| Message ID | 1524761612-5307-6-git-send-email-ian.jackson@eu.citrix.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 04/26/2018 11:53 AM, Ian Jackson wrote: > This will let us replace more open coded calls to error_report and > strerror. > > I have chosen to provide all of > error_report_errno error_vreport_errno > error_report_errnoval error_vreport_errnoval > because the former are much more common, and deserve a short spelling; > whereas there are still at least 30-40 potential callers of the latter. As mentioned in 2/7, that's inconsistent with error_setg_errno(). I'd MUCH rather see us have JUST error_[v]report_errno with a mandatory error parameter, rather than blindly relying on implicit use of errno; it's not that much harder to write: error_report_errno(errno, "fmt string...", args); in the common case when directly using errno is intended. > > +void error_vreport_errnoval(int errnoval, > + const char *fmt, va_list ap) GCC_FMT_ATTR(2, 0); > +void error_report_errnoval(int errnoval, > + const char *fmt, ...) GCC_FMT_ATTR(2, 3); Bikeshedding - can we name the parameter 'os_error' (as in error_seg_errno), or 'err' or 'errval', rather than the longer 'errnoval'? > +++ b/util/qemu-error.c > @@ -257,6 +257,18 @@ void error_vreport_errno(const char *fmt, va_list ap) > } > > /* > + * Print an error message to current monitor if we have one, else to stderr. > + * Format arguments like vsprintf(). The resulting message should be > + * a single phrase, with no newline or trailing punctuation. > + * Prepend the current location and append ": " strerror(errnoval) "\n". > + * It's wrong to call this in a QMP monitor. Use error_setg() there. > + */ > +void error_vreport_errnoval(int errnoval, const char *fmt, va_list ap) > +{ > + vreport(REPORT_TYPE_ERROR, errnoval, fmt, ap); > +} Should this explicitly document that passing 0 for errnoval is acceptable or forbidden? If acceptable, does that mean no suffix (other than \n) is added? If forbidden, do we want to assert() that?
Eric Blake writes ("Re: [RFC PATCH 5/7] error reporting: Provide error_report_errnoval (and error_vreport_errnoval)"):
> On 04/26/2018 11:53 AM, Ian Jackson wrote:
> > I have chosen to provide all of
> > error_report_errno error_vreport_errno
> > error_report_errnoval error_vreport_errnoval
> > because the former are much more common, and deserve a short spelling;
> > whereas there are still at least 30-40 potential callers of the latter.
>
> As mentioned in 2/7, that's inconsistent with error_setg_errno().
I didn't see error_setg_errno(). But I don't mind your alternative
approach, with the explicit errno, if that's what people prefer. I
agree about the names of the functions, in that case.
> > +void error_vreport_errnoval(int errnoval,
> > + const char *fmt, va_list ap) GCC_FMT_ATTR(2, 0);
> > +void error_report_errnoval(int errnoval,
> > + const char *fmt, ...) GCC_FMT_ATTR(2, 3);
>
> Bikeshedding - can we name the parameter 'os_error' (as in
> error_seg_errno), or 'err' or 'errval', rather than the longer 'errnoval'?
In speech, one always refers to these things as `errno values'.
`os_error' and `errnoval' are the same length of course. See my other
mail about this particular bikeshed.
> Should this explicitly document that passing 0 for errnoval is
> acceptable or forbidden? If acceptable, does that mean no suffix (other
> than \n) is added? If forbidden, do we want to assert() that?
My intend was that passing 0 for errnoval is exactly as permitted or
forbidden as passing 0 to strerror. I think that this is neatly
implied by the specification:
> > + * Prepend the current location and append ": " strerror(errnoval) "\n".
These functions already have a problem with excessive boilerplate in
their language. I'm loathe to make that worse by being other than
terse. I wouldn't mind a note somewhere else.
I would be open to asserting that the value is not negative, because
we do have some of the confusing -errno convention in some of qemu.
OTOH that turns a mishandling of -errno on an error path from a wrong
error message into a crash which is a bit unfortunate.
Ian.
diff --git a/include/qemu/error-report.h b/include/qemu/error-report.h index 2b29678..5178173 100644 --- a/include/qemu/error-report.h +++ b/include/qemu/error-report.h @@ -46,6 +46,11 @@ void error_report_errno(const char *fmt, ...) GCC_FMT_ATTR(1, 2); void warn_report(const char *fmt, ...) GCC_FMT_ATTR(1, 2); void info_report(const char *fmt, ...) GCC_FMT_ATTR(1, 2); +void error_vreport_errnoval(int errnoval, + const char *fmt, va_list ap) GCC_FMT_ATTR(2, 0); +void error_report_errnoval(int errnoval, + const char *fmt, ...) GCC_FMT_ATTR(2, 3); + const char *error_get_progname(void); extern bool enable_timestamp_msg; diff --git a/util/qemu-error.c b/util/qemu-error.c index 428c762..8add1f3 100644 --- a/util/qemu-error.c +++ b/util/qemu-error.c @@ -257,6 +257,18 @@ void error_vreport_errno(const char *fmt, va_list ap) } /* + * Print an error message to current monitor if we have one, else to stderr. + * Format arguments like vsprintf(). The resulting message should be + * a single phrase, with no newline or trailing punctuation. + * Prepend the current location and append ": " strerror(errnoval) "\n". + * It's wrong to call this in a QMP monitor. Use error_setg() there. + */ +void error_vreport_errnoval(int errnoval, const char *fmt, va_list ap) +{ + vreport(REPORT_TYPE_ERROR, errnoval, fmt, ap); +} + +/* * Print a warning message to current monitor if we have one, else to stderr. * Format arguments like vsprintf(). The resulting message should be * a single phrase, with no newline or trailing punctuation. @@ -314,6 +326,22 @@ void error_report_errno(const char *fmt, ...) } /* + * Print an error message to current monitor if we have one, else to stderr. + * Format arguments like sprintf(). The resulting message should be + * a single phrase, with no newline or trailing punctuation. + * Prepend the current location and append ": " strerror(errnoval) "\n". + * It's wrong to call this in a QMP monitor. Use error_setg() there. + */ +void error_report_errnoval(int errnoval, const char *fmt, ...) +{ + va_list ap; + + va_start(ap, fmt); + vreport(REPORT_TYPE_ERROR, errnoval, fmt, ap); + va_end(ap); +} + +/* * Print a warning message to current monitor if we have one, else to stderr. * Format arguments like sprintf(). The resulting message should be a * single phrase, with no newline or trailing punctuation.
This will let us replace more open coded calls to error_report and strerror. I have chosen to provide all of error_report_errno error_vreport_errno error_report_errnoval error_vreport_errnoval because the former are much more common, and deserve a short spelling; whereas there are still at least 30-40 potential callers of the latter. No callers yet so no functional change. Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com> --- include/qemu/error-report.h | 5 +++++ util/qemu-error.c | 28 ++++++++++++++++++++++++++++ 2 files changed, 33 insertions(+)