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

use llvm_sys::core::{
    LLVMCreateMemoryBufferWithContentsOfFile, LLVMCreateMemoryBufferWithMemoryRange,
    LLVMCreateMemoryBufferWithMemoryRangeCopy, LLVMCreateMemoryBufferWithSTDIN, LLVMDisposeMemoryBuffer,
    LLVMGetBufferSize, LLVMGetBufferStart,
};
use llvm_sys::object::LLVMCreateObjectFile;
use llvm_sys::prelude::LLVMMemoryBufferRef;

use crate::object_file::ObjectFile;
use crate::support::{to_c_str, LLVMString};

use std::mem::{forget, MaybeUninit};
use std::path::Path;
use std::ptr;
use std::slice;

#[derive(Debug)]
pub struct MemoryBuffer {
    pub(crate) memory_buffer: LLVMMemoryBufferRef,
}

impl MemoryBuffer {
    pub unsafe fn new(memory_buffer: LLVMMemoryBufferRef) -> Self {
        assert!(!memory_buffer.is_null());

        MemoryBuffer { memory_buffer }
    }

    pub fn as_mut_ptr(&self) -> LLVMMemoryBufferRef {
        self.memory_buffer
    }

    pub fn create_from_file(path: &Path) -> Result<Self, LLVMString> {
        let path = to_c_str(path.to_str().expect("Did not find a valid Unicode path string"));
        let mut memory_buffer = ptr::null_mut();
        let mut err_string = MaybeUninit::uninit();

        let return_code = unsafe {
            LLVMCreateMemoryBufferWithContentsOfFile(
                path.as_ptr() as *const ::libc::c_char,
                &mut memory_buffer,
                err_string.as_mut_ptr(),
            )
        };

        // TODO: Verify 1 is error code (LLVM can be inconsistent)
        if return_code == 1 {
            unsafe {
                return Err(LLVMString::new(err_string.assume_init()));
            }
        }

        unsafe { Ok(MemoryBuffer::new(memory_buffer)) }
    }

    pub fn create_from_stdin() -> Result<Self, LLVMString> {
        let mut memory_buffer = ptr::null_mut();
        let mut err_string = MaybeUninit::uninit();

        let return_code = unsafe { LLVMCreateMemoryBufferWithSTDIN(&mut memory_buffer, err_string.as_mut_ptr()) };

        // TODO: Verify 1 is error code (LLVM can be inconsistent)
        if return_code == 1 {
            unsafe {
                return Err(LLVMString::new(err_string.assume_init()));
            }
        }

        unsafe { Ok(MemoryBuffer::new(memory_buffer)) }
    }

    /// This function is likely slightly cheaper than `create_from_memory_range_copy` since it intentionally
    /// leaks data to LLVM so that it doesn't have to reallocate. `create_from_memory_range_copy` may be removed
    /// in the future
    pub fn create_from_memory_range(input: &[u8], name: &str) -> Self {
        let name_c_string = to_c_str(name);

        let memory_buffer = unsafe {
            LLVMCreateMemoryBufferWithMemoryRange(
                input.as_ptr() as *const ::libc::c_char,
                input.len(),
                name_c_string.as_ptr(),
                false as i32,
            )
        };

        unsafe { MemoryBuffer::new(memory_buffer) }
    }

    /// This will create a new `MemoryBuffer` from the given input.
    ///
    /// This function is likely slightly more expensive than `create_from_memory_range` since it does not leak
    /// data to LLVM, forcing LLVM to make a copy. This function may be removed in the future in favor of
    /// `create_from_memory_range`
    pub fn create_from_memory_range_copy(input: &[u8], name: &str) -> Self {
        let name_c_string = to_c_str(name);

        let memory_buffer = unsafe {
            LLVMCreateMemoryBufferWithMemoryRangeCopy(
                input.as_ptr() as *const ::libc::c_char,
                input.len(),
                name_c_string.as_ptr(),
            )
        };

        unsafe { MemoryBuffer::new(memory_buffer) }
    }

    /// Gets a byte slice of this `MemoryBuffer`.
    pub fn as_slice(&self) -> &[u8] {
        unsafe {
            let start = LLVMGetBufferStart(self.memory_buffer);

            slice::from_raw_parts(start as *const _, self.get_size())
        }
    }

    /// Gets the byte size of this `MemoryBuffer`.
    pub fn get_size(&self) -> usize {
        unsafe { LLVMGetBufferSize(self.memory_buffer) }
    }

    /// Convert this `MemoryBuffer` into an `ObjectFile`. LLVM does not currently
    /// provide any way to determine the cause of error if conversion fails.
    pub fn create_object_file(self) -> Result<ObjectFile, ()> {
        let object_file = unsafe { LLVMCreateObjectFile(self.memory_buffer) };

        forget(self);

        if object_file.is_null() {
            return Err(());
        }

        unsafe { Ok(ObjectFile::new(object_file)) }
    }
}

impl Drop for MemoryBuffer {
    fn drop(&mut self) {
        unsafe {
            LLVMDisposeMemoryBuffer(self.memory_buffer);
        }
    }
}