qemu/util/error.c
Markus Armbruster 4b5766488f error: Fix use of error_prepend() with &error_fatal, &error_abort
From include/qapi/error.h:

  * Pass an existing error to the caller with the message modified:
  *     error_propagate(errp, err);
  *     error_prepend(errp, "Could not frobnicate '%s': ", name);

Fei Li pointed out that doing error_propagate() first doesn't work
well when @errp is &error_fatal or &error_abort: the error_prepend()
is never reached.

Since I doubt fixing the documentation will stop people from getting
it wrong, introduce error_propagate_prepend(), in the hope that it
lures people away from using its constituents in the wrong order.
Update the instructions in error.h accordingly.

Convert existing error_prepend() next to error_propagate to
error_propagate_prepend().  If any of these get reached with
&error_fatal or &error_abort, the error messages improve.  I didn't
check whether that's the case anywhere.

Cc: Fei Li <fli@suse.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20181017082702.5581-2-armbru@redhat.com>
2018-10-19 14:51:34 +02:00

308 lines
6.6 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);
g_free((*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 warn_report_err(Error *err)
{
warn_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 warn_reportf_err(Error *err, const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
error_vprepend(&err, fmt, ap);
va_end(ap);
warn_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);
}
}
void error_propagate_prepend(Error **dst_errp, Error *err,
const char *fmt, ...)
{
va_list ap;
if (dst_errp && !*dst_errp) {
va_start(ap, fmt);
error_vprepend(&err, fmt, ap);
va_end(ap);
} /* else error is being ignored, don't bother with prepending */
error_propagate(dst_errp, err);
}