qemu/util/error.c
Daniel P. Berrange d59ce6f344 migration: add reporting of errors for outgoing migration
Currently if an application initiates an outgoing migration,
it may or may not, get an error reported back on failure. If
the error occurs synchronously to the 'migrate' command
execution, the client app will see the error message. This
is the case for DNS lookup failures. If the error occurs
asynchronously to the monitor command though, the error
will be thrown away and the client left guessing about
what went wrong. This is the case for failure to connect
to the TCP server (eg due to wrong port, or firewall
rules, or other similar errors).

In the future we'll be adding more scope for errors to
happen asynchronously with the TLS protocol handshake.
TLS errors are hard to diagnose even when they are well
reported, so discarding errors entirely will make it
impossible to debug TLS connection problems.

Management apps which do migration are already using
'query-migrate' / 'info migrate' to check up on progress
of background migration operations and to see their end
status. This is a fine place to also include the error
message when things go wrong.

This patch thus adds an 'error-desc' field to the
MigrationInfo struct, which will be populated when
the 'status' is set to 'failed':

(qemu) migrate -d tcp:localhost:9001
(qemu) info migrate
capabilities: xbzrle: off rdma-pin-all: off auto-converge: off zero-blocks: off compress: off events: off x-postcopy-ram: off
Migration status: failed (Error connecting to socket: Connection refused)
total time: 0 milliseconds

In the HMP, when doing non-detached migration, it is
also possible to display this error message directly
to the app.

(qemu) migrate tcp:localhost:9001
Error connecting to socket: Connection refused

Or with QMP

  {
    "execute": "query-migrate",
    "arguments": {}
  }
  {
    "return": {
      "status": "failed",
      "error-desc": "address resolution failed for myhost:9000: No address associated with hostname"
    }
  }

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Message-Id: <1461751518-12128-11-git-send-email-berrange@redhat.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
2016-05-26 11:31:30 +05:30

274 lines
5.8 KiB
C

/*
* QEMU Error Objects
*
* Copyright IBM, Corp. 2011
* Copyright (C) 2011-2015 Red Hat, Inc.
*
* Authors:
* Anthony Liguori <aliguori@us.ibm.com>
* Markus Armbruster <armbru@redhat.com>,
*
* This work is licensed under the terms of the GNU LGPL, version 2. See
* the COPYING.LIB file in the top-level directory.
*/
#include "qemu/osdep.h"
#include "qapi/error.h"
#include "qemu-common.h"
#include "qemu/error-report.h"
struct Error
{
char *msg;
ErrorClass err_class;
const char *src, *func;
int line;
GString *hint;
};
Error *error_abort;
Error *error_fatal;
static void error_handle_fatal(Error **errp, Error *err)
{
if (errp == &error_abort) {
fprintf(stderr, "Unexpected error in %s() at %s:%d:\n",
err->func, err->src, err->line);
error_report_err(err);
abort();
}
if (errp == &error_fatal) {
error_report_err(err);
exit(1);
}
}
static void error_setv(Error **errp,
const char *src, int line, const char *func,
ErrorClass err_class, const char *fmt, va_list ap,
const char *suffix)
{
Error *err;
int saved_errno = errno;
if (errp == NULL) {
return;
}
assert(*errp == NULL);
err = g_malloc0(sizeof(*err));
err->msg = g_strdup_vprintf(fmt, ap);
if (suffix) {
char *msg = err->msg;
err->msg = g_strdup_printf("%s: %s", msg, suffix);
g_free(msg);
}
err->err_class = err_class;
err->src = src;
err->line = line;
err->func = func;
error_handle_fatal(errp, err);
*errp = err;
errno = saved_errno;
}
void error_set_internal(Error **errp,
const char *src, int line, const char *func,
ErrorClass err_class, const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
error_setv(errp, src, line, func, err_class, fmt, ap, NULL);
va_end(ap);
}
void error_setg_internal(Error **errp,
const char *src, int line, const char *func,
const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
error_setv(errp, src, line, func, ERROR_CLASS_GENERIC_ERROR, fmt, ap, NULL);
va_end(ap);
}
void error_setg_errno_internal(Error **errp,
const char *src, int line, const char *func,
int os_errno, const char *fmt, ...)
{
va_list ap;
int saved_errno = errno;
if (errp == NULL) {
return;
}
va_start(ap, fmt);
error_setv(errp, src, line, func, ERROR_CLASS_GENERIC_ERROR, fmt, ap,
os_errno != 0 ? strerror(os_errno) : NULL);
va_end(ap);
errno = saved_errno;
}
void error_setg_file_open_internal(Error **errp,
const char *src, int line, const char *func,
int os_errno, const char *filename)
{
error_setg_errno_internal(errp, src, line, func, os_errno,
"Could not open '%s'", filename);
}
void error_vprepend(Error **errp, const char *fmt, va_list ap)
{
GString *newmsg;
if (!errp) {
return;
}
newmsg = g_string_new(NULL);
g_string_vprintf(newmsg, fmt, ap);
g_string_append(newmsg, (*errp)->msg);
(*errp)->msg = g_string_free(newmsg, 0);
}
void error_prepend(Error **errp, const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
error_vprepend(errp, fmt, ap);
va_end(ap);
}
void error_append_hint(Error **errp, const char *fmt, ...)
{
va_list ap;
int saved_errno = errno;
Error *err;
if (!errp) {
return;
}
err = *errp;
assert(err && errp != &error_abort && errp != &error_fatal);
if (!err->hint) {
err->hint = g_string_new(NULL);
}
va_start(ap, fmt);
g_string_append_vprintf(err->hint, fmt, ap);
va_end(ap);
errno = saved_errno;
}
#ifdef _WIN32
void error_setg_win32_internal(Error **errp,
const char *src, int line, const char *func,
int win32_err, const char *fmt, ...)
{
va_list ap;
char *suffix = NULL;
if (errp == NULL) {
return;
}
if (win32_err != 0) {
suffix = g_win32_error_message(win32_err);
}
va_start(ap, fmt);
error_setv(errp, src, line, func, ERROR_CLASS_GENERIC_ERROR,
fmt, ap, suffix);
va_end(ap);
g_free(suffix);
}
#endif
Error *error_copy(const Error *err)
{
Error *err_new;
err_new = g_malloc0(sizeof(*err));
err_new->msg = g_strdup(err->msg);
err_new->err_class = err->err_class;
err_new->src = err->src;
err_new->line = err->line;
err_new->func = err->func;
if (err->hint) {
err_new->hint = g_string_new(err->hint->str);
}
return err_new;
}
ErrorClass error_get_class(const Error *err)
{
return err->err_class;
}
const char *error_get_pretty(const Error *err)
{
return err->msg;
}
void error_report_err(Error *err)
{
error_report("%s", error_get_pretty(err));
if (err->hint) {
error_printf_unless_qmp("%s", err->hint->str);
}
error_free(err);
}
void error_reportf_err(Error *err, const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
error_vprepend(&err, fmt, ap);
va_end(ap);
error_report_err(err);
}
void error_free(Error *err)
{
if (err) {
g_free(err->msg);
if (err->hint) {
g_string_free(err->hint, true);
}
g_free(err);
}
}
void error_free_or_abort(Error **errp)
{
assert(errp && *errp);
error_free(*errp);
*errp = NULL;
}
void error_propagate(Error **dst_errp, Error *local_err)
{
if (!local_err) {
return;
}
error_handle_fatal(dst_errp, local_err);
if (dst_errp && !*dst_errp) {
*dst_errp = local_err;
} else {
error_free(local_err);
}
}