Add memory pool, also let the user know that libzahl is not designed for cryptography

Signed-off-by: Mattias Andrée <maandree@kth.se>

1 files changed, 41 insertions, 0 deletions

diff --git a/src/allocator.c b/src/allocator.c
new file mode 100644
index 0000000..46cca89
--- /dev/null
+++ b/src/allocator.c
@@ -0,0 +1,41 @@
+/* See LICENSE file for copyright and license details. */
+#include "internals.h"
+
+#include <stdint.h>
+
+
+void
+libzahl_realloc(z_t a, size_t need)
+{
+	size_t i, x;
+	zahl_char_t *new;
+
+	/* Find n such that n is a minimal power of 2 ≥ need. */
+	if ((need & (~need + 1)) != need) {
+		need |= need >> 1;
+		need |= need >> 2;
+		need |= need >> 4;
+		for (i = sizeof(need), x = 8; i; i >>= 1, x <<= 1)
+			need |= need >> x;
+		need += 1;
+	}
+
+	for (i = 0, x = need; x; x >>= 1)
+		i += 1;
+
+	if (libzahl_pool_n[i]) {
+		libzahl_pool_n[i]--;
+		new = libzahl_pool[i][libzahl_pool_n[i]];
+		zmemcpy(new, a->chars, a->alloced);
+		zfree(a);
+		a->chars = new;
+	} else {
+		a->chars = realloc(a->chars, need * sizeof(zahl_char_t));
+		if (!a->chars) {
+			if (!errno) /* sigh... */
+				errno = ENOMEM;
+			FAILURE(errno);
+		}
+	}
+	a->alloced = need;
+}