1 /* Copyright (c) 2007-2023. The SimGrid Team. All rights reserved. */
3 /* This program is free software; you can redistribute it and/or modify it
4 * under the terms of the license (GNU LGPL) which comes with this package. */
6 #include "src/mc/remote/CheckerSide.hpp"
7 #include "src/mc/explo/Exploration.hpp"
8 #include "xbt/config.hpp"
9 #include "xbt/system_error.hpp"
11 #if SIMGRID_HAVE_STATEFUL_MC
12 #include "src/mc/explo/LivenessChecker.hpp"
13 #include "src/mc/sosp/RemoteProcessMemory.hpp"
17 #include <sys/prctl.h>
20 #include <boost/tokenizer.hpp>
23 #include <sys/ptrace.h>
27 #define WAITPID_CHECKED_FLAGS __WALL
29 #define WAITPID_CHECKED_FLAGS 0
32 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_checkerside, mc, "MC communication with the application");
34 static simgrid::config::Flag<std::string> _sg_mc_setenv{
35 "model-check/setenv", "Extra environment variables to pass to the child process (ex: 'AZE=aze;QWE=qwe').", "",
36 [](std::string_view value) {
37 xbt_assert(value.empty() || value.find('=', 0) != std::string_view::npos,
38 "The 'model-check/setenv' parameter must be like 'AZE=aze', but it does not contain an equal sign.");
41 namespace simgrid::mc {
43 XBT_ATTRIB_NORETURN static void run_child_process(int socket, const std::vector<char*>& args, bool need_ptrace)
45 /* On startup, simix_global_init() calls simgrid::mc::Client::initialize(), which checks whether the MC_ENV_SOCKET_FD
46 * env variable is set. If so, MC mode is assumed, and the client is setup from its side
50 // Make sure we do not outlive our parent
53 xbt_assert(sigprocmask(SIG_SETMASK, &mask, nullptr) >= 0, "Could not unblock signals");
54 xbt_assert(prctl(PR_SET_PDEATHSIG, SIGHUP) == 0, "Could not PR_SET_PDEATHSIG");
57 setenv(MC_ENV_SOCKET_FD, std::to_string(socket).c_str(), 1);
59 setenv("MC_NEED_PTRACE", "1", 1);
61 /* Setup the tokenizer that parses the cfg:model-check/setenv parameter */
62 using Tokenizer = boost::tokenizer<boost::char_separator<char>>;
63 boost::char_separator<char> semicol_sep(";");
64 boost::char_separator<char> equal_sep("=");
65 Tokenizer token_vars(_sg_mc_setenv.get(), semicol_sep); /* Iterate over all FOO=foo parts */
66 for (const auto& token : token_vars) {
67 std::vector<std::string> kv;
68 Tokenizer token_kv(token, equal_sep);
69 for (const auto& t : token_kv) /* Iterate over 'FOO' and then 'foo' in that 'FOO=foo' */
71 xbt_assert(kv.size() == 2, "Parse error on 'model-check/setenv' value %s. Does it contain an equal sign?",
73 XBT_INFO("setenv '%s'='%s'", kv[0].c_str(), kv[1].c_str());
74 setenv(kv[0].c_str(), kv[1].c_str(), 1);
77 /* And now, exec the child process */
79 while (args[i] != nullptr && args[i][0] == '-')
82 xbt_assert(args[i] != nullptr,
83 "Unable to find a binary to exec on the command line. Did you only pass config flags?");
85 execvp(args[i], args.data() + i);
86 XBT_CRITICAL("The model-checked process failed to exec(%s): %s.\n"
87 " Make sure that your binary exists on disk and is executable.",
88 args[i], strerror(errno));
89 if (strchr(args[i], '=') != nullptr)
90 XBT_CRITICAL("If you want to pass environment variables to the application, please use --cfg=model-check/setenv:%s",
93 xbt_die("Aborting now.");
96 static void wait_application_process(pid_t pid)
98 XBT_DEBUG("Waiting for the model-checked process");
101 // The model-checked process SIGSTOP itself to signal it's ready:
102 xbt_assert(waitpid(pid, &status, WAITPID_CHECKED_FLAGS) == pid && WIFSTOPPED(status) && WSTOPSIG(status) == SIGSTOP,
103 "Could not wait model-checked process");
107 ptrace(PTRACE_SETOPTIONS, pid, nullptr, PTRACE_O_TRACEEXIT);
108 ptrace(PTRACE_CONT, pid, 0, 0);
110 ptrace(PT_CONTINUE, pid, (caddr_t)1, 0);
112 xbt_die("no ptrace equivalent coded for this platform, stateful model-checking is impossible.");
114 xbt_assert(errno == 0,
115 "Ptrace does not seem to be usable in your setup (errno: %d). "
116 "If you run from within a docker, adding `--cap-add SYS_PTRACE` to the docker line may help. "
117 "If it does not help, please report this bug.",
119 XBT_DEBUG("%d ptrace correctly setup.", getpid());
122 void CheckerSide::setup_events(bool socket_only)
124 auto* base = event_base_new();
127 socket_event_ = event_new(
128 base, get_channel().get_socket(), EV_READ | EV_PERSIST,
129 [](evutil_socket_t, short events, void* arg) {
130 auto checker = static_cast<simgrid::mc::CheckerSide*>(arg);
131 if (events == EV_READ) {
134 std::array<char, MC_MESSAGE_LENGTH> buffer;
135 ssize_t size = checker->get_channel().receive(buffer.data(), buffer.size(), MSG_DONTWAIT);
137 XBT_ERROR("Channel::receive failure: %s", strerror(errno));
139 throw simgrid::xbt::errno_error();
142 if (size == 0) // The app closed the socket. It must be dead by now.
143 checker->handle_waitpid();
144 else if (not checker->handle_message(buffer.data(), size)) {
145 checker->break_loop();
148 } while (checker->get_channel().has_pending_data());
150 xbt_die("Unexpected event");
154 event_add(socket_event_, nullptr);
157 signal_event_ = nullptr;
159 signal_event_ = event_new(
160 base, SIGCHLD, EV_SIGNAL | EV_PERSIST,
161 [](evutil_socket_t sig, short events, void* arg) {
162 auto checker = static_cast<simgrid::mc::CheckerSide*>(arg);
163 if (events == EV_SIGNAL) {
165 checker->handle_waitpid();
167 xbt_die("Unexpected signal: %d", sig);
169 xbt_die("Unexpected event");
173 event_add(signal_event_, nullptr);
177 /* When this constructor is called, no other checkerside exists */
178 CheckerSide::CheckerSide(const std::vector<char*>& args, bool need_memory_info) : running_(true)
180 XBT_DEBUG("Create a CheckerSide. Needs_meminfo: %s", need_memory_info ? "YES" : "no");
182 // Create an AF_UNIX socketpair used for exchanging messages between the model-checker process (ancestor)
183 // and the application process (child)
185 xbt_assert(socketpair(AF_UNIX, SOCK_STREAM, 0, sockets) != -1, "Could not create socketpair: %s", strerror(errno));
188 xbt_assert(pid_ >= 0, "Could not fork application process");
190 if (pid_ == 0) { // Child
192 run_child_process(sockets[0], args, need_memory_info); // We need ptrace if we need the mem info
196 // Parent (model-checker):
198 channel_.reset_socket(sockets[1]);
200 setup_events(false); /* we need a signal handler too */
201 if (need_memory_info) {
202 #if SIMGRID_HAVE_STATEFUL_MC
203 // setup ptrace and sync with the app
204 wait_application_process(pid_);
206 // Request the initial memory on need
207 channel_.send(MessageType::NEED_MEMINFO);
208 s_mc_message_need_meminfo_reply_t answer;
209 ssize_t answer_size = channel_.receive(answer);
210 xbt_assert(answer_size != -1, "Could not receive message");
211 xbt_assert(answer.type == MessageType::NEED_MEMINFO_REPLY,
212 "The received message is not the NEED_MEMINFO_REPLY I was expecting but of type %s",
213 to_c_str(answer.type));
214 xbt_assert(answer_size == sizeof answer, "Broken message (size=%zd; expected %zu)", answer_size, sizeof answer);
216 /* We now have enough info to create the memory address space */
217 remote_memory_ = std::make_unique<simgrid::mc::RemoteProcessMemory>(pid_, answer.mmalloc_default_mdp);
219 xbt_die("Cannot introspect memory without MC support");
226 CheckerSide::~CheckerSide()
228 event_del(socket_event_);
229 event_free(socket_event_);
230 if (signal_event_ != nullptr) {
231 event_del(signal_event_);
232 event_free(signal_event_);
236 /* This constructor is called when cloning a checkerside to get its application to fork away */
237 CheckerSide::CheckerSide(int socket, CheckerSide* child_checker)
238 : channel_(socket, child_checker->channel_), running_(true), child_checker_(child_checker)
240 setup_events(true); // We already have a signal handled in that case
242 s_mc_message_int_t answer;
243 ssize_t s = get_channel().receive(answer);
244 xbt_assert(s != -1, "Could not receive answer to FORK_REPLY");
245 xbt_assert(s == sizeof answer, "Broken message (size=%zd; expected %zu)", s, sizeof answer);
246 xbt_assert(answer.type == MessageType::FORK_REPLY,
247 "Received unexpected message %s (%i); expected MessageType::FORK_REPLY (%i)", to_c_str(answer.type),
248 (int)answer.type, (int)MessageType::FORK_REPLY);
254 std::unique_ptr<CheckerSide> CheckerSide::clone(int master_socket)
256 s_mc_message_int_t m = {};
257 m.type = MessageType::FORK;
259 xbt_assert(get_channel().send(m) == 0, "Could not ask the app to fork on need.");
261 int sock = accept(master_socket, nullptr /* I know who's connecting*/, nullptr);
262 xbt_assert(sock > 0, "Cannot accept the incomming connection of the forked app: %s.", strerror(errno));
264 return std::make_unique<CheckerSide>(sock, this);
267 void CheckerSide::finalize(bool terminate_asap)
269 s_mc_message_int_t m = {};
270 m.type = MessageType::FINALIZE;
271 m.value = terminate_asap;
272 xbt_assert(get_channel().send(m) == 0, "Could not ask the app to finalize on need");
274 s_mc_message_t answer;
275 ssize_t s = get_channel().receive(answer);
276 xbt_assert(s != -1, "Could not receive answer to FINALIZE");
277 xbt_assert(s == sizeof answer, "Broken message (size=%zd; expected %zu)", s, sizeof answer);
278 xbt_assert(answer.type == MessageType::FINALIZE_REPLY,
279 "Received unexpected message %s (%i); expected MessageType::FINALIZE_REPLY (%i)", to_c_str(answer.type),
280 (int)answer.type, (int)MessageType::FINALIZE_REPLY);
283 void CheckerSide::dispatch_events()
285 event_base_dispatch(base_.get());
288 void CheckerSide::break_loop() const
290 event_base_loopbreak(base_.get());
293 bool CheckerSide::handle_message(const char* buffer, ssize_t size)
295 s_mc_message_t base_message;
297 xbt_assert(size >= (ssize_t)sizeof(base_message), "Broken message. Got only %ld bytes.", size);
298 memcpy(&base_message, buffer, sizeof(base_message));
300 switch (base_message.type) {
301 case MessageType::IGNORE_HEAP: {
302 consumed = sizeof(s_mc_message_ignore_heap_t);
303 #if SIMGRID_HAVE_STATEFUL_MC
304 if (remote_memory_ != nullptr) {
305 s_mc_message_ignore_heap_t message;
306 xbt_assert(size >= static_cast<ssize_t>(sizeof(message)), "Broken message");
307 memcpy(&message, buffer, sizeof(message));
309 IgnoredHeapRegion region;
310 region.block = message.block;
311 region.fragment = message.fragment;
312 region.address = message.address;
313 region.size = message.size;
314 get_remote_memory()->ignore_heap(region);
317 XBT_INFO("Ignoring a IGNORE_HEAP message because we don't need to introspect memory.");
321 case MessageType::UNIGNORE_HEAP: {
322 consumed = sizeof(s_mc_message_ignore_memory_t);
323 #if SIMGRID_HAVE_STATEFUL_MC
324 if (remote_memory_ != nullptr) {
325 s_mc_message_ignore_memory_t message;
326 xbt_assert(size == static_cast<ssize_t>(sizeof(message)), "Broken message");
327 memcpy(&message, buffer, sizeof(message));
328 get_remote_memory()->unignore_heap((void*)message.addr, message.size);
331 XBT_INFO("Ignoring an UNIGNORE_HEAP message because we don't need to introspect memory.");
335 case MessageType::IGNORE_MEMORY: {
336 consumed = sizeof(s_mc_message_ignore_memory_t);
337 #if SIMGRID_HAVE_STATEFUL_MC
338 if (remote_memory_ != nullptr) {
339 s_mc_message_ignore_memory_t message;
340 xbt_assert(size >= static_cast<ssize_t>(sizeof(message)), "Broken message");
341 memcpy(&message, buffer, sizeof(message));
342 get_remote_memory()->ignore_region(message.addr, message.size);
345 XBT_INFO("Ignoring an IGNORE_MEMORY message because we don't need to introspect memory.");
349 case MessageType::STACK_REGION: {
350 consumed = sizeof(s_mc_message_stack_region_t);
351 #if SIMGRID_HAVE_STATEFUL_MC
352 if (remote_memory_ != nullptr) {
353 s_mc_message_stack_region_t message;
354 xbt_assert(size >= static_cast<ssize_t>(sizeof(message)), "Broken message");
355 memcpy(&message, buffer, sizeof(message));
356 get_remote_memory()->stack_areas().push_back(message.stack_region);
359 XBT_INFO("Ignoring an STACK_REGION message because we don't need to introspect memory.");
363 case MessageType::REGISTER_SYMBOL: {
364 consumed = sizeof(s_mc_message_register_symbol_t);
365 #if SIMGRID_HAVE_STATEFUL_MC
366 s_mc_message_register_symbol_t message;
367 xbt_assert(size >= static_cast<ssize_t>(sizeof(message)), "Broken message");
368 memcpy(&message, buffer, sizeof(message));
369 xbt_assert(not message.callback, "Support for client-side function proposition is not implemented.");
370 XBT_DEBUG("Received symbol: %s", message.name.data());
372 LivenessChecker::automaton_register_symbol(*get_remote_memory(), message.name.data(), remote((int*)message.data));
374 xbt_die("Please don't use liveness properties when MC is compiled out.");
379 case MessageType::WAITING:
380 consumed = sizeof(s_mc_message_t);
381 if (size > consumed) {
382 XBT_DEBUG("%d reinject %d bytes after a %s message", getpid(), (int)(size - consumed),
383 to_c_str(base_message.type));
384 channel_.reinject(&buffer[consumed], size - consumed);
389 case MessageType::ASSERTION_FAILED:
390 consumed = sizeof(s_mc_message_t);
391 Exploration::get_instance()->report_assertion_failure();
395 xbt_die("Unexpected message from the application");
397 if (size > consumed) {
398 XBT_DEBUG("%d reinject %d bytes after a %s message", getpid(), (int)(size - consumed), to_c_str(base_message.type));
399 channel_.reinject(&buffer[consumed], size - consumed);
404 void CheckerSide::wait_for_requests()
406 XBT_DEBUG("Resume the application");
407 if (get_channel().send(MessageType::CONTINUE) != 0)
408 throw xbt::errno_error();
409 clear_memory_cache();
415 void CheckerSide::clear_memory_cache()
417 #if SIMGRID_HAVE_STATEFUL_MC
419 remote_memory_->clear_cache();
423 void CheckerSide::handle_dead_child(int status)
425 // From PTRACE_O_TRACEEXIT:
427 if (status >> 8 == (SIGTRAP | (PTRACE_EVENT_EXIT << 8))) {
428 unsigned long eventmsg;
429 xbt_assert(ptrace(PTRACE_GETEVENTMSG, pid_, 0, &eventmsg) != -1, "Could not get exit status");
430 status = static_cast<int>(eventmsg);
431 if (WIFSIGNALED(status)) {
433 Exploration::get_instance()->report_crash(status);
438 // We don't care about non-lethal signals, just reinject them:
439 if (WIFSTOPPED(status)) {
440 XBT_DEBUG("Stopped with signal %i", (int)WSTOPSIG(status));
443 ptrace(PTRACE_CONT, pid_, 0, WSTOPSIG(status));
445 ptrace(PT_CONTINUE, pid_, (caddr_t)1, WSTOPSIG(status));
447 xbt_assert(errno == 0, "Could not PTRACE_CONT: %s", strerror(errno));
450 else if (WIFSIGNALED(status)) {
452 Exploration::get_instance()->report_crash(status);
453 } else if (WIFEXITED(status)) {
454 XBT_DEBUG("Child process is over");
459 void CheckerSide::handle_waitpid()
461 XBT_DEBUG("%d checks for wait event. %s", getpid(),
462 child_checker_ == nullptr ? "Wait directly." : "Ask our proxy to wait for its child.");
464 if (child_checker_ == nullptr) { // Wait directly
467 while ((pid = waitpid(-1, &status, WNOHANG)) != 0) {
469 if (errno == ECHILD) { // No more children:
470 xbt_assert(not this->running(), "Inconsistent state");
473 xbt_die("Could not wait for pid: %s", strerror(errno));
477 if (pid == get_pid())
478 handle_dead_child(status);
481 } else { // Ask our proxy to wait for us
483 s_mc_message_int_t request = {};
484 request.type = MessageType::WAIT_CHILD;
485 request.value = pid_;
486 xbt_assert(child_checker_->get_channel().send(request) == 0,
487 "Could not ask my child to waitpid its child for me: %s", strerror(errno));
489 s_mc_message_int_t answer;
490 ssize_t answer_size = child_checker_->get_channel().receive(answer);
491 xbt_assert(answer_size != -1, "Could not receive message");
492 xbt_assert(answer.type == MessageType::WAIT_CHILD_REPLY,
493 "The received message is not the WAIT_CHILD_REPLY I was expecting but of type %s",
494 to_c_str(answer.type));
495 xbt_assert(answer_size == sizeof answer, "Broken message (size=%zd; expected %zu)", answer_size, sizeof answer);
496 handle_dead_child(answer.value);
499 } // namespace simgrid::mc