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author | Michael Roth <mdroth@linux.vnet.ibm.com> | 2012-01-20 19:01:30 -0600 |
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committer | Michael Roth <mdroth@linux.vnet.ibm.com> | 2012-02-23 15:43:49 -0600 |
commit | 7868e26e5930f49ca942311885776b938dcf3b77 (patch) | |
tree | d1fad8cd6f57209d7812d55dd5fe13d2460a05df /qga/channel-win32.c | |
parent | d8ca685acbd06b5cccd9fcd7866ded1f453b8311 (diff) | |
download | qemu-7868e26e5930f49ca942311885776b938dcf3b77.zip qemu-7868e26e5930f49ca942311885776b938dcf3b77.tar.gz qemu-7868e26e5930f49ca942311885776b938dcf3b77.tar.bz2 |
qemu-ga: add initial win32 support
This adds a win32 channel implementation that makes qemu-ga functional
on Windows using virtio-serial (unix-listen/isa-serial not currently
implemented). Unlike with the posix implementation, we do not use
GIOChannel for the following reasons:
- glib calls stat() on an fd to check whether S_IFCHR is set, which is
the case for virtio-serial on win32. Because of that, a one-time
check to determine whether the channel is readable is done by making
a call to PeekConsoleInput(), which reports the underlying handle is
not a valid console handle, and thus we can never read from the
channel.
- if one goes as far as to "trick" glib into thinking it is a normal
file descripter, the buffering is done in such a way that data
written to the output stream will subsequently result in that same
data being read back as if it were input, causing an error loop.
furthermore, a forced flush of the channel only moves the data into a
secondary buffer managed by glib, so there's no way to prevent output
from getting read back as input.
The implementation here ties into the glib main loop by implementing a
custom GSource that continually submits asynchronous/overlapped I/O to
fill an GAChannel-managed read buffer, and tells glib to poll the
corresponding event handle for a completion whenever there is no
data/RPC in the read buffer to notify the main application about.
Diffstat (limited to 'qga/channel-win32.c')
-rw-r--r-- | qga/channel-win32.c | 340 |
1 files changed, 340 insertions, 0 deletions
diff --git a/qga/channel-win32.c b/qga/channel-win32.c new file mode 100644 index 0000000..190251b --- /dev/null +++ b/qga/channel-win32.c @@ -0,0 +1,340 @@ +#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; + } + + 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); +} |