/**************************************************************************** ** ** Copyright (C) 2016 Intel Corporation. ** Copyright (C) 2015 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com ** ** Permission is hereby granted, free of charge, to any person obtaining a copy ** of this software and associated documentation files (the "Software"), to deal ** in the Software without restriction, including without limitation the rights ** to use, copy, modify, merge, publish, distribute, sublicense, and/or sell ** copies of the Software, and to permit persons to whom the Software is ** furnished to do so, subject to the following conditions: ** ** The above copyright notice and this permission notice shall be included in ** all copies or substantial portions of the Software. ** ** THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR ** IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, ** FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE ** AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER ** LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, ** OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN ** THE SOFTWARE. ** ****************************************************************************/ #ifndef _GNU_SOURCE # define _GNU_SOURCE #endif #include "forkfd.h" #include #if defined(__OpenBSD__) || defined(__NetBSD__) # include #endif #include #include #include #include #include #include #include #include #include #include #include #ifdef __linux__ # define HAVE_WAIT4 1 # if defined(__BIONIC__) || (defined(__GLIBC__) && (__GLIBC__ << 8) + __GLIBC_MINOR__ >= 0x208 && \ (!defined(__UCLIBC__) || ((__UCLIBC_MAJOR__ << 16) + (__UCLIBC_MINOR__ << 8) + __UCLIBC_SUBLEVEL__ > 0x90201))) # include # ifdef EFD_CLOEXEC # define HAVE_EVENTFD 1 # endif # endif # if defined(__BIONIC__) || (defined(__GLIBC__) && (__GLIBC__ << 8) + __GLIBC_MINOR__ >= 0x209 && \ (!defined(__UCLIBC__) || ((__UCLIBC_MAJOR__ << 16) + (__UCLIBC_MINOR__ << 8) + __UCLIBC_SUBLEVEL__ > 0x90201))) # define HAVE_PIPE2 1 # endif #endif #if defined(__FreeBSD__) && __FreeBSD__ >= 9 # include #endif #if _POSIX_VERSION-0 >= 200809L || _XOPEN_VERSION-0 >= 500 # define HAVE_WAITID 1 #endif #if !defined(WEXITED) || !defined(WNOWAIT) # undef HAVE_WAITID #endif #if (defined(__FreeBSD__) && defined(__FreeBSD_version) && __FreeBSD_version >= 1000032) || \ (defined(__OpenBSD__) && OpenBSD >= 201505) || \ (defined(__NetBSD__) && __NetBSD_Version__ >= 600000000) # define HAVE_PIPE2 1 #endif #if defined(__FreeBSD__) || defined(__DragonFly__) || defined(__FreeBSD_kernel__) || \ defined(__OpenBSD__) || defined(__NetBSD__) || defined(__APPLE__) # define HAVE_WAIT4 1 #endif #if defined(__APPLE__) /* Up until OS X 10.7, waitid(P_ALL, ...) will return success, but will not * fill in the details of the dead child. That means waitid is not useful to us. * Therefore, we only enable waitid() support if we're targetting OS X 10.8 or * later. */ # include # include # if MAC_OS_X_VERSION_MIN_REQUIRED <= 1070 # define HAVE_BROKEN_WAITID 1 # endif #endif #ifndef FFD_ATOMIC_RELAXED # include "forkfd_gcc.h" #endif #define CHILDREN_IN_SMALL_ARRAY 16 #define CHILDREN_IN_BIG_ARRAY 256 #define sizeofarray(array) (sizeof(array)/sizeof(array[0])) #define EINTR_LOOP(ret, call) \ do { \ ret = call; \ } while (ret == -1 && errno == EINTR) struct pipe_payload { struct forkfd_info info; struct rusage rusage; }; typedef struct process_info { ffd_atomic_int pid; int deathPipe; } ProcessInfo; struct BigArray; typedef struct Header { ffd_atomic_pointer(struct BigArray) nextArray; ffd_atomic_int busyCount; } Header; typedef struct BigArray { Header header; ProcessInfo entries[CHILDREN_IN_BIG_ARRAY]; } BigArray; typedef struct SmallArray { Header header; ProcessInfo entries[CHILDREN_IN_SMALL_ARRAY]; } SmallArray; static SmallArray children; static struct sigaction old_sigaction; static pthread_once_t forkfd_initialization = PTHREAD_ONCE_INIT; static ffd_atomic_int forkfd_status = FFD_ATOMIC_INIT(0); #ifdef HAVE_BROKEN_WAITID static int waitid_works = 0; #else static const int waitid_works = 1; #endif static ProcessInfo *tryAllocateInSection(Header *header, ProcessInfo entries[], int maxCount) { /* we use ACQUIRE here because the signal handler might have released the PID */ int busyCount = ffd_atomic_add_fetch(&header->busyCount, 1, FFD_ATOMIC_ACQUIRE); if (busyCount <= maxCount) { /* there's an available entry in this section, find it and take it */ int i; for (i = 0; i < maxCount; ++i) { /* if the PID is 0, it's free; mark it as used by swapping it with -1 */ int expected_pid = 0; if (ffd_atomic_compare_exchange(&entries[i].pid, &expected_pid, -1, FFD_ATOMIC_RELAXED, FFD_ATOMIC_RELAXED)) return &entries[i]; } } /* there isn't an available entry, undo our increment */ (void)ffd_atomic_add_fetch(&header->busyCount, -1, FFD_ATOMIC_RELAXED); return NULL; } static ProcessInfo *allocateInfo(Header **header) { Header *currentHeader = &children.header; /* try to find an available entry in the small array first */ ProcessInfo *info = tryAllocateInSection(currentHeader, children.entries, sizeofarray(children.entries)); /* go on to the next arrays */ while (info == NULL) { BigArray *array = ffd_atomic_load(¤tHeader->nextArray, FFD_ATOMIC_ACQUIRE); if (array == NULL) { /* allocate an array and try to use it */ BigArray *allocatedArray = (BigArray *)calloc(1, sizeof(BigArray)); if (allocatedArray == NULL) return NULL; if (ffd_atomic_compare_exchange(¤tHeader->nextArray, &array, allocatedArray, FFD_ATOMIC_RELEASE, FFD_ATOMIC_ACQUIRE)) { /* success */ array = allocatedArray; } else { /* failed, the atomic updated 'array' */ free(allocatedArray); } } currentHeader = &array->header; info = tryAllocateInSection(currentHeader, array->entries, sizeofarray(array->entries)); } *header = currentHeader; return info; } #ifdef HAVE_WAITID static int isChildReady(pid_t pid, siginfo_t *info) { info->si_pid = 0; return waitid(P_PID, pid, info, WEXITED | WNOHANG | WNOWAIT) == 0 && info->si_pid == pid; } #endif static void convertStatusToForkfdInfo(int status, struct forkfd_info *info) { if (WIFEXITED(status)) { info->code = CLD_EXITED; info->status = WEXITSTATUS(status); } else if (WIFSIGNALED(status)) { info->code = CLD_KILLED; # ifdef WCOREDUMP if (WCOREDUMP(status)) info->code = CLD_DUMPED; # endif info->status = WTERMSIG(status); } } static int tryReaping(pid_t pid, struct pipe_payload *payload) { /* reap the child */ #if defined(HAVE_WAIT4) int status; if (wait4(pid, &status, WNOHANG, &payload->rusage) <= 0) return 0; convertStatusToForkfdInfo(status, &payload->info); #else # if defined(HAVE_WAITID) if (waitid_works) { /* we have waitid(2), which gets us some payload values on some systems */ siginfo_t info; info.si_pid = 0; int ret = waitid(P_PID, pid, &info, WEXITED | WNOHANG) == 0 && info.si_pid == pid; if (!ret) return ret; payload->info.code = info.si_code; payload->info.status = info.si_status; # ifdef __linux__ payload->rusage.ru_utime.tv_sec = info.si_utime / CLOCKS_PER_SEC; payload->rusage.ru_utime.tv_usec = info.si_utime % CLOCKS_PER_SEC; payload->rusage.ru_stime.tv_sec = info.si_stime / CLOCKS_PER_SEC; payload->rusage.ru_stime.tv_usec = info.si_stime % CLOCKS_PER_SEC; # endif return 1; } # endif // HAVE_WAITID int status; if (waitpid(pid, &status, WNOHANG) <= 0) return 0; // child did not change state convertStatusToForkfdInfo(status, &payload->info); #endif // !HAVE_WAIT4 return 1; } static void freeInfo(Header *header, ProcessInfo *entry) { entry->deathPipe = -1; entry->pid = 0; (void)ffd_atomic_add_fetch(&header->busyCount, -1, FFD_ATOMIC_RELEASE); assert(header->busyCount >= 0); } static void notifyAndFreeInfo(Header *header, ProcessInfo *entry, const struct pipe_payload *payload) { ssize_t ret; EINTR_LOOP(ret, write(entry->deathPipe, payload, sizeof(*payload))); EINTR_LOOP(ret, close(entry->deathPipe)); freeInfo(header, entry); } static void sigchld_handler(int signum, siginfo_t *handler_info, void *handler_context) { /* * This is a signal handler, so we need to be careful about which functions * we can call. See the full, official listing in the POSIX.1-2008 * specification at: * http://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html#tag_15_04_03 * * The handler_info and handler_context parameters may not be valid, if * we're a chained handler from another handler that did not use * SA_SIGINFO. Therefore, we must obtain the siginfo ourselves directly by * calling waitid. * * But we pass them anyway. Let's call the chained handler first, while * those two arguments have a chance of being correct. */ if (old_sigaction.sa_handler != SIG_IGN && old_sigaction.sa_handler != SIG_DFL) { if (old_sigaction.sa_flags & SA_SIGINFO) old_sigaction.sa_sigaction(signum, handler_info, handler_context); else old_sigaction.sa_handler(signum); } if (ffd_atomic_load(&forkfd_status, FFD_ATOMIC_RELAXED) == 1) { /* is this one of our children? */ BigArray *array; siginfo_t info; struct pipe_payload payload; int i; memset(&info, 0, sizeof info); memset(&payload, 0, sizeof payload); #ifdef HAVE_WAITID if (!waitid_works) goto search_arrays; /* be optimistic: try to see if we can get the child that exited */ search_next_child: /* waitid returns -1 ECHILD if there are no further children at all; * it returns 0 and sets si_pid to 0 if there are children but they are not ready * to be waited (we're passing WNOHANG). We should not get EINTR because * we're passing WNOHANG and we should definitely not get EINVAL or anything else. * That means we can actually ignore the return code and only inspect si_pid. */ info.si_pid = 0; waitid(P_ALL, 0, &info, WNOHANG | WNOWAIT | WEXITED); if (info.si_pid == 0) { /* there are no further un-waited-for children, so we can just exit. */ return; } for (i = 0; i < (int)sizeofarray(children.entries); ++i) { /* acquire the child first: swap the PID with -1 to indicate it's busy */ int pid = info.si_pid; if (ffd_atomic_compare_exchange(&children.entries[i].pid, &pid, -1, FFD_ATOMIC_ACQUIRE, FFD_ATOMIC_RELAXED)) { /* this is our child, send notification and free up this entry */ /* ### FIXME: what if tryReaping returns false? */ if (tryReaping(pid, &payload)) notifyAndFreeInfo(&children.header, &children.entries[i], &payload); goto search_next_child; } } /* try the arrays */ array = ffd_atomic_load(&children.header.nextArray, FFD_ATOMIC_ACQUIRE); while (array != NULL) { for (i = 0; i < (int)sizeofarray(array->entries); ++i) { int pid = info.si_pid; if (ffd_atomic_compare_exchange(&array->entries[i].pid, &pid, -1, FFD_ATOMIC_ACQUIRE, FFD_ATOMIC_RELAXED)) { /* this is our child, send notification and free up this entry */ /* ### FIXME: what if tryReaping returns false? */ if (tryReaping(pid, &payload)) notifyAndFreeInfo(&array->header, &array->entries[i], &payload); goto search_next_child; } } array = ffd_atomic_load(&array->header.nextArray, FFD_ATOMIC_ACQUIRE); } /* if we got here, we couldn't find this child in our list. That means this child * belongs to one of the chained SIGCHLD handlers. However, there might be another * child that exited and does belong to us, so we need to check each one individually. */ search_arrays: #endif for (i = 0; i < (int)sizeofarray(children.entries); ++i) { int pid = ffd_atomic_load(&children.entries[i].pid, FFD_ATOMIC_ACQUIRE); if (pid <= 0) continue; #ifdef HAVE_WAITID if (waitid_works) { /* The child might have been reaped by the block above in another thread, * so first check if it's ready and, if it is, lock it */ if (!isChildReady(pid, &info) || !ffd_atomic_compare_exchange(&children.entries[i].pid, &pid, -1, FFD_ATOMIC_RELAXED, FFD_ATOMIC_RELAXED)) continue; } #endif if (tryReaping(pid, &payload)) { /* this is our child, send notification and free up this entry */ notifyAndFreeInfo(&children.header, &children.entries[i], &payload); } } /* try the arrays */ array = ffd_atomic_load(&children.header.nextArray, FFD_ATOMIC_ACQUIRE); while (array != NULL) { for (i = 0; i < (int)sizeofarray(array->entries); ++i) { int pid = ffd_atomic_load(&array->entries[i].pid, FFD_ATOMIC_ACQUIRE); if (pid <= 0) continue; #ifdef HAVE_WAITID if (waitid_works) { /* The child might have been reaped by the block above in another thread, * so first check if it's ready and, if it is, lock it */ if (!isChildReady(pid, &info) || !ffd_atomic_compare_exchange(&array->entries[i].pid, &pid, -1, FFD_ATOMIC_RELAXED, FFD_ATOMIC_RELAXED)) continue; } #endif if (tryReaping(pid, &payload)) { /* this is our child, send notification and free up this entry */ notifyAndFreeInfo(&array->header, &array->entries[i], &payload); } } array = ffd_atomic_load(&array->header.nextArray, FFD_ATOMIC_ACQUIRE); } } } static void ignore_sigpipe() { #ifdef O_NOSIGPIPE static ffd_atomic_int done = FFD_ATOMIC_INIT(0); if (ffd_atomic_load(&done, FFD_ATOMIC_RELAXED)) return; #endif struct sigaction action; memset(&action, 0, sizeof action); sigemptyset(&action.sa_mask); action.sa_handler = SIG_IGN; action.sa_flags = 0; sigaction(SIGPIPE, &action, NULL); #ifdef O_NOSIGPIPE ffd_atomic_store(&done, 1, FFD_ATOMIC_RELAXED); #endif } static void forkfd_initialize() { #if defined(HAVE_BROKEN_WAITID) pid_t pid = fork(); if (pid == 0) { _exit(0); } else if (pid > 0) { siginfo_t info; waitid(P_ALL, 0, &info, WNOWAIT | WEXITED); waitid_works = (info.si_pid != 0); info.si_pid = 0; // now really reap the child waitid(P_PID, pid, &info, WEXITED); waitid_works = waitid_works && (info.si_pid != 0); } #endif /* install our signal handler */ struct sigaction action; memset(&action, 0, sizeof action); sigemptyset(&action.sa_mask); action.sa_flags = SA_NOCLDSTOP | SA_SIGINFO; action.sa_sigaction = sigchld_handler; /* ### RACE CONDITION * The sigaction function does a memcpy from an internal buffer * to old_sigaction, which we use in the SIGCHLD handler. If a * SIGCHLD is delivered before or during that memcpy, the handler will * see an inconsistent state. * * There is no solution. pthread_sigmask doesn't work here because the * signal could be delivered to another thread. */ sigaction(SIGCHLD, &action, &old_sigaction); #ifndef O_NOSIGPIPE /* disable SIGPIPE too */ ignore_sigpipe(); #endif #ifndef __GNUC__ atexit(cleanup); #endif ffd_atomic_store(&forkfd_status, 1, FFD_ATOMIC_RELAXED); } #ifdef __GNUC__ __attribute((destructor, unused)) static void cleanup(); #endif static void cleanup() { BigArray *array; /* This function is not thread-safe! * It must only be called when the process is shutting down. * At shutdown, we expect no one to be calling forkfd(), so we don't * need to be thread-safe with what is done there. * * But SIGCHLD might be delivered to any thread, including this one. * There's no way to prevent that. The correct solution would be to * cooperatively delete. We don't do that. */ if (ffd_atomic_load(&forkfd_status, FFD_ATOMIC_RELAXED) == 0) return; /* notify the handler that we're no longer in operation */ ffd_atomic_store(&forkfd_status, 0, FFD_ATOMIC_RELAXED); /* free any arrays we might have */ array = children.header.nextArray; while (array != NULL) { BigArray *next = array->header.nextArray; free(array); array = next; } } static int create_pipe(int filedes[], int flags) { int ret = -1; #ifdef HAVE_PIPE2 /* use pipe2(2) whenever possible, since it can thread-safely create a * cloexec pair of pipes. Without it, we have a race condition setting * FD_CLOEXEC */ # ifdef O_NOSIGPIPE /* try first with O_NOSIGPIPE */ ret = pipe2(filedes, O_CLOEXEC | O_NOSIGPIPE); if (ret == -1) { /* O_NOSIGPIPE not supported, ignore SIGPIPE */ ignore_sigpipe(); } # endif if (ret == -1) ret = pipe2(filedes, O_CLOEXEC); if (ret == -1) return ret; if ((flags & FFD_CLOEXEC) == 0) fcntl(filedes[0], F_SETFD, 0); #else ret = pipe(filedes); if (ret == -1) return ret; fcntl(filedes[1], F_SETFD, FD_CLOEXEC); if (flags & FFD_CLOEXEC) fcntl(filedes[0], F_SETFD, FD_CLOEXEC); #endif if (flags & FFD_NONBLOCK) fcntl(filedes[0], F_SETFL, fcntl(filedes[0], F_GETFL) | O_NONBLOCK); return ret; } #if defined(FORKFD_NO_SPAWNFD) && defined(__FreeBSD__) && __FreeBSD__ >= 9 # if __FreeBSD__ == 9 /* PROCDESC is an optional feature in the kernel and wasn't enabled * by default on FreeBSD 9. So we need to check for it at runtime. */ static ffd_atomic_int system_has_forkfd = FFD_ATOMIC_INIT(1); # else /* On FreeBSD 10, PROCDESC was enabled by default. On v11, it's not an option * anymore and can't be disabled. */ static const int system_has_forkfd = 1; # endif static int system_forkfd(int flags, pid_t *ppid) { int ret; pid_t pid; pid = pdfork(&ret, PD_DAEMON); if (__builtin_expect(pid == -1, 0)) { # if __FreeBSD__ == 9 if (errno == ENOSYS) { /* PROCDESC wasn't compiled into the kernel: don't try it again. */ ffd_atomic_store(&system_has_forkfd, 0, FFD_ATOMIC_RELAXED); } # endif return -1; } if (pid == 0) { /* child process */ return FFD_CHILD_PROCESS; } /* parent process */ if (flags & FFD_CLOEXEC) fcntl(ret, F_SETFD, FD_CLOEXEC); if (flags & FFD_NONBLOCK) fcntl(ret, F_SETFL, fcntl(ret, F_GETFL) | O_NONBLOCK); if (ppid) *ppid = pid; return ret; } #else static const int system_has_forkfd = 0; static int system_forkfd(int flags, pid_t *ppid) { (void)flags; (void)ppid; return -1; } #endif #ifndef FORKFD_NO_FORKFD /** * @brief forkfd returns a file descriptor representing a child process * @return a file descriptor, or -1 in case of failure * * forkfd() creates a file descriptor that can be used to be notified of when a * child process exits. This file descriptor can be monitored using select(2), * poll(2) or similar mechanisms. * * The @a flags parameter can contain the following values ORed to change the * behaviour of forkfd(): * * @li @c FFD_NONBLOCK Set the O_NONBLOCK file status flag on the new open file * descriptor. Using this flag saves extra calls to fnctl(2) to achieve the same * result. * * @li @c FFD_CLOEXEC Set the close-on-exec (FD_CLOEXEC) flag on the new file * descriptor. You probably want to set this flag, since forkfd() does not work * if the original parent process dies. * * The file descriptor returned by forkfd() supports the following operations: * * @li read(2) When the child process exits, then the buffer supplied to * read(2) is used to return information about the status of the child in the * form of one @c siginfo_t structure. The buffer must be at least * sizeof(siginfo_t) bytes. The return value of read(2) is the total number of * bytes read. * * @li poll(2), select(2) (and similar) The file descriptor is readable (the * select(2) readfds argument; the poll(2) POLLIN flag) if the child has exited * or signalled via SIGCHLD. * * @li close(2) When the file descriptor is no longer required it should be closed. */ int forkfd(int flags, pid_t *ppid) { Header *header; ProcessInfo *info; pid_t pid; int fd = -1; int death_pipe[2]; int sync_pipe[2]; int ret; #ifdef __linux__ int efd; #endif if (system_has_forkfd) { ret = system_forkfd(flags, ppid); if (system_has_forkfd) return ret; } (void) pthread_once(&forkfd_initialization, forkfd_initialize); info = allocateInfo(&header); if (info == NULL) { errno = ENOMEM; return -1; } /* create the pipes before we fork */ if (create_pipe(death_pipe, flags) == -1) goto err_free; /* failed to create the pipes, pass errno */ #ifdef HAVE_EVENTFD /* try using an eventfd, which consumes less resources */ efd = eventfd(0, EFD_CLOEXEC); if (efd == -1) #endif { /* try a pipe */ if (create_pipe(sync_pipe, FFD_CLOEXEC) == -1) { /* failed both at eventfd and pipe; fail and pass errno */ goto err_close; } } /* now fork */ pid = fork(); if (pid == -1) goto err_close2; /* failed to fork, pass errno */ if (ppid) *ppid = pid; /* * We need to store the child's PID in the info structure, so * the SIGCHLD handler knows that this child is present and it * knows the writing end of the pipe to pass information on. * However, the child process could exit before we stored the * information (or the handler could run for other children exiting). * We prevent that from happening by blocking the child process in * a read(2) until we're finished storing the information. */ if (pid == 0) { /* this is the child process */ /* first, wait for the all clear */ #ifdef HAVE_EVENTFD if (efd != -1) { eventfd_t val64; EINTR_LOOP(ret, eventfd_read(efd, &val64)); EINTR_LOOP(ret, close(efd)); } else #endif { char c; EINTR_LOOP(ret, close(sync_pipe[1])); EINTR_LOOP(ret, read(sync_pipe[0], &c, sizeof c)); EINTR_LOOP(ret, close(sync_pipe[0])); } /* now close the pipes and return to the caller */ EINTR_LOOP(ret, close(death_pipe[0])); EINTR_LOOP(ret, close(death_pipe[1])); fd = FFD_CHILD_PROCESS; } else { /* parent process */ info->deathPipe = death_pipe[1]; fd = death_pipe[0]; ffd_atomic_store(&info->pid, pid, FFD_ATOMIC_RELEASE); /* release the child */ #ifdef HAVE_EVENTFD if (efd != -1) { eventfd_t val64 = 42; EINTR_LOOP(ret, eventfd_write(efd, val64)); EINTR_LOOP(ret, close(efd)); } else #endif { /* * Usually, closing would be enough to make read(2) return and the child process * continue. We need to write here: another thread could be calling forkfd at the * same time, which means auxpipe[1] might be open in another child process. */ EINTR_LOOP(ret, close(sync_pipe[0])); EINTR_LOOP(ret, write(sync_pipe[1], "", 1)); EINTR_LOOP(ret, close(sync_pipe[1])); } } return fd; err_close2: #ifdef HAVE_EVENTFD if (efd != -1) { EINTR_LOOP(ret, close(efd)); } else #endif { EINTR_LOOP(ret, close(sync_pipe[0])); EINTR_LOOP(ret, close(sync_pipe[1])); } err_close: EINTR_LOOP(ret, close(death_pipe[0])); EINTR_LOOP(ret, close(death_pipe[1])); err_free: /* free the info pointer */ freeInfo(header, info); return -1; } #endif // FORKFD_NO_FORKFD #if _POSIX_SPAWN > 0 && !defined(FORKFD_NO_SPAWNFD) int spawnfd(int flags, pid_t *ppid, const char *path, const posix_spawn_file_actions_t *file_actions, posix_spawnattr_t *attrp, char *const argv[], char *const envp[]) { Header *header; ProcessInfo *info; struct pipe_payload payload; pid_t pid; int death_pipe[2]; int ret = -1; /* we can only do work if we have a way to start the child in stopped mode; * otherwise, we have a major race condition. */ assert(!system_has_forkfd); (void) pthread_once(&forkfd_initialization, forkfd_initialize); info = allocateInfo(&header); if (info == NULL) { errno = ENOMEM; goto out; } /* create the pipe before we spawn */ if (create_pipe(death_pipe, flags) == -1) goto err_free; /* failed to create the pipes, pass errno */ /* start the process */ if (flags & FFD_SPAWN_SEARCH_PATH) { /* use posix_spawnp */ if (posix_spawnp(&pid, path, file_actions, attrp, argv, envp) != 0) goto err_close; } else { if (posix_spawn(&pid, path, file_actions, attrp, argv, envp) != 0) goto err_close; } if (ppid) *ppid = pid; /* Store the child's PID in the info structure. */ info->deathPipe = death_pipe[1]; ffd_atomic_store(&info->pid, pid, FFD_ATOMIC_RELEASE); /* check if the child has already exited */ if (tryReaping(pid, &payload)) notifyAndFreeInfo(header, info, &payload); ret = death_pipe[0]; return ret; err_close: EINTR_LOOP(ret, close(death_pipe[0])); EINTR_LOOP(ret, close(death_pipe[1])); err_free: /* free the info pointer */ freeInfo(header, info); out: return -1; } #endif // _POSIX_SPAWN && !FORKFD_NO_SPAWNFD int forkfd_wait(int ffd, forkfd_info *info, struct rusage *rusage) { struct pipe_payload payload; int ret; if (system_has_forkfd) { #if defined(__FreeBSD__) && __FreeBSD__ >= 9 pid_t pid; int status; int options = WEXITED; ret = pdgetpid(ffd, &pid); if (ret == -1) return ret; ret = fcntl(ffd, F_GETFL); if (ret == -1) return ret; options |= (ret & O_NONBLOCK) ? WNOHANG : 0; ret = wait4(pid, &status, options, rusage); if (ret != -1 && info) convertStatusToForkfdInfo(status, info); return ret == -1 ? -1 : 0; #endif } ret = read(ffd, &payload, sizeof(payload)); if (ret == -1) return ret; /* pass errno, probably EINTR, EBADF or EWOULDBLOCK */ assert(ret == sizeof(payload)); if (info) *info = payload.info; if (rusage) *rusage = payload.rusage; return 0; /* success */ } int forkfd_close(int ffd) { return close(ffd); }