[PATCH v7 5/9] Add an implentation of asprintf() for xen

[Paul Durrant <paul.durrant@citrix.com>]

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Keir Fraser <keir@xen.org>
Cc: Tim Deegan <tim@xen.org>
---
 xen/common/vsprintf.c    |   54 ++++++++++++++++++++++++++++++++++++++++++++++
 xen/include/xen/lib.h    |    4 ++++
 xen/include/xen/stdarg.h |    1 +
 3 files changed, 59 insertions(+)

diff --git a/xen/common/vsprintf.c b/xen/common/vsprintf.c
index 8c43282..c4a3962 100644
--- a/xen/common/vsprintf.c
+++ b/xen/common/vsprintf.c
@@ -631,6 +631,60 @@ int scnprintf(char * buf, size_t size, const char *fmt, ...)
 }
 EXPORT_SYMBOL(scnprintf);
 
+/**
+ * vasprintf - Format a string and allocate a buffer to place it in
+ *
+ * @bufp: Pointer to a pointer to receive the allocated buffer
+ * @fmt: The format string to use
+ * @args: Arguments for the format string
+ *
+ * -ENOMEM is returned on failure and @bufp is not touched.
+ * On success, 0 is returned. The buffer passed back is
+ * guaranteed to be null terminated. The memory is allocated
+ * from xenheap, so the buffer should be freed with xfree().
+ */
+int vasprintf(char **bufp, const char *fmt, va_list args)
+{
+    va_list args_copy;
+    size_t size;
+    char *buf, dummy[1];
+
+    va_copy(args_copy, args);
+    size = vsnprintf(dummy, 0, fmt, args_copy);
+    va_end(args_copy);
+
+    buf = xmalloc_array(char, ++size);
+    if ( !buf )
+        return -ENOMEM;
+
+    (void) vsnprintf(buf, size, fmt, args);
+
+    *bufp = buf;
+    return 0;
+}
+
+/**
+ * asprintf - Format a string and place it in a buffer
+ * @bufp: Pointer to a pointer to receive the allocated buffer
+ * @fmt: The format string to use
+ * @...: Arguments for the format string
+ *
+ * -ENOMEM is returned on failure and @bufp is not touched.
+ * On success, 0 is returned. The buffer passed back is
+ * guaranteed to be null terminated. The memory is allocated
+ * from xenheap, so the buffer should be freed with xfree().
+ */
+int asprintf(char **bufp, const char *fmt, ...)
+{
+    va_list args;
+    int i;
+
+    va_start(args, fmt);
+    i=vasprintf(bufp,fmt,args);
+    va_end(args);
+    return i;
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/xen/include/xen/lib.h b/xen/include/xen/lib.h
index 1369b2b..e81b80e 100644
--- a/xen/include/xen/lib.h
+++ b/xen/include/xen/lib.h
@@ -104,6 +104,10 @@ extern int scnprintf(char * buf, size_t size, const char * fmt, ...)
     __attribute__ ((format (printf, 3, 4)));
 extern int vscnprintf(char *buf, size_t size, const char *fmt, va_list args)
     __attribute__ ((format (printf, 3, 0)));
+extern int asprintf(char ** bufp, const char * fmt, ...)
+    __attribute__ ((format (printf, 2, 3)));
+extern int vasprintf(char ** bufp, const char * fmt, va_list args)
+    __attribute__ ((format (printf, 2, 0)));
 
 long simple_strtol(
     const char *cp,const char **endp, unsigned int base);
diff --git a/xen/include/xen/stdarg.h b/xen/include/xen/stdarg.h
index 216fe6d..29249a1 100644
--- a/xen/include/xen/stdarg.h
+++ b/xen/include/xen/stdarg.h
@@ -2,6 +2,7 @@
 #define __XEN_STDARG_H__
 
 typedef __builtin_va_list va_list;
+#define va_copy(dest, src)    __builtin_va_copy((dest), (src))
 #define va_start(ap, last)    __builtin_va_start((ap), (last))
 #define va_end(ap)            __builtin_va_end(ap)
 #define va_arg                __builtin_va_arg
-- 
1.7.10.4