Add kmem_vasprintf function

We might as well have both asprintf() variants.  This allows us
to safely pass a va_list through several levels of the stack
using va_copy() instead of va_start().

2 files changed, 21 insertions, 4 deletions

diff --git a/include/sys/kmem.h b/include/sys/kmem.h
index a5ee4e0df..9688b116d 100644
--- a/include/sys/kmem.h
+++ b/include/sys/kmem.h
@@ -248,6 +248,7 @@ enum {
 #define KMC_DEFAULT_SEEKS		1
 
 extern int kmem_debugging(void);
+extern char *kmem_vasprintf(const char *fmt, va_list ap);
 extern char *kmem_asprintf(const char *fmt, ...);
 #define strfree(str)		kfree(str)
 #define strdup(str)		kstrdup(str, GFP_KERNEL)
diff --git a/module/spl/spl-kmem.c b/module/spl/spl-kmem.c
index 4620eb9bf..a348021d8 100644
--- a/module/spl/spl-kmem.c
+++ b/module/spl/spl-kmem.c
@@ -239,16 +239,32 @@ EXPORT_SYMBOL(kvasprintf);
 #endif /* HAVE_KVASPRINTF */
 
 char *
+kmem_vasprintf(const char *fmt, va_list ap)
+{
+	va_list aq;
+	char *ptr;
+
+	va_copy(aq, ap);
+	do {
+		ptr = kvasprintf(GFP_KERNEL, fmt, aq);
+	} while (ptr == NULL);
+	va_end(aq);
+
+	return ptr;
+}
+EXPORT_SYMBOL(kmem_vasprintf);
+
+char *
 kmem_asprintf(const char *fmt, ...)
 {
-	va_list args;
+	va_list ap;
 	char *ptr;
 
-	va_start(args, fmt);
+	va_start(ap, fmt);
 	do {
-		ptr = kvasprintf(GFP_KERNEL, fmt, args);
+		ptr = kvasprintf(GFP_KERNEL, fmt, ap);
 	} while (ptr == NULL);
-	va_end(args);
+	va_end(ap);
 
 	return ptr;
 }