From 4b5766488fd3549dc47a75331cf4db62f477536c Mon Sep 17 00:00:00 2001 From: Markus Armbruster Date: Wed, 17 Oct 2018 10:26:25 +0200 Subject: 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 Signed-off-by: Markus Armbruster Reviewed-by: Philippe Mathieu-Daudé Reviewed-by: Eric Blake Message-Id: <20181017082702.5581-2-armbru@redhat.com> --- include/qapi/error.h | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'include/qapi/error.h') diff --git a/include/qapi/error.h b/include/qapi/error.h index bcb86a79f5..51b63dd4b5 100644 --- a/include/qapi/error.h +++ b/include/qapi/error.h @@ -52,8 +52,12 @@ * where Error **errp is a parameter, by convention the last one. * * Pass an existing error to the caller with the message modified: + * error_propagate_prepend(errp, err); + * + * Avoid * error_propagate(errp, err); * error_prepend(errp, "Could not frobnicate '%s': ", name); + * because this fails to prepend when @errp is &error_fatal. * * Create a new error and pass it to the caller: * error_setg(errp, "situation normal, all fouled up"); @@ -215,6 +219,16 @@ void error_setg_win32_internal(Error **errp, */ void error_propagate(Error **dst_errp, Error *local_err); + +/* + * Propagate error object (if any) with some text prepended. + * Behaves like + * error_prepend(&local_err, fmt, ...); + * error_propagate(dst_errp, local_err); + */ +void error_propagate_prepend(Error **dst_errp, Error *local_err, + const char *fmt, ...); + /* * Prepend some text to @errp's human-readable error message. * The text is made by formatting @fmt, @ap like vprintf(). -- cgit v1.2.3-55-g7522