Currently, most src/* files have their own ReportError function. Some support printf style arguments, others only allow reporting a single string message. The code for all of them does virtually the same thing, possibly passing a different constant off to another function. The attached patch adds a function to virterror.c which encapsulates the common ReportError logic. I used this to replace qemudReportError with a macro, which also allows passing off filename and line number info if we wanted to do something with it later. I did just the one function conversion to see what people think: if I'm missing something, or ideas for anything else to add. Seems to work as expected in my testing.

+ +/** + * __virReportErrorHelper + * + * @conn: the connection to the hypervisor if available + * @dom: the domain if available + * @net: the network if available + * @domcode: the virErrorDomain indicating where it's coming from + * @errcode: the virErrorNumber code for the error + * @filename: Source file error is dispatched from + * @linenr: Line number error is dispatched from + * @msg: the message to display/transmit + * @...: extra parameters for the message display + * + * Helper function to do most of the grunt work for individual driver ReportError + */ +void __virReportErrorHelper(virConnectPtr conn, virDomainPtr dom, virNetworkPtr net, + int domcode, int errcode, + const char *filename ATTRIBUTE_UNUSED, + long long linenr ATTRIBUTE_UNUSED, + const char *fmt, ...)

+{ + va_list args; + char errorMessage[1024]; + const char *virerr; + + if (fmt) { + va_start(args, fmt); + vsnprintf(errorMessage, sizeof(errorMessage)-1, fmt, args); + va_end(args); + } else { + errorMessage[0] = '\0'; + } + + virerr = __virErrorMsg(errcode, (errorMessage[0] ? errorMessage : NULL)); + __virRaiseError(conn, dom, net, domcode, errcode, VIR_ERR_ERROR, + virerr, errorMessage, NULL, -1, -1, virerr, errorMessage); + +}

Daniel P. Berrange wrote: > On Thu, Oct 02, 2008 at 03:41:21PM -0400, Cole Robinson wrote: >> Currently, most src/* files have their own ReportError >> function. Some support printf style arguments, others >> only allow reporting a single string message. The code >> for all of them does virtually the same thing, possibly >> passing a different constant off to another function. >> >> The attached patch adds a function to virterror.c which >> encapsulates the common ReportError logic. I used this >> to replace qemudReportError with a macro, which also >> allows passing off filename and line number info if >> we wanted to do something with it later. >> >> I did just the one function conversion to see what >> people think: if I'm missing something, or ideas for >> anything else to add. Seems to work as expected in >> my testing. > > > Basically a good idea - we've discussed doing exactly this in the past. > You can do further though, and kill off the 'dom' and 'net' parameters > here too. Those are deprecated and should always be left NULL these > days. Sounds good.

> Likewise passing the filename/linenr is not much use - if a > particular error message wants to include file/line number then they > can be includes as args to the printf fmt string. Hmm, I kind of like the idea of having this info by default, rather than offloading it to the error message. We could for example append filename:lineno to all error messages if debugging is enabled, or stick the data as extra string or int info to RaiseError. I know there have been times when, using virt-manager/ virtinst, libvirt prints some generic lookup error msg, yet nothing seems to fail. It would be nice to get a definitive line number of the culprit just by using LIBVIRT_DEBUG.

On Thu, Oct 02, 2008 at 03:41:21PM -0400, Cole Robinson wrote: > Currently, most src/* files have their own ReportError > function. Some support printf style arguments, others > only allow reporting a single string message. The code > for all of them does virtually the same thing, possibly > passing a different constant off to another function. > > The attached patch adds a function to virterror.c which > encapsulates the common ReportError logic. I used this > to replace qemudReportError with a macro, which also > allows passing off filename and line number info if > we wanted to do something with it later. > > I did just the one function conversion to see what > people think: if I'm missing something, or ideas for > anything else to add. Seems to work as expected in > my testing. Basically a good idea - we've discussed doing exactly this in the past. You can do further though, and kill off the 'dom' and 'net' parameters here too. Those are deprecated and should always be left NULL these days.