petpav01 created this revision.
Store file descriptors from `loop.m_read_fds` (if `FORCE_PSELECT` is defined)
and signals from `loop.m_signals` that need to be processed in
`MainLoop::RunImpl::ProcessEvents()` into a separate vector and then iterate
over this container to invoke the callbacks.
This prevents a problem where when the code iterated directly over
`m_read_fds`/`m_signals`, a callback invoked from within the loop could modify
these variables and invalidate the loop iterator. This would then result in the
following assertion failure:
> llvm/include/llvm/ADT/DenseMap.h:1099: llvm::DenseMapIterator<KeyT, ValueT,
> KeyInfoT, Bucket, IsConst>& llvm::DenseMapIterator<KeyT, ValueT, KeyInfoT,
> Bucket, IsConst>::operator++() [with KeyT = int; ValueT =
> std::function<void(lldb_private::MainLoopBase&)>; KeyInfoT =
> llvm::DenseMapInfo<int>; Bucket = llvm::detail::DenseMapPair<int,
> std::function<void(lldb_private::MainLoopBase&)> >; bool IsConst = false]:
> assertion "isHandleInSync() && "invalid iterator access!"" failed
https://reviews.llvm.org/D35298
Files:
source/Host/common/MainLoop.cpp
Index: source/Host/common/MainLoop.cpp
===================================================================
--- source/Host/common/MainLoop.cpp
+++ source/Host/common/MainLoop.cpp
@@ -193,10 +193,16 @@
void MainLoop::RunImpl::ProcessEvents() {
#ifdef FORCE_PSELECT
- for (const auto &fd : loop.m_read_fds) {
- if (!FD_ISSET(fd.first, &read_fd_set))
- continue;
- IOObject::WaitableHandle handle = fd.first;
+ // Collect first all readable file descriptors into a separate vector and
then
+ // iterate over it to invoke callbacks. Iterating directly over
+ // loop.m_read_fds is not possible because the callbacks can modify the
+ // container which could invalidate the iterator.
+ std::vector<IOObject::WaitableHandle> fds;
+ for (const auto &fd : loop.m_read_fds)
+ if (FD_ISSET(fd.first, &read_fd_set))
+ fds.push_back(fd.first);
+
+ for (const auto &handle : fds) {
#else
for (const auto &fd : read_fds) {
if ((fd.revents & POLLIN) == 0)
@@ -209,13 +215,16 @@
loop.ProcessReadObject(handle);
}
- for (const auto &entry : loop.m_signals) {
+ std::vector<int> signals;
+ for (const auto &entry : loop.m_signals)
+ if (g_signal_flags[entry.first] != 0)
+ signals.push_back(entry.first);
+
+ for (const auto &signal : signals) {
if (loop.m_terminate_request)
return;
- if (g_signal_flags[entry.first] == 0)
- continue; // No signal
- g_signal_flags[entry.first] = 0;
- loop.ProcessSignal(entry.first);
+ g_signal_flags[signal] = 0;
+ loop.ProcessSignal(signal);
}
}
#endif
Index: source/Host/common/MainLoop.cpp
===================================================================
--- source/Host/common/MainLoop.cpp
+++ source/Host/common/MainLoop.cpp
@@ -193,10 +193,16 @@
void MainLoop::RunImpl::ProcessEvents() {
#ifdef FORCE_PSELECT
- for (const auto &fd : loop.m_read_fds) {
- if (!FD_ISSET(fd.first, &read_fd_set))
- continue;
- IOObject::WaitableHandle handle = fd.first;
+ // Collect first all readable file descriptors into a separate vector and then
+ // iterate over it to invoke callbacks. Iterating directly over
+ // loop.m_read_fds is not possible because the callbacks can modify the
+ // container which could invalidate the iterator.
+ std::vector<IOObject::WaitableHandle> fds;
+ for (const auto &fd : loop.m_read_fds)
+ if (FD_ISSET(fd.first, &read_fd_set))
+ fds.push_back(fd.first);
+
+ for (const auto &handle : fds) {
#else
for (const auto &fd : read_fds) {
if ((fd.revents & POLLIN) == 0)
@@ -209,13 +215,16 @@
loop.ProcessReadObject(handle);
}
- for (const auto &entry : loop.m_signals) {
+ std::vector<int> signals;
+ for (const auto &entry : loop.m_signals)
+ if (g_signal_flags[entry.first] != 0)
+ signals.push_back(entry.first);
+
+ for (const auto &signal : signals) {
if (loop.m_terminate_request)
return;
- if (g_signal_flags[entry.first] == 0)
- continue; // No signal
- g_signal_flags[entry.first] = 0;
- loop.ProcessSignal(entry.first);
+ g_signal_flags[signal] = 0;
+ loop.ProcessSignal(signal);
}
}
#endif
_______________________________________________
lldb-commits mailing list
lldb-commits@lists.llvm.org
http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
