tree-wide: fix a pile of lints

This:
- Converts a bunch of C style casts into C++ casts.
- Removes some very silly pointer subtraction code (which is no more or
  less busted on i686 than it began)
- Fixes some "technically UB" that never had to be UB in the first
  place.
- Makes finally follow the noexcept status of the inner function. Maybe
  in the future we should ban the function from not being noexcept, but
  that is not today.
- Makes various locally-used exceptions inherit from std::exception.

Change-Id: I22e66972602604989b5e494fd940b93e0e6e9297

1 files changed, 7 insertions, 2 deletions

diff --git a/src/libstore/daemon.cc b/src/libstore/daemon.cc
index aada43253..5ac9cd2ef 100644
--- a/src/libstore/daemon.cc
+++ b/src/libstore/daemon.cc
@@ -453,7 +453,11 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
                 hashAlgo = parseHashType(hashAlgoRaw);
             }
 
-            GeneratorSource dumpSource{[&]() -> WireFormatGenerator {
+            // Note to future maintainers: do *not* inline this into the
+            // generator statement as the lambda itself needs to live to the
+            // end of the generator's lifetime and is otherwise a UAF.
+            // NOLINTNEXTLINE(cppcoreguidelines-avoid-capturing-lambda-coroutines): does not outlive the outer function
+            auto g = [&]() -> WireFormatGenerator {
                 if (method == FileIngestionMethod::Recursive) {
                     /* We parse the NAR dump through into `saved` unmodified,
                        so why all this extra work? We still parse the NAR so
@@ -489,7 +493,8 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
                     }
                     co_yield std::move(file->contents);
                 }
-            }()};
+            };
+            GeneratorSource dumpSource{g()};
             logger->startWork();
             auto path = store->addToStoreFromDump(dumpSource, baseName, method, hashAlgo);
             logger->stopWork();