source: trunk/minix/drivers/random/main.c@ 20

Last change on this file since 20 was 9, checked in by Mattia Monga, 14 years ago

Minix 3.1.2a
File size: 7.6 KB
RevLine 
[9]1/* This file contains the device dependent part of the drivers for the
2 * following special files:
3 * /dev/random - random number generator
4 */
5
6#include "../drivers.h"
7#include "../libdriver/driver.h"
8#include <sys/ioc_memory.h>
9#include "../../kernel/const.h"
10#include "../../kernel/config.h"
11#include "../../kernel/type.h"
12
13#include "assert.h"
14#include "random.h"
15
16#define NR_DEVS 1 /* number of minor devices */
17# define RANDOM_DEV 0 /* minor device for /dev/random */
18
19#define KRANDOM_PERIOD 1 /* ticks between krandom calls */
20
21PRIVATE struct device m_geom[NR_DEVS]; /* base and size of each device */
22PRIVATE int m_device; /* current device */
23
24extern int errno; /* error number for PM calls */
25
26FORWARD _PROTOTYPE( char *r_name, (void) );
27FORWARD _PROTOTYPE( struct device *r_prepare, (int device) );
28FORWARD _PROTOTYPE( int r_transfer, (int proc_nr, int opcode, off_t position,
29 iovec_t *iov, unsigned nr_req) );
30FORWARD _PROTOTYPE( int r_do_open, (struct driver *dp, message *m_ptr) );
31FORWARD _PROTOTYPE( void r_init, (void) );
32FORWARD _PROTOTYPE( int r_ioctl, (struct driver *dp, message *m_ptr) );
33FORWARD _PROTOTYPE( void r_geometry, (struct partition *entry) );
34FORWARD _PROTOTYPE( void r_random, (struct driver *dp, message *m_ptr) );
35
36/* Entry points to this driver. */
37PRIVATE struct driver r_dtab = {
38 r_name, /* current device's name */
39 r_do_open, /* open or mount */
40 do_nop, /* nothing on a close */
41 r_ioctl, /* specify ram disk geometry */
42 r_prepare, /* prepare for I/O on a given minor device */
43 r_transfer, /* do the I/O */
44 nop_cleanup, /* no need to clean up */
45 r_geometry, /* device "geometry" */
46 nop_signal, /* system signals */
47 r_random, /* get randomness from kernel (alarm) */
48 nop_cancel,
49 nop_select,
50 NULL,
51 NULL
52};
53
54/* Buffer for the /dev/random number generator. */
55#define RANDOM_BUF_SIZE 1024
56PRIVATE char random_buf[RANDOM_BUF_SIZE];
57
58/*===========================================================================*
59 * main *
60 *===========================================================================*/
61PUBLIC int main(void)
62{
63 r_init(); /* initialize the memory driver */
64 driver_task(&r_dtab); /* start driver's main loop */
65 return(OK);
66}
67
68/*===========================================================================*
69 * r_name *
70 *===========================================================================*/
71PRIVATE char *r_name()
72{
73/* Return a name for the current device. */
74 static char name[] = "random";
75 return name;
76}
77
78/*===========================================================================*
79 * r_prepare *
80 *===========================================================================*/
81PRIVATE struct device *r_prepare(device)
82int device;
83{
84/* Prepare for I/O on a device: check if the minor device number is ok. */
85
86 if (device < 0 || device >= NR_DEVS) return(NIL_DEV);
87 m_device = device;
88
89 return(&m_geom[device]);
90}
91
92/*===========================================================================*
93 * r_transfer *
94 *===========================================================================*/
95PRIVATE int r_transfer(proc_nr, opcode, position, iov, nr_req)
96int proc_nr; /* process doing the request */
97int opcode; /* DEV_GATHER or DEV_SCATTER */
98off_t position; /* offset on device to read or write */
99iovec_t *iov; /* pointer to read or write request vector */
100unsigned nr_req; /* length of request vector */
101{
102/* Read or write one the driver's minor devices. */
103 unsigned count, left, chunk;
104 vir_bytes user_vir;
105 struct device *dv;
106 unsigned long dv_size;
107
108 /* Get minor device number and check for /dev/null. */
109 dv = &m_geom[m_device];
110 dv_size = cv64ul(dv->dv_size);
111
112 while (nr_req > 0) {
113
114 /* How much to transfer and where to / from. */
115 count = iov->iov_size;
116 user_vir = iov->iov_addr;
117
118 switch (m_device) {
119
120 /* Random number generator. Character instead of block device. */
121 case RANDOM_DEV:
122 if (opcode == DEV_GATHER && !random_isseeded())
123 return(EAGAIN);
124 left = count;
125 while (left > 0) {
126 chunk = (left > RANDOM_BUF_SIZE) ? RANDOM_BUF_SIZE : left;
127 if (opcode == DEV_GATHER) {
128 random_getbytes(random_buf, chunk);
129 sys_vircopy(SELF, D, (vir_bytes) random_buf,
130 proc_nr, D, user_vir, chunk);
131 } else if (opcode == DEV_SCATTER) {
132 sys_vircopy(proc_nr, D, user_vir,
133 SELF, D, (vir_bytes) random_buf, chunk);
134 random_putbytes(random_buf, chunk);
135 }
136 user_vir += chunk;
137 left -= chunk;
138 }
139 break;
140
141 /* Unknown (illegal) minor device. */
142 default:
143 return(EINVAL);
144 }
145
146 /* Book the number of bytes transferred. */
147 position += count;
148 iov->iov_addr += count;
149 if ((iov->iov_size -= count) == 0) { iov++; nr_req--; }
150
151 }
152 return(OK);
153}
154
155/*============================================================================*
156 * r_do_open *
157 *============================================================================*/
158PRIVATE int r_do_open(dp, m_ptr)
159struct driver *dp;
160message *m_ptr;
161{
162/* Check device number on open.
163 */
164 if (r_prepare(m_ptr->DEVICE) == NIL_DEV) return(ENXIO);
165
166 return(OK);
167}
168
169/*===========================================================================*
170 * r_init *
171 *===========================================================================*/
172PRIVATE void r_init()
173{
174 /* Initialize this task. All minor devices are initialized one by one. */
175 random_init();
176 r_random(NULL, NULL); /* also set periodic timer */
177}
178
179/*===========================================================================*
180 * r_ioctl *
181 *===========================================================================*/
182PRIVATE int r_ioctl(dp, m_ptr)
183struct driver *dp; /* pointer to driver structure */
184message *m_ptr; /* pointer to control message */
185{
186 struct device *dv;
187 if ((dv = r_prepare(m_ptr->DEVICE)) == NIL_DEV) return(ENXIO);
188
189 switch (m_ptr->REQUEST) {
190
191 default:
192 return(do_diocntl(&r_dtab, m_ptr));
193 }
194 return(OK);
195}
196
197/*============================================================================*
198 * r_random *
199 *============================================================================*/
200PRIVATE void r_random(dp, m_ptr)
201struct driver *dp; /* pointer to driver structure */
202message *m_ptr; /* pointer to alarm message */
203{
204 /* Fetch random information from the kernel to update /dev/random. */
205 int i, s, r_next, r_size, r_high;
206 struct randomness krandom;
207
208 if (OK != (s=sys_getrandomness(&krandom)))
209 report("RANDOM", "sys_getrandomness failed", s);
210
211 for (i= 0; i<RANDOM_SOURCES; i++)
212 {
213 r_next= krandom.bin[i].r_next;
214 r_size= krandom.bin[i].r_size;
215 r_high= r_next+r_size;
216 if (r_high <= RANDOM_ELEMENTS)
217 {
218 random_update(i, &krandom.bin[i].r_buf[r_next], r_size);
219 }
220 else
221 {
222 assert(r_next < RANDOM_ELEMENTS);
223 random_update(i, &krandom.bin[i].r_buf[r_next],
224 RANDOM_ELEMENTS-r_next);
225 random_update(i, &krandom.bin[i].r_buf[0],
226 r_high-RANDOM_ELEMENTS);
227 }
228 }
229
230 /* Schedule new alarm for next m_random call. */
231 if (OK != (s=sys_setalarm(KRANDOM_PERIOD, 0)))
232 report("RANDOM", "sys_setalarm failed", s);
233}
234
235/*============================================================================*
236 * r_geometry *
237 *============================================================================*/
238PRIVATE void r_geometry(entry)
239struct partition *entry;
240{
241 /* Memory devices don't have a geometry, but the outside world insists. */
242 entry->cylinders = div64u(m_geom[m_device].dv_size, SECTOR_SIZE) / (64 * 32);
243 entry->heads = 64;
244 entry->sectors = 32;
245}
246
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