From b4edc3ca61c1f1a98052ec8ffc41d1b533b08fd7 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 13 Dec 2019 19:05:09 +0100
Subject: [PATCH] Don't leak exceptions
---
nix-rust/src/error.rs | 20 ++++++++++++++++++--
src/libutil/rust-ffi.cc | 6 +++++-
src/libutil/rust-ffi.hh | 31 +++++++++++++++++++++++++------
3 files changed, 48 insertions(+), 9 deletions(-)
diff --git a/nix-rust/src/error.rs b/nix-rust/src/error.rs
index 586a8f53d..85ac926e9 100644
--- a/nix-rust/src/error.rs
+++ b/nix-rust/src/error.rs
@@ -76,7 +76,7 @@ impl From<Error> for CppException {
fn from(err: Error) -> Self {
match err {
Error::Foreign(ex) => ex,
- _ => unsafe { make_error(&err.to_string()) },
+ _ => CppException::new(&err.to_string()),
}
}
}
@@ -85,7 +85,23 @@ impl From<Error> for CppException {
#[derive(Debug)]
pub struct CppException(*const libc::c_void); // == std::exception_ptr*
+impl CppException {
+ fn new(s: &str) -> Self {
+ Self(unsafe { make_error(s) })
+ }
+}
+
+impl Drop for CppException {
+ fn drop(&mut self) {
+ unsafe {
+ destroy_error(self.0);
+ }
+ }
+}
+
extern "C" {
#[allow(improper_ctypes)] // YOLO
- fn make_error(s: &str) -> CppException;
+ fn make_error(s: &str) -> *const libc::c_void;
+
+ fn destroy_error(exc: *const libc::c_void);
}
diff --git a/src/libutil/rust-ffi.cc b/src/libutil/rust-ffi.cc
index accc5e22b..6f36b3192 100644
--- a/src/libutil/rust-ffi.cc
+++ b/src/libutil/rust-ffi.cc
@@ -3,10 +3,14 @@
extern "C" std::exception_ptr * make_error(rust::StringSlice s)
{
- // FIXME: leak
return new std::exception_ptr(std::make_exception_ptr(nix::Error(std::string(s.ptr, s.size))));
}
+extern "C" void destroy_error(std::exception_ptr * ex)
+{
+ free(ex);
+}
+
namespace rust {
std::ostream & operator << (std::ostream & str, const String & s)
diff --git a/src/libutil/rust-ffi.hh b/src/libutil/rust-ffi.hh
index 1466eabec..4fecce606 100644
--- a/src/libutil/rust-ffi.hh
+++ b/src/libutil/rust-ffi.hh
@@ -152,28 +152,47 @@ struct Source
template<typename T>
struct Result
{
- unsigned int tag;
+ enum { Ok = 0, Err = 1, Uninit = 2 } tag;
union {
T data;
std::exception_ptr * exc;
};
+ Result() : tag(Uninit) { }; // FIXME: remove
+
+ Result(const Result &) = delete;
+
+ Result(Result && other)
+ : tag(other.tag)
+ {
+ other.tag = Uninit;
+ if (tag == Ok)
+ data = std::move(other.data);
+ else if (tag == Err)
+ exc = other.exc;
+ }
+
~Result()
{
- if (tag == 0)
+ if (tag == Ok)
data.~T();
- else if (tag == 1)
- // FIXME: don't leak exc
+ else if (tag == Err)
+ free(exc);
+ else if (tag == Uninit)
;
+ else
+ abort();
}
/* Rethrow the wrapped exception or return the wrapped value. */
T unwrap()
{
- if (tag == 0)
+ if (tag == Ok) {
+ tag = Uninit;
return std::move(data);
- else if (tag == 1)
+ }
+ else if (tag == Err)
std::rethrow_exception(*exc);
else
abort();
--
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