Author: Vedant Kumar Date: 2021-01-08T15:13:04-08:00 New Revision: e05baf40de8a3bbfcf4a765761b1147e94b7309c
URL: https://github.com/llvm/llvm-project/commit/e05baf40de8a3bbfcf4a765761b1147e94b7309c DIFF: https://github.com/llvm/llvm-project/commit/e05baf40de8a3bbfcf4a765761b1147e94b7309c.diff LOG: [InitLLVM] Ensure SIGPIPE handler installed before sigaction() The pipe signal handler must be installed before any other handlers are registered. This is because the Unix RegisterHandlers function does not perform a sigaction() for SIGPIPE unless a one-shot handler is present, to allow long-lived processes (like lldb) to fully opt-out of llvm's SIGPIPE handling and ignore the signal safely. Fixes a bug introduced in D70277. Tested by running Nick's test case: % xcrun ./bin/clang -E -fno-integrated-cc1 x.c | tee foo.txt | head I verified that child cc1 process exits with IO_ERR, and that the parent recognizes the error code, exiting cleanly. Differential Revision: https://reviews.llvm.org/D94324 Added: clang/test/Driver/sigpipe-handling.c Modified: llvm/include/llvm/Support/InitLLVM.h llvm/lib/Support/InitLLVM.cpp Removed: ################################################################################ diff --git a/clang/test/Driver/sigpipe-handling.c b/clang/test/Driver/sigpipe-handling.c new file mode 100644 index 000000000000..852f0bfaf798 --- /dev/null +++ b/clang/test/Driver/sigpipe-handling.c @@ -0,0 +1,9 @@ +// REQUIRES: shell +// RUN: %clang -E -fno-integrated-cc1 %s | head | FileCheck %s + +// Test that the parent clang driver process doesn't crash when the child cc1 +// process receives a SIGPIPE (Unix-only). +// +// The child should exit with IO_ERR, and the parent should exit cleanly. + +// CHECK: sigpipe-handling.c diff --git a/llvm/include/llvm/Support/InitLLVM.h b/llvm/include/llvm/Support/InitLLVM.h index 3be8d6b6d2e0..879dc1514d10 100644 --- a/llvm/include/llvm/Support/InitLLVM.h +++ b/llvm/include/llvm/Support/InitLLVM.h @@ -9,6 +9,7 @@ #ifndef LLVM_SUPPORT_LLVM_H #define LLVM_SUPPORT_LLVM_H +#include "llvm/ADT/Optional.h" #include "llvm/ADT/SmallVector.h" #include "llvm/Support/Allocator.h" #include "llvm/Support/PrettyStackTrace.h" @@ -44,7 +45,7 @@ class InitLLVM { private: BumpPtrAllocator Alloc; SmallVector<const char *, 0> Args; - PrettyStackTraceProgram StackPrinter; + Optional<PrettyStackTraceProgram> StackPrinter; }; } // namespace llvm diff --git a/llvm/lib/Support/InitLLVM.cpp b/llvm/lib/Support/InitLLVM.cpp index 5c56b773ea69..152de6ebae0a 100644 --- a/llvm/lib/Support/InitLLVM.cpp +++ b/llvm/lib/Support/InitLLVM.cpp @@ -22,10 +22,17 @@ using namespace llvm; using namespace llvm::sys; InitLLVM::InitLLVM(int &Argc, const char **&Argv, - bool InstallPipeSignalExitHandler) - : StackPrinter(Argc, Argv) { + bool InstallPipeSignalExitHandler) { if (InstallPipeSignalExitHandler) + // The pipe signal handler must be installed before any other handlers are + // registered. This is because the Unix \ref RegisterHandlers function does + // not perform a sigaction() for SIGPIPE unless a one-shot handler is + // present, to allow long-lived processes (like lldb) to fully opt-out of + // llvm's SIGPIPE handling and ignore the signal safely. sys::SetOneShotPipeSignalFunction(sys::DefaultOneShotPipeSignalHandler); + // Initialize the stack printer after installing the one-shot pipe signal + // handler, so we can perform a sigaction() for SIGPIPE on Unix if requested. + StackPrinter.emplace(Argc, Argv); sys::PrintStackTraceOnErrorSignal(Argv[0]); install_out_of_memory_new_handler(); _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits