/**************************************************************************** * drivers/pipes/pipe.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 #include #include #include #include #include #include #include #include #include "pipe_common.h" #if CONFIG_DEV_PIPE_SIZE > 0 /**************************************************************************** * Pre-processor Definitions ****************************************************************************/ #define MAX_PIPES 32 /**************************************************************************** * Private Types ****************************************************************************/ /**************************************************************************** * Private Function Prototypes ****************************************************************************/ static int pipe_close(FAR struct file *filep); /**************************************************************************** * Private Data ****************************************************************************/ static const struct file_operations pipe_fops = { pipecommon_open, /* open */ pipe_close, /* close */ pipecommon_read, /* read */ pipecommon_write, /* write */ NULL, /* seek */ pipecommon_ioctl, /* ioctl */ pipecommon_poll /* poll */ #ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS , pipecommon_unlink /* unlink */ #endif }; static sem_t g_pipesem = SEM_INITIALIZER(1); static uint32_t g_pipeset = 0; static uint32_t g_pipecreated = 0; /**************************************************************************** * Private Functions ****************************************************************************/ /**************************************************************************** * Name: pipe_allocate ****************************************************************************/ static inline int pipe_allocate(void) { int pipeno; int ret = -ENFILE; for (pipeno = 0; pipeno < MAX_PIPES; pipeno++) { if ((g_pipeset & (1 << pipeno)) == 0) { g_pipeset |= (1 << pipeno); ret = pipeno; break; } } return ret; } /**************************************************************************** * Name: pipe_free ****************************************************************************/ static inline void pipe_free(int pipeno) { int ret; ret = nxsem_wait(&g_pipesem); if (ret == OK) { g_pipeset &= ~(1 << pipeno); nxsem_post(&g_pipesem); } } /**************************************************************************** * Name: pipe_close ****************************************************************************/ static int pipe_close(FAR struct file *filep) { FAR struct inode *inode = filep->f_inode; FAR struct pipe_dev_s *dev = inode->i_private; int ret; DEBUGASSERT(dev); /* Perform common close operations */ ret = pipecommon_close(filep); if (ret == 0 && inode->i_crefs == 1) { /* Release the pipe when there are no further open references to it. */ pipe_free(dev->d_pipeno); } return ret; } /**************************************************************************** * Name: pipe_register ****************************************************************************/ static int pipe_register(size_t bufsize, int flags, FAR char *devname, size_t namesize) { FAR struct pipe_dev_s *dev; int pipeno; int ret; /* Get exclusive access to the pipe allocation data */ ret = nxsem_wait(&g_pipesem); if (ret < 0) { goto errout; } /* Allocate a minor number for the pipe device */ pipeno = pipe_allocate(); if (pipeno < 0) { ret = pipeno; goto errout_with_sem; } /* Create a pathname to the pipe device */ snprintf(devname, namesize, "/dev/pipe%d", pipeno); /* Check if the pipe device has already been created */ if ((g_pipecreated & (1 << pipeno)) == 0) { /* No.. Allocate and initialize a new device structure instance */ dev = pipecommon_allocdev(bufsize); if (!dev) { ret = -ENOMEM; goto errout_with_pipe; } dev->d_pipeno = pipeno; /* Register the pipe device */ ret = register_driver(devname, &pipe_fops, 0666, (FAR void *)dev); if (ret != 0) { nxsem_post(&g_pipesem); goto errout_with_dev; } /* Remember that we created this device */ g_pipecreated |= (1 << pipeno); } nxsem_post(&g_pipesem); return OK; errout_with_dev: pipecommon_freedev(dev); errout_with_pipe: pipe_free(pipeno); errout_with_sem: nxsem_post(&g_pipesem); errout: return ret; } /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: nx_pipe * * Description: * nx_pipe() creates a pair of file descriptors, pointing to a pipe inode, * and places them in the array pointed to by 'fd'. fd[0] is for reading, * fd[1] is for writing. * * NOTE: nx_pipe is a special, non-standard, NuttX-only interface. Since * the NuttX FIFOs are based in in-memory, circular buffers, the ability * to control the size of those buffers is critical for system tuning. * * Input Parameters: * fd[2] - The user provided array in which to catch the pipe file * descriptors * bufsize - The size of the in-memory, circular buffer in bytes. * flags - The file status flags. * * Returned Value: * 0 is returned on success; a negated errno value is returned on a * failure. * ****************************************************************************/ int file_pipe(FAR struct file *filep[2], size_t bufsize, int flags) { char devname[16]; int ret; /* Register a new pipe device */ ret = pipe_register(bufsize, flags, devname, sizeof(devname)); if (ret < 0) { return ret; } /* Get a write file descriptor */ ret = file_open(filep[1], devname, O_WRONLY | flags); if (ret < 0) { goto errout_with_driver; } /* Get a read file descriptor */ ret = file_open(filep[0], devname, O_RDONLY | flags); if (ret < 0) { goto errout_with_wrfd; } return OK; errout_with_wrfd: file_close(filep[1]); errout_with_driver: unregister_driver(devname); return ret; } int nx_pipe(int fd[2], size_t bufsize, int flags) { char devname[16]; int ret; /* Register a new pipe device */ ret = pipe_register(bufsize, flags, devname, sizeof(devname)); if (ret < 0) { return ret; } /* Get a write file descriptor */ fd[1] = nx_open(devname, O_WRONLY | flags); if (fd[1] < 0) { ret = fd[1]; goto errout_with_driver; } /* Get a read file descriptor */ fd[0] = nx_open(devname, O_RDONLY | flags); if (fd[0] < 0) { ret = fd[0]; goto errout_with_wrfd; } return OK; errout_with_wrfd: nx_close(fd[1]); errout_with_driver: unregister_driver(devname); return ret; } #endif /* CONFIG_DEV_PIPE_SIZE > 0 */