windows_registry/
data.rs

1use super::*;
2
3// Minimal `Vec<u8>` replacement providing at least `u16` alignment so that it can be used for wide strings.
4pub struct Data {
5    ptr: *mut u8,
6    len: usize,
7}
8
9impl Data {
10    // Creates a buffer with the specified length of zero bytes.
11    pub fn new(len: usize) -> Self {
12        unsafe {
13            let bytes = Self::alloc(len);
14
15            if len > 0 {
16                core::ptr::write_bytes(bytes.ptr, 0, len);
17            }
18
19            bytes
20        }
21    }
22
23    // Returns the buffer as a slice of u16 for reading wide characters.
24    pub fn as_wide(&self) -> &[u16] {
25        if self.ptr.is_null() {
26            &[]
27        } else {
28            unsafe { core::slice::from_raw_parts(self.ptr as *const u16, self.len / 2) }
29        }
30    }
31
32    // Creates a buffer by copying the bytes from the slice.
33    pub fn from_slice(slice: &[u8]) -> Self {
34        unsafe {
35            let bytes = Self::alloc(slice.len());
36
37            if !slice.is_empty() {
38                core::ptr::copy_nonoverlapping(slice.as_ptr(), bytes.ptr, slice.len());
39            }
40
41            bytes
42        }
43    }
44
45    // Allocates an uninitialized buffer.
46    unsafe fn alloc(len: usize) -> Self {
47        if len == 0 {
48            Self {
49                ptr: null_mut(),
50                len: 0,
51            }
52        } else {
53            // This pointer will have at least 8 byte alignment.
54            let ptr = unsafe { HeapAlloc(GetProcessHeap(), 0, len) as *mut u8 };
55
56            if ptr.is_null() {
57                panic!("allocation failed");
58            }
59
60            Self { ptr, len }
61        }
62    }
63}
64
65impl Drop for Data {
66    fn drop(&mut self) {
67        if !self.ptr.is_null() {
68            unsafe {
69                HeapFree(GetProcessHeap(), 0, self.ptr as *mut _);
70            }
71        }
72    }
73}
74
75impl Deref for Data {
76    type Target = [u8];
77
78    fn deref(&self) -> &[u8] {
79        if self.ptr.is_null() {
80            &[]
81        } else {
82            unsafe { core::slice::from_raw_parts(self.ptr, self.len) }
83        }
84    }
85}
86
87impl core::ops::DerefMut for Data {
88    fn deref_mut(&mut self) -> &mut [u8] {
89        if self.ptr.is_null() {
90            &mut []
91        } else {
92            unsafe { core::slice::from_raw_parts_mut(self.ptr, self.len) }
93        }
94    }
95}
96
97impl Clone for Data {
98    fn clone(&self) -> Self {
99        Self::from_slice(self)
100    }
101}
102
103impl PartialEq for Data {
104    fn eq(&self, other: &Self) -> bool {
105        self.deref() == other.deref()
106    }
107}
108
109impl Eq for Data {}
110
111impl core::fmt::Debug for Data {
112    fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
113        self.deref().fmt(f)
114    }
115}
116
117impl<const N: usize> From<[u8; N]> for Data {
118    fn from(from: [u8; N]) -> Self {
119        Self::from_slice(&from)
120    }
121}
windows_registry/data.rs

windows_registry/
data.rs
