[libvirt] [PATCH 0/2] error: Allow better reporting of errors in some nested cases
Peter Krempa (2): util: error: Add API for prefixing last set error with a string qemu: process: Report better error when virtlogd connection fails cfg.mk | 1 + src/libvirt_private.syms | 1 + src/qemu/qemu_process.c | 4 +++- src/util/virerror.c | 38 ++++++++++++++++++++++++++++++++++++++ src/util/virerror.h | 3 +++ 5 files changed, 46 insertions(+), 1 deletion(-) -- 2.21.0
In some cases we report a low level error message which does not have enough information to see what the problem is. To allow improving on this add an API which will prefix the error message with another error message string which can be used to describe where the error comes from. Signed-off-by: Peter Krempa <pkrempa@redhat.com> --- cfg.mk | 1 + src/libvirt_private.syms | 1 + src/util/virerror.c | 38 ++++++++++++++++++++++++++++++++++++++ src/util/virerror.h | 3 +++ 4 files changed, 43 insertions(+) diff --git a/cfg.mk b/cfg.mk index 5074ef611a..f99b0d0b55 100644 --- a/cfg.mk +++ b/cfg.mk @@ -614,6 +614,7 @@ msg_gen_function += virReportError msg_gen_function += virReportErrorHelper msg_gen_function += virReportSystemError msg_gen_function += xenapiSessionErrorHandler +msg_gen_function += virLastErrorPrefixMessage # Uncomment the following and run "make syntax-check" to see diagnostics # that are not yet marked for translation, but that need to be rewritten diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms index 8ee76645cd..1ded794931 100644 --- a/src/libvirt_private.syms +++ b/src/libvirt_private.syms @@ -1810,6 +1810,7 @@ virErrorPreserveLast; virErrorRestore; virErrorSetErrnoFromLastError; virLastErrorIsSystemErrno; +virLastErrorPrefixMessage; virRaiseErrorFull; virRaiseErrorObject; virReportErrorHelper; diff --git a/src/util/virerror.c b/src/util/virerror.c index 37b5b2f3f9..7c5f4da8e8 100644 --- a/src/util/virerror.c +++ b/src/util/virerror.c @@ -1452,3 +1452,41 @@ bool virLastErrorIsSystemErrno(int errnum) return false; return true; } + + +/** + * virLastErrorPrefixMessage: + * @fmt: printf-style formatting string + * @...: Arguments for @fmt + * + * Prefixes last error reported with message formatted from @fmt. This is useful + * if the low level error message does not convey enough information to describe + * the problem. + */ +void +virLastErrorPrefixMessage(const char *fmt, ...) +{ + int save_errno = errno; + virErrorPtr err = virGetLastError(); + VIR_AUTOFREE(char *) fmtmsg = NULL; + VIR_AUTOFREE(char *) newmsg = NULL; + va_list args; + + if (!err) + return; + + va_start(args, fmt); + + if (virVasprintfQuiet(&fmtmsg, fmt, args) < 0) + goto cleanup; + + if (virAsprintfQuiet(&newmsg, "%s: %s", fmtmsg, err->message) < 0) + goto cleanup; + + VIR_FREE(err->message); + VIR_STEAL_PTR(err->message, newmsg); + + cleanup: + va_end(args); + errno = save_errno; +} diff --git a/src/util/virerror.h b/src/util/virerror.h index 8f51510dc2..ca875fb8f4 100644 --- a/src/util/virerror.h +++ b/src/util/virerror.h @@ -206,6 +206,9 @@ bool virLastErrorIsSystemErrno(int errnum); void virErrorPreserveLast(virErrorPtr *saveerr); void virErrorRestore(virErrorPtr *savederr); +void virLastErrorPrefixMessage(const char *fmt, ...) + ATTRIBUTE_FMT_PRINTF(1, 2); + VIR_DEFINE_AUTOPTR_FUNC(virError, virFreeError); #endif /* LIBVIRT_VIRERROR_H */ -- 2.21.0
When connecting to virtlogd fails e.g. due to wrong libvirtd selinux process label we'd report an utterly useless error message: $ virsh start upstream error: Failed to start domain upstream error: Cannot recv data: Connection reset by peer Use virLastErrorPrefixMessage in the correct place to give a better sense of what's going on: $ virsh start upstream error: Failed to start domain upstream error: can't connect to virtlogd: Cannot recv data: Connection reset by peer Signed-off-by: Peter Krempa <pkrempa@redhat.com> --- src/qemu/qemu_process.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c index 50a76aa0ed..0ac3e0727b 100644 --- a/src/qemu/qemu_process.c +++ b/src/qemu/qemu_process.c @@ -6604,8 +6604,10 @@ qemuProcessLaunch(virConnectPtr conn, VIR_DEBUG("Creating domain log file"); if (!(logCtxt = qemuDomainLogContextNew(driver, vm, - QEMU_DOMAIN_LOG_CONTEXT_MODE_START))) + QEMU_DOMAIN_LOG_CONTEXT_MODE_START))) { + virLastErrorPrefixMessage("%s", _("can't connect to virtlogd")); goto cleanup; + } logfile = qemuDomainLogContextGetWriteFD(logCtxt); if (qemuProcessGenID(vm, flags) < 0) -- 2.21.0
On 6/11/19 2:01 PM, Peter Krempa wrote:
Peter Krempa (2): util: error: Add API for prefixing last set error with a string qemu: process: Report better error when virtlogd connection fails
cfg.mk | 1 + src/libvirt_private.syms | 1 + src/qemu/qemu_process.c | 4 +++- src/util/virerror.c | 38 ++++++++++++++++++++++++++++++++++++++ src/util/virerror.h | 3 +++ 5 files changed, 46 insertions(+), 1 deletion(-)
ACK Michal
participants (2)
-
Michal Privoznik -
Peter Krempa