Move libFuzzer to compiler_rt.
Resulting library binaries will be named libclang_rt.fuzzer*, and will
be placed in Clang toolchain, allowing redistribution.
Differential Revision: https://reviews.llvm.org/D36908
llvm-svn: 311407
diff --git a/compiler-rt/lib/fuzzer/FuzzerUtilDarwin.cpp b/compiler-rt/lib/fuzzer/FuzzerUtilDarwin.cpp
new file mode 100644
index 0000000..2df4872
--- /dev/null
+++ b/compiler-rt/lib/fuzzer/FuzzerUtilDarwin.cpp
@@ -0,0 +1,161 @@
+//===- FuzzerUtilDarwin.cpp - Misc utils ----------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+// Misc utils for Darwin.
+//===----------------------------------------------------------------------===//
+#include "FuzzerDefs.h"
+#if LIBFUZZER_APPLE
+
+#include "FuzzerIO.h"
+#include <mutex>
+#include <signal.h>
+#include <spawn.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/wait.h>
+
+// There is no header for this on macOS so declare here
+extern "C" char **environ;
+
+namespace fuzzer {
+
+static std::mutex SignalMutex;
+// Global variables used to keep track of how signal handling should be
+// restored. They should **not** be accessed without holding `SignalMutex`.
+static int ActiveThreadCount = 0;
+static struct sigaction OldSigIntAction;
+static struct sigaction OldSigQuitAction;
+static sigset_t OldBlockedSignalsSet;
+
+// This is a reimplementation of Libc's `system()`. On Darwin the Libc
+// implementation contains a mutex which prevents it from being used
+// concurrently. This implementation **can** be used concurrently. It sets the
+// signal handlers when the first thread enters and restores them when the last
+// thread finishes execution of the function and ensures this is not racey by
+// using a mutex.
+int ExecuteCommand(const std::string &Command) {
+ posix_spawnattr_t SpawnAttributes;
+ if (posix_spawnattr_init(&SpawnAttributes))
+ return -1;
+ // Block and ignore signals of the current process when the first thread
+ // enters.
+ {
+ std::lock_guard<std::mutex> Lock(SignalMutex);
+ if (ActiveThreadCount == 0) {
+ static struct sigaction IgnoreSignalAction;
+ sigset_t BlockedSignalsSet;
+ memset(&IgnoreSignalAction, 0, sizeof(IgnoreSignalAction));
+ IgnoreSignalAction.sa_handler = SIG_IGN;
+
+ if (sigaction(SIGINT, &IgnoreSignalAction, &OldSigIntAction) == -1) {
+ Printf("Failed to ignore SIGINT\n");
+ (void)posix_spawnattr_destroy(&SpawnAttributes);
+ return -1;
+ }
+ if (sigaction(SIGQUIT, &IgnoreSignalAction, &OldSigQuitAction) == -1) {
+ Printf("Failed to ignore SIGQUIT\n");
+ // Try our best to restore the signal handlers.
+ (void)sigaction(SIGINT, &OldSigIntAction, NULL);
+ (void)posix_spawnattr_destroy(&SpawnAttributes);
+ return -1;
+ }
+
+ (void)sigemptyset(&BlockedSignalsSet);
+ (void)sigaddset(&BlockedSignalsSet, SIGCHLD);
+ if (sigprocmask(SIG_BLOCK, &BlockedSignalsSet, &OldBlockedSignalsSet) ==
+ -1) {
+ Printf("Failed to block SIGCHLD\n");
+ // Try our best to restore the signal handlers.
+ (void)sigaction(SIGQUIT, &OldSigQuitAction, NULL);
+ (void)sigaction(SIGINT, &OldSigIntAction, NULL);
+ (void)posix_spawnattr_destroy(&SpawnAttributes);
+ return -1;
+ }
+ }
+ ++ActiveThreadCount;
+ }
+
+ // NOTE: Do not introduce any new `return` statements past this
+ // point. It is important that `ActiveThreadCount` always be decremented
+ // when leaving this function.
+
+ // Make sure the child process uses the default handlers for the
+ // following signals rather than inheriting what the parent has.
+ sigset_t DefaultSigSet;
+ (void)sigemptyset(&DefaultSigSet);
+ (void)sigaddset(&DefaultSigSet, SIGQUIT);
+ (void)sigaddset(&DefaultSigSet, SIGINT);
+ (void)posix_spawnattr_setsigdefault(&SpawnAttributes, &DefaultSigSet);
+ // Make sure the child process doesn't block SIGCHLD
+ (void)posix_spawnattr_setsigmask(&SpawnAttributes, &OldBlockedSignalsSet);
+ short SpawnFlags = POSIX_SPAWN_SETSIGDEF | POSIX_SPAWN_SETSIGMASK;
+ (void)posix_spawnattr_setflags(&SpawnAttributes, SpawnFlags);
+
+ pid_t Pid;
+ char **Environ = environ; // Read from global
+ const char *CommandCStr = Command.c_str();
+ char *const Argv[] = {
+ strdup("sh"),
+ strdup("-c"),
+ strdup(CommandCStr),
+ NULL
+ };
+ int ErrorCode = 0, ProcessStatus = 0;
+ // FIXME: We probably shouldn't hardcode the shell path.
+ ErrorCode = posix_spawn(&Pid, "/bin/sh", NULL, &SpawnAttributes,
+ Argv, Environ);
+ (void)posix_spawnattr_destroy(&SpawnAttributes);
+ if (!ErrorCode) {
+ pid_t SavedPid = Pid;
+ do {
+ // Repeat until call completes uninterrupted.
+ Pid = waitpid(SavedPid, &ProcessStatus, /*options=*/0);
+ } while (Pid == -1 && errno == EINTR);
+ if (Pid == -1) {
+ // Fail for some other reason.
+ ProcessStatus = -1;
+ }
+ } else if (ErrorCode == ENOMEM || ErrorCode == EAGAIN) {
+ // Fork failure.
+ ProcessStatus = -1;
+ } else {
+ // Shell execution failure.
+ ProcessStatus = W_EXITCODE(127, 0);
+ }
+ for (unsigned i = 0, n = sizeof(Argv) / sizeof(Argv[0]); i < n; ++i)
+ free(Argv[i]);
+
+ // Restore the signal handlers of the current process when the last thread
+ // using this function finishes.
+ {
+ std::lock_guard<std::mutex> Lock(SignalMutex);
+ --ActiveThreadCount;
+ if (ActiveThreadCount == 0) {
+ bool FailedRestore = false;
+ if (sigaction(SIGINT, &OldSigIntAction, NULL) == -1) {
+ Printf("Failed to restore SIGINT handling\n");
+ FailedRestore = true;
+ }
+ if (sigaction(SIGQUIT, &OldSigQuitAction, NULL) == -1) {
+ Printf("Failed to restore SIGQUIT handling\n");
+ FailedRestore = true;
+ }
+ if (sigprocmask(SIG_BLOCK, &OldBlockedSignalsSet, NULL) == -1) {
+ Printf("Failed to unblock SIGCHLD\n");
+ FailedRestore = true;
+ }
+ if (FailedRestore)
+ ProcessStatus = -1;
+ }
+ }
+ return ProcessStatus;
+}
+
+} // namespace fuzzer
+
+#endif // LIBFUZZER_APPLE