From 11ca718deb6ce1b2e4eb6978fd5a953b187ad511 Mon Sep 17 00:00:00 2001 From: Gabriel Corona Date: Wed, 24 Feb 2016 12:14:01 +0100 Subject: [PATCH 1/1] [mc] Cleanup/reorganise the code of simgrid_mc --- src/mc/simgrid_mc.cpp | 175 +++++++++++++++++++++++------------------- 1 file changed, 97 insertions(+), 78 deletions(-) diff --git a/src/mc/simgrid_mc.cpp b/src/mc/simgrid_mc.cpp index e0f61709de..f6e998d825 100644 --- a/src/mc/simgrid_mc.cpp +++ b/src/mc/simgrid_mc.cpp @@ -10,6 +10,8 @@ #include #include +#include + #include #include @@ -39,7 +41,30 @@ XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_main, mc, "Entry point for simgrid-mc"); -static int do_child(int socket, char** argv) +/** Execute some code in a forked process */ +template +static inline +pid_t do_fork(F f) +{ + pid_t pid = fork(); + if (pid < 0) + throw new std::system_error(errno, std::generic_category()); + if (pid != 0) + return pid; + + // Child-process: + try { + f(); + std::exit(EXIT_SUCCESS); + } + catch(...) { + // The callback should catch exceptions: + abort(); + } +} + +static +int exec_model_checked(int socket, char** argv) { XBT_DEBUG("Inside the child process PID=%i", (int) getpid()); @@ -47,36 +72,25 @@ static int do_child(int socket, char** argv) // Make sure we do not outlive our parent: sigset_t mask; sigemptyset (&mask); - if (sigprocmask(SIG_SETMASK, &mask, nullptr) < 0) { - std::perror ("sigprocmask"); - return SIMGRID_MC_EXIT_ERROR; - } - - if (prctl(PR_SET_PDEATHSIG, SIGHUP) != 0) { - std::perror("simgrid-mc"); - return SIMGRID_MC_EXIT_ERROR; - } + if (sigprocmask(SIG_SETMASK, &mask, nullptr) < 0) + throw new std::system_error(errno, std::generic_category(), "sigprocmask"); + if (prctl(PR_SET_PDEATHSIG, SIGHUP) != 0) + throw new std::system_error(errno, std::generic_category(), "PR_SET_PDEATHSIG"); #endif int res; // Remove CLOEXEC in order to pass the socket to the exec-ed program: int fdflags = fcntl(socket, F_GETFD, 0); - if (fdflags == -1) { - std::perror("simgrid-mc"); - return SIMGRID_MC_EXIT_ERROR; - } - if (fcntl(socket, F_SETFD, fdflags & ~FD_CLOEXEC) == -1) { - std::perror("simgrid-mc"); - return SIMGRID_MC_EXIT_ERROR; - } - - XBT_DEBUG("CLOEXEC removed on socket %i", socket); + if (fdflags == -1) + throw new std::system_error(errno, std::generic_category(), "F_GETFD"); + if (fcntl(socket, F_SETFD, fdflags & ~FD_CLOEXEC) == -1) + throw new std::system_error(errno, std::generic_category(), "Remove FD_CLOEXEC"); // Set environment: setenv(MC_ENV_VARIABLE, "1", 1); - // Disable lazy relocation in the model-ched process. + // Disable lazy relocation in the model-checked process. // We don't want the model-checked process to modify its .got.plt during // snapshot. setenv("LC_BIND_NOW", "1", 1); @@ -84,22 +98,74 @@ static int do_child(int socket, char** argv) char buffer[64]; res = std::snprintf(buffer, sizeof(buffer), "%i", socket); if ((size_t) res >= sizeof(buffer) || res == -1) - return SIMGRID_MC_EXIT_ERROR; + std::abort(); setenv(MC_ENV_SOCKET_FD, buffer, 1); execvp(argv[1], argv+1); - XBT_ERROR("Could not execute the child process"); - return SIMGRID_MC_EXIT_ERROR; + + XBT_ERROR("Could not run the model-checked program"); + // This is the value used by system() and popen() in this case: + return 127; } -static int do_parent(int socket, pid_t child) +static +std::pair create_model_checked(char** argv) +{ + // Create a AF_LOCAL socketpair used for exchanging messages + // bewteen the model-checker process (ourselves) and the model-checked + // process: + int res; + int sockets[2]; + res = socketpair(AF_LOCAL, SOCK_DGRAM | SOCK_CLOEXEC, 0, sockets); + if (res == -1) + throw new std::system_error(errno, std::generic_category(), "socketpair"); + + pid_t pid = do_fork([&] { + close(sockets[1]); + int res = exec_model_checked(sockets[0], argv); + XBT_DEBUG("Error in the child process creation"); + exit(res); + }); + + // Parent (model-checker): + close(sockets[0]); + return std::make_pair(pid, sockets[1]); +} + +static +char** argvdup(int argc, char** argv) +{ + char** argv_copy = xbt_new(char*, argc+1); + std::memcpy(argv_copy, argv, sizeof(char*) * argc); + argv_copy[argc] = NULL; + return argv_copy; +} + +int main(int argc, char** argv) { - XBT_DEBUG("Inside the parent process"); - if (mc_model_checker) - xbt_die("MC server already present"); try { + if (argc < 2) + xbt_die("Missing arguments.\n"); + + _sg_do_model_check = 1; + + // The initialisation function can touch argv. + // We need to keep the original parameters in order to pass them to the + // model-checked process so we make a copy of them: + int argc_copy = argc; + char** argv_copy = argvdup(argc, argv); + xbt_log_init(&argc_copy, argv_copy); + sg_config_init(&argc_copy, argv_copy); + + int sock; + pid_t model_checked_pid; + std::tie(model_checked_pid, sock) = create_model_checked(argv); + XBT_DEBUG("Inside the parent process"); + if (mc_model_checker) + xbt_die("MC server already present"); + mc_mode = MC_MODE_SERVER; - std::unique_ptr process(new simgrid::mc::Process(child, socket)); + std::unique_ptr process(new simgrid::mc::Process(model_checked_pid, sock)); process->privatized(sg_cfg_get_boolean("smpi/privatize_global_variables")); mc_model_checker = new simgrid::mc::ModelChecker(std::move(process)); mc_model_checker->start(); @@ -117,55 +183,8 @@ static int do_parent(int socket, pid_t child) XBT_ERROR("Exception: %s", e.what()); return SIMGRID_MC_EXIT_ERROR; } -} - -static char** argvdup(int argc, char** argv) -{ - char** argv_copy = xbt_new(char*, argc+1); - std::memcpy(argv_copy, argv, sizeof(char*) * argc); - argv_copy[argc] = NULL; - return argv_copy; -} - -int main(int argc, char** argv) -{ - _sg_do_model_check = 1; - - // We need to keep the original parameters in order to pass them to the - // model-checked process: - int argc_copy = argc; - char** argv_copy = argvdup(argc, argv); - xbt_log_init(&argc_copy, argv_copy); - sg_config_init(&argc_copy, argv_copy); - - if (argc < 2) - xbt_die("Missing arguments.\n"); - - // Create a AF_LOCAL socketpair: - int res; - - int sockets[2]; - res = socketpair(AF_LOCAL, SOCK_DGRAM | SOCK_CLOEXEC, 0, sockets); - if (res == -1) { - perror("simgrid-mc"); - return SIMGRID_MC_EXIT_ERROR; - } - - XBT_DEBUG("Created socketpair"); - - pid_t pid = fork(); - if (pid < 0) { - perror("simgrid-mc"); + catch(...) { + XBT_ERROR("Unknown exception"); return SIMGRID_MC_EXIT_ERROR; - } else if (pid == 0) { - close(sockets[1]); - int res = do_child(sockets[0], argv); - XBT_DEBUG("Error in the child process creation"); - return res; - } else { - close(sockets[0]); - return do_parent(sockets[1], pid); } - - return 0; } -- 2.20.1