add misc/exparray

misc/exparray.h

@@ -0,0 +1,90 @@
+/**
+ * @file exparray.h
+ * @author Ambroz Bizjak <ambrop7@gmail.com>
+ * 
+ * @section LICENSE
+ * 
+ * This file is part of BadVPN.
+ * 
+ * BadVPN is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ * 
+ * BadVPN is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ * 
+ * @section DESCRIPTION
+ * 
+ * Dynamic array which grows exponentionally on demand.
+ */
+
+#ifndef BADVPN_MISC_EXPARRAY_H
+#define BADVPN_MISC_EXPARRAY_H
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <limits.h>
+
+#include <misc/debug.h>
+
+struct ExpArray {
+    size_t esize;
+    size_t size;
+    void *v;
+};
+
+static int ExpArray_init (struct ExpArray *o, size_t esize, size_t size)
+{
+    ASSERT(esize > 0)
+    ASSERT(size > 0)
+    
+    o->esize = esize;
+    o->size = size;
+    
+    if (o->size > SIZE_MAX / o->esize) {
+        return 0;
+    }
+    
+    if (!(o->v = malloc(o->size * o->esize))) {
+        return 0;
+    }
+    
+    return 1;
+}
+
+static int ExpArray_resize (struct ExpArray *o, size_t size)
+{
+    ASSERT(size > 0)
+    
+    if (size <= o->size) {
+        return 1;
+    }
+    
+    size_t newsize = o->size;
+    
+    while (newsize < size) {
+        if (2 > SIZE_MAX / newsize) {
+            return 0;
+        }
+        
+        newsize = 2 * newsize;
+    }
+    
+    void *newarr = realloc(o->v, newsize * o->esize);
+    if (!newarr) {
+        return 0;
+    }
+    
+    o->size = newsize;
+    o->v = newarr;
+    
+    return 1;
+}
+
+#endif