70524490ee
Basically an in-kernel implementation of tee, which uses splice and the pipe buffers as an intelligent way to pass data around by reference. Where the user space tee consumes the input and produces a stdout and file output, this syscall merely duplicates the data inside a pipe to another pipe. No data is copied, the output just grabs a reference to the input pipe data. Signed-off-by: Jens Axboe <axboe@suse.de>
64 lines
1.9 KiB
C
64 lines
1.9 KiB
C
#ifndef _LINUX_PIPE_FS_I_H
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#define _LINUX_PIPE_FS_I_H
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#define PIPEFS_MAGIC 0x50495045
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#define PIPE_BUFFERS (16)
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#define PIPE_BUF_FLAG_STOLEN 0x01
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#define PIPE_BUF_FLAG_LRU 0x02
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struct pipe_buffer {
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struct page *page;
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unsigned int offset, len;
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struct pipe_buf_operations *ops;
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unsigned int flags;
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};
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struct pipe_buf_operations {
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int can_merge;
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void * (*map)(struct file *, struct pipe_inode_info *, struct pipe_buffer *);
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void (*unmap)(struct pipe_inode_info *, struct pipe_buffer *);
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void (*release)(struct pipe_inode_info *, struct pipe_buffer *);
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int (*steal)(struct pipe_inode_info *, struct pipe_buffer *);
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void (*get)(struct pipe_inode_info *, struct pipe_buffer *);
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};
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struct pipe_inode_info {
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wait_queue_head_t wait;
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unsigned int nrbufs, curbuf;
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struct pipe_buffer bufs[PIPE_BUFFERS];
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struct page *tmp_page;
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unsigned int start;
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unsigned int readers;
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unsigned int writers;
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unsigned int waiting_writers;
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unsigned int r_counter;
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unsigned int w_counter;
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struct fasync_struct *fasync_readers;
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struct fasync_struct *fasync_writers;
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struct inode *inode;
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};
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/* Differs from PIPE_BUF in that PIPE_SIZE is the length of the actual
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memory allocation, whereas PIPE_BUF makes atomicity guarantees. */
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#define PIPE_SIZE PAGE_SIZE
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/* Drop the inode semaphore and wait for a pipe event, atomically */
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void pipe_wait(struct pipe_inode_info *pipe);
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struct pipe_inode_info * alloc_pipe_info(struct inode * inode);
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void free_pipe_info(struct inode * inode);
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void __free_pipe_info(struct pipe_inode_info *);
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/*
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* splice is tied to pipes as a transport (at least for now), so we'll just
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* add the splice flags here.
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*/
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#define SPLICE_F_MOVE (0x01) /* move pages instead of copying */
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#define SPLICE_F_NONBLOCK (0x02) /* don't block on the pipe splicing (but */
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/* we may still block on the fd we splice */
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/* from/to, of course */
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#define SPLICE_F_MORE (0x04) /* expect more data */
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#endif
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