summaryrefslogtreecommitdiff
path: root/ftpfs/ccache.c
blob: c942378a0f2c893819c5c7c5db5aae7ecf983ebe (plain)
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
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
/* Remote file contents caching

   Copyright (C) 1997 Free Software Foundation, Inc.
   Written by Miles Bader <miles@gnu.ai.mit.edu>
   This file is part of the GNU Hurd.

   The GNU Hurd 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, or (at
   your option) any later version.

   The GNU Hurd 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 this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA. */

#include <unistd.h>
#include <string.h>

#include <hurd/netfs.h>

#include "ccache.h"

#define READ_CHUNK_SIZE   (8*1024)
#define ALLOC_CHUNK_SIZE  (64*1024)

/* Read LEN bytes at OFFS in the file referred to by CC into DATA, or return
   an error.  */
error_t
ccache_read (struct ccache *cc, off_t offs, size_t len, void *data)
{
  error_t err = 0;
  size_t max = offs + len;

  mutex_lock (&cc->lock);

  if (max > cc->size)
    max = cc->size;

  while (cc->max < max && !err)
    {
      if (cc->fetching_active)
	/* Some thread is fetching data, so just let it do its thing, but get
	   a wakeup call when it's done.  */
	{
	  if (hurd_condition_wait (&cc->wakeup, &cc->lock))
	    err = EINTR;
	}
      else
	{
	  int re_connected = 0;
	  struct netnode *nn = cc->node->nn;

	  cc->fetching_active = 1;

	  while (cc->max < max && !err)
	    {
	      mutex_unlock (&cc->lock);

	      if (! cc->conn)
		/* We need to setup a connection to fetch data over.  */
		{
		  err = ftpfs_get_ftp_conn (nn->fs, &cc->conn);
		  if (! err)
		    {
		      err = ftp_conn_start_retrieve (cc->conn, nn->rmt_path,
						     &cc->data_conn);
		      if (err == ENOENT)
			err = ESTALE;
		      if (err)
			{
			  ftpfs_release_ftp_conn (nn->fs, cc->conn);
			  cc->conn = 0;
			}
		      else
			cc->data_conn_pos = 0;
		    }
		  re_connected = 1;
		}

	      if (! err)
		/* Try and read some data over the connection.  */
		{
		  size_t new_end = cc->max + READ_CHUNK_SIZE;

		  if (new_end > cc->size)
		    new_end = cc->size;

		  if (new_end > cc->alloced)
		    /* Make some room in memory for the new part of the
		       image.  */
		    {
		      size_t alloc_end = cc->alloced + ALLOC_CHUNK_SIZE;

		      if (alloc_end < new_end)
			alloc_end = new_end;
		      else if (alloc_end > cc->size)
			alloc_end = cc->size;

		      if (cc->alloced == 0)
			{
			  vm_address_t addr = 0;
			  err = vm_allocate (mach_task_self (),
					     &addr, alloc_end, 1);
			  if (! err)
			    cc->image = (char *)addr;
			}
		      else
			{
			  vm_address_t addr =
			    (vm_address_t)cc->image + cc->alloced;
			  err = vm_allocate (mach_task_self (),
					     &addr, alloc_end - cc->alloced,
					     0);
			  if (err == EKERN_NO_SPACE)
			    /* Gack.  We've goota move the whole splooge.  */
			    {
			      addr = 0;
			      err = vm_allocate (mach_task_self (),
						 &addr, alloc_end, 1);
			      if (! err)
				/* That worked; copy what's already-fetched. */
				{
				  bcopy (cc->image, (void *)addr, cc->max);
				  vm_deallocate (mach_task_self (),
						 (vm_address_t)cc->image,
						 cc->alloced);
				  cc->image = (char *)addr;
				}
			    }
			}
		      if (! err)
			cc->alloced = alloc_end;
		    }

		  if (! err)
		    {
		      ssize_t rd =
			read (cc->data_conn,
			      cc->image + cc->data_conn_pos,
			      new_end - cc->data_conn_pos);
		      if (rd < 0)
			err = errno;
		      else if (rd == 0)
			/* EOF.  This either means the file changed size, or
			   our data-connection got closed; we just try to
			   open the connection a second time, and then if
			   that fails, assume the size changed.  */
			{
			  if (re_connected)
			    err = EIO; /* Something's fucked */
			  else
			    /* Try opening the connection again.  */
			    {
			      close (cc->data_conn);
			      ftp_conn_finish_transfer (cc->conn);
			      ftpfs_release_ftp_conn (nn->fs, cc->conn);
			      cc->conn = 0;
			    }
			}
		      else
			{
			  cc->data_conn_pos += rd;
			  if (cc->data_conn_pos > cc->max)
			    cc->max = cc->data_conn_pos;
			}
		    }

		  if (!err && ports_self_interrupted ())
		    err = EINTR;
		}

	      mutex_lock (&cc->lock);

	      if (cc->max < max && !err)
		/* If anyone's waiting for data, let them look (if we're done
		   fetching, this gets delayed until below).  */
		condition_broadcast (&cc->wakeup);
	    }

	  if (!err && cc->conn && cc->max == cc->size)
	    /* We're finished reading all data, close the data connection.  */
	    {
	      close (cc->data_conn);
	      ftp_conn_finish_transfer (cc->conn);
	      ftpfs_release_ftp_conn (nn->fs, cc->conn);
	      cc->conn = 0;
	    }

	  /* We're done, error or no.  */
	  cc->fetching_active = 0;

	  /* Let others know something's going on.  */
	  condition_broadcast (&cc->wakeup);
	}
    }

  if (! err)
    bcopy (cc->image + offs, data, max - offs);

  mutex_unlock (&cc->lock);

  return err;
}

/* Discard any cached contents in CC.  */
error_t
ccache_invalidate (struct ccache *cc)
{
  error_t err = 0;

  mutex_lock (&cc->lock);

  while  (cc->fetching_active && !err)
    /* Some thread is fetching data, so just let it do its thing, but get
       a wakeup call when it's done.  */
    {
      if (hurd_condition_wait (&cc->wakeup, &cc->lock))
	err = EINTR;
    }

  if (! err)
    {
      if (cc->alloced > 0)
	{
	  vm_deallocate (mach_task_self (),
			 (vm_address_t)cc->image, cc->alloced);
	  cc->image = 0;
	  cc->alloced = 0;
	  cc->max = 0;
	}
      if (cc->conn)
	{
	  close (cc->data_conn);
	  ftp_conn_finish_transfer (cc->conn);
	  ftpfs_release_ftp_conn (cc->node->nn->fs, cc->conn);
	  cc->conn = 0;
	}
    }

  mutex_unlock (&cc->lock);

  return err;
}

/* Return a ccache object for NODE in CC.  */
error_t
ccache_create (struct node *node, struct ccache **cc)
{
  struct ccache *new = malloc (sizeof (struct ccache));

  if (! new)
    return ENOMEM;

  new->node = node;
  new->image = 0;
  new->size = node->nn_stat.st_size;
  new->max = 0;
  new->alloced = 0;
  mutex_init (&new->lock);
  condition_init (&new->wakeup);
  new->fetching_active = 0;
  new->conn = 0;
  new->data_conn = -1;

  *cc = new;

  return 0;
}

/* Free all resources used by CC.  */
void
ccache_free (struct ccache *cc)
{
  if (cc->alloced > 0)
    vm_deallocate (mach_task_self (), (vm_address_t)cc->image, cc->alloced);
  if (cc->data_conn >= 0)
    close (cc->data_conn);
  if (cc->conn)
    {
      ftp_conn_finish_transfer (cc->conn);
      ftpfs_release_ftp_conn (cc->node->nn->fs, cc->conn);
    }
  free (cc);
}