libduckdb_sys/
string.rs

1use std::{
2    ffi::{c_char, CStr},
3    ops::Deref,
4};
5
6use crate::duckdb_free;
7
8pub struct DuckDbString {
9    // Invariant: ptr[0..len+1] is valid C string, i.e. ptr[len] is NUL byte.
10    ptr: core::ptr::NonNull<c_char>,
11    len: usize,
12}
13
14impl DuckDbString {
15    /// Creates a `DuckDbString` from a raw pointer to a C string.
16    ///
17    /// # Safety
18    ///
19    /// The caller must ensure that the pointer is valid and points to a null-terminated C string.
20    /// The memory must remain valid for the lifetime of the returned `DuckDbString`.
21    pub unsafe fn from_ptr(ptr: *const c_char) -> Self {
22        let len = unsafe { CStr::from_ptr(ptr) }.to_bytes().len();
23        unsafe { Self::from_raw_parts(ptr, len) }
24    }
25
26    /// Creates a `DuckDbString` from raw parts.
27    ///
28    /// # Safety
29    ///
30    /// The caller must ensure that:
31    /// - `ptr` is a valid pointer to a null-terminated C string.
32    /// - `len` accurately represents the length of the string (excluding the null terminator).
33    /// - The memory referenced by `ptr` remains valid for the lifetime of the returned `DuckDbString`.
34    /// - The string data is not mutated for the lifetime of the returned `DuckDbString`.
35    pub unsafe fn from_raw_parts(ptr: *const c_char, len: usize) -> Self {
36        let ptr = unsafe { core::ptr::NonNull::new_unchecked(ptr as *mut c_char) };
37        Self { ptr, len }
38    }
39
40    fn to_bytes_with_nul(&self) -> &[u8] {
41        let ptr = self.ptr.as_ptr() as *const u8;
42        unsafe { core::slice::from_raw_parts(ptr, self.len + 1) }
43    }
44}
45
46impl Deref for DuckDbString {
47    type Target = std::ffi::CStr;
48
49    fn deref(&self) -> &Self::Target {
50        let bytes = self.to_bytes_with_nul();
51        unsafe { CStr::from_bytes_with_nul_unchecked(bytes) }
52    }
53}
54
55impl Drop for DuckDbString {
56    fn drop(&mut self) {
57        let ptr = self.ptr.as_ptr() as *mut core::ffi::c_void;
58        unsafe { duckdb_free(ptr) };
59    }
60}
libduckdb_sys/string.rs

libduckdb_sys/
string.rs
