take: new module for parameter ownership.

[ccan] / ccan / take / take.c

diff --git a/ccan/take/take.c b/ccan/take/take.c
new file mode 100644 (file)
index 0000000..73e5c29
--- /dev/null
+++ b/ccan/take/take.c
@@ -0,0 +1,86 @@
+/* CC0 (Public domain) - see LICENSE file for details */
+#include <ccan/take/take.h>
+#include <ccan/likely/likely.h>
+#include <stdlib.h>
+#include <string.h>
+
+static const void **takenarr;
+static size_t max_taken, num_taken;
+static size_t allocfail;
+static void (*allocfailfn)(const void *p);
+
+void *take_(const void *p)
+{
+       if (unlikely(num_taken == max_taken)) {
+               const void **new;
+
+               new = realloc(takenarr, sizeof(*takenarr) * (max_taken+1));
+               if (unlikely(!new)) {
+                       if (allocfailfn) {
+                               allocfail++;
+                               allocfailfn(p);
+                               return NULL;
+                       }
+                       /* Otherwise we leak p. */
+                       return (void *)p;
+               }
+               takenarr = new;
+               max_taken++;
+       }
+       takenarr[num_taken++] = p;
+       return (void *)p;
+}
+
+static size_t find_taken(const void *p)
+{
+       size_t i;
+
+       for (i = 0; i < num_taken; i++) {
+               if (takenarr[i] == p)
+                       return i+1;
+       }
+       return 0;
+}
+
+bool taken(const void *p)
+{
+       size_t i;
+
+       if (!p && unlikely(allocfail)) {
+               allocfail--;
+               return true;
+       }
+
+       i = find_taken(p);
+       if (!i)
+               return false;
+
+       memmove(&takenarr[i-1], &takenarr[i],
+               (--num_taken - (i - 1))*sizeof(takenarr[0]));
+       return true;
+}
+
+bool is_taken(const void *p)
+{
+       if (!p && unlikely(allocfail))
+               return true;
+
+       return find_taken(p) > 0;
+}
+
+bool taken_any(void)
+{
+       return num_taken != 0;
+}
+
+void take_cleanup(void)
+{
+       max_taken = num_taken = 0;
+       free(takenarr);
+       takenarr = NULL;
+}
+
+void take_allocfail(void (*fn)(const void *p))
+{
+       allocfailfn = fn;
+}