qemu/io/channel-buffer.c
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   1/*
   2 * QEMU I/O channels memory buffer driver
   3 *
   4 * Copyright (c) 2015 Red Hat, Inc.
   5 *
   6 * This library is free software; you can redistribute it and/or
   7 * modify it under the terms of the GNU Lesser General Public
   8 * License as published by the Free Software Foundation; either
   9 * version 2 of the License, or (at your option) any later version.
  10 *
  11 * This library is distributed in the hope that it will be useful,
  12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 * Lesser General Public License for more details.
  15 *
  16 * You should have received a copy of the GNU Lesser General Public
  17 * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  18 *
  19 */
  20
  21#include "qemu/osdep.h"
  22#include "io/channel-buffer.h"
  23#include "io/channel-watch.h"
  24#include "qemu/module.h"
  25#include "qemu/sockets.h"
  26#include "trace.h"
  27
  28QIOChannelBuffer *
  29qio_channel_buffer_new(size_t capacity)
  30{
  31    QIOChannelBuffer *ioc;
  32
  33    ioc = QIO_CHANNEL_BUFFER(object_new(TYPE_QIO_CHANNEL_BUFFER));
  34
  35    if (capacity) {
  36        ioc->data = g_new0(uint8_t, capacity);
  37        ioc->capacity = capacity;
  38    }
  39
  40    return ioc;
  41}
  42
  43
  44static void qio_channel_buffer_finalize(Object *obj)
  45{
  46    QIOChannelBuffer *ioc = QIO_CHANNEL_BUFFER(obj);
  47    g_free(ioc->data);
  48    ioc->capacity = ioc->usage = ioc->offset = 0;
  49}
  50
  51
  52static ssize_t qio_channel_buffer_readv(QIOChannel *ioc,
  53                                        const struct iovec *iov,
  54                                        size_t niov,
  55                                        int **fds,
  56                                        size_t *nfds,
  57                                        Error **errp)
  58{
  59    QIOChannelBuffer *bioc = QIO_CHANNEL_BUFFER(ioc);
  60    ssize_t ret = 0;
  61    size_t i;
  62
  63    for (i = 0; i < niov; i++) {
  64        size_t want = iov[i].iov_len;
  65        if (bioc->offset >= bioc->usage) {
  66            break;
  67        }
  68        if ((bioc->offset + want) > bioc->usage)  {
  69            want = bioc->usage - bioc->offset;
  70        }
  71        memcpy(iov[i].iov_base, bioc->data + bioc->offset, want);
  72        ret += want;
  73        bioc->offset += want;
  74    }
  75
  76    return ret;
  77}
  78
  79static ssize_t qio_channel_buffer_writev(QIOChannel *ioc,
  80                                         const struct iovec *iov,
  81                                         size_t niov,
  82                                         int *fds,
  83                                         size_t nfds,
  84                                         Error **errp)
  85{
  86    QIOChannelBuffer *bioc = QIO_CHANNEL_BUFFER(ioc);
  87    ssize_t ret = 0;
  88    size_t i;
  89    size_t towrite = 0;
  90
  91    for (i = 0; i < niov; i++) {
  92        towrite += iov[i].iov_len;
  93    }
  94
  95    if ((bioc->offset + towrite) > bioc->capacity) {
  96        bioc->capacity = bioc->offset + towrite;
  97        bioc->data = g_realloc(bioc->data, bioc->capacity);
  98    }
  99
 100    if (bioc->offset > bioc->usage) {
 101        memset(bioc->data, 0, bioc->offset - bioc->usage);
 102        bioc->usage = bioc->offset;
 103    }
 104
 105    for (i = 0; i < niov; i++) {
 106        memcpy(bioc->data + bioc->usage,
 107               iov[i].iov_base,
 108               iov[i].iov_len);
 109        bioc->usage += iov[i].iov_len;
 110        bioc->offset += iov[i].iov_len;
 111        ret += iov[i].iov_len;
 112    }
 113
 114    return ret;
 115}
 116
 117static int qio_channel_buffer_set_blocking(QIOChannel *ioc G_GNUC_UNUSED,
 118                                           bool enabled G_GNUC_UNUSED,
 119                                           Error **errp G_GNUC_UNUSED)
 120{
 121    return 0;
 122}
 123
 124
 125static off_t qio_channel_buffer_seek(QIOChannel *ioc,
 126                                     off_t offset,
 127                                     int whence,
 128                                     Error **errp)
 129{
 130    QIOChannelBuffer *bioc = QIO_CHANNEL_BUFFER(ioc);
 131
 132    bioc->offset = offset;
 133
 134    return offset;
 135}
 136
 137
 138static int qio_channel_buffer_close(QIOChannel *ioc,
 139                                    Error **errp)
 140{
 141    QIOChannelBuffer *bioc = QIO_CHANNEL_BUFFER(ioc);
 142
 143    g_free(bioc->data);
 144    bioc->data = NULL;
 145    bioc->capacity = bioc->usage = bioc->offset = 0;
 146
 147    return 0;
 148}
 149
 150
 151typedef struct QIOChannelBufferSource QIOChannelBufferSource;
 152struct QIOChannelBufferSource {
 153    GSource parent;
 154    QIOChannelBuffer *bioc;
 155    GIOCondition condition;
 156};
 157
 158static gboolean
 159qio_channel_buffer_source_prepare(GSource *source,
 160                                  gint *timeout)
 161{
 162    QIOChannelBufferSource *bsource = (QIOChannelBufferSource *)source;
 163
 164    *timeout = -1;
 165
 166    return (G_IO_IN | G_IO_OUT) & bsource->condition;
 167}
 168
 169static gboolean
 170qio_channel_buffer_source_check(GSource *source)
 171{
 172    QIOChannelBufferSource *bsource = (QIOChannelBufferSource *)source;
 173
 174    return (G_IO_IN | G_IO_OUT) & bsource->condition;
 175}
 176
 177static gboolean
 178qio_channel_buffer_source_dispatch(GSource *source,
 179                                   GSourceFunc callback,
 180                                   gpointer user_data)
 181{
 182    QIOChannelFunc func = (QIOChannelFunc)callback;
 183    QIOChannelBufferSource *bsource = (QIOChannelBufferSource *)source;
 184
 185    return (*func)(QIO_CHANNEL(bsource->bioc),
 186                   ((G_IO_IN | G_IO_OUT) & bsource->condition),
 187                   user_data);
 188}
 189
 190static void
 191qio_channel_buffer_source_finalize(GSource *source)
 192{
 193    QIOChannelBufferSource *ssource = (QIOChannelBufferSource *)source;
 194
 195    object_unref(OBJECT(ssource->bioc));
 196}
 197
 198GSourceFuncs qio_channel_buffer_source_funcs = {
 199    qio_channel_buffer_source_prepare,
 200    qio_channel_buffer_source_check,
 201    qio_channel_buffer_source_dispatch,
 202    qio_channel_buffer_source_finalize
 203};
 204
 205static GSource *qio_channel_buffer_create_watch(QIOChannel *ioc,
 206                                                GIOCondition condition)
 207{
 208    QIOChannelBuffer *bioc = QIO_CHANNEL_BUFFER(ioc);
 209    QIOChannelBufferSource *ssource;
 210    GSource *source;
 211
 212    source = g_source_new(&qio_channel_buffer_source_funcs,
 213                          sizeof(QIOChannelBufferSource));
 214    ssource = (QIOChannelBufferSource *)source;
 215
 216    ssource->bioc = bioc;
 217    object_ref(OBJECT(bioc));
 218
 219    ssource->condition = condition;
 220
 221    return source;
 222}
 223
 224
 225static void qio_channel_buffer_class_init(ObjectClass *klass,
 226                                          void *class_data G_GNUC_UNUSED)
 227{
 228    QIOChannelClass *ioc_klass = QIO_CHANNEL_CLASS(klass);
 229
 230    ioc_klass->io_writev = qio_channel_buffer_writev;
 231    ioc_klass->io_readv = qio_channel_buffer_readv;
 232    ioc_klass->io_set_blocking = qio_channel_buffer_set_blocking;
 233    ioc_klass->io_seek = qio_channel_buffer_seek;
 234    ioc_klass->io_close = qio_channel_buffer_close;
 235    ioc_klass->io_create_watch = qio_channel_buffer_create_watch;
 236}
 237
 238static const TypeInfo qio_channel_buffer_info = {
 239    .parent = TYPE_QIO_CHANNEL,
 240    .name = TYPE_QIO_CHANNEL_BUFFER,
 241    .instance_size = sizeof(QIOChannelBuffer),
 242    .instance_finalize = qio_channel_buffer_finalize,
 243    .class_init = qio_channel_buffer_class_init,
 244};
 245
 246static void qio_channel_buffer_register_types(void)
 247{
 248    type_register_static(&qio_channel_buffer_info);
 249}
 250
 251type_init(qio_channel_buffer_register_types);
 252