Introduce 64 bit integer write interface to xenstore

The current implementation of xen_backend only provides 32 bit integer
functions to write to xenstore. This patch adds two functions that
allow writing 64 bit integers (one generic function and another for
the backend only).

This patch also fixes the size of the char arrays used to represent
these integers as strings (originally 32 bytes, however no more than
12 bytes are needed for 32 bit integers and no more than 21 bytes are
needed for 64 bit integers).
Signed-off-by: NFelipe Franciosi <felipe@paradoxo.org>
Signed-off-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>

hw/xen_backend.c

@@ -85,12 +85,20 @@ char *xenstore_read_str(const char *base, const char *node)
 
 int xenstore_write_int(const char *base, const char *node, int ival)
 {
-    char val[32];
+    char val[12];
 
     snprintf(val, sizeof(val), "%d", ival);
     return xenstore_write_str(base, node, val);
 }
 
+int xenstore_write_int64(const char *base, const char *node, int64_t ival)
+{
+    char val[21];
+
+    snprintf(val, sizeof(val), "%"PRId64, ival);
+    return xenstore_write_str(base, node, val);
+}
+
 int xenstore_read_int(const char *base, const char *node, int *ival)
 {
     char *val;
@@ -114,6 +122,11 @@ int xenstore_write_be_int(struct XenDevice *xendev, const char *node, int ival)
     return xenstore_write_int(xendev->be, node, ival);
 }
 
+int xenstore_write_be_int64(struct XenDevice *xendev, const char *node, int64_t ival)
+{
+    return xenstore_write_int64(xendev->be, node, ival);
+}
+
 char *xenstore_read_be_str(struct XenDevice *xendev, const char *node)
 {
     return xenstore_read_str(xendev->be, node);

hw/xen_backend.h

@@ -63,11 +63,13 @@ extern const char *xen_protocol;
 /* xenstore helper functions */
 int xenstore_write_str(const char *base, const char *node, const char *val);
 int xenstore_write_int(const char *base, const char *node, int ival);
+int xenstore_write_int64(const char *base, const char *node, int64_t ival);
 char *xenstore_read_str(const char *base, const char *node);
 int xenstore_read_int(const char *base, const char *node, int *ival);
 
 int xenstore_write_be_str(struct XenDevice *xendev, const char *node, const char *val);
 int xenstore_write_be_int(struct XenDevice *xendev, const char *node, int ival);
+int xenstore_write_be_int64(struct XenDevice *xendev, const char *node, int64_t ival);
 char *xenstore_read_be_str(struct XenDevice *xendev, const char *node);
 int xenstore_read_be_int(struct XenDevice *xendev, const char *node, int *ival);
 char *xenstore_read_fe_str(struct XenDevice *xendev, const char *node);