From 8277d2aa58fe4f8f3ee394ea647ea652faf822a4 Mon Sep 17 00:00:00 2001 From: Markus Armbruster Date: Fri, 18 Dec 2015 16:35:12 +0100 Subject: 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 Reviewed-by: Eric Blake Message-Id: <1450452927-8346-10-git-send-email-armbru@redhat.com> --- util/error.c | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) (limited to 'util') diff --git a/util/error.c b/util/error.c index ebfb74b02e..57303fd05c 100644 --- a/util/error.c +++ b/util/error.c @@ -122,6 +122,29 @@ void error_setg_file_open_internal(Error **errp, "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; @@ -209,6 +232,16 @@ void error_report_err(Error *err) 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) { -- cgit v1.2.3