source: trunk/kernel/kern/pipe.h @ 676

Last change on this file since 676 was 669, checked in by alain, 4 years ago

1) Introduce up to 4 command lines arguments in the KSH "load" command.
These arguments are transfered to the user process through the
argc/argv mechanism, using the user space "args" vseg.

2) Introduce the named and anonymous "pipes", for inter-process communication
through the pipe() and mkfifo() syscalls.

3) Introduce the "chat" application to validate the two above mechanisms.

4) Improve printk() and assert() fonctions in printk.c.

File size: 5.5 KB
Line 
1/*
2 * pipe.h - single writer, single reader pipe specification. 
3 *
4 * Author     Alain Greiner (2016,2017,2018,2019,2020)
5 *
6 * Copyright (c) UPMC Sorbonne Universites
7 *
8 * This file is part of ALMOS-MKH.
9 *
10 * ALMOS-MKH is free software; you can redistribute it and/or modify it
11 * under the terms of the GNU General Public License as published by
12 * the Free Software Foundation; version 2.0 of the License.
13 *
14 * ALMOS-MKH is distributed in the hope that it will be useful, but
15 * WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
17 * General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with ALMOS-MKH; if not, write to the Free Software Foundation,
21 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
22 */
23
24
25#ifndef _PIPE_H_
26#define _PIPE_H_
27
28#include <hal_kernel_types.h>
29
30/*******************************************************************************************
31 * This structure defines a generic, single writer, single reader, inter-processes
32 * communication channel, used to implement both the POSIX named fifos, and the POSIX
33 * anonymous pipes.
34 *
35 * It uses the (lower level) remote_buf_t object and access functions, and can be
36 * allocated in any cluster, and accessed by threads running in any cluster.
37 * The default buffer size is defined by the CONFIG_PIPE_BUF_SIZE parameter.
38 * It it accessed by the user processes through the POSIX read/write syscalls, that call
39 * the pipe_move_user() to move data between the kernel remote buf and the user buffer.
40 * These access functions are blocking when the kernel buffer is full (for a write),
41 * or empty (for a read), and use a desheduling policy, blocking on THREAD_ BLOCKED_IO.
42 ******************************************************************************************/
43 
44typedef struct pipe_s
45{
46    remote_buf_t * buffer;       /*! local pointer on the remote_buf_t                    */
47    xptr_t         writer_xp;    /*! extended pointer on the writer thread                */
48    xptr_t         reader_xp;    /*! extended pointer on the reader thread                */
49}
50pipe_t;
51
52/*******************************************************************************************
53 * This function allocates memory for the pipe descriptor, for the remote_buf descriptor,
54 * and for the associated data buffer, in the cluster defined by the <cxy> argument.
55 * The buffer size is defined by the <size> argument.
56 * The "buffer" field is set in the pipe descriptor, but the "writer_xp" and "reader_xp"
57 * fields are not set by this function.
58 *******************************************************************************************
59 * @ cxy        : target cluster identifier.
60 * @ size       : data buffer size (in bytes).
61 * @ return a local pointer on pipe_t if success /:w NULL if error.
62 ******************************************************************************************/
63pipe_t * pipe_create( cxy_t     cxy,
64                      uint32_t  size );
65
66/*******************************************************************************************
67 * This function releases all memory allocated fo a pipe: pipe descriptor,
68 * remote_buffer_t descriptor, and associated data buffer.
69 *******************************************************************************************
70 * @ pipe_xp    : extended pointer on target pipe.
71 ******************************************************************************************/
72void pipe_destroy( xptr_t pipe_xp );
73
74/*******************************************************************************************
75 * These two functions update the "writer_xp" or "reader_xp" field in the pipe descriptor.
76 * They are called when the user process open a file descriptor to access the pipe.
77 *******************************************************************************************
78 * @ pipe_xp    : extended pointer on the target thread
79 * @ thread_xp  : extended pointer on the client (writer/reader) thread.
80 ******************************************************************************************/
81void pipe_register_writer( xptr_t pipe_xp,
82                           xptr_t thread_xp );
83
84void pipe_register_reader( xptr_t pipe_xp,
85                           xptr_t thread_xp );
86
87/*******************************************************************************************
88 * This blocking function is called by the sys_read() and sys_write() functions.
89 * It moves up to <size> bytes between an user buffer, defined by the <u_buf> argument,
90 * and the kernel pipe, identified by the <file_xp> argument.
91 * The file descriptor is always located in the same cluster as the pipe descriptor.
92 * The read/write direction is defined by the <to_buffer> argument.
93 * It returns the number of bytes actually moved.
94 * It uses a desheduling policy, blocking on THREAD_ BLOCKED_IO.
95 *******************************************************************************************
96 * @ to_buffer : pipe -> buffer if true / buffer -> pipe if false.
97 * @ file_xp   : extended pointer on the remote file descriptor.
98 * @ u_buf     : user space buffer (virtual address).
99 * @ size      : requested number of bytes to move.
100 * @ return number of bytes actually moved if success / -1 if error.
101 ******************************************************************************************/
102int pipe_user_move( bool_t   to_buffer,
103                    xptr_t   file_xp,
104                    void   * u_buf,
105                    uint32_t size );
106
107
108#endif  /* _PIPE_H_ */
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