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Fix crash/hang with CA derivations

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The curl download can outlive DrvOutputSubstitutionGoal (if some other
error occurs), so at shutdown setting the promise to an exception will
fail because 'this' is no longer valid in the callback. This can
manifest itself as a segfault, "corrupted double-linked list" or hang.

(cherry picked from commit 7bfed34367)
This commit is contained in:
Eelco Dolstra 2023-03-07 13:51:02 +01:00
parent 3913366f6d
commit 2639911c8b
2 changed files with 22 additions and 13 deletions
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23
src/libstore/build/drv-output-substitution-goal.cc
View file

@ -61,20 +61,25 @@ void DrvOutputSubstitutionGoal::tryNext()
// FIXME: Make async
// outputInfo = sub->queryRealisation(id);
outPipe.create();
promise = decltype(promise)();
/* The callback of the curl download below can outlive `this` (if
some other error occurs), so it must not touch `this`. So put
the shared state in a separate refcounted object. */
downloadState = std::make_shared<DownloadState>();
downloadState->outPipe.create();
sub->queryRealisation(
id, { [&](std::future<std::shared_ptr<const Realisation>> res) {
id,
{ [downloadState(downloadState)](std::future<std::shared_ptr<const Realisation>> res) {
try {
Finally updateStats([this]() { outPipe.writeSide.close(); });
promise.set_value(res.get());
Finally updateStats([&]() { downloadState->outPipe.writeSide.close(); });
downloadState->promise.set_value(res.get());
} catch (...) {
promise.set_exception(std::current_exception());
downloadState->promise.set_exception(std::current_exception());
}
} });
worker.childStarted(shared_from_this(), {outPipe.readSide.get()}, true, false);
worker.childStarted(shared_from_this(), {downloadState->outPipe.readSide.get()}, true, false);
state = &DrvOutputSubstitutionGoal::realisationFetched;
}
@ -84,7 +89,7 @@ void DrvOutputSubstitutionGoal::realisationFetched()
worker.childTerminated(this);
try {
outputInfo = promise.get_future().get();
outputInfo = downloadState->promise.get_future().get();
} catch (std::exception & e) {
printError(e.what());
substituterFailed = true;
@ -155,7 +160,7 @@ void DrvOutputSubstitutionGoal::work()
void DrvOutputSubstitutionGoal::handleEOF(int fd)
{
if (fd == outPipe.readSide.get()) worker.wakeUp(shared_from_this());
if (fd == downloadState->outPipe.readSide.get()) worker.wakeUp(shared_from_this());
}

12
src/libstore/build/drv-output-substitution-goal.hh
View file

@ -16,7 +16,7 @@ class Worker;
// 2. Substitute the corresponding output path
// 3. Register the output info
class DrvOutputSubstitutionGoal : public Goal {
private:
// The drv output we're trying to substitue
DrvOutput id;
@ -30,9 +30,13 @@ private:
/* The current substituter. */
std::shared_ptr<Store> sub;
Pipe outPipe;
std::thread thr;
std::promise<std::shared_ptr<const Realisation>> promise;
struct DownloadState
{
Pipe outPipe;
std::promise<std::shared_ptr<const Realisation>> promise;
};
std::shared_ptr<DownloadState> downloadState;
/* Whether a substituter failed. */
bool substituterFailed = false;