1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192

#[cfg(feature = "std")]
use std::error;
use core::fmt::{self, Display, Formatter};
use core::str::{from_utf8, Utf8Error};

use super::{read_marker, RmpRead, RmpReadErr, ValueReadError};
use crate::Marker;

#[derive(Debug)]
#[allow(deprecated)] // Only for compatibility
pub enum DecodeStringError<'a, E: RmpReadErr = super::Error> {
    InvalidMarkerRead(E),
    InvalidDataRead(E),
    TypeMismatch(Marker),
    /// The given buffer is not large enough to accumulate the specified amount of bytes.
    BufferSizeTooSmall(u32),
    InvalidUtf8(&'a [u8], Utf8Error),
}

#[cfg(feature = "std")]
impl<'a, E: RmpReadErr> error::Error for DecodeStringError<'a, E> {
    #[cold]
    fn source(&self) -> Option<&(dyn error::Error + 'static)> {
        match *self {
            DecodeStringError::InvalidMarkerRead(ref err) |
            DecodeStringError::InvalidDataRead(ref err) => Some(err),
            DecodeStringError::TypeMismatch(..) |
            DecodeStringError::BufferSizeTooSmall(..) => None,
            DecodeStringError::InvalidUtf8(_, ref err) => Some(err),
        }
    }
}

impl<'a, E: RmpReadErr> Display for DecodeStringError<'a, E> {
    #[cold]
    fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), fmt::Error> {
        f.write_str("error while decoding string")
    }
}

impl<'a, E: RmpReadErr> From<ValueReadError<E>> for DecodeStringError<'a, E> {
    #[cold]
    fn from(err: ValueReadError<E>) -> DecodeStringError<'a, E> {
        match err {
            ValueReadError::InvalidMarkerRead(err) => DecodeStringError::InvalidMarkerRead(err),
            ValueReadError::InvalidDataRead(err) => DecodeStringError::InvalidDataRead(err),
            ValueReadError::TypeMismatch(marker) => DecodeStringError::TypeMismatch(marker),
        }
    }
}

/// Attempts to read up to 9 bytes from the given reader and to decode them as a string `u32` size
/// value.
///
/// According to the MessagePack specification, the string format family stores an byte array in 1,
/// 2, 3, or 5 bytes of extra bytes in addition to the size of the byte array.
///
/// # Errors
///
/// This function will return `ValueReadError` on any I/O error while reading either the marker or
/// the data.
///
/// It also returns `ValueReadError::TypeMismatch` if the actual type is not equal with the
/// expected one, indicating you with the actual type.
#[inline]
pub fn read_str_len<R: RmpRead>(rd: &mut R) -> Result<u32, ValueReadError<R::Error>> {
    Ok(read_str_len_with_nread(rd)?.0)
}

fn read_str_len_with_nread<R>(rd: &mut R) -> Result<(u32, usize), ValueReadError<R::Error>>
    where R: RmpRead
{
    match read_marker(rd)? {
        Marker::FixStr(size) => Ok((u32::from(size), 1)),
        Marker::Str8 => Ok((u32::from(rd.read_data_u8()?), 2)),
        Marker::Str16 => Ok((u32::from(rd.read_data_u16()?), 3)),
        Marker::Str32 => Ok((rd.read_data_u32()?, 5)),
        marker => Err(ValueReadError::TypeMismatch(marker)),
    }
}

/// Attempts to read a string data from the given reader and copy it to the buffer provided.
///
/// On success returns a borrowed string type, allowing to view the copied bytes as properly utf-8
/// string.
/// According to the spec, the string's data must to be encoded using utf-8.
///
/// # Errors
///
/// Returns `Err` in the following cases:
///
///  - if any IO error (including unexpected EOF) occurs, while reading an `rd`, except the EINTR,
///    which is handled internally.
///  - if the `out` buffer size is not large enough to keep all the data copied.
///  - if the data is not utf-8, with a description as to why the provided data is not utf-8 and
///    with a size of bytes actually copied to be able to get them from `out`.
///
/// # Examples
/// ```
/// use rmp::decode::read_str;
///
/// let buf = [0xaa, 0x6c, 0x65, 0x20, 0x6d, 0x65, 0x73, 0x73, 0x61, 0x67, 0x65];
/// let mut out = [0u8; 16];
///
/// assert_eq!("le message", read_str(&mut &buf[..], &mut &mut out[..]).unwrap());
/// ```
///
/// # Unstable
///
/// This function is **unstable**, because it needs review.
// TODO: Stabilize. Mark error values for each error case (in docs).
pub fn read_str<'r, R>(rd: &mut R, buf: &'r mut [u8]) -> Result<&'r str, DecodeStringError<'r, R::Error>>
where
    R: RmpRead,
{
    let len = read_str_len(rd)?;
    let ulen = len as usize;

    if buf.len() < ulen {
        return Err(DecodeStringError::BufferSizeTooSmall(len));
    }

    read_str_data(rd, len, &mut buf[0..ulen])
}

pub fn read_str_data<'r, R>(rd: &mut R,
                            len: u32,
                            buf: &'r mut [u8])
                            -> Result<&'r str, DecodeStringError<'r, R::Error>>
    where R: RmpRead
{
    debug_assert_eq!(len as usize, buf.len());

    // Trying to copy exact `len` bytes.
    match rd.read_exact_buf(buf) {
        Ok(()) => match from_utf8(buf) {
            Ok(decoded) => Ok(decoded),
            Err(err) => Err(DecodeStringError::InvalidUtf8(buf, err)),
        },
        Err(err) => Err(DecodeStringError::InvalidDataRead(err)),
    }
}

/// Attempts to read and decode a string value from the reader, returning a borrowed slice from it.
///
// TODO: Also it's possible to implement all borrowing functions for all `BufRead` implementors.
#[deprecated(since = "0.8.6", note = "useless, use `read_str_from_slice` instead")]
pub fn read_str_ref(rd: &[u8]) -> Result<&[u8], DecodeStringError<'_, super::bytes::BytesReadError>> {
    let mut cur = super::Bytes::new(rd);
    let len = read_str_len(&mut cur)?;
    Ok(&cur.remaining_slice()[..len as usize])
}

/// Attempts to read and decode a string value from the reader, returning a borrowed slice from it.
///
/// # Examples
///
/// ```
/// use rmp::encode::write_str;
/// use rmp::decode::read_str_from_slice;
///
/// let mut buf = Vec::new();
/// write_str(&mut buf, "Unpacking").unwrap();
/// write_str(&mut buf, "multiple").unwrap();
/// write_str(&mut buf, "strings").unwrap();
///
/// let mut chunks = Vec::new();
/// let mut unparsed = &buf[..];
/// while let Ok((chunk, tail)) = read_str_from_slice(unparsed) {
///     chunks.push(chunk);
///     unparsed = tail;
/// }
///
/// assert_eq!(vec!["Unpacking", "multiple", "strings"], chunks);
/// ```
pub fn read_str_from_slice<T: ?Sized + AsRef<[u8]>>(
    buf: &T,
) -> Result<(&str, &[u8]), DecodeStringError<'_, super::bytes::BytesReadError>> {
    let buf = buf.as_ref();
    let (len, nread) = read_str_len_with_nread(&mut super::Bytes::new(buf))?;
    let ulen = len as usize;

    if buf[nread..].len() >= ulen {
        let (head, tail) = buf.split_at(nread + ulen);
        match from_utf8(&head[nread..]) {
            Ok(val) => Ok((val, tail)),
            Err(err) => Err(DecodeStringError::InvalidUtf8(buf, err)),
        }
    } else {
        Err(DecodeStringError::BufferSizeTooSmall(len))
    }
}