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81 lines
2.2 KiB
81 lines
2.2 KiB
//! Buffer management.
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//!
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//! Some convenience functions to copying data between Rust and C.
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//! When moving data to C, we use libc's allocator, which means that
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//! the C code can free the memory in the usual way, i.e., using
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//! libc's free.
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use std::{
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ptr::{
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copy_nonoverlapping,
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},
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};
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use libc::{
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c_char,
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};
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use crate::Error;
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use crate::Result;
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use crate::ffi::MM;
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/// Copies a Rust string to a buffer, adding a terminating zero.
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pub fn rust_str_to_c_str<S: AsRef<str>>(mm: MM, s: S)
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-> Result<*mut c_char>
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{
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let malloc = mm.malloc;
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let s = s.as_ref();
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let bytes = s.as_bytes();
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unsafe {
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let buf = malloc(bytes.len() + 1);
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if buf.is_null() {
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return Err(Error::OutOfMemory("rust_bytes_to_c_str_lossy".into(),
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bytes.len() + 1));
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};
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copy_nonoverlapping(bytes.as_ptr(), buf as *mut _, bytes.len());
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*((buf as *mut u8).add(bytes.len())) = 0; // Terminate.
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Ok(buf as *mut c_char)
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}
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}
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/// Copies a C string to a buffer, adding a terminating zero.
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///
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/// Replaces embedded zeros with '_'.
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pub fn rust_bytes_to_c_str_lossy<S: AsRef<[u8]>>(mm: MM, s: S)
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-> Result<*mut c_char>
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{
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let malloc = mm.malloc;
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let bytes = s.as_ref();
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unsafe {
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let buf = malloc(bytes.len() + 1);
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if buf.is_null() {
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return Err(Error::OutOfMemory("rust_bytes_to_c_str_lossy".into(),
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bytes.len() + 1));
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};
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copy_nonoverlapping(bytes.as_ptr(), buf as *mut _, bytes.len());
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// Replace embedded zeros.
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let bytes_mut = std::slice::from_raw_parts_mut(buf as *mut u8,
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bytes.len());
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bytes_mut.iter_mut().for_each(|b| if *b == 0 { *b = b'_' });
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*((buf as *mut u8).add(bytes.len())) = 0; // Terminate.
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Ok(buf as *mut c_char)
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}
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}
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pub fn malloc_cleared<T>(mm: MM) -> Result<*mut T>
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{
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let malloc = mm.malloc;
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let size = std::mem::size_of::<T>();
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let buffer = unsafe { malloc(size) };
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if buffer.is_null() {
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return Err(Error::OutOfMemory("malloc".into(), size));
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};
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unsafe { libc::memset(buffer, 0, size) };
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Ok(buffer as *mut T)
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}
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