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Vedant Kumar 4f6955c715 [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
2019-11-18 10:27:27 -08:00

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1.8 KiB
C++

//===- InitLLVM.h -----------------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_SUPPORT_LLVM_H
#define LLVM_SUPPORT_LLVM_H
#include "llvm/ADT/SmallVector.h"
#include "llvm/Support/Allocator.h"
#include "llvm/Support/PrettyStackTrace.h"
// The main() functions in typical LLVM tools start with InitLLVM which does
// the following one-time initializations:
//
// 1. Setting up a signal handler so that pretty stack trace is printed out
// if a process crashes. A signal handler that exits when a failed write to
// a pipe occurs may optionally be installed: this is on-by-default.
//
// 2. Set up the global new-handler which is called when a memory allocation
// attempt fails.
//
// 3. If running on Windows, obtain command line arguments using a
// multibyte character-aware API and convert arguments into UTF-8
// encoding, so that you can assume that command line arguments are
// always encoded in UTF-8 on any platform.
//
// InitLLVM calls llvm_shutdown() on destruction, which cleans up
// ManagedStatic objects.
namespace llvm {
class InitLLVM {
public:
InitLLVM(int &Argc, const char **&Argv,
bool InstallPipeSignalExitHandler = true);
InitLLVM(int &Argc, char **&Argv, bool InstallPipeSignalExitHandler = true)
: InitLLVM(Argc, const_cast<const char **&>(Argv),
InstallPipeSignalExitHandler) {}
~InitLLVM();
private:
BumpPtrAllocator Alloc;
SmallVector<const char *, 0> Args;
PrettyStackTraceProgram StackPrinter;
};
} // namespace llvm
#endif