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author | Al Viro <viro@zeniv.linux.org.uk> | 2013-03-12 17:46:27 +0400 |
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committer | Al Viro <viro@zeniv.linux.org.uk> | 2013-04-09 22:12:58 +0400 |
commit | f776c738883bc949e654568a565aee5a7d3fe133 (patch) | |
tree | b83f74a02ebcb8341d689f63c65899da17ef0b39 /fs/pipe.c | |
parent | 2dd8c9ad376ccc5d2980b38e96372a8e252ae8d0 (diff) | |
download | linux-f776c738883bc949e654568a565aee5a7d3fe133.tar.xz |
fold fifo.c into pipe.c
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/pipe.c')
-rw-r--r-- | fs/pipe.c | 138 |
1 files changed, 138 insertions, 0 deletions
diff --git a/fs/pipe.c b/fs/pipe.c index 2234f3f61f8d..aed80c25cd40 100644 --- a/fs/pipe.c +++ b/fs/pipe.c @@ -1144,6 +1144,144 @@ SYSCALL_DEFINE1(pipe, int __user *, fildes) return sys_pipe2(fildes, 0); } +static int wait_for_partner(struct inode* inode, unsigned int *cnt) +{ + int cur = *cnt; + + while (cur == *cnt) { + pipe_wait(inode->i_pipe); + if (signal_pending(current)) + break; + } + return cur == *cnt ? -ERESTARTSYS : 0; +} + +static void wake_up_partner(struct inode* inode) +{ + wake_up_interruptible(&inode->i_pipe->wait); +} + +static int fifo_open(struct inode *inode, struct file *filp) +{ + struct pipe_inode_info *pipe; + int ret; + + mutex_lock(&inode->i_mutex); + pipe = inode->i_pipe; + if (!pipe) { + ret = -ENOMEM; + pipe = alloc_pipe_info(inode); + if (!pipe) + goto err_nocleanup; + inode->i_pipe = pipe; + } + filp->f_version = 0; + + /* We can only do regular read/write on fifos */ + filp->f_mode &= (FMODE_READ | FMODE_WRITE); + + switch (filp->f_mode) { + case FMODE_READ: + /* + * O_RDONLY + * POSIX.1 says that O_NONBLOCK means return with the FIFO + * opened, even when there is no process writing the FIFO. + */ + filp->f_op = &read_pipefifo_fops; + pipe->r_counter++; + if (pipe->readers++ == 0) + wake_up_partner(inode); + + if (!pipe->writers) { + if ((filp->f_flags & O_NONBLOCK)) { + /* suppress POLLHUP until we have + * seen a writer */ + filp->f_version = pipe->w_counter; + } else { + if (wait_for_partner(inode, &pipe->w_counter)) + goto err_rd; + } + } + break; + + case FMODE_WRITE: + /* + * O_WRONLY + * POSIX.1 says that O_NONBLOCK means return -1 with + * errno=ENXIO when there is no process reading the FIFO. + */ + ret = -ENXIO; + if ((filp->f_flags & O_NONBLOCK) && !pipe->readers) + goto err; + + filp->f_op = &write_pipefifo_fops; + pipe->w_counter++; + if (!pipe->writers++) + wake_up_partner(inode); + + if (!pipe->readers) { + if (wait_for_partner(inode, &pipe->r_counter)) + goto err_wr; + } + break; + + case FMODE_READ | FMODE_WRITE: + /* + * O_RDWR + * POSIX.1 leaves this case "undefined" when O_NONBLOCK is set. + * This implementation will NEVER block on a O_RDWR open, since + * the process can at least talk to itself. + */ + filp->f_op = &rdwr_pipefifo_fops; + + pipe->readers++; + pipe->writers++; + pipe->r_counter++; + pipe->w_counter++; + if (pipe->readers == 1 || pipe->writers == 1) + wake_up_partner(inode); + break; + + default: + ret = -EINVAL; + goto err; + } + + /* Ok! */ + mutex_unlock(&inode->i_mutex); + return 0; + +err_rd: + if (!--pipe->readers) + wake_up_interruptible(&pipe->wait); + ret = -ERESTARTSYS; + goto err; + +err_wr: + if (!--pipe->writers) + wake_up_interruptible(&pipe->wait); + ret = -ERESTARTSYS; + goto err; + +err: + if (!pipe->readers && !pipe->writers) + free_pipe_info(inode); + +err_nocleanup: + mutex_unlock(&inode->i_mutex); + return ret; +} + +/* + * Dummy default file-operations: the only thing this does + * is contain the open that then fills in the correct operations + * depending on the access mode of the file... + */ +const struct file_operations def_fifo_fops = { + .open = fifo_open, /* will set read_ or write_pipefifo_fops */ + .llseek = noop_llseek, +}; + /* * Allocate a new array of pipe buffers and copy the info over. Returns the * pipe size if successful, or return -ERROR on error. |