chardev/char-ringbuf.c

   1 /*
   2  * QEMU System Emulator
   3  *
   4  * Copyright (c) 2003-2008 Fabrice Bellard
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a copy
   7  * of this software and associated documentation files (the "Software"), to deal
   8  * in the Software without restriction, including without limitation the rights
   9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10  * copies of the Software, and to permit persons to whom the Software is
  11  * furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  22  * THE SOFTWARE.
  23  */
  24
  25 #include "qemu/osdep.h"
  26 #include "chardev/char.h"
  27 #include "qapi/error.h"
  28 #include "qapi/qapi-commands-char.h"
  29 #include "qemu/base64.h"
  30 #include "qemu/option.h"
  31
  32 /* Ring buffer chardev */
  33
  34 typedef struct {
  35     Chardev parent;
  36     size_t size;
  37     size_t prod;
  38     size_t cons;
  39     uint8_t *cbuf;
  40 } RingBufChardev;
  41
  42 #define RINGBUF_CHARDEV(obj)                                    \
  43     OBJECT_CHECK(RingBufChardev, (obj), TYPE_CHARDEV_RINGBUF)
  44
  45 static size_t ringbuf_count(const Chardev *chr)
  46 {
  47     const RingBufChardev *d = RINGBUF_CHARDEV(chr);
  48
  49     return d->prod - d->cons;
  50 }
  51
  52 static int ringbuf_chr_write(Chardev *chr, const uint8_t *buf, int len)
  53 {
  54     RingBufChardev *d = RINGBUF_CHARDEV(chr);
  55     int i;
  56
  57     if (!buf || (len < 0)) {
  58         return -1;
  59     }
  60
  61     for (i = 0; i < len; i++) {
  62         d->cbuf[d->prod++ & (d->size - 1)] = buf[i];
  63         if (d->prod - d->cons > d->size) {
  64             d->cons = d->prod - d->size;
  65         }
  66     }
  67
  68     return len;
  69 }
  70
  71 static int ringbuf_chr_read(Chardev *chr, uint8_t *buf, int len)
  72 {
  73     RingBufChardev *d = RINGBUF_CHARDEV(chr);
  74     int i;
  75
  76     qemu_mutex_lock(&chr->chr_write_lock);
  77     for (i = 0; i < len && d->cons != d->prod; i++) {
  78         buf[i] = d->cbuf[d->cons++ & (d->size - 1)];
  79     }
  80     qemu_mutex_unlock(&chr->chr_write_lock);
  81
  82     return i;
  83 }
  84
  85 static void char_ringbuf_finalize(Object *obj)
  86 {
  87     RingBufChardev *d = RINGBUF_CHARDEV(obj);
  88
  89     g_free(d->cbuf);
  90 }
  91
  92 static void qemu_chr_open_ringbuf(Chardev *chr,
  93                                   ChardevBackend *backend,
  94                                   bool *be_opened,
  95                                   Error **errp)
  96 {
  97     ChardevRingbuf *opts = backend->u.ringbuf.data;
  98     RingBufChardev *d = RINGBUF_CHARDEV(chr);
  99
 100     d->size = opts->has_size ? opts->size : 65536;
 101
 102     /* The size must be power of 2 */
 103     if (d->size & (d->size - 1)) {
 104         error_setg(errp, "size of ringbuf chardev must be power of two");
 105         return;
 106     }
 107
 108     d->prod = 0;
 109     d->cons = 0;
 110     d->cbuf = g_malloc0(d->size);
 111 }
 112
 113 void qmp_ringbuf_write(const char *device, const char *data,
 114                        bool has_format, enum DataFormat format,
 115                        Error **errp)
 116 {
 117     Chardev *chr;
 118     const uint8_t *write_data;
 119     int ret;
 120     gsize write_count;
 121
 122     chr = qemu_chr_find(device);
 123     if (!chr) {
 124         error_setg(errp, "Device '%s' not found", device);
 125         return;
 126     }
 127
 128     if (!CHARDEV_IS_RINGBUF(chr)) {
 129         error_setg(errp, "%s is not a ringbuf device", device);
 130         return;
 131     }
 132
 133     if (has_format && (format == DATA_FORMAT_BASE64)) {
 134         write_data = qbase64_decode(data, -1,
 135                                     &write_count,
 136                                     errp);
 137         if (!write_data) {
 138             return;
 139         }
 140     } else {
 141         write_data = (uint8_t *)data;
 142         write_count = strlen(data);
 143     }
 144
 145     ret = ringbuf_chr_write(chr, write_data, write_count);
 146
 147     if (write_data != (uint8_t *)data) {
 148         g_free((void *)write_data);
 149     }
 150
 151     if (ret < 0) {
 152         error_setg(errp, "Failed to write to device %s", device);
 153         return;
 154     }
 155 }
 156
 157 char *qmp_ringbuf_read(const char *device, int64_t size,
 158                        bool has_format, enum DataFormat format,
 159                        Error **errp)
 160 {
 161     Chardev *chr;
 162     uint8_t *read_data;
 163     size_t count;
 164     char *data;
 165
 166     chr = qemu_chr_find(device);
 167     if (!chr) {
 168         error_setg(errp, "Device '%s' not found", device);
 169         return NULL;
 170     }
 171
 172     if (!CHARDEV_IS_RINGBUF(chr)) {
 173         error_setg(errp, "%s is not a ringbuf device", device);
 174         return NULL;
 175     }
 176
 177     if (size <= 0) {
 178         error_setg(errp, "size must be greater than zero");
 179         return NULL;
 180     }
 181
 182     count = ringbuf_count(chr);
 183     size = size > count ? count : size;
 184     read_data = g_malloc(size + 1);
 185
 186     ringbuf_chr_read(chr, read_data, size);
 187
 188     if (has_format && (format == DATA_FORMAT_BASE64)) {
 189         data = g_base64_encode(read_data, size);
 190         g_free(read_data);
 191     } else {
 192         /*
 193          * FIXME should read only complete, valid UTF-8 characters up
 194          * to @size bytes.  Invalid sequences should be replaced by a
 195          * suitable replacement character.  Except when (and only
 196          * when) ring buffer lost characters since last read, initial
 197          * continuation characters should be dropped.
 198          */
 199         read_data[size] = 0;
 200         data = (char *)read_data;
 201     }
 202
 203     return data;
 204 }
 205
 206 static void qemu_chr_parse_ringbuf(QemuOpts *opts, ChardevBackend *backend,
 207                                    Error **errp)
 208 {
 209     int val;
 210     ChardevRingbuf *ringbuf;
 211
 212     backend->type = CHARDEV_BACKEND_KIND_RINGBUF;
 213     ringbuf = backend->u.ringbuf.data = g_new0(ChardevRingbuf, 1);
 214     qemu_chr_parse_common(opts, qapi_ChardevRingbuf_base(ringbuf));
 215
 216     val = qemu_opt_get_size(opts, "size", 0);
 217     if (val != 0) {
 218         ringbuf->has_size = true;
 219         ringbuf->size = val;
 220     }
 221 }
 222
 223 static void char_ringbuf_class_init(ObjectClass *oc, void *data)
 224 {
 225     ChardevClass *cc = CHARDEV_CLASS(oc);
 226
 227     cc->parse = qemu_chr_parse_ringbuf;
 228     cc->open = qemu_chr_open_ringbuf;
 229     cc->chr_write = ringbuf_chr_write;
 230 }
 231
 232 static const TypeInfo char_ringbuf_type_info = {
 233     .name = TYPE_CHARDEV_RINGBUF,
 234     .parent = TYPE_CHARDEV,
 235     .class_init = char_ringbuf_class_init,
 236     .instance_size = sizeof(RingBufChardev),
 237     .instance_finalize = char_ringbuf_finalize,
 238 };
 239
 240 /* Bug-compatibility: */
 241 static const TypeInfo char_memory_type_info = {
 242     .name = TYPE_CHARDEV_MEMORY,
 243     .parent = TYPE_CHARDEV_RINGBUF,
 244 };
 245
 246 static void register_types(void)
 247 {
 248     type_register_static(&char_ringbuf_type_info);
 249     type_register_static(&char_memory_type_info);
 250 }
 251
 252 type_init(register_types);