qga/channel-win32.c

   1 #include <stdlib.h>
   2 #include <stdio.h>
   3 #include <stdbool.h>
   4 #include <glib.h>
   5 #include <windows.h>
   6 #include <errno.h>
   7 #include <io.h>
   8 #include "qga/guest-agent-core.h"
   9 #include "qga/channel.h"
  10
  11 typedef struct GAChannelReadState {
  12     guint thread_id;
  13     uint8_t *buf;
  14     size_t buf_size;
  15     size_t cur; /* current buffer start */
  16     size_t pending; /* pending buffered bytes to read */
  17     OVERLAPPED ov;
  18     bool ov_pending; /* whether on async read is outstanding */
  19 } GAChannelReadState;
  20
  21 struct GAChannel {
  22     HANDLE handle;
  23     GAChannelCallback cb;
  24     gpointer user_data;
  25     GAChannelReadState rstate;
  26     GIOCondition pending_events; /* TODO: use GAWatch.pollfd.revents */
  27     GSource *source;
  28 };
  29
  30 typedef struct GAWatch {
  31     GSource source;
  32     GPollFD pollfd;
  33     GAChannel *channel;
  34     GIOCondition events_mask;
  35 } GAWatch;
  36
  37 /*
  38  * Called by glib prior to polling to set up poll events if polling is needed.
  39  *
  40  */
  41 static gboolean ga_channel_prepare(GSource *source, gint *timeout_ms)
  42 {
  43     GAWatch *watch = (GAWatch *)source;
  44     GAChannel *c = (GAChannel *)watch->channel;
  45     GAChannelReadState *rs = &c->rstate;
  46     DWORD count_read, count_to_read = 0;
  47     bool success;
  48     GIOCondition new_events = 0;
  49
  50     g_debug("prepare");
  51     /* go ahead and submit another read if there's room in the buffer
  52      * and no previous reads are outstanding
  53      */
  54     if (!rs->ov_pending) {
  55         if (rs->cur + rs->pending >= rs->buf_size) {
  56             if (rs->cur) {
  57                 memmove(rs->buf, rs->buf + rs->cur, rs->pending);
  58                 rs->cur = 0;
  59             }
  60         }
  61         count_to_read = rs->buf_size - rs->cur - rs->pending;
  62     }
  63
  64     if (rs->ov_pending || count_to_read <= 0) {
  65             goto out;
  66     }
  67
  68     /* submit the read */
  69     success = ReadFile(c->handle, rs->buf + rs->cur + rs->pending,
  70                        count_to_read, &count_read, &rs->ov);
  71     if (success) {
  72         rs->pending += count_read;
  73         rs->ov_pending = false;
  74     } else {
  75         if (GetLastError() == ERROR_IO_PENDING) {
  76             rs->ov_pending = true;
  77         } else {
  78             new_events |= G_IO_ERR;
  79         }
  80     }
  81
  82 out:
  83     /* dont block forever, iterate the main loop every once and a while */
  84     *timeout_ms = 500;
  85     /* if there's data in the read buffer, or another event is pending,
  86      * skip polling and issue user cb.
  87      */
  88     if (rs->pending) {
  89         new_events |= G_IO_IN;
  90     }
  91     c->pending_events |= new_events;
  92     return !!c->pending_events;
  93 }
  94
  95 /*
  96  * Called by glib after an outstanding read request is completed.
  97  */
  98 static gboolean ga_channel_check(GSource *source)
  99 {
 100     GAWatch *watch = (GAWatch *)source;
 101     GAChannel *c = (GAChannel *)watch->channel;
 102     GAChannelReadState *rs = &c->rstate;
 103     DWORD count_read, error;
 104     BOOL success;
 105
 106     GIOCondition new_events = 0;
 107
 108     g_debug("check");
 109
 110     /* failing this implies we issued a read that completed immediately,
 111      * yet no data was placed into the buffer (and thus we did not skip
 112      * polling). but since EOF is not obtainable until we retrieve an
 113      * overlapped result, it must be the case that there was data placed
 114      * into the buffer, or an error was generated by Readfile(). in either
 115      * case, we should've skipped the polling for this round.
 116      */
 117     g_assert(rs->ov_pending);
 118
 119     success = GetOverlappedResult(c->handle, &rs->ov, &count_read, FALSE);
 120     if (success) {
 121         g_debug("thread: overlapped result, count_read: %d", (int)count_read);
 122         rs->pending += count_read;
 123         new_events |= G_IO_IN;
 124     } else {
 125         error = GetLastError();
 126         if (error == 0 || error == ERROR_HANDLE_EOF ||
 127             error == ERROR_NO_SYSTEM_RESOURCES ||
 128             error == ERROR_OPERATION_ABORTED) {
 129             /* note: On WinXP SP3 with rhel6ga virtio-win-1.1.16 vioser drivers,
 130              * ENSR seems to be synonymous with when we'd normally expect
 131              * ERROR_HANDLE_EOF. So treat it as such. Microsoft's
 132              * recommendation for ERROR_NO_SYSTEM_RESOURCES is to
 133              * retry the read, so this happens to work out anyway. On newer
 134              * virtio-win driver, this seems to be replaced with EOA, so
 135              * handle that in the same fashion.
 136              */
 137             new_events |= G_IO_HUP;
 138         } else if (error != ERROR_IO_INCOMPLETE) {
 139             g_critical("error retrieving overlapped result: %d", (int)error);
 140             new_events |= G_IO_ERR;
 141         }
 142     }
 143
 144     if (new_events) {
 145         rs->ov_pending = 0;
 146     }
 147     c->pending_events |= new_events;
 148
 149     return !!c->pending_events;
 150 }
 151
 152 /*
 153  * Called by glib after either prepare or check routines signal readiness
 154  */
 155 static gboolean ga_channel_dispatch(GSource *source, GSourceFunc unused,
 156                                     gpointer user_data)
 157 {
 158     GAWatch *watch = (GAWatch *)source;
 159     GAChannel *c = (GAChannel *)watch->channel;
 160     GAChannelReadState *rs = &c->rstate;
 161     gboolean success;
 162
 163     g_debug("dispatch");
 164     success = c->cb(watch->pollfd.revents, c->user_data);
 165
 166     if (c->pending_events & G_IO_ERR) {
 167         g_critical("channel error, removing source");
 168         return false;
 169     }
 170
 171     /* TODO: replace rs->pending with watch->revents */
 172     c->pending_events &= ~G_IO_HUP;
 173     if (!rs->pending) {
 174         c->pending_events &= ~G_IO_IN;
 175     } else {
 176         c->pending_events = 0;
 177     }
 178     return success;
 179 }
 180
 181 static void ga_channel_finalize(GSource *source)
 182 {
 183     g_debug("finalize");
 184 }
 185
 186 GSourceFuncs ga_channel_watch_funcs = {
 187     ga_channel_prepare,
 188     ga_channel_check,
 189     ga_channel_dispatch,
 190     ga_channel_finalize
 191 };
 192
 193 static GSource *ga_channel_create_watch(GAChannel *c)
 194 {
 195     GSource *source = g_source_new(&ga_channel_watch_funcs, sizeof(GAWatch));
 196     GAWatch *watch = (GAWatch *)source;
 197
 198     watch->channel = c;
 199     watch->pollfd.fd = (gintptr) c->rstate.ov.hEvent;
 200     g_source_add_poll(source, &watch->pollfd);
 201
 202     return source;
 203 }
 204
 205 GIOStatus ga_channel_read(GAChannel *c, char *buf, size_t size, gsize *count)
 206 {
 207     GAChannelReadState *rs = &c->rstate;
 208     GIOStatus status;
 209     size_t to_read = 0;
 210
 211     if (c->pending_events & G_IO_ERR) {
 212         return G_IO_STATUS_ERROR;
 213     }
 214
 215     *count = to_read = MIN(size, rs->pending);
 216     if (to_read) {
 217         memcpy(buf, rs->buf + rs->cur, to_read);
 218         rs->cur += to_read;
 219         rs->pending -= to_read;
 220         status = G_IO_STATUS_NORMAL;
 221     } else {
 222         status = G_IO_STATUS_AGAIN;
 223     }
 224
 225     return status;
 226 }
 227
 228 static GIOStatus ga_channel_write(GAChannel *c, const char *buf, size_t size,
 229                                   size_t *count)
 230 {
 231     GIOStatus status;
 232     OVERLAPPED ov = {0};
 233     BOOL ret;
 234     DWORD written;
 235
 236     ov.hEvent = CreateEvent(NULL, FALSE, FALSE, NULL);
 237     ret = WriteFile(c->handle, buf, size, &written, &ov);
 238     if (!ret) {
 239         if (GetLastError() == ERROR_IO_PENDING) {
 240             /* write is pending */
 241             ret = GetOverlappedResult(c->handle, &ov, &written, TRUE);
 242             if (!ret) {
 243                 if (!GetLastError()) {
 244                     status = G_IO_STATUS_AGAIN;
 245                 } else {
 246                     status = G_IO_STATUS_ERROR;
 247                 }
 248             } else {
 249                 /* write is complete */
 250                 status = G_IO_STATUS_NORMAL;
 251                 *count = written;
 252             }
 253         } else {
 254             status = G_IO_STATUS_ERROR;
 255         }
 256     } else {
 257         /* write returned immediately */
 258         status = G_IO_STATUS_NORMAL;
 259         *count = written;
 260     }
 261
 262     if (ov.hEvent) {
 263         CloseHandle(ov.hEvent);
 264         ov.hEvent = NULL;
 265     }
 266     return status;
 267 }
 268
 269 GIOStatus ga_channel_write_all(GAChannel *c, const char *buf, size_t size)
 270 {
 271     GIOStatus status = G_IO_STATUS_NORMAL;
 272     size_t count;
 273
 274     while (size) {
 275         status = ga_channel_write(c, buf, size, &count);
 276         if (status == G_IO_STATUS_NORMAL) {
 277             size -= count;
 278             buf += count;
 279         } else if (status != G_IO_STATUS_AGAIN) {
 280             break;
 281         }
 282     }
 283
 284     return status;
 285 }
 286
 287 static gboolean ga_channel_open(GAChannel *c, GAChannelMethod method,
 288                                 const gchar *path)
 289 {
 290     if (method != GA_CHANNEL_VIRTIO_SERIAL) {
 291         g_critical("unsupported communication method");
 292         return false;
 293     }
 294
 295     c->handle = CreateFile(path, GENERIC_READ | GENERIC_WRITE, 0, NULL,
 296                            OPEN_EXISTING,
 297                            FILE_FLAG_NO_BUFFERING | FILE_FLAG_OVERLAPPED, NULL);
 298     if (c->handle == INVALID_HANDLE_VALUE) {
 299         g_critical("error opening path");
 300         return false;
 301     }
 302
 303     return true;
 304 }
 305
 306 GAChannel *ga_channel_new(GAChannelMethod method, const gchar *path,
 307                           GAChannelCallback cb, gpointer opaque)
 308 {
 309     GAChannel *c = g_malloc0(sizeof(GAChannel));
 310     SECURITY_ATTRIBUTES sec_attrs;
 311
 312     if (!ga_channel_open(c, method, path)) {
 313         g_critical("error opening channel");
 314         g_free(c);
 315         return NULL;
 316     }
 317
 318     c->cb = cb;
 319     c->user_data = opaque;
 320
 321     sec_attrs.nLength = sizeof(SECURITY_ATTRIBUTES);
 322     sec_attrs.lpSecurityDescriptor = NULL;
 323     sec_attrs.bInheritHandle = false;
 324
 325     c->rstate.buf_size = QGA_READ_COUNT_DEFAULT;
 326     c->rstate.buf = g_malloc(QGA_READ_COUNT_DEFAULT);
 327     c->rstate.ov.hEvent = CreateEvent(&sec_attrs, FALSE, FALSE, NULL);
 328
 329     c->source = ga_channel_create_watch(c);
 330     g_source_attach(c->source, NULL);
 331     return c;
 332 }
 333
 334 void ga_channel_free(GAChannel *c)
 335 {
 336     if (c->source) {
 337         g_source_destroy(c->source);
 338     }
 339     if (c->rstate.ov.hEvent) {
 340         CloseHandle(c->rstate.ov.hEvent);
 341     }
 342     g_free(c->rstate.buf);
 343     g_free(c);
 344 }