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commit f85d9a933257436d46da1c41037523a942558a9b Author: dongjiuzhu1 <[email protected]> AuthorDate: Wed Oct 12 13:10:02 2022 +0800 fs/signalfd: using file descriptor to accept signal Reference here: https://man7.org/linux/man-pages/man2/signalfd.2.html Signed-off-by: dongjiuzhu1 <[email protected]> --- fs/vfs/Kconfig | 16 ++ fs/vfs/Make.defs | 6 + fs/vfs/fs_signalfd.c | 403 +++++++++++++++++++++++++++++++++++++++++++++++++ include/sys/signalfd.h | 88 +++++++++++ 4 files changed, 513 insertions(+) diff --git a/fs/vfs/Kconfig b/fs/vfs/Kconfig index 9b3c63ec6a..7760e29d01 100644 --- a/fs/vfs/Kconfig +++ b/fs/vfs/Kconfig @@ -48,3 +48,19 @@ config TIMER_FD_NPOLLWAITERS Maximum number of threads that can be waiting on poll() endif # TIMER_FD + +config SIGNAL_FD + bool "SignalFD" + default n + ---help--- + Create a file descriptor for accepting signals + +if SIGNAL_FD + +config SIGNAL_FD_NPOLLWAITERS + int "Number of signalFD poll waiters" + default 2 + ---help--- + Maximum number of threads that can be waiting on poll() + +endif # SIGNAL_FD diff --git a/fs/vfs/Make.defs b/fs/vfs/Make.defs index 1efdd4216b..20272d745d 100644 --- a/fs/vfs/Make.defs +++ b/fs/vfs/Make.defs @@ -54,6 +54,12 @@ ifeq ($(CONFIG_TIMER_FD),y) CSRCS += fs_timerfd.c endif +# Support for signalfd + +ifeq ($(CONFIG_SIGNAL_FD),y) +CSRCS += fs_signalfd.c +endif + # Include vfs build support DEPPATH += --dep-path vfs diff --git a/fs/vfs/fs_signalfd.c b/fs/vfs/fs_signalfd.c new file mode 100644 index 0000000000..f8f5741b7a --- /dev/null +++ b/fs/vfs/fs_signalfd.c @@ -0,0 +1,403 @@ +/**************************************************************************** + * fs/vfs/fs_signalfd.c + * + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. The + * ASF licenses this file to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance with the + * License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT + * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the + * License for the specific language governing permissions and limitations + * under the License. + * + ****************************************************************************/ + +/**************************************************************************** + * Included Files + ****************************************************************************/ + +#include <nuttx/config.h> +#include <stdio.h> +#include <poll.h> +#include <assert.h> +#include <errno.h> +#include <fcntl.h> + +#include <debug.h> + +#include <nuttx/mutex.h> +#include <nuttx/signal.h> + +#include <sys/signalfd.h> + +#include "inode/inode.h" + +/**************************************************************************** + * Pre-processor Definitions + ****************************************************************************/ + +/**************************************************************************** + * Private Types + ****************************************************************************/ + +/* This structure describes the internal state of the driver */ + +struct signalfd_priv_s +{ + sigset_t sigmask; /* The set of signals caller wishes */ + mutex_t mutex; /* Enforces device exclusive access */ + uint8_t crefs; /* References counts on signalfd (max: 255) */ + FAR struct pollfd *fds[CONFIG_SIGNAL_FD_NPOLLWAITERS]; +}; + +/**************************************************************************** + * Private Function Prototypes + ****************************************************************************/ + +static int signalfd_file_open(FAR struct file *filep); +static int signalfd_file_close(FAR struct file *filep); +static ssize_t signalfd_file_read(FAR struct file *filep, + FAR char *buffer, size_t len); +static int signalfd_file_poll(FAR struct file *filep, + FAR struct pollfd *fds, bool setup); + +/**************************************************************************** + * Private Data + ****************************************************************************/ + +static const struct file_operations g_signalfd_fileops = +{ + signalfd_file_open, /* open */ + signalfd_file_close, /* close */ + signalfd_file_read, /* read */ + NULL, /* write */ + NULL, /* seek */ + NULL, /* ioctl */ + signalfd_file_poll /* poll */ +#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS + , NULL /* unlink */ +#endif +}; + +static struct inode g_signalfd_inode = +{ + NULL, /* i_parent */ + NULL, /* i_peer */ + NULL, /* i_child */ + 1, /* i_crefs */ + FSNODEFLAG_TYPE_DRIVER, /* i_flags */ + { + &g_signalfd_fileops /* u */ + } +}; + +/**************************************************************************** + * Private Functions + ****************************************************************************/ + +static void signalfd_action(int signo, FAR siginfo_t *info, + FAR void *ucontext) +{ + FAR struct signalfd_priv_s *dev = info->si_user; + + if (sigismember(&dev->sigmask, signo) > 0) + { + poll_notify(dev->fds, CONFIG_SIGNAL_FD_NPOLLWAITERS, POLLIN); + } +} + +static int signalfd_file_open(FAR struct file *filep) +{ + FAR struct signalfd_priv_s *dev = filep->f_priv; + int ret; + + nxmutex_lock(&dev->mutex); + if (dev->crefs >= 255) + { + ret = -EMFILE; + } + else + { + dev->crefs += 1; + ret = OK; + } + + nxmutex_unlock(&dev->mutex); + return ret; +} + +static int signalfd_file_close(FAR struct file *filep) +{ + FAR struct signalfd_priv_s *dev = filep->f_priv; + int signo; + + nxmutex_lock(&dev->mutex); + if (dev->crefs > 1) + { + dev->crefs--; + nxmutex_unlock(&dev->mutex); + return OK; + } + + for (signo = MIN_SIGNO; signo <= MAX_SIGNO; signo++) + { + if (nxsig_ismember(&dev->sigmask, signo)) + { + signal(signo, SIG_DFL); + } + } + + nxmutex_unlock(&dev->mutex); + nxmutex_destroy(&dev->mutex); + kmm_free(dev); + + return OK; +} + +static ssize_t signalfd_file_read(FAR struct file *filep, + FAR char *buffer, size_t len) +{ + FAR struct signalfd_priv_s *dev = filep->f_priv; + FAR struct signalfd_siginfo *siginfo; + struct siginfo info; + sigset_t pendmask; + ssize_t ret; + int count; + + count = len / sizeof(struct signalfd_siginfo); + if (buffer == NULL || count == 0) + { + return -EINVAL; + } + + pendmask = nxsig_pendingset(NULL) & dev->sigmask; + if (pendmask == 0) + { + if (filep->f_oflags & O_NONBLOCK) + { + return -EAGAIN; + } + else + { + pendmask = dev->sigmask; + } + } + + siginfo = (FAR struct signalfd_siginfo *)buffer; + do + { + ret = nxsig_waitinfo(&pendmask, &info); + if (ret < 0) + { + goto errout; + } + + memset(siginfo, 0, sizeof(*siginfo)); + siginfo->ssi_signo = info.si_signo; + siginfo->ssi_errno = info.si_errno; + siginfo->ssi_code = info.si_code; +#ifdef CONFIG_SCHED_HAVE_PARENT + siginfo->ssi_pid = info.si_pid; + siginfo->ssi_status = info.si_status; +#endif + siginfo->ssi_int = info.si_value.sival_int; + siginfo->ssi_ptr = (uint64_t)(uintptr_t)info.si_value.sival_ptr; + siginfo++; + pendmask = nxsig_pendingset(NULL) & dev->sigmask; + } + while (--count != 0 && pendmask != 0); + +errout: + len = (FAR char *)siginfo - buffer; + return len > 0 ? len : ret; +} + +static int signalfd_file_poll(FAR struct file *filep, + FAR struct pollfd *fds, bool setup) +{ + FAR struct signalfd_priv_s *dev = filep->f_priv; + int ret = 0; + int i; + + nxmutex_lock(&dev->mutex); + if (!setup) + { + /* This is a request to tear down the poll. */ + + FAR struct pollfd **slot = (FAR struct pollfd **)fds->priv; + + /* Remove all memory of the poll setup */ + + *slot = NULL; + fds->priv = NULL; + goto out; + } + + /* This is a request to set up the poll. Find an available + * slot for the poll structure reference + */ + + for (i = 0; i < CONFIG_SIGNAL_FD_NPOLLWAITERS; i++) + { + /* Find an available slot */ + + if (!dev->fds[i]) + { + /* Bind the poll structure and this slot */ + + dev->fds[i] = fds; + fds->priv = &dev->fds[i]; + break; + } + } + + if (i >= CONFIG_SIGNAL_FD_NPOLLWAITERS) + { + ret = -EBUSY; + goto out; + } + + /* Notify the POLLIN event if the counter is not zero */ + + if ((nxsig_pendingset(NULL) & dev->sigmask) != 0) + { + poll_notify(dev->fds, CONFIG_SIGNAL_FD_NPOLLWAITERS, POLLIN); + } + +out: + nxmutex_unlock(&dev->mutex); + return ret; +} + +/**************************************************************************** + * Public Functions + ****************************************************************************/ + +/**************************************************************************** + * Name: signalfd + * + * Description: + * signalfd() creates a file descriptor that can be used to accept signals + * targeted at the caller. + * + * The mask argument specifies the set of signals that the caller wishes + * to accept via the file descriptor. This argument is a signal set whose + * contents can be initialized using the macros described in sigsetops. + * Normally, the set of signals to be received via the file descriptor + * should be blocked using sigprocmask, to prevent the signals being + * handled according to their default dispositions. It is not possible + * to receive SIGKILL or SIGSTOP signals via a signalfd file descriptor. + * these signals are silently ignored if specified in mask. + * + * If the fd argument is -1, then the call creates a new file descriptor + * and associates the signal set specified in mask with that file + * descriptor. If fd is not -1, then it must specify a valid existing + * signalfd file descriptor, and mask is used to replace the signal + * set associated with that file descriptor. + * + * The following values may be bitwise ORed in flags to change the + * behavior of signalfd(): + * + * SFD_NONBLOCK Set the O_NONBLOCK file status flag on the open file + * description referred to by the new file descriptor. + * Using this flag saves extra calls to fcntl to achieve + * the same result. + * + * SFD_CLOEXEC Set the close-on-exec (FD_CLOEXEC) flag on the new file + * descriptor. See the description of the O_CLOEXEC flag + * in open for reasons why this may be useful. + * + * Returned Value: + * On success, signalfd() returns a signalfd file descriptor; this is + * either a new file descriptor (if fd was -1), or fd if fd was a valid + * signalfd file descriptor. On error, -1 is returned and errno is set + * to indicate the error. + * + ****************************************************************************/ + +int signalfd(int fd, FAR const sigset_t *mask, int flags) +{ + FAR struct signalfd_priv_s *dev; + struct sigaction act; + int ret = EINVAL; + int signo; + + if (flags & ~(SFD_CLOEXEC | SFD_NONBLOCK)) + { + goto errout; + } + + if (fd == -1) + { + dev = kmm_zalloc(sizeof(*dev)); + if (dev == NULL) + { + ret = ENOMEM; + goto errout; + } + + nxmutex_init(&dev->mutex); + + fd = file_allocate(&g_signalfd_inode, O_RDOK | flags, + 0, dev, 0, true); + if (fd < 0) + { + ret = -fd; + goto errout_with_dev; + } + } + else + { + FAR struct file *filep; + + if (fs_getfilep(fd, &filep) < 0) + { + ret = EBADF; + goto errout; + } + + if (filep->f_inode->u.i_ops != &g_signalfd_fileops) + { + goto errout; + } + + dev = filep->f_priv; + for (signo = MIN_SIGNO; signo <= MAX_SIGNO; signo++) + { + if (nxsig_ismember(&dev->sigmask, signo)) + { + signal(signo, SIG_DFL); + } + } + } + + dev->sigmask = *mask; + nxsig_delset(&dev->sigmask, SIGKILL); + nxsig_delset(&dev->sigmask, SIGSTOP); + act.sa_sigaction = signalfd_action; + act.sa_flags = SA_KERNELHAND | SA_SIGINFO; + act.sa_user = dev; + for (signo = MIN_SIGNO; signo <= MAX_SIGNO; signo++) + { + if (nxsig_ismember(&dev->sigmask, signo)) + { + nxsig_action(signo, &act, NULL, false); + } + } + + return fd; + +errout_with_dev: + nxmutex_destroy(&dev->mutex); + kmm_free(dev); + +errout: + set_errno(ret); + return ERROR; +} diff --git a/include/sys/signalfd.h b/include/sys/signalfd.h new file mode 100644 index 0000000000..29de6bf1e4 --- /dev/null +++ b/include/sys/signalfd.h @@ -0,0 +1,88 @@ +/**************************************************************************** + * include/sys/signalfd.h + * + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. The + * ASF licenses this file to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance with the + * License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT + * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the + * License for the specific language governing permissions and limitations + * under the License. + * + ****************************************************************************/ + +#ifndef __INCLUDE_SYS_SIGNALFD_H +#define __INCLUDE_SYS_SIGNALFD_H + +/**************************************************************************** + * Included Files + ****************************************************************************/ + +#include <stdint.h> +#include <signal.h> +#include <fcntl.h> + +/**************************************************************************** + * Pre-processor Definitions + ****************************************************************************/ + +#define SFD_CLOEXEC O_CLOEXEC +#define SFD_NONBLOCK O_NONBLOCK + +/**************************************************************************** + * Public Types + ****************************************************************************/ + +struct signalfd_siginfo +{ + uint32_t ssi_signo; + int32_t ssi_errno; + int32_t ssi_code; + uint32_t ssi_pid; + uint32_t ssi_uid; + int32_t ssi_fd; + uint32_t ssi_tid; + uint32_t ssi_band; + uint32_t ssi_overrun; + uint32_t ssi_trapno; + int32_t ssi_status; + int32_t ssi_int; + uint64_t ssi_ptr; + uint64_t ssi_utime; + uint64_t ssi_stime; + uint64_t ssi_addr; + uint16_t ssi_addr_lsb; + uint16_t __pad2; + int32_t ssi_syscall; + uint64_t ssi_call_addr; + uint32_t ssi_arch; + uint8_t __pad[28]; +}; + +/**************************************************************************** + * Public Function Prototypes + ****************************************************************************/ + +#ifdef __cplusplus +#define EXTERN extern "C" +extern "C" +{ +#else +#define EXTERN extern +#endif + +int signalfd(int fd, FAR const sigset_t *mask, int flags); + +#undef EXTERN +#ifdef __cplusplus +} +#endif + +#endif /* __INCLUDE_SYS_TIMERFD_H */
