1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
|
/* sane - Scanner Access Now Easy.
Copyright (C) 1998-2001 Yuri Dario
Copyright (C) 2002-2003 Henning Meier-Geinitz (documentation)
Copyright (C) 2003-2004 Gerhard Jaeger (pthread/process support)
This file is part of the SANE package.
SANE is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 2 of the License, or (at your
option) any later version.
SANE is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
You should have received a copy of the GNU General Public License
along with sane; see the file COPYING. If not, write to the Free
Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
As a special exception, the authors of SANE give permission for
additional uses of the libraries contained in this release of SANE.
The exception is that, if you link a SANE library with other files
to produce an executable, this does not by itself cause the
resulting executable to be covered by the GNU General Public
License. Your use of that executable is in no way restricted on
account of linking the SANE library code into it.
This exception does not, however, invalidate any other reasons why
the executable file might be covered by the GNU General Public
License.
If you submit changes to SANE to the maintainers to be included in
a subsequent release, you agree by submitting the changes that
those changes may be distributed with this exception intact.
If you write modifications of your own for SANE, it is your choice
whether to permit this exception to apply to your modifications.
If you do not wish that, delete this exception notice.
*/
/** @file sanei_thread.h
* Support for forking processes and threading.
*
* Backends should not use fork() directly because fork() does not work
* correctly on some platforms. Use the functions provided by sanei_thread
* instead. The build system decides if fork() or threads are used.
*
* Please keep in mind that the behaviour of the child process depends
* on if it's a process or thread especially concerning variables.
*
* In this file we use "task" as an umbrella term for process and thread.
*
* @sa sanei.h sanei_backend.h
*/
#ifndef sanei_thread_h
#define sanei_thread_h
#include "../include/sane/config.h"
#ifdef USE_PTHREAD
#include <pthread.h>
typedef pthread_t SANE_Pid;
#else
typedef int SANE_Pid;
#endif
/** Initialize sanei_thread.
*
* This function must be called before any other sanei_thread function.
*/
extern void sanei_thread_init (void);
/** Do we use processes or threads?
*
* This function can be used to check if processes or threads are used.
*
* @return
* - SANE_TRUE - if processes are used (fork)
* - SANE_FALSE - i threads are used
*/
extern SANE_Bool sanei_thread_is_forked (void);
/** Is SANE_Pid valid pid?
*
* This function can be used to check if thread/fork creation worked
* regardless of SANE_Pid's data type.
*
* @return
* - SANE_TRUE - if pid is a valid process
* - SANE_FALSE - if pid is not a valid process
*/
extern SANE_Bool sanei_thread_is_valid (SANE_Pid pid);
/** Spawn a new task.
*
* This function should be used to start a new task.
*
* @param func() function to call as child task
* @param args argument of the function (only one!)
*
* @return
* - task id
* - -1 if creating the new task failed
*/
extern SANE_Pid sanei_thread_begin (int (*func) (void *args), void *args);
/** Terminate spawned task.
*
* This function terminates the task that was created with sanei_thread_begin.
*
* For processes, SIGTERM is sent. If threads are used, pthread_cancel()
* terminates the task.
*
* @param pid - the id of the task
*
* @return
* - 0 on success
* - any other value if an error occured while terminating the task
*/
extern int sanei_thread_kill (SANE_Pid pid);
/** Send a signal to a task.
*
* This function can be used to send a signal to a task.
*
* For terminating the task, sanei_thread_kill() should be used.
*
* @param pid - the id of the task
* @param sig - the signal to send
*
* @return
* - 0 - on success
* - any other value - if an error occured while sending the signal
*/
extern int sanei_thread_sendsig (SANE_Pid pid, int sig);
/** Wait for task termination.
*
* This function waits until a task that has been terminated by
* sanei_thread_kill(), sanei_thread_sendsys() or by any other means
* is finished.
*
* @param pid - the id of the task
* @param status - status of the task that has just finished
*
* @return
* - the pid of the task we have been waiting for
*/
extern SANE_Pid sanei_thread_waitpid (SANE_Pid pid, int *status);
/** Check the current status of the spawned task
*
*
* @param pid - the id of the task
*
* @return
* - SANE_STATUS_GOOD - if the task finished without errors
* - any other value - if the task finished unexpectantly or hasn't finished yet
*/
extern SANE_Status sanei_thread_get_status (SANE_Pid pid);
#endif /* sanei_thread_h */
|
