[PATCH 6/9] libxc: add hypercall buffer arrays

[David Vrabel <david.vrabel@citrix.com>]

From: David Vrabel <david.vrabel@citrix.com>

Hypercall buffer arrays are used when a hypercall takes a variable
length array of buffers.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Tested-by: Daniel Kiper <daniel.kiper@oracle.com>
---
 tools/libxc/xc_hcall_buf.c |   73 ++++++++++++++++++++++++++++++++++++++++++++
 tools/libxc/xenctrl.h      |   27 ++++++++++++++++
 2 files changed, 100 insertions(+), 0 deletions(-)

diff --git a/tools/libxc/xc_hcall_buf.c b/tools/libxc/xc_hcall_buf.c
index c354677..e762a93 100644
--- a/tools/libxc/xc_hcall_buf.c
+++ b/tools/libxc/xc_hcall_buf.c
@@ -228,6 +228,79 @@ void xc__hypercall_bounce_post(xc_interface *xch, xc_hypercall_buffer_t *b)
     xc__hypercall_buffer_free(xch, b);
 }
 
+struct xc_hypercall_buffer_array {
+    unsigned max_bufs;
+    xc_hypercall_buffer_t *bufs;
+};
+
+xc_hypercall_buffer_array_t *xc_hypercall_buffer_array_create(xc_interface *xch,
+                                                              unsigned n)
+{
+    xc_hypercall_buffer_array_t *array;
+    xc_hypercall_buffer_t *bufs = NULL;
+
+    array = malloc(sizeof(*array));
+    if ( array == NULL )
+        goto error;
+
+    bufs = calloc(n, sizeof(*bufs));
+    if ( bufs == NULL )
+        goto error;
+
+    array->max_bufs = n;
+    array->bufs     = bufs;
+
+    return array;
+
+error:
+    free(bufs);
+    free(array);
+    return NULL;
+}
+
+void *xc__hypercall_buffer_array_alloc(xc_interface *xch,
+                                       xc_hypercall_buffer_array_t *array,
+                                       unsigned index,
+                                       xc_hypercall_buffer_t *hbuf,
+                                       size_t size)
+{
+    void *buf;
+
+    if ( index >= array->max_bufs || array->bufs[index].hbuf )
+        abort();
+
+    buf = xc__hypercall_buffer_alloc(xch, hbuf, size);
+    if ( buf )
+        array->bufs[index] = *hbuf;
+    return buf;
+}
+
+void *xc__hypercall_buffer_array_get(xc_interface *xch,
+                                     xc_hypercall_buffer_array_t *array,
+                                     unsigned index,
+                                     xc_hypercall_buffer_t *hbuf)
+{
+    if ( index >= array->max_bufs || array->bufs[index].hbuf == NULL )
+        abort();
+
+    *hbuf = array->bufs[index];
+    return array->bufs[index].hbuf;
+}
+
+void xc_hypercall_buffer_array_destroy(xc_interface *xc,
+                                       xc_hypercall_buffer_array_t *array)
+{
+    unsigned i;
+
+    if ( array == NULL )
+        return;
+
+    for (i = 0; i < array->max_bufs; i++ )
+        xc__hypercall_buffer_free(xc, &array->bufs[i]);
+    free(array->bufs);
+    free(array);
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/tools/libxc/xenctrl.h b/tools/libxc/xenctrl.h
index 58d51f3..1119943 100644
--- a/tools/libxc/xenctrl.h
+++ b/tools/libxc/xenctrl.h
@@ -321,6 +321,33 @@ void xc__hypercall_buffer_free_pages(xc_interface *xch, xc_hypercall_buffer_t *b
 #define xc_hypercall_buffer_free_pages(_xch, _name, _nr) xc__hypercall_buffer_free_pages(_xch, HYPERCALL_BUFFER(_name), _nr)
 
 /*
+ * Array of hypercall buffers.
+ *
+ * Create an array with xc_hypercall_buffer_array_create() and
+ * populate it by declaring one hypercall buffer in a loop and
+ * allocating the buffer with xc_hypercall_buffer_array_alloc().
+ *
+ * To access a previously allocated buffers, declare a new hypercall
+ * buffer and call xc_hypercall_buffer_array_get().
+ *
+ * Destroy the array with xc_hypercall_buffer_array_destroy() to free
+ * the array and all its alocated hypercall buffers.
+ */
+struct xc_hypercall_buffer_array;
+typedef struct xc_hypercall_buffer_array xc_hypercall_buffer_array_t;
+
+xc_hypercall_buffer_array_t *xc_hypercall_buffer_array_create(xc_interface *xch, unsigned n);
+void *xc__hypercall_buffer_array_alloc(xc_interface *xch, xc_hypercall_buffer_array_t *array,
+                                       unsigned index, xc_hypercall_buffer_t *hbuf, size_t size);
+#define xc_hypercall_buffer_array_alloc(_xch, _array, _index, _name, _size) \
+    xc__hypercall_buffer_array_alloc(_xch, _array, _index, HYPERCALL_BUFFER(_name), _size)
+void *xc__hypercall_buffer_array_get(xc_interface *xch, xc_hypercall_buffer_array_t *array,
+                                     unsigned index, xc_hypercall_buffer_t *hbuf);
+#define xc_hypercall_buffer_array_get(_xch, _array, _index, _name, _size) \
+    xc__hypercall_buffer_array_get(_xch, _array, _index, HYPERCALL_BUFFER(_name))
+void xc_hypercall_buffer_array_destroy(xc_interface *xc, xc_hypercall_buffer_array_t *array);
+
+/*
  * CPUMAP handling
  */
 typedef uint8_t *xc_cpumap_t;
-- 
1.7.2.5