[Signal] Allow llvm clients to opt into one-shot SIGPIPE handling

Allow clients of the llvm library to opt-in to one-shot SIGPIPE
handling, instead of forcing them to undo llvm's SIGPIPE handler
registration (which is brittle).

The current behavior is preserved for all llvm-derived tools (except
lldb) by means of a default-`true` flag in the InitLLVM constructor.

This prevents "IO error" crashes in long-lived processes (lldb is the
motivating example) which both a) load llvm as a dynamic library and b)
*really* need to ignore SIGPIPE.

As llvm signal handlers can be installed when calling into libclang
(say, via RemoveFileOnSignal), thereby overriding a previous SIG_IGN for
SIGPIPE, there is no clean way to opt-out of "exit-on-SIGPIPE" in the
current model.

Differential Revision: https://reviews.llvm.org/D70277

1 files changed, 5 insertions, 1 deletions

diff --git a/llvm/lib/Support/InitLLVM.cpp b/llvm/lib/Support/InitLLVM.cpp
index 0d7d7fcc8cb..bb9b569d2de 100644
--- a/llvm/lib/Support/InitLLVM.cpp
+++ b/llvm/lib/Support/InitLLVM.cpp
@@ -21,7 +21,11 @@
 using namespace llvm;
 using namespace llvm::sys;
 
-InitLLVM::InitLLVM(int &Argc, const char **&Argv) : StackPrinter(Argc, Argv) {
+InitLLVM::InitLLVM(int &Argc, const char **&Argv,
+                   bool InstallPipeSignalExitHandler)
+    : StackPrinter(Argc, Argv) {
+  if (InstallPipeSignalExitHandler)
+    sys::SetOneShotPipeSignalFunction(sys::DefaultOneShotPipeSignalHandler);
   sys::PrintStackTraceOnErrorSignal(Argv[0]);
   install_out_of_memory_new_handler();