use crate::io::Error;
18use crate::{error, fmt};
19
20/// An error returned by [`BufWriter::into_inner`] which combines an error that
21/// happened while writing out the buffer, and the buffered writer object
22/// which may be used to recover from the condition.
23///
24/// # Examples
25///
26/// ```no_run
27/// use std::io::BufWriter;
28/// use std::net::TcpStream;
29///
30/// let mut stream = BufWriter::new(TcpStream::connect("127.0.0.1:34254").unwrap());
31///
32/// // do stuff with the stream
33///
34/// // we want to get our `TcpStream` back, so let's try:
35///
36/// let stream = match stream.into_inner() {
37/// Ok(s) => s,
38/// Err(e) => {
39/// // Here, e is an IntoInnerError
40/// panic!("An error occurred");
41/// }
42/// };
43/// ```
44#[derive(Debug)]
45#[stable(feature = "rust1", since = "1.0.0")]
46pub struct IntoInnerError<W>(W, Error);
47
48impl<W> IntoInnerError<W> {
49 /// Constructs a new IntoInnerError
50 fn new(writer: W, error: Error) -> Self {
51 Self(writer, error)
52 }
53
54 /// Helper to construct a new IntoInnerError; intended to help with
55 /// adapters that wrap other adapters
56 fn new_wrapped<W2>(self, f: impl FnOnce(W) -> W2) -> IntoInnerError<W2> {
57 let Self(writer, error) = self;
58 IntoInnerError::new(f(writer), error)
59 }
60
61 /// Returns the error which caused the call to [`BufWriter::into_inner()`]
62 /// to fail.
63 ///
64 /// This error was returned when attempting to write the internal buffer.
65 ///
66 /// # Examples
67 ///
68 /// ```no_run
69 /// use std::io::BufWriter;
70 /// use std::net::TcpStream;
71 ///
72 /// let mut stream = BufWriter::new(TcpStream::connect("127.0.0.1:34254").unwrap());
73 ///
74 /// // do stuff with the stream
75 ///
76 /// // we want to get our `TcpStream` back, so let's try:
77 ///
78 /// let stream = match stream.into_inner() {
79 /// Ok(s) => s,
80 /// Err(e) => {
81 /// // Here, e is an IntoInnerError, let's log the inner error.
82 /// //
83 /// // We'll just 'log' to stdout for this example.
84 /// println!("{}", e.error());
85 ///
86 /// panic!("An unexpected error occurred.");
87 /// }
88 /// };
89 /// ```
90 #[stable(feature = "rust1", since = "1.0.0")]
91 pub fn error(&self) -> &Error {
92 &self.1
93 }
94
95 /// Returns the buffered writer instance which generated the error.
96 ///
97 /// The returned object can be used for error recovery, such as
98 /// re-inspecting the buffer.
99 ///
100 /// # Examples
101 ///
102 /// ```no_run
103 /// use std::io::BufWriter;
104 /// use std::net::TcpStream;
105 ///
106 /// let mut stream = BufWriter::new(TcpStream::connect("127.0.0.1:34254").unwrap());
107 ///
108 /// // do stuff with the stream
109 ///
110 /// // we want to get our `TcpStream` back, so let's try:
111 ///
112 /// let stream = match stream.into_inner() {
113 /// Ok(s) => s,
114 /// Err(e) => {
115 /// // Here, e is an IntoInnerError, let's re-examine the buffer:
116 /// let buffer = e.into_inner();
117 ///
118 /// // do stuff to try to recover
119 ///
120 /// // afterwards, let's just return the stream
121 /// buffer.into_inner().unwrap()
122 /// }
123 /// };
124 /// ```
125 #[stable(feature = "rust1", since = "1.0.0")]
126 pub fn into_inner(self) -> W {
127 self.0
128 }
129
130 /// Consumes the [`IntoInnerError`] and returns the error which caused the call to
131 /// [`BufWriter::into_inner()`] to fail. Unlike `error`, this can be used to
132 /// obtain ownership of the underlying error.
133 ///
134 /// # Example
135 /// ```
136 /// use std::io::{BufWriter, ErrorKind, Write};
137 ///
138 /// let mut not_enough_space = [0u8; 10];
139 /// let mut stream = BufWriter::new(not_enough_space.as_mut());
140 /// write!(stream, "this cannot be actually written").unwrap();
141 /// let into_inner_err = stream.into_inner().expect_err("now we discover it's too small");
142 /// let err = into_inner_err.into_error();
143 /// assert_eq!(err.kind(), ErrorKind::WriteZero);
144 /// ```
145 #[stable(feature = "io_into_inner_error_parts", since = "1.55.0")]
146 pub fn into_error(self) -> Error {
147 self.1
148 }
149
150 /// Consumes the [`IntoInnerError`] and returns the error which caused the call to
151 /// [`BufWriter::into_inner()`] to fail, and the underlying writer.
152 ///
153 /// This can be used to simply obtain ownership of the underlying error; it can also be used for
154 /// advanced error recovery.
155 ///
156 /// # Example
157 /// ```
158 /// use std::io::{BufWriter, ErrorKind, Write};
159 ///
160 /// let mut not_enough_space = [0u8; 10];
161 /// let mut stream = BufWriter::new(not_enough_space.as_mut());
162 /// write!(stream, "this cannot be actually written").unwrap();
163 /// let into_inner_err = stream.into_inner().expect_err("now we discover it's too small");
164 /// let (err, recovered_writer) = into_inner_err.into_parts();
165 /// assert_eq!(err.kind(), ErrorKind::WriteZero);
166 /// assert_eq!(recovered_writer.buffer(), b"t be actually written");
167 /// ```
168 #[stable(feature = "io_into_inner_error_parts", since = "1.55.0")]
169 pub fn into_parts(self) -> (Error, W) {
170 (self.1, self.0)
171 }
172}
173
174#[stable(feature = "rust1", since = "1.0.0")]
175impl<W> From<IntoInnerError<W>> for Error {
176 fn from(iie: IntoInnerError<W>) -> Error {
177 iie.1
178 }
179}
180
181#[stable(feature = "rust1", since = "1.0.0")]
182impl<W: Send + fmt::Debug> error::Error for IntoInnerError<W> {
183 #[allow(deprecated, deprecated_in_future)]
184 fn description(&self) -> &str {
185 error::Error::description(self.error())
186 }
187}
188
189#[stable(feature = "rust1", since = "1.0.0")]
190impl<W> fmt::Display for IntoInnerError<W> {
191 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
192 self.error().fmt(f)
193 }
194}
195

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