qemu/spice-qemu-char.c
Markus Armbruster 1f51470d04 Revert "qemu-char: Print strerror message on failure" and deps
The commit's purpose is laudable:

    The only way for chardev drivers to communicate an error was to
    return a NULL pointer, which resulted in an error message that
    said _that_ something went wrong, but not _why_.

It attempts to achieve it by changing the interface to return 0/-errno
and update qemu_chr_open_opts() to use strerror() to display a more
helpful error message.  Unfortunately, it has serious flaws:

1. Backends "socket" and "udp" return bogus error codes, because
qemu_chr_open_socket() and qemu_chr_open_udp() assume that
unix_listen_opts(), unix_connect_opts(), inet_listen_opts(),
inet_connect_opts() and inet_dgram_opts() fail with errno set
appropriately.  That assumption is wrong, and the commit turns
unspecific error messages into misleading error messages.  For
instance:

    $ qemu-system-x86_64 -nodefaults -vnc :0 -chardev socket,id=bar,host=xxx
    inet_connect: host and/or port not specified
    chardev: opening backend "socket" failed: No such file or directory

ENOENT is what happens to be in my errno when the backend returns
-errno.  Let's put ERANGE there just for giggles:

    $ qemu-system-x86_64 -nodefaults -vnc :0 -chardev socket,id=bar,host=xxx -drive if=none,iops=99999999999999999999
    inet_connect: host and/or port not specified
    chardev: opening backend "socket" failed: Numerical result out of range

Worse: when errno happens to be zero, return -errno erroneously
signals success, and qemu_chr_new_from_opts() dies dereferencing
uninitialized chr.  I observe this with "-serial unix:".

2. All qemu_chr_open_opts() knows about the error is an errno error
code.  That's simply not enough for a decent message.  For instance,
when inet_dgram() can't resolve the parameter host, which errno code
should it use?  What if it can't resolve parameter localaddr?

Clue: many backends already report errors in their open methods.
Let's revert the flawed commit along with its dependencies, and fix up
the silent error paths instead.

This reverts commit 6e1db57b2a.

Conflicts:

	console.c
	hw/baum.c
	qemu-char.c

This reverts commit aad04cd024.

The parts of commit db418a0a "Add stdio char device on windows" that
depend on the reverted change fixed up.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2012-02-24 09:06:56 -06:00

238 lines
6.7 KiB
C

#include "config-host.h"
#include "trace.h"
#include "ui/qemu-spice.h"
#include <spice.h>
#include <spice-experimental.h>
#include "osdep.h"
#define dprintf(_scd, _level, _fmt, ...) \
do { \
static unsigned __dprintf_counter = 0; \
if (_scd->debug >= _level) { \
fprintf(stderr, "scd: %3d: " _fmt, ++__dprintf_counter, ## __VA_ARGS__);\
} \
} while (0)
#define VMC_MAX_HOST_WRITE 2048
typedef struct SpiceCharDriver {
CharDriverState* chr;
SpiceCharDeviceInstance sin;
char *subtype;
bool active;
uint8_t *buffer;
uint8_t *datapos;
ssize_t bufsize, datalen;
uint32_t debug;
} SpiceCharDriver;
static int vmc_write(SpiceCharDeviceInstance *sin, const uint8_t *buf, int len)
{
SpiceCharDriver *scd = container_of(sin, SpiceCharDriver, sin);
ssize_t out = 0;
ssize_t last_out;
uint8_t* p = (uint8_t*)buf;
while (len > 0) {
last_out = MIN(len, VMC_MAX_HOST_WRITE);
if (qemu_chr_be_can_write(scd->chr) < last_out) {
break;
}
qemu_chr_be_write(scd->chr, p, last_out);
out += last_out;
len -= last_out;
p += last_out;
}
dprintf(scd, 3, "%s: %zu/%zd\n", __func__, out, len + out);
trace_spice_vmc_write(out, len + out);
return out;
}
static int vmc_read(SpiceCharDeviceInstance *sin, uint8_t *buf, int len)
{
SpiceCharDriver *scd = container_of(sin, SpiceCharDriver, sin);
int bytes = MIN(len, scd->datalen);
dprintf(scd, 2, "%s: %p %d/%d/%zd\n", __func__, scd->datapos, len, bytes, scd->datalen);
if (bytes > 0) {
memcpy(buf, scd->datapos, bytes);
scd->datapos += bytes;
scd->datalen -= bytes;
assert(scd->datalen >= 0);
if (scd->datalen == 0) {
scd->datapos = 0;
}
}
trace_spice_vmc_read(bytes, len);
return bytes;
}
static void vmc_state(SpiceCharDeviceInstance *sin, int connected)
{
SpiceCharDriver *scd = container_of(sin, SpiceCharDriver, sin);
#if SPICE_SERVER_VERSION < 0x000901
/*
* spice-server calls the state callback for the agent channel when the
* spice client connects / disconnects. Given that not the client but
* the server is doing the parsing of the messages this is wrong as the
* server is still listening. Worse, this causes the parser in the server
* to go out of sync, so we ignore state calls for subtype vdagent
* spicevmc chardevs. For the full story see:
* http://lists.freedesktop.org/archives/spice-devel/2011-July/004837.html
*/
if (strcmp(sin->subtype, "vdagent") == 0) {
return;
}
#endif
if ((scd->chr->opened && connected) ||
(!scd->chr->opened && !connected)) {
return;
}
qemu_chr_be_event(scd->chr,
connected ? CHR_EVENT_OPENED : CHR_EVENT_CLOSED);
}
static SpiceCharDeviceInterface vmc_interface = {
.base.type = SPICE_INTERFACE_CHAR_DEVICE,
.base.description = "spice virtual channel char device",
.base.major_version = SPICE_INTERFACE_CHAR_DEVICE_MAJOR,
.base.minor_version = SPICE_INTERFACE_CHAR_DEVICE_MINOR,
.state = vmc_state,
.write = vmc_write,
.read = vmc_read,
};
static void vmc_register_interface(SpiceCharDriver *scd)
{
if (scd->active) {
return;
}
dprintf(scd, 1, "%s\n", __func__);
scd->sin.base.sif = &vmc_interface.base;
qemu_spice_add_interface(&scd->sin.base);
scd->active = true;
trace_spice_vmc_register_interface(scd);
}
static void vmc_unregister_interface(SpiceCharDriver *scd)
{
if (!scd->active) {
return;
}
dprintf(scd, 1, "%s\n", __func__);
spice_server_remove_interface(&scd->sin.base);
scd->active = false;
trace_spice_vmc_unregister_interface(scd);
}
static int spice_chr_write(CharDriverState *chr, const uint8_t *buf, int len)
{
SpiceCharDriver *s = chr->opaque;
dprintf(s, 2, "%s: %d\n", __func__, len);
vmc_register_interface(s);
assert(s->datalen == 0);
if (s->bufsize < len) {
s->bufsize = len;
s->buffer = g_realloc(s->buffer, s->bufsize);
}
memcpy(s->buffer, buf, len);
s->datapos = s->buffer;
s->datalen = len;
spice_server_char_device_wakeup(&s->sin);
return len;
}
static void spice_chr_close(struct CharDriverState *chr)
{
SpiceCharDriver *s = chr->opaque;
printf("%s\n", __func__);
vmc_unregister_interface(s);
g_free(s);
}
static void spice_chr_guest_open(struct CharDriverState *chr)
{
SpiceCharDriver *s = chr->opaque;
vmc_register_interface(s);
}
static void spice_chr_guest_close(struct CharDriverState *chr)
{
SpiceCharDriver *s = chr->opaque;
vmc_unregister_interface(s);
}
static void print_allowed_subtypes(void)
{
const char** psubtype;
int i;
fprintf(stderr, "allowed names: ");
for(i=0, psubtype = spice_server_char_device_recognized_subtypes();
*psubtype != NULL; ++psubtype, ++i) {
if (i == 0) {
fprintf(stderr, "%s", *psubtype);
} else {
fprintf(stderr, ", %s", *psubtype);
}
}
fprintf(stderr, "\n");
}
CharDriverState *qemu_chr_open_spice(QemuOpts *opts)
{
CharDriverState *chr;
SpiceCharDriver *s;
const char* name = qemu_opt_get(opts, "name");
uint32_t debug = qemu_opt_get_number(opts, "debug", 0);
const char** psubtype = spice_server_char_device_recognized_subtypes();
const char *subtype = NULL;
if (name == NULL) {
fprintf(stderr, "spice-qemu-char: missing name parameter\n");
print_allowed_subtypes();
return NULL;
}
for(;*psubtype != NULL; ++psubtype) {
if (strcmp(name, *psubtype) == 0) {
subtype = *psubtype;
break;
}
}
if (subtype == NULL) {
fprintf(stderr, "spice-qemu-char: unsupported name\n");
print_allowed_subtypes();
return NULL;
}
chr = g_malloc0(sizeof(CharDriverState));
s = g_malloc0(sizeof(SpiceCharDriver));
s->chr = chr;
s->debug = debug;
s->active = false;
s->sin.subtype = subtype;
chr->opaque = s;
chr->chr_write = spice_chr_write;
chr->chr_close = spice_chr_close;
chr->chr_guest_open = spice_chr_guest_open;
chr->chr_guest_close = spice_chr_guest_close;
#if SPICE_SERVER_VERSION < 0x000901
/* See comment in vmc_state() */
if (strcmp(subtype, "vdagent") == 0) {
qemu_chr_generic_open(chr);
}
#endif
return chr;
}