qemu-patch-raspberry4/util/error.c
Markus Armbruster 8277d2aa58 error: New error_prepend(), error_reportf_err()
Instead of simply propagating an error verbatim, we sometimes want to
add to its message, like this:

    frobnicate(arg, &err);
    error_setg(errp, "Can't frobnicate %s: %s",
                     arg, error_get_pretty(err));
    error_free(err);

This is suboptimal, because it loses err's hint (if any).  Moreover,
when errp is &error_abort or is subsequently propagated to
&error_abort, the abort message points to the place where we last
added to the error, not to the place where it originated.

To avoid these issues, provide means to add to an error's message in
place:

    frobnicate(arg, errp);
    error_prepend(errp, "Can't frobnicate %s: ", arg);

Likewise, reporting an error like

    frobnicate(arg, &err);
    error_report("Can't frobnicate %s: %s", arg, error_get_pretty(err));

can lose err's hint.  To avoid:

    error_reportf_err(err, "Can't frobnicate %s: ", arg);

The next commits will put these functions to use.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <1450452927-8346-10-git-send-email-armbru@redhat.com>
2016-01-13 15:16:17 +01:00

275 lines
5.9 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-common.h"
#include "qapi/error.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)
{
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);
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);
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);
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;
char *msg;
int saved_errno = errno;
if (errp == NULL) {
return;
}
va_start(ap, fmt);
error_setv(errp, src, line, func, ERROR_CLASS_GENERIC_ERROR, fmt, ap);
va_end(ap);
if (os_errno != 0) {
msg = (*errp)->msg;
(*errp)->msg = g_strdup_printf("%s: %s", msg, strerror(os_errno));
g_free(msg);
}
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 *msg1, *msg2;
if (errp == NULL) {
return;
}
va_start(ap, fmt);
error_setv(errp, src, line, func, ERROR_CLASS_GENERIC_ERROR, fmt, ap);
va_end(ap);
if (win32_err != 0) {
msg1 = (*errp)->msg;
msg2 = g_win32_error_message(win32_err);
(*errp)->msg = g_strdup_printf("%s: %s (error: %x)", msg1, msg2,
(unsigned)win32_err);
g_free(msg2);
g_free(msg1);
}
}
#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(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);
}
}