aboutsummaryrefslogtreecommitdiff
path: root/qga/channel-win32.c
blob: 16bf44a376bd5ce096d6e96d7eedd73f09b939d2 (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
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
#include <stdlib.h>
#include <stdio.h>
#include <stdbool.h>
#include <glib.h>
#include <windows.h>
#include <errno.h>
#include <io.h>
#include "qga/guest-agent-core.h"
#include "qga/channel.h"

typedef struct GAChannelReadState {
    guint thread_id;
    uint8_t *buf;
    size_t buf_size;
    size_t cur; /* current buffer start */
    size_t pending; /* pending buffered bytes to read */
    OVERLAPPED ov;
    bool ov_pending; /* whether on async read is outstanding */
} GAChannelReadState;

struct GAChannel {
    HANDLE handle;
    GAChannelCallback cb;
    gpointer user_data;
    GAChannelReadState rstate;
    GIOCondition pending_events; /* TODO: use GAWatch.pollfd.revents */
    GSource *source;
};

typedef struct GAWatch {
    GSource source;
    GPollFD pollfd;
    GAChannel *channel;
    GIOCondition events_mask;
} GAWatch;

/*
 * Called by glib prior to polling to set up poll events if polling is needed.
 *
 */
static gboolean ga_channel_prepare(GSource *source, gint *timeout_ms)
{
    GAWatch *watch = (GAWatch *)source;
    GAChannel *c = (GAChannel *)watch->channel;
    GAChannelReadState *rs = &c->rstate;
    DWORD count_read, count_to_read = 0;
    bool success;
    GIOCondition new_events = 0;

    g_debug("prepare");
    /* go ahead and submit another read if there's room in the buffer
     * and no previous reads are outstanding
     */
    if (!rs->ov_pending) {
        if (rs->cur + rs->pending >= rs->buf_size) {
            if (rs->cur) {
                memmove(rs->buf, rs->buf + rs->cur, rs->pending);
                rs->cur = 0;
            }
        }
        count_to_read = rs->buf_size - rs->cur - rs->pending;
    }

    if (rs->ov_pending || count_to_read <= 0) {
            goto out;
    }

    /* submit the read */
    success = ReadFile(c->handle, rs->buf + rs->cur + rs->pending,
                       count_to_read, &count_read, &rs->ov);
    if (success) {
        rs->pending += count_read;
        rs->ov_pending = false;
    } else {
        if (GetLastError() == ERROR_IO_PENDING) {
            rs->ov_pending = true;
        } else {
            new_events |= G_IO_ERR;
        }
    }

out:
    /* dont block forever, iterate the main loop every once and a while */
    *timeout_ms = 500;
    /* if there's data in the read buffer, or another event is pending,
     * skip polling and issue user cb.
     */
    if (rs->pending) {
        new_events |= G_IO_IN;
    }
    c->pending_events |= new_events;
    return !!c->pending_events;
}

/*
 * Called by glib after an outstanding read request is completed.
 */
static gboolean ga_channel_check(GSource *source)
{
    GAWatch *watch = (GAWatch *)source;
    GAChannel *c = (GAChannel *)watch->channel;
    GAChannelReadState *rs = &c->rstate;
    DWORD count_read, error;
    BOOL success;

    GIOCondition new_events = 0;

    g_debug("check");

    /* failing this implies we issued a read that completed immediately,
     * yet no data was placed into the buffer (and thus we did not skip
     * polling). but since EOF is not obtainable until we retrieve an
     * overlapped result, it must be the case that there was data placed
     * into the buffer, or an error was generated by Readfile(). in either
     * case, we should've skipped the polling for this round.
     */
    g_assert(rs->ov_pending);

    success = GetOverlappedResult(c->handle, &rs->ov, &count_read, FALSE);
    if (success) {
        g_debug("thread: overlapped result, count_read: %d", (int)count_read);
        rs->pending += count_read;
        new_events |= G_IO_IN;
    } else {
        error = GetLastError();
        if (error == 0 || error == ERROR_HANDLE_EOF ||
            error == ERROR_NO_SYSTEM_RESOURCES ||
            error == ERROR_OPERATION_ABORTED) {
            /* note: On WinXP SP3 with rhel6ga virtio-win-1.1.16 vioser drivers,
             * ENSR seems to be synonymous with when we'd normally expect
             * ERROR_HANDLE_EOF. So treat it as such. Microsoft's
             * recommendation for ERROR_NO_SYSTEM_RESOURCES is to
             * retry the read, so this happens to work out anyway. On newer
             * virtio-win driver, this seems to be replaced with EOA, so
             * handle that in the same fashion.
             */
            new_events |= G_IO_HUP;
        } else if (error != ERROR_IO_INCOMPLETE) {
            g_critical("error retrieving overlapped result: %d", (int)error);
            new_events |= G_IO_ERR;
        }
    }

    if (new_events) {
        rs->ov_pending = 0;
    }
    c->pending_events |= new_events;

    return !!c->pending_events;
}

/*
 * Called by glib after either prepare or check routines signal readiness
 */
static gboolean ga_channel_dispatch(GSource *source, GSourceFunc unused,
                                    gpointer user_data)
{
    GAWatch *watch = (GAWatch *)source;
    GAChannel *c = (GAChannel *)watch->channel;
    GAChannelReadState *rs = &c->rstate;
    gboolean success;

    g_debug("dispatch");
    success = c->cb(watch->pollfd.revents, c->user_data);

    if (c->pending_events & G_IO_ERR) {
        g_critical("channel error, removing source");
        return false;
    }

    /* TODO: replace rs->pending with watch->revents */
    c->pending_events &= ~G_IO_HUP;
    if (!rs->pending) {
        c->pending_events &= ~G_IO_IN;
    } else {
        c->pending_events = 0;
    }
    return success;
}

static void ga_channel_finalize(GSource *source)
{
    g_debug("finalize");
}

GSourceFuncs ga_channel_watch_funcs = {
    ga_channel_prepare,
    ga_channel_check,
    ga_channel_dispatch,
    ga_channel_finalize
};

static GSource *ga_channel_create_watch(GAChannel *c)
{
    GSource *source = g_source_new(&ga_channel_watch_funcs, sizeof(GAWatch));
    GAWatch *watch = (GAWatch *)source;

    watch->channel = c;
    watch->pollfd.fd = (gintptr) c->rstate.ov.hEvent;
    g_source_add_poll(source, &watch->pollfd);

    return source;
}

GIOStatus ga_channel_read(GAChannel *c, char *buf, size_t size, gsize *count)
{
    GAChannelReadState *rs = &c->rstate;
    GIOStatus status;
    size_t to_read = 0;

    if (c->pending_events & G_IO_ERR) {
        return G_IO_STATUS_ERROR;
    }

    *count = to_read = MIN(size, rs->pending);
    if (to_read) {
        memcpy(buf, rs->buf + rs->cur, to_read);
        rs->cur += to_read;
        rs->pending -= to_read;
        status = G_IO_STATUS_NORMAL;
    } else {
        status = G_IO_STATUS_AGAIN;
    }

    return status;
}

static GIOStatus ga_channel_write(GAChannel *c, const char *buf, size_t size,
                                  size_t *count)
{
    GIOStatus status;
    OVERLAPPED ov = {0};
    BOOL ret;
    DWORD written;

    ov.hEvent = CreateEvent(NULL, FALSE, FALSE, NULL);
    ret = WriteFile(c->handle, buf, size, &written, &ov);
    if (!ret) {
        if (GetLastError() == ERROR_IO_PENDING) {
            /* write is pending */
            ret = GetOverlappedResult(c->handle, &ov, &written, TRUE);
            if (!ret) {
                if (!GetLastError()) {
                    status = G_IO_STATUS_AGAIN;
                } else {
                    status = G_IO_STATUS_ERROR;
                }
            } else {
                /* write is complete */
                status = G_IO_STATUS_NORMAL;
                *count = written;
            }
        } else {
            status = G_IO_STATUS_ERROR;
        }
    } else {
        /* write returned immediately */
        status = G_IO_STATUS_NORMAL;
        *count = written;
    }

    if (ov.hEvent) {
        CloseHandle(ov.hEvent);
        ov.hEvent = NULL;
    }
    return status;
}

GIOStatus ga_channel_write_all(GAChannel *c, const char *buf, size_t size)
{
    GIOStatus status = G_IO_STATUS_NORMAL;;
    size_t count;

    while (size) {
        status = ga_channel_write(c, buf, size, &count);
        if (status == G_IO_STATUS_NORMAL) {
            size -= count;
            buf += count;
        } else if (status != G_IO_STATUS_AGAIN) {
            break;
        }
    }

    return status;
}

static gboolean ga_channel_open(GAChannel *c, GAChannelMethod method,
                                const gchar *path)
{
    if (!method == GA_CHANNEL_VIRTIO_SERIAL) {
        g_critical("unsupported communication method");
        return false;
    }

    c->handle = CreateFile(path, GENERIC_READ | GENERIC_WRITE, 0, NULL,
                           OPEN_EXISTING,
                           FILE_FLAG_NO_BUFFERING | FILE_FLAG_OVERLAPPED, NULL);
    if (c->handle == INVALID_HANDLE_VALUE) {
        g_critical("error opening path");
        return false;
    }

    return true;
}

GAChannel *ga_channel_new(GAChannelMethod method, const gchar *path,
                          GAChannelCallback cb, gpointer opaque)
{
    GAChannel *c = g_malloc0(sizeof(GAChannel));
    SECURITY_ATTRIBUTES sec_attrs;

    if (!ga_channel_open(c, method, path)) {
        g_critical("error opening channel");
        g_free(c);
        return NULL;
    }

    c->cb = cb;
    c->user_data = opaque;

    sec_attrs.nLength = sizeof(SECURITY_ATTRIBUTES);
    sec_attrs.lpSecurityDescriptor = NULL;
    sec_attrs.bInheritHandle = false;

    c->rstate.buf_size = QGA_READ_COUNT_DEFAULT;
    c->rstate.buf = g_malloc(QGA_READ_COUNT_DEFAULT);
    c->rstate.ov.hEvent = CreateEvent(&sec_attrs, FALSE, FALSE, NULL);

    c->source = ga_channel_create_watch(c);
    g_source_attach(c->source, NULL);
    return c;
}

void ga_channel_free(GAChannel *c)
{
    if (c->source) {
        g_source_destroy(c->source);
    }
    if (c->rstate.ov.hEvent) {
        CloseHandle(c->rstate.ov.hEvent);
    }
    g_free(c->rstate.buf);
    g_free(c);
}