[libvirt] [PATCH 2/3] build: drop need for VIR_DOMAIN_DEBUG0()

This one's tricker than the VIR_DEBUG0() removal, but the end result is still C99 compliant, and reasonable with enough comments. * src/libvirt.c (VIR_ARG10, VIR_HAS_COMMA) (VIR_DOMAIN_DEBUG_EXPAND, VIR_DOMAIN_DEBUG_PASTE): New macros. (VIR_DOMAIN_DEBUG): Rewrite to handle one argument, moving multi-argument guts to... (VIR_DOMAIN_DEBUG_1): New macro. (VIR_DOMAIN_DEBUG0): Rename to VIR_DOMAIN_DEBUG_0. --- This one was much tougher, because both fmt and its arguments were optional, and because the expansion does not stick fmt next to __VA_ARGS__. But the end result is still that you can blindly use VIR_DOMAIN_DEBUG with 1 or 3+ arguments, and get the right behavior automagically, instead of having to remember to call a different macro for the 1-arg case. I specifically did not cater to the 2-arg case; that would be easy enough to support, though, if we had a reason for it. src/libvirt.c | 67 +++++++++++++++++++++++++++++++++++++++----------------- 1 files changed, 46 insertions(+), 21 deletions(-) diff --git a/src/libvirt.c b/src/libvirt.c index 13cb74a..79278b9 100644 --- a/src/libvirt.c +++ b/src/libvirt.c @@ -311,10 +311,26 @@ static struct gcry_thread_cbs virTLSThreadImpl = { NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL }; -/* Helper macro to print debugging information about a domain DOM, - * followed by a literal string FMT and any other printf arguments. - */ -#define VIR_DOMAIN_DEBUG(dom, fmt, ...) \ +/* Helper macros to implement VIR_DOMAIN_DEBUG using just C99. This + * assumes you pass fewer than 10 arguments to VIR_DOMAIN_DEBUG, but + * can easily be expanded if needed. */ +#define VIR_ARG10(_1, _2, _3, _4, _5, _6, _7, _8, _9, _10, ...) _10 +#define VIR_HAS_COMMA(...) VIR_ARG10(__VA_ARGS__, 1, 1, 1, 1, 1, 1, 1, 1, 0) + +/* Form the name VIR_DOMAIN_DEBUG_[01], then call that macro, + * according to how many arguments are present. Two-phase due to + * macro expansion rules. */ +#define VIR_DOMAIN_DEBUG_EXPAND(a, b, ...) \ + VIR_DOMAIN_DEBUG_PASTE(a, b, __VA_ARGS__) +#define VIR_DOMAIN_DEBUG_PASTE(a, b, ...) \ + a##b(__VA_ARGS__) + +/* Internal use only, when VIR_DOMAIN_DEBUG has one argument. */ +#define VIR_DOMAIN_DEBUG_0(dom) \ + VIR_DOMAIN_DEBUG_1(dom, "%s", "") + +/* Internal use only, when VIR_DOMAIN_DEBUG has three or more arguments. */ +#define VIR_DOMAIN_DEBUG_1(dom, fmt, ...) \ char _uuidstr[VIR_UUID_STRING_BUFLEN]; \ const char *_domname = NULL; \ \ @@ -328,7 +344,16 @@ static struct gcry_thread_cbs virTLSThreadImpl = { VIR_DEBUG("dom=%p, (VM: name=%s, uuid=%s), " fmt, \ dom, NULLSTR(_domname), _uuidstr, __VA_ARGS__) -#define VIR_DOMAIN_DEBUG0(dom) VIR_DOMAIN_DEBUG(dom, "%s", "") +/** + * VIR_DOMAIN_DEBUG: + * @dom: domain + * @fmt: optional format for additional information + * @...: optional arguments corresponding to @fmt. + */ +#define VIR_DOMAIN_DEBUG(...) \ + VIR_DOMAIN_DEBUG_EXPAND(VIR_DOMAIN_DEBUG_, \ + VIR_HAS_COMMA(__VA_ARGS__), \ + __VA_ARGS__) /** * virInitialize: @@ -1767,7 +1792,7 @@ error: virConnectPtr virDomainGetConnect (virDomainPtr dom) { - VIR_DOMAIN_DEBUG0(dom); + VIR_DOMAIN_DEBUG(dom); virResetLastError(); @@ -2036,7 +2061,7 @@ virDomainDestroy(virDomainPtr domain) { virConnectPtr conn; - VIR_DOMAIN_DEBUG0(domain); + VIR_DOMAIN_DEBUG(domain); virResetLastError(); @@ -2079,7 +2104,7 @@ error: int virDomainFree(virDomainPtr domain) { - VIR_DOMAIN_DEBUG0(domain); + VIR_DOMAIN_DEBUG(domain); virResetLastError(); @@ -2145,7 +2170,7 @@ virDomainSuspend(virDomainPtr domain) { virConnectPtr conn; - VIR_DOMAIN_DEBUG0(domain); + VIR_DOMAIN_DEBUG(domain); virResetLastError(); @@ -2191,7 +2216,7 @@ virDomainResume(virDomainPtr domain) { virConnectPtr conn; - VIR_DOMAIN_DEBUG0(domain); + VIR_DOMAIN_DEBUG(domain); virResetLastError(); @@ -2429,7 +2454,7 @@ virDomainShutdown(virDomainPtr domain) { virConnectPtr conn; - VIR_DOMAIN_DEBUG0(domain); + VIR_DOMAIN_DEBUG(domain); virResetLastError(); @@ -2614,7 +2639,7 @@ error: unsigned int virDomainGetID(virDomainPtr domain) { - VIR_DOMAIN_DEBUG0(domain); + VIR_DOMAIN_DEBUG(domain); virResetLastError(); @@ -2640,7 +2665,7 @@ virDomainGetOSType(virDomainPtr domain) { virConnectPtr conn; - VIR_DOMAIN_DEBUG0(domain); + VIR_DOMAIN_DEBUG(domain); virResetLastError(); @@ -2682,7 +2707,7 @@ virDomainGetMaxMemory(virDomainPtr domain) { virConnectPtr conn; - VIR_DOMAIN_DEBUG0(domain); + VIR_DOMAIN_DEBUG(domain); virResetLastError(); @@ -4923,7 +4948,7 @@ int virDomainUndefine(virDomainPtr domain) { virConnectPtr conn; - VIR_DOMAIN_DEBUG0(domain); + VIR_DOMAIN_DEBUG(domain); virResetLastError(); @@ -5046,7 +5071,7 @@ int virDomainCreate(virDomainPtr domain) { virConnectPtr conn; - VIR_DOMAIN_DEBUG0(domain); + VIR_DOMAIN_DEBUG(domain); virResetLastError(); @@ -5596,7 +5621,7 @@ virDomainGetMaxVcpus(virDomainPtr domain) { virConnectPtr conn; - VIR_DOMAIN_DEBUG0(domain); + VIR_DOMAIN_DEBUG(domain); virResetLastError(); @@ -11661,7 +11686,7 @@ error: */ int virDomainIsPersistent(virDomainPtr dom) { - VIR_DOMAIN_DEBUG0(dom); + VIR_DOMAIN_DEBUG(dom); virResetLastError(); @@ -11694,7 +11719,7 @@ error: */ int virDomainIsUpdated(virDomainPtr dom) { - VIR_DOMAIN_DEBUG0(dom); + VIR_DOMAIN_DEBUG(dom); virResetLastError(); @@ -12633,7 +12658,7 @@ virDomainAbortJob(virDomainPtr domain) { virConnectPtr conn; - VIR_DOMAIN_DEBUG0(domain); + VIR_DOMAIN_DEBUG(domain); virResetLastError(); @@ -13126,7 +13151,7 @@ virDomainSnapshotNum(virDomainPtr domain, unsigned int flags) { virConnectPtr conn; - VIR_DOMAIN_DEBUG0(domain); + VIR_DOMAIN_DEBUG(domain); virResetLastError(); -- 1.7.4.4