source: rtems/cpukit/include/rtems/stdio-redirect.h @ 2fd31117

5
Last change on this file since 2fd31117 was 2fd31117, checked in by Sebastian Huber <sebastian.huber@…>, on 01/09/18 at 05:13:32

stdio-redirector: Use self-contained mutex

Update #2843.

  • Property mode set to 100644
File size: 4.3 KB
Line 
1/*
2 * Copyright (C) 2014 Chris Johns (chrisj@rtems.org)
3 *
4 * The license and distribution terms for this file may be
5 * found in the file LICENSE in this distribution.
6 *
7 * This software with is provided ``as is'' and with NO WARRANTY.
8 */
9
10/*
11 * @brief Redirect an stdio file decriptor.
12 *
13 * The is a helper module of code design to redirect an stdio file
14 * descriptor. You can optionally have the data buffered and/or you can provide
15 * a handler function that is called when data arrives.
16 *
17 * The module uses standard POSIX calls to implement the redirection and if the
18 * threading was POSIX based the code would be portable. Currently the code
19 * uses RTEMS threads.
20 *
21 * Redirecting stderr and stdout is useful in embedded system because you can
22 * transport the output off your device or create a web interface that can
23 * display the output. This can be a very powerful diagnostic and support tool.
24 *
25 * The implementation does:
26 *
27 *  1. Duplicate the file descriptor (fd) to redirect using the dup call. The
28 *     duplicated desciptor is used to echo the output out the existing path.
29 *
30 *  2. Create a pipe using the pipe call.
31 *
32 *  3. Duplicate the pipe's writer file descriptor to user's file
33 *     descriptor. This results in any writes to the user's fd being written to
34 *     the pipe.
35 *
36 *  4. Create a reader task that blocks on the pipe. It optionally calls a
37 *     handler and if configured buffers the data.
38 */
39
40#if !defined(RTEMS_STDIO_REDIRECT_H)
41#define RTEMS_STDIO_REDIRECT_H
42
43#include <stdbool.h>
44#include <rtems.h>
45#include <rtems/thread.h>
46
47#ifdef __cplusplus
48extern "C" {
49#endif /* __cplusplus */
50
51/*
52 * Handler called whenever redirected data arrives.
53 *
54 * @param buffer The data.
55 * @param length The amount of data in the buffer.
56 */
57typedef void (*rtems_stdio_redirect_handler)(const char* buffer,
58                                             ssize_t     length);
59
60/*
61 * Redirector data.
62 */
63typedef struct
64{
65  volatile uint32_t            state;       /**< The state. */
66  rtems_id                     reader;      /**< The reader thread. */
67  rtems_mutex                  lock;        /**< Lock for this struct. */
68  int                          fd;          /**< The file descriptor to redirect. */
69  int                          fd_dup;      /**< Duplicated fd to write to. */
70  int                          pipe[2];     /**< The pipe to the reader thread. */
71  char*                        input;       /**< The input buffer the reader uses. */
72  ssize_t                      input_size;  /**< The input buffer size. */
73  char*                        buffer;      /**< Captured redirected data. */
74  ssize_t                      buffer_size; /**< Capture buffer size. */
75  ssize_t                      in;          /**< Buffer in index. */
76  bool                         full;        /**< The buffer is full. */
77  bool                         echo;        /**< Echo the data out the existing path. */
78  rtems_stdio_redirect_handler handler;     /**< Redirected data handler. */
79} rtems_stdio_redirect;
80
81/*
82 * Open a redirector returning the handle to it.
83 *
84 * @param fd The file descriptor to redirect.
85 * @param priority The priority of the reader thread.
86 */
87rtems_stdio_redirect* rtems_stdio_redirect_open(int                          fd,
88                                                rtems_task_priority          priority,
89                                                size_t                       stack_size,
90                                                ssize_t                      input_size,
91                                                ssize_t                      buffer_size,
92                                                bool                         echo,
93                                                rtems_stdio_redirect_handler handler);
94
95/*
96 * Close the redirector.
97 */
98void rtems_stdio_redirect_close(rtems_stdio_redirect* sr);
99
100/*
101 * Get data from the capture buffer. Data read is removed from the buffer.
102 *
103 * @param sr The stdio redirection handle.
104 * @param buffer The buffer data is written into.
105 * @param length The size of the buffer.
106 * @return ssize_t The amount of data written and -1 or an error.
107 */
108ssize_t rtems_stdio_redirect_read(rtems_stdio_redirect* sr,
109                                  char*                 buffer,
110                                  ssize_t               length);
111
112#ifdef __cplusplus
113}
114#endif /* __cplusplus */
115
116#endif
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