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refact: Clean up Context interface to be safer

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The mutation-based methods had some pitfalls, and we don't really
need them.

We could re-add them if we need to.

(cherry picked from commit ca92b8491d87cebf54dd2468599168fc7a16c07f)
This commit is contained in:
Robert Hensing 2024-06-14 19:58:44 +02:00
parent 93a2db836a
commit 2f3a5fb039
4 changed files with 38 additions and 35 deletions
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25
rust/nix-util/src/context.rs
View file

@ -20,10 +20,22 @@ impl Context {
};
ctx
}
pub fn ptr(&self) -> *mut raw::c_context {
/// This is currently private because of the switch to `check_one_call`, which is more ergonomic.
/// The pattern its callers use make it hard to forget to use this function.
///
/// If we have a good use case for `check_err`, we can expose it again.
fn ptr(&self) -> *mut raw::c_context {
self.inner.as_ptr()
}
pub fn check_err(&self) -> Result<()> {
/// Check the error code and return an error if it's not `NIX_OK`.
///
/// This is currently private because of the switch to `check_one_call`, which is more ergonomic.
/// The pattern its callers use make it hard to forget to use this function.
///
/// If we have a good use case for `check_err`, we can expose it again.
fn check_err(&self) -> Result<()> {
let err = unsafe { raw::err_code(self.inner.as_ptr()) };
if err != raw::NIX_OK.try_into().unwrap() {
// msgp is a borrowed pointer (pointing into the context), so we don't need to free it
@ -35,7 +47,7 @@ impl Context {
Ok(())
}
pub fn clear(&self) {
fn clear(&self) {
unsafe {
raw::set_err_msg(
self.inner.as_ptr(),
@ -67,18 +79,13 @@ impl Context {
f: F,
) -> Result<Option<T>> {
let t = f(self.ptr());
if self.is_key_error() {
if unsafe { raw::err_code(self.inner.as_ptr()) == raw::NIX_ERR_KEY } {
self.clear();
return Ok(None);
}
self.check_err_and_clear()?;
Ok(Some(t))
}
/// NIX_ERR_KEY is returned when e.g. an attribute is missing. Return true if the error is of this type.
pub fn is_key_error(&self) -> bool {
unsafe { raw::err_code(self.inner.as_ptr()) == raw::NIX_ERR_KEY }
}
}
impl Drop for Context {