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

/* Copyright 2018 Mozilla Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

use super::{
    BinaryReader, BinaryReaderError, InitExpr, Result, SectionIteratorLimited, SectionReader,
    SectionWithLimitedItems,
};

#[derive(Debug, Copy, Clone)]
pub struct Data<'a> {
    pub kind: DataKind<'a>,
    pub data: &'a [u8],
}

#[derive(Debug, Copy, Clone)]
pub enum DataKind<'a> {
    Passive,
    Active {
        memory_index: u32,
        init_expr: InitExpr<'a>,
    },
}

pub struct DataSectionReader<'a> {
    reader: BinaryReader<'a>,
    count: u32,
}

impl<'a> DataSectionReader<'a> {
    pub fn new(data: &'a [u8], offset: usize) -> Result<DataSectionReader<'a>> {
        let mut reader = BinaryReader::new_with_offset(data, offset);
        let count = reader.read_var_u32()?;
        Ok(DataSectionReader { reader, count })
    }

    pub fn original_position(&self) -> usize {
        self.reader.original_position()
    }

    pub fn get_count(&self) -> u32 {
        self.count
    }

    fn verify_data_end(&self, end: usize) -> Result<()> {
        if self.reader.buffer.len() < end {
            return Err(BinaryReaderError {
                message: "Data segment extends past end of the data section",
                offset: self.reader.original_offset + self.reader.buffer.len(),
            });
        }
        Ok(())
    }

    /// Reads content of the data section.
    ///
    /// # Examples
    /// ```
    /// # let data: &[u8] = &[0x00, 0x61, 0x73, 0x6d, 0x01, 0x00, 0x00, 0x00,
    /// #     0x01, 0x4, 0x01, 0x60, 0x00, 0x00, 0x03, 0x02, 0x01, 0x00,
    /// #     0x05, 0x03, 0x01, 0x00, 0x02,
    /// #     0x0a, 0x05, 0x01, 0x03, 0x00, 0x01, 0x0b,
    /// #     0x0b, 0x0b, 0x01, 0x00, 0x41, 0x80, 0x08, 0x0b, 0x04, 0x00, 0x00, 0x00, 0x00];
    /// use wasmparser::{ModuleReader, DataKind};
    /// let mut reader = ModuleReader::new(data).expect("module reader");
    /// let section = reader.read().expect("type section");
    /// let section = reader.read().expect("function section");
    /// let section = reader.read().expect("memory section");
    /// let section = reader.read().expect("code section");
    /// let section = reader.read().expect("data section");
    /// let mut data_reader = section.get_data_section_reader().expect("data section reader");
    /// for _ in 0..data_reader.get_count() {
    ///     let data = data_reader.read().expect("data");
    ///     println!("Data: {:?}", data);
    ///     if let DataKind::Active { init_expr, .. } = data.kind {
    ///         let mut init_expr_reader = init_expr.get_binary_reader();
    ///         let op = init_expr_reader.read_operator().expect("op");
    ///         println!("Init const: {:?}", op);
    ///     }
    /// }
    /// ```
    pub fn read<'b>(&mut self) -> Result<Data<'b>>
    where
        'a: 'b,
    {
        let flags = self.reader.read_var_u32()?;
        let kind = if flags == 1 {
            DataKind::Passive
        } else {
            let memory_index = match flags {
                0 => 0,
                2 => self.reader.read_var_u32()?,
                _ => {
                    return Err(BinaryReaderError {
                        message: "invalid flags byte in data segment",
                        offset: self.reader.original_position() - 1,
                    });
                }
            };
            let init_expr = {
                let expr_offset = self.reader.position;
                self.reader.skip_init_expr()?;
                let data = &self.reader.buffer[expr_offset..self.reader.position];
                InitExpr::new(data, self.reader.original_offset + expr_offset)
            };
            DataKind::Active {
                memory_index,
                init_expr,
            }
        };
        let data_len = self.reader.read_var_u32()? as usize;
        let data_end = self.reader.position + data_len;
        self.verify_data_end(data_end)?;
        let data = &self.reader.buffer[self.reader.position..data_end];
        self.reader.skip_to(data_end);
        Ok(Data { kind, data })
    }
}

impl<'a> SectionReader for DataSectionReader<'a> {
    type Item = Data<'a>;
    fn read(&mut self) -> Result<Self::Item> {
        DataSectionReader::read(self)
    }
    fn eof(&self) -> bool {
        self.reader.eof()
    }
    fn original_position(&self) -> usize {
        DataSectionReader::original_position(self)
    }
}

impl<'a> SectionWithLimitedItems for DataSectionReader<'a> {
    fn get_count(&self) -> u32 {
        DataSectionReader::get_count(self)
    }
}

impl<'a> IntoIterator for DataSectionReader<'a> {
    type Item = Result<Data<'a>>;
    type IntoIter = SectionIteratorLimited<DataSectionReader<'a>>;

    fn into_iter(self) -> Self::IntoIter {
        SectionIteratorLimited::new(self)
    }
}