rmp/decode/
str.rs

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1#[cfg(feature = "std")]
2use std::error;
3use core::fmt::{self, Display, Formatter};
4use core::str::{from_utf8, Utf8Error};
5
6use super::{read_marker, RmpRead, RmpReadErr, ValueReadError};
7use crate::Marker;
8
9#[derive(Debug)]
10#[allow(deprecated)] // Only for compatibility
11pub enum DecodeStringError<'a, E: RmpReadErr = super::Error> {
12    InvalidMarkerRead(E),
13    InvalidDataRead(E),
14    TypeMismatch(Marker),
15    /// The given buffer is not large enough to accumulate the specified amount of bytes.
16    BufferSizeTooSmall(u32),
17    InvalidUtf8(&'a [u8], Utf8Error),
18}
19
20#[cfg(feature = "std")]
21impl<'a, E: RmpReadErr> error::Error for DecodeStringError<'a, E> {
22    #[cold]
23    fn source(&self) -> Option<&(dyn error::Error + 'static)> {
24        match *self {
25            DecodeStringError::InvalidMarkerRead(ref err) |
26            DecodeStringError::InvalidDataRead(ref err) => Some(err),
27            DecodeStringError::TypeMismatch(..) |
28            DecodeStringError::BufferSizeTooSmall(..) => None,
29            DecodeStringError::InvalidUtf8(_, ref err) => Some(err),
30        }
31    }
32}
33
34impl<'a, E: RmpReadErr> Display for DecodeStringError<'a, E> {
35    #[cold]
36    fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), fmt::Error> {
37        f.write_str("error while decoding string")
38    }
39}
40
41impl<'a, E: RmpReadErr> From<ValueReadError<E>> for DecodeStringError<'a, E> {
42    #[cold]
43    fn from(err: ValueReadError<E>) -> DecodeStringError<'a, E> {
44        match err {
45            ValueReadError::InvalidMarkerRead(err) => DecodeStringError::InvalidMarkerRead(err),
46            ValueReadError::InvalidDataRead(err) => DecodeStringError::InvalidDataRead(err),
47            ValueReadError::TypeMismatch(marker) => DecodeStringError::TypeMismatch(marker),
48        }
49    }
50}
51
52/// Attempts to read up to 9 bytes from the given reader and to decode them as a string `u32` size
53/// value.
54///
55/// According to the MessagePack specification, the string format family stores an byte array in 1,
56/// 2, 3, or 5 bytes of extra bytes in addition to the size of the byte array.
57///
58/// # Errors
59///
60/// This function will return `ValueReadError` on any I/O error while reading either the marker or
61/// the data.
62///
63/// It also returns `ValueReadError::TypeMismatch` if the actual type is not equal with the
64/// expected one, indicating you with the actual type.
65#[inline]
66pub fn read_str_len<R: RmpRead>(rd: &mut R) -> Result<u32, ValueReadError<R::Error>> {
67    Ok(read_str_len_with_nread(rd)?.0)
68}
69
70fn read_str_len_with_nread<R>(rd: &mut R) -> Result<(u32, usize), ValueReadError<R::Error>>
71    where R: RmpRead
72{
73    match read_marker(rd)? {
74        Marker::FixStr(size) => Ok((u32::from(size), 1)),
75        Marker::Str8 => Ok((u32::from(rd.read_data_u8()?), 2)),
76        Marker::Str16 => Ok((u32::from(rd.read_data_u16()?), 3)),
77        Marker::Str32 => Ok((rd.read_data_u32()?, 5)),
78        marker => Err(ValueReadError::TypeMismatch(marker)),
79    }
80}
81
82/// Attempts to read a string data from the given reader and copy it to the buffer provided.
83///
84/// On success returns a borrowed string type, allowing to view the copied bytes as properly utf-8
85/// string.
86/// According to the spec, the string's data must to be encoded using utf-8.
87///
88/// # Errors
89///
90/// Returns `Err` in the following cases:
91///
92///  - if any IO error (including unexpected EOF) occurs, while reading an `rd`, except the EINTR,
93///    which is handled internally.
94///  - if the `out` buffer size is not large enough to keep all the data copied.
95///  - if the data is not utf-8, with a description as to why the provided data is not utf-8 and
96///    with a size of bytes actually copied to be able to get them from `out`.
97///
98/// # Examples
99/// ```
100/// use rmp::decode::read_str;
101///
102/// let buf = [0xaa, 0x6c, 0x65, 0x20, 0x6d, 0x65, 0x73, 0x73, 0x61, 0x67, 0x65];
103/// let mut out = [0u8; 16];
104///
105/// assert_eq!("le message", read_str(&mut &buf[..], &mut &mut out[..]).unwrap());
106/// ```
107///
108/// # Unstable
109///
110/// This function is **unstable**, because it needs review.
111// TODO: Stabilize. Mark error values for each error case (in docs).
112pub fn read_str<'r, R>(rd: &mut R, buf: &'r mut [u8]) -> Result<&'r str, DecodeStringError<'r, R::Error>>
113where
114    R: RmpRead,
115{
116    let len = read_str_len(rd)?;
117    let ulen = len as usize;
118
119    if buf.len() < ulen {
120        return Err(DecodeStringError::BufferSizeTooSmall(len));
121    }
122
123    read_str_data(rd, len, &mut buf[0..ulen])
124}
125
126pub fn read_str_data<'r, R>(rd: &mut R,
127                            len: u32,
128                            buf: &'r mut [u8])
129                            -> Result<&'r str, DecodeStringError<'r, R::Error>>
130    where R: RmpRead
131{
132    debug_assert_eq!(len as usize, buf.len());
133
134    // Trying to copy exact `len` bytes.
135    match rd.read_exact_buf(buf) {
136        Ok(()) => match from_utf8(buf) {
137            Ok(decoded) => Ok(decoded),
138            Err(err) => Err(DecodeStringError::InvalidUtf8(buf, err)),
139        },
140        Err(err) => Err(DecodeStringError::InvalidDataRead(err)),
141    }
142}
143
144/// Attempts to read and decode a string value from the reader, returning a borrowed slice from it.
145///
146// TODO: Also it's possible to implement all borrowing functions for all `BufRead` implementors.
147#[deprecated(since = "0.8.6", note = "useless, use `read_str_from_slice` instead")]
148pub fn read_str_ref(rd: &[u8]) -> Result<&[u8], DecodeStringError<'_, super::bytes::BytesReadError>> {
149    let mut cur = super::Bytes::new(rd);
150    let len = read_str_len(&mut cur)?;
151    Ok(&cur.remaining_slice()[..len as usize])
152}
153
154/// Attempts to read and decode a string value from the reader, returning a borrowed slice from it.
155///
156/// # Examples
157///
158/// ```
159/// use rmp::encode::write_str;
160/// use rmp::decode::read_str_from_slice;
161///
162/// let mut buf = Vec::new();
163/// write_str(&mut buf, "Unpacking").unwrap();
164/// write_str(&mut buf, "multiple").unwrap();
165/// write_str(&mut buf, "strings").unwrap();
166///
167/// let mut chunks = Vec::new();
168/// let mut unparsed = &buf[..];
169/// while let Ok((chunk, tail)) = read_str_from_slice(unparsed) {
170///     chunks.push(chunk);
171///     unparsed = tail;
172/// }
173///
174/// assert_eq!(vec!["Unpacking", "multiple", "strings"], chunks);
175/// ```
176pub fn read_str_from_slice<T: ?Sized + AsRef<[u8]>>(
177    buf: &T,
178) -> Result<(&str, &[u8]), DecodeStringError<'_, super::bytes::BytesReadError>> {
179    let buf = buf.as_ref();
180    let (len, nread) = read_str_len_with_nread(&mut super::Bytes::new(buf))?;
181    let ulen = len as usize;
182
183    if buf[nread..].len() >= ulen {
184        let (head, tail) = buf.split_at(nread + ulen);
185        match from_utf8(&head[nread..]) {
186            Ok(val) => Ok((val, tail)),
187            Err(err) => Err(DecodeStringError::InvalidUtf8(buf, err)),
188        }
189    } else {
190        Err(DecodeStringError::BufferSizeTooSmall(len))
191    }
192}
rmp/decode/str.rs

rmp/decode/
str.rs
