Re: [libvirt] [PATCH 07/14] driver: use normal error reporting APIs when loading modules

[Michal Privoznik]

On 04/19/2018 07:09 PM, Daniel P. Berrangé wrote:
> The driver module loading code is one of the few places that still uses
> VIR_ERROR for reporting failures. Convert it to normal error reporting
> APIs.
> 
> Signed-off-by: Daniel P. Berrangé 
> ---
>  src/driver.c | 34 +++---
>  1 file changed, 27 insertions(+), 7 deletions(-)
> 
> diff --git a/src/driver.c b/src/driver.c
> index e02efe2615..9b137c39e4 100644
> --- a/src/driver.c
> +++ b/src/driver.c
> @@ -33,6 +33,7 @@
>  
>  VIR_LOG_INIT("driver");
>  
> +#define VIR_FROM_THIS VIR_FROM_NONE
>  
>  /* XXX re-implement this for other OS, or use libtools helper lib ? */
>  #define DEFAULT_DRIVER_DIR LIBDIR "/libvirt/connection-driver"
> @@ -55,8 +56,11 @@ virDriverLoadModuleFile(const char *file)
>  
>  virUpdateSelfLastChanged(file);
>  
> -if (!(handle = dlopen(file, flags)))
> -VIR_ERROR(_("failed to load module %s %s"), file, dlerror());
> +if (!(handle = dlopen(file, flags))) {
> +virReportError(VIR_ERR_INTERNAL_ERROR,
> +   _("Failed to load module '%s': %s"), file, dlerror());

Sweet. dlerror() returns 'char *' instead of 'const char *' even though
it's returning a pointer to statically allocated buffer.

> +return NULL;
> +}
>  
>  return handle;
>  }

ACK

Michal

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[libvirt] [PATCH 07/14] driver: use normal error reporting APIs when loading modules

[Daniel P . Berrangé]

The driver module loading code is one of the few places that still uses
VIR_ERROR for reporting failures. Convert it to normal error reporting
APIs.

Signed-off-by: Daniel P. Berrangé 
---
 src/driver.c | 34 +++---
 1 file changed, 27 insertions(+), 7 deletions(-)

diff --git a/src/driver.c b/src/driver.c
index e02efe2615..9b137c39e4 100644
--- a/src/driver.c
+++ b/src/driver.c
@@ -33,6 +33,7 @@
 
 VIR_LOG_INIT("driver");
 
+#define VIR_FROM_THIS VIR_FROM_NONE
 
 /* XXX re-implement this for other OS, or use libtools helper lib ? */
 #define DEFAULT_DRIVER_DIR LIBDIR "/libvirt/connection-driver"
@@ -55,8 +56,11 @@ virDriverLoadModuleFile(const char *file)
 
 virUpdateSelfLastChanged(file);
 
-if (!(handle = dlopen(file, flags)))
-VIR_ERROR(_("failed to load module %s %s"), file, dlerror());
+if (!(handle = dlopen(file, flags))) {
+virReportError(VIR_ERR_INTERNAL_ERROR,
+   _("Failed to load module '%s': %s"), file, dlerror());
+return NULL;
+}
 
 return handle;
 }
@@ -64,14 +68,19 @@ virDriverLoadModuleFile(const char *file)
 
 static void *
 virDriverLoadModuleFunc(void *handle,
+const char *file,
 const char *funcname)
 {
 void *regsym;
 
 VIR_DEBUG("Lookup function '%s'", funcname);
 
-if (!(regsym = dlsym(handle, funcname)))
-VIR_ERROR(_("Missing module registration symbol %s"), funcname);
+if (!(regsym = dlsym(handle, funcname))) {
+virReportError(VIR_ERR_INTERNAL_ERROR,
+   _("Failed to find symbol '%s' in module '%s': %s"),
+   funcname, file, dlerror());
+return NULL;
+}
 
 return regsym;
 }
@@ -108,11 +117,18 @@ virDriverLoadModuleFull(const char *path,
 if (!(rethandle = virDriverLoadModuleFile(path)))
 goto cleanup;
 
-if (!(regsym = virDriverLoadModuleFunc(rethandle, regfunc)))
+if (!(regsym = virDriverLoadModuleFunc(rethandle, path, regfunc)))
 goto cleanup;
 
 if ((*regsym)() < 0) {
-VIR_ERROR(_("Failed module registration %s"), regfunc);
+/* regsym() should report an error itself, but lets
+ * just make sure */
+virErrorPtr err = virGetLastError();
+if (err == NULL) {
+virReportError(VIR_ERR_INTERNAL_ERROR,
+   _("Failed to execute symbol '%s' in module '%s'"),
+   regfunc, path);
+}
 goto cleanup;
 }
 
@@ -131,7 +147,11 @@ virDriverLoadModuleFull(const char *path ATTRIBUTE_UNUSED,
 const char *regfunc ATTRIBUTE_UNUSED)
 {
 VIR_DEBUG("dlopen not available on this platform");
-return -1;
+/* Since we have no dlopen(), but definition we have no
+ * loadable modules on disk, so we can resaonably
+ * return '1' instead of an error.
+ */
+return 1;
 }
 #endif /* ! HAVE_DLFCN_H */
 
-- 
2.14.3

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