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use super::AsyncBody;
use crate::util::io::write_all_async;
use futures_lite::future::yield_now;
use sluice::pipe::{pipe, PipeWriter};
use std::{
borrow::Cow,
fmt,
fs::File,
io::{Cursor, ErrorKind, Read, Result},
};
/// Contains the body of a synchronous HTTP request or response.
///
/// This type is used to encapsulate the underlying stream or region of memory
/// where the contents of the body are stored. A [`Body`] can be created from
/// many types of sources using the [`Into`](std::convert::Into) trait or one of
/// its constructor functions. It can also be created from anything that
/// implements [`Read`], which [`Body`] itself also implements.
///
/// For asynchronous requests, use [`AsyncBody`] instead.
pub struct Body(Inner);
enum Inner {
Empty,
Buffer(Cursor<Cow<'static, [u8]>>),
Reader(Box<dyn Read + Send + Sync>, Option<u64>),
}
impl Body {
/// Create a new empty body.
///
/// An empty body represents the *absence* of a body, which is semantically
/// different than the presence of a body of zero length.
pub const fn empty() -> Self {
Self(Inner::Empty)
}
/// Create a new body from a potentially static byte buffer.
///
/// The body will have a known length equal to the number of bytes given.
///
/// This will try to prevent a copy if the type passed in can be re-used,
/// otherwise the buffer will be copied first. This method guarantees to not
/// require a copy for the following types:
///
/// - `&'static [u8]`
/// - `&'static str`
///
/// # Examples
///
/// ```
/// use isahc::Body;
///
/// // Create a body from a static string.
/// let body = Body::from_bytes_static("hello world");
/// ```
#[inline]
pub fn from_bytes_static<B>(bytes: B) -> Self
where
B: AsRef<[u8]> + 'static,
{
castaway::match_type!(bytes, {
Cursor<Cow<'static, [u8]>> as bytes => Self(Inner::Buffer(bytes)),
Vec<u8> as bytes => Self::from(bytes),
String as bytes => Self::from(bytes.into_bytes()),
bytes => Self::from(bytes.as_ref().to_vec()),
})
}
/// Create a streaming body that reads from the given reader.
///
/// The body will have an unknown length. When used as a request body,
/// [chunked transfer
/// encoding](https://tools.ietf.org/html/rfc7230#section-4.1) might be used
/// to send the request.
pub fn from_reader<R>(reader: R) -> Self
where
R: Read + Send + Sync + 'static,
{
Self(Inner::Reader(Box::new(reader), None))
}
/// Create a streaming body with a known length.
///
/// If the size of the body is known in advance, such as with a file, then
/// this function can be used to create a body that can determine its
/// `Content-Length` while still reading the bytes asynchronously.
///
/// Giving a value for `length` that doesn't actually match how much data
/// the reader will produce may result in errors when sending the body in a
/// request.
pub fn from_reader_sized<R>(reader: R, length: u64) -> Self
where
R: Read + Send + Sync + 'static,
{
Self(Inner::Reader(Box::new(reader), Some(length)))
}
/// Report if this body is empty.
///
/// This is not necessarily the same as checking for `self.len() ==
/// Some(0)`. Since HTTP message bodies are optional, there is a semantic
/// difference between the absence of a body and the presence of a
/// zero-length body. This method will only return `true` for the former.
pub fn is_empty(&self) -> bool {
match self.0 {
Inner::Empty => true,
_ => false,
}
}
/// Get the size of the body, if known.
///
/// The value reported by this method is used to set the `Content-Length`
/// for outgoing requests.
///
/// When coming from a response, this method will report the value of the
/// `Content-Length` response header if present. If this method returns
/// `None` then there's a good chance that the server used something like
/// chunked transfer encoding to send the response body.
///
/// Since the length may be determined totally separately from the actual
/// bytes, even if a value is returned it should not be relied on as always
/// being accurate, and should be treated as a "hint".
pub fn len(&self) -> Option<u64> {
match &self.0 {
Inner::Empty => Some(0),
Inner::Buffer(bytes) => Some(bytes.get_ref().len() as u64),
Inner::Reader(_, len) => *len,
}
}
/// If this body is repeatable, reset the body stream back to the start of
/// the content. Returns `false` if the body cannot be reset.
pub fn reset(&mut self) -> bool {
match &mut self.0 {
Inner::Empty => true,
Inner::Buffer(cursor) => {
cursor.set_position(0);
true
}
_ => false,
}
}
/// Convert this body into an asynchronous one.
///
/// Turning a synchronous operation into an asynchronous one can be quite
/// the challenge, so this method is used internally only for limited
/// scenarios in which this can work. If this body is an in-memory buffer,
/// then the translation is trivial.
///
/// If this body was created from an underlying synchronous reader, then we
/// create a temporary asynchronous pipe and return a [`Writer`] which will
/// copy the bytes from the reader to the writing half of the pipe in a
/// blocking fashion.
pub(crate) fn into_async(self) -> (AsyncBody, Option<Writer>) {
match self.0 {
Inner::Empty => (AsyncBody::empty(), None),
Inner::Buffer(cursor) => (AsyncBody::from_bytes_static(cursor.into_inner()), None),
Inner::Reader(reader, len) => {
let (pipe_reader, writer) = pipe();
(
if let Some(len) = len {
AsyncBody::from_reader_sized(pipe_reader, len)
} else {
AsyncBody::from_reader(pipe_reader)
},
Some(Writer {
reader,
writer,
}),
)
}
}
}
}
impl Read for Body {
fn read(&mut self, buf: &mut [u8]) -> Result<usize> {
match &mut self.0 {
Inner::Empty => Ok(0),
Inner::Buffer(cursor) => cursor.read(buf),
Inner::Reader(reader, _) => reader.read(buf),
}
}
}
impl Default for Body {
fn default() -> Self {
Self::empty()
}
}
impl From<()> for Body {
fn from(_: ()) -> Self {
Self::empty()
}
}
impl From<Vec<u8>> for Body {
fn from(body: Vec<u8>) -> Self {
Self(Inner::Buffer(Cursor::new(Cow::Owned(body))))
}
}
impl From<&'_ [u8]> for Body {
fn from(body: &[u8]) -> Self {
body.to_vec().into()
}
}
impl From<String> for Body {
fn from(body: String) -> Self {
body.into_bytes().into()
}
}
impl From<&'_ str> for Body {
fn from(body: &str) -> Self {
body.as_bytes().into()
}
}
impl From<File> for Body {
fn from(file: File) -> Self {
if let Ok(metadata) = file.metadata() {
Self::from_reader_sized(file, metadata.len())
} else {
Self::from_reader(file)
}
}
}
impl fmt::Debug for Body {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self.len() {
Some(len) => write!(f, "Body({})", len),
None => write!(f, "Body(?)"),
}
}
}
/// Helper struct for writing a synchronous reader into an asynchronous pipe.
pub(crate) struct Writer {
reader: Box<dyn Read + Send + Sync>,
writer: PipeWriter,
}
impl Writer {
/// The size of the temporary buffer to use for writing. Larger buffers can
/// improve performance, but at the cost of more memory.
///
/// Curl's internal buffer size just happens to default to 16 KiB as well,
/// so this is a natural choice.
const BUF_SIZE: usize = 16384;
/// Write the response body from the synchronous reader.
///
/// While this function is async, it isn't a well-behaved one as it blocks
/// frequently while reading from the request body reader. As long as this
/// method is invoked in a controlled environment within a thread dedicated
/// to blocking operations, this is OK.
pub(crate) async fn write(&mut self) -> Result<()> {
let mut buf = [0; Self::BUF_SIZE];
loop {
let len = match self.reader.read(&mut buf) {
Ok(0) => return Ok(()),
Ok(len) => len,
Err(e) if e.kind() == ErrorKind::Interrupted => {
yield_now().await;
continue;
}
Err(e) => return Err(e),
};
write_all_async(&mut self.writer, &buf[..len]).await?;
}
}
}
#[cfg(test)]
mod tests {
use super::*;
static_assertions::assert_impl_all!(Body: Send, Sync);
#[test]
fn empty_body() {
let body = Body::empty();
assert!(body.is_empty());
assert_eq!(body.len(), Some(0));
}
#[test]
fn zero_length_body() {
let body = Body::from(vec![]);
assert!(!body.is_empty());
assert_eq!(body.len(), Some(0));
}
#[test]
fn reader_with_unknown_length() {
let body = Body::from_reader(std::io::empty());
assert!(!body.is_empty());
assert_eq!(body.len(), None);
}
#[test]
fn reader_with_known_length() {
let body = Body::from_reader_sized(std::io::empty(), 0);
assert!(!body.is_empty());
assert_eq!(body.len(), Some(0));
}
#[test]
fn reset_memory_body() {
let mut body = Body::from("hello world");
let mut buf = String::new();
assert_eq!(body.read_to_string(&mut buf).unwrap(), 11);
assert_eq!(buf, "hello world");
assert!(body.reset());
assert_eq!(body.read_to_string(&mut buf).unwrap(), 11);
assert_eq!(buf, "hello worldhello world");
}
#[test]
fn cannot_reset_reader() {
let mut body = Body::from_reader(std::io::empty());
assert!(!body.reset());
}
}