root / logic / trunk / src / drv_comm / drv_comm.c @ 93
History | View | Annotate | Download (2.21 KB)
1 | 71 | Janez1 | /*
|
---|---|---|---|
2 | * ioctl.c โ the process to use ioctl's to control the kernel module
|
||
3 | *
|
||
4 | * Until now we could have used cat for input and output. But now
|
||
5 | * we need to do ioctl's, which require writing our own process.
|
||
6 | */
|
||
7 | /*
|
||
8 | * device specifics, such as ioctl numbers and the
|
||
9 | * major device file.
|
||
10 | */
|
||
11 | #include "drv_comm.h" |
||
12 | #include "generator.h" |
||
13 | #include <stdio.h> |
||
14 | #include <stdlib.h> |
||
15 | #include <fcntl.h> /* open */ |
||
16 | #include <unistd.h> /* exit */ |
||
17 | //#include <sys/ioctl.h> /* ioctl */
|
||
18 | /*
|
||
19 | * Functions for the ioctl calls
|
||
20 | */
|
||
21 | ioctl_set_msg(int file_desc, char *message) |
||
22 | { |
||
23 | int ret_val;
|
||
24 | ret_val = ioctl(file_desc, IOCTL_SET_MSG, message); |
||
25 | if (ret_val < 0) { |
||
26 | printf("ioctl_set_msg failed:%d\n", ret_val);
|
||
27 | exit(-1);
|
||
28 | } |
||
29 | } |
||
30 | |||
31 | ioctl_get_msg(int file_desc)
|
||
32 | { |
||
33 | int ret_val;
|
||
34 | char message[100]; |
||
35 | /*
|
||
36 | * Warning โ this is dangerous because we don't tell
|
||
37 | * the kernel how far it's allowed to write, so it
|
||
38 | * might overflow the buffer. In a real production
|
||
39 | * program, we would have used two ioctls โ one to tell
|
||
40 | * the kernel the buffer length and another to give
|
||
41 | * it the buffer to fill
|
||
42 | */
|
||
43 | ret_val = ioctl(file_desc, IOCTL_GET_MSG, message); |
||
44 | if (ret_val < 0) { |
||
45 | printf("ioctl_get_msg failed:%d\n", ret_val);
|
||
46 | exit(-1);
|
||
47 | } |
||
48 | //printf("get_msg message:%s\n", message);
|
||
49 | } |
||
50 | |||
51 | int ioctl_get_nth_byte(int file_desc) |
||
52 | { |
||
53 | int i, val;
|
||
54 | char c;
|
||
55 | |||
56 | val=0;
|
||
57 | i = 0;
|
||
58 | do {
|
||
59 | c = ioctl(file_desc, IOCTL_GET_NTH_BYTE, i++); |
||
60 | if (c < 0) { |
||
61 | printf("ioctl_get_nth_byte failed at the %d'th byte:\n",i);
|
||
62 | exit(-1);
|
||
63 | } |
||
64 | val=val*10+atoi(&c);
|
||
65 | } while (c != 0); |
||
66 | return (int)val/10; //because string termination character also gets read in loop we have to divide by 10 |
||
67 | } |
||
68 | |||
69 | int get_device_value(const char *dev) |
||
70 | { |
||
71 | //TODO use mutex?
|
||
72 | int file_desc, ret_val;
|
||
73 | |||
74 | char *msg = int_to_str(generate_value());
|
||
75 | |||
76 | file_desc = open(dev, 0);
|
||
77 | |||
78 | if (file_desc < 0) { |
||
79 | printf("Can't open device file: %s\n", dev);
|
||
80 | ret_val = generate_value(); // TODO fake value in case driver doesnt work
|
||
81 | } |
||
82 | else{
|
||
83 | //printf("Open device file: %s\n", dev);
|
||
84 | //ioctl_set_msg(file_desc, msg);
|
||
85 | ret_val = ioctl_get_nth_byte(file_desc); |
||
86 | } |
||
87 | |||
88 | close(file_desc); |
||
89 | ret_val = ret_val+((random()%3-1)*5); //+- 5 (conversion to fload needed later) |
||
90 | printf("Returning val %d\n", ret_val);
|
||
91 | |||
92 | return ret_val;
|
||
93 | } |