xref: /illumos-kvm-cmd/buffered_file.c (revision 68396ea9)
1 /*
2  * QEMU buffered QEMUFile
3  *
4  * Copyright IBM, Corp. 2008
5  *
6  * Authors:
7  *  Anthony Liguori   <aliguori@us.ibm.com>
8  *
9  * This work is licensed under the terms of the GNU GPL, version 2.  See
10  * the COPYING file in the top-level directory.
11  *
12  */
13 
14 #include "qemu-common.h"
15 #include "hw/hw.h"
16 #include "qemu-timer.h"
17 #include "sysemu.h"
18 #include "qemu-char.h"
19 #include "buffered_file.h"
20 
21 //#define DEBUG_BUFFERED_FILE
22 
23 typedef struct QEMUFileBuffered
24 {
25     BufferedPutFunc *put_buffer;
26     BufferedPutReadyFunc *put_ready;
27     BufferedWaitForUnfreezeFunc *wait_for_unfreeze;
28     BufferedCloseFunc *close;
29     void *opaque;
30     QEMUFile *file;
31     int has_error;
32     int freeze_output;
33     size_t bytes_xfer;
34     size_t xfer_limit;
35     uint8_t *buffer;
36     size_t buffer_size;
37     size_t buffer_capacity;
38     QEMUTimer *timer;
39 } QEMUFileBuffered;
40 
41 #ifdef DEBUG_BUFFERED_FILE
42 #define DPRINTF(fmt, ...) \
43     do { printf("buffered-file: " fmt, ## __VA_ARGS__); } while (0)
44 #else
45 #define DPRINTF(fmt, ...) \
46     do { } while (0)
47 #endif
48 
buffered_append(QEMUFileBuffered * s,const uint8_t * buf,size_t size)49 static void buffered_append(QEMUFileBuffered *s,
50                             const uint8_t *buf, size_t size)
51 {
52     if (size > (s->buffer_capacity - s->buffer_size)) {
53         void *tmp;
54 
55         DPRINTF("increasing buffer capacity from %zu by %zu\n",
56                 s->buffer_capacity, size + 1024);
57 
58         s->buffer_capacity += size + 1024;
59 
60         tmp = qemu_realloc(s->buffer, s->buffer_capacity);
61         if (tmp == NULL) {
62             fprintf(stderr, "qemu file buffer expansion failed\n");
63             exit(1);
64         }
65 
66         s->buffer = tmp;
67     }
68 
69     memcpy(s->buffer + s->buffer_size, buf, size);
70     s->buffer_size += size;
71 }
72 
buffered_flush(QEMUFileBuffered * s)73 static void buffered_flush(QEMUFileBuffered *s)
74 {
75     size_t offset = 0;
76 
77     if (s->has_error) {
78         DPRINTF("flush when error, bailing\n");
79         return;
80     }
81 
82     DPRINTF("flushing %zu byte(s) of data\n", s->buffer_size);
83 
84     while (offset < s->buffer_size) {
85         ssize_t ret;
86 
87         ret = s->put_buffer(s->opaque, s->buffer + offset,
88                             s->buffer_size - offset);
89         if (ret == -EAGAIN) {
90             DPRINTF("backend not ready, freezing\n");
91             s->freeze_output = 1;
92             break;
93         }
94 
95         if (ret <= 0) {
96             DPRINTF("error flushing data, %zd\n", ret);
97             s->has_error = 1;
98             break;
99         } else {
100             DPRINTF("flushed %zd byte(s)\n", ret);
101             offset += ret;
102         }
103     }
104 
105     DPRINTF("flushed %zu of %zu byte(s)\n", offset, s->buffer_size);
106     memmove(s->buffer, s->buffer + offset, s->buffer_size - offset);
107     s->buffer_size -= offset;
108 }
109 
buffered_put_buffer(void * opaque,const uint8_t * buf,int64_t pos,int size)110 static int buffered_put_buffer(void *opaque, const uint8_t *buf, int64_t pos, int size)
111 {
112     QEMUFileBuffered *s = opaque;
113     int offset = 0;
114     ssize_t ret;
115 
116     DPRINTF("putting %d bytes at %" PRId64 "\n", size, pos);
117 
118     if (s->has_error) {
119         DPRINTF("flush when error, bailing\n");
120         return -EINVAL;
121     }
122 
123     DPRINTF("unfreezing output\n");
124     s->freeze_output = 0;
125 
126     buffered_flush(s);
127 
128     while (!s->freeze_output && offset < size) {
129         if (s->bytes_xfer > s->xfer_limit) {
130             DPRINTF("transfer limit exceeded when putting\n");
131             break;
132         }
133 
134         ret = s->put_buffer(s->opaque, buf + offset, size - offset);
135         if (ret == -EAGAIN) {
136             DPRINTF("backend not ready, freezing\n");
137             s->freeze_output = 1;
138             break;
139         }
140 
141         if (ret <= 0) {
142             DPRINTF("error putting\n");
143             s->has_error = 1;
144             offset = -EINVAL;
145             break;
146         }
147 
148         DPRINTF("put %zd byte(s)\n", ret);
149         offset += ret;
150         s->bytes_xfer += ret;
151     }
152 
153     if (offset >= 0) {
154         DPRINTF("buffering %d bytes\n", size - offset);
155         buffered_append(s, buf + offset, size - offset);
156         offset = size;
157     }
158 
159     if (pos == 0 && size == 0) {
160         DPRINTF("file is ready\n");
161         if (s->bytes_xfer <= s->xfer_limit) {
162             DPRINTF("notifying client\n");
163             s->put_ready(s->opaque);
164         }
165     }
166 
167     return offset;
168 }
169 
buffered_close(void * opaque)170 static int buffered_close(void *opaque)
171 {
172     QEMUFileBuffered *s = opaque;
173     int ret;
174 
175     DPRINTF("closing\n");
176 
177     while (!s->has_error && s->buffer_size) {
178         buffered_flush(s);
179         if (s->freeze_output)
180             s->wait_for_unfreeze(s);
181     }
182 
183     ret = s->close(s->opaque);
184 
185     qemu_del_timer(s->timer);
186     qemu_free_timer(s->timer);
187     qemu_free(s->buffer);
188     qemu_free(s);
189 
190     return ret;
191 }
192 
buffered_rate_limit(void * opaque)193 static int buffered_rate_limit(void *opaque)
194 {
195     QEMUFileBuffered *s = opaque;
196 
197     if (s->has_error)
198         return 0;
199 
200     if (s->freeze_output)
201         return 1;
202 
203     if (s->bytes_xfer > s->xfer_limit)
204         return 1;
205 
206     return 0;
207 }
208 
buffered_set_rate_limit(void * opaque,int64_t new_rate)209 static int64_t buffered_set_rate_limit(void *opaque, int64_t new_rate)
210 {
211     QEMUFileBuffered *s = opaque;
212     if (s->has_error)
213         goto out;
214 
215     if (new_rate > SIZE_MAX) {
216         new_rate = SIZE_MAX;
217     }
218 
219     s->xfer_limit = new_rate / 10;
220 
221 out:
222     return s->xfer_limit;
223 }
224 
buffered_get_rate_limit(void * opaque)225 static int64_t buffered_get_rate_limit(void *opaque)
226 {
227     QEMUFileBuffered *s = opaque;
228 
229     return s->xfer_limit;
230 }
231 
buffered_rate_tick(void * opaque)232 static void buffered_rate_tick(void *opaque)
233 {
234     QEMUFileBuffered *s = opaque;
235 
236     if (s->has_error) {
237         buffered_close(s);
238         return;
239     }
240 
241     qemu_mod_timer(s->timer, qemu_get_clock(rt_clock) + 100);
242 
243     if (s->freeze_output)
244         return;
245 
246     s->bytes_xfer = 0;
247 
248     buffered_flush(s);
249 
250     /* Add some checks around this */
251     s->put_ready(s->opaque);
252 }
253 
qemu_fopen_ops_buffered(void * opaque,size_t bytes_per_sec,BufferedPutFunc * put_buffer,BufferedPutReadyFunc * put_ready,BufferedWaitForUnfreezeFunc * wait_for_unfreeze,BufferedCloseFunc * close)254 QEMUFile *qemu_fopen_ops_buffered(void *opaque,
255                                   size_t bytes_per_sec,
256                                   BufferedPutFunc *put_buffer,
257                                   BufferedPutReadyFunc *put_ready,
258                                   BufferedWaitForUnfreezeFunc *wait_for_unfreeze,
259                                   BufferedCloseFunc *close)
260 {
261     QEMUFileBuffered *s;
262 
263     s = qemu_mallocz(sizeof(*s));
264 
265     s->opaque = opaque;
266     s->xfer_limit = bytes_per_sec / 10;
267     s->put_buffer = put_buffer;
268     s->put_ready = put_ready;
269     s->wait_for_unfreeze = wait_for_unfreeze;
270     s->close = close;
271 
272     s->file = qemu_fopen_ops(s, buffered_put_buffer, NULL,
273                              buffered_close, buffered_rate_limit,
274                              buffered_set_rate_limit,
275 			     buffered_get_rate_limit);
276 
277     s->timer = qemu_new_timer(rt_clock, buffered_rate_tick, s);
278 
279     qemu_mod_timer(s->timer, qemu_get_clock(rt_clock) + 100);
280 
281     return s->file;
282 }
283