1 files changed, 124 insertions, 0 deletions
diff --git a/src/util/array.h b/src/util/array.h
new file mode 100644
index 000000000..cbab52ad1
--- /dev/null
+++ b/src/util/array.h
@@ -0,0 +1,124 @@
+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+#ifndef INCLUDE_array_h__
+#define INCLUDE_array_h__
+
+#include "git2_util.h"
+
+/*
+ * Use this to declare a typesafe resizable array of items, a la:
+ *
+ *     git_array_t(int) my_ints = GIT_ARRAY_INIT;
+ *     ...
+ *     int *i = git_array_alloc(my_ints);
+ *     GIT_ERROR_CHECK_ALLOC(i);
+ *     ...
+ *     git_array_clear(my_ints);
+ *
+ * You may also want to do things like:
+ *
+ *     typedef git_array_t(my_struct) my_struct_array_t;
+ */
+#define git_array_t(type) struct { type *ptr; size_t size, asize; }
+
+#define GIT_ARRAY_INIT { NULL, 0, 0 }
+
+#define git_array_init(a) \
+	do { (a).size = (a).asize = 0; (a).ptr = NULL; } while (0)
+
+#define git_array_init_to_size(a, desired) \
+	do { (a).size = 0; (a).asize = desired; (a).ptr = git__calloc(desired, sizeof(*(a).ptr)); } while (0)
+
+#define git_array_clear(a) \
+	do { git__free((a).ptr); git_array_init(a); } while (0)
+
+#define GIT_ERROR_CHECK_ARRAY(a) GIT_ERROR_CHECK_ALLOC((a).ptr)
+
+
+typedef git_array_t(char) git_array_generic_t;
+
+/* use a generic array for growth, return 0 on success */
+GIT_INLINE(int) git_array_grow(void *_a, size_t item_size)
+{
+	volatile git_array_generic_t *a = _a;
+	size_t new_size;
+	char *new_array;
+
+	if (a->size < 8) {
+		new_size = 8;
+	} else {
+		if (GIT_MULTIPLY_SIZET_OVERFLOW(&new_size, a->size, 3))
+			goto on_oom;
+		new_size /= 2;
+	}
+
+	if ((new_array = git__reallocarray(a->ptr, new_size, item_size)) == NULL)
+		goto on_oom;
+
+	a->ptr = new_array;
+	a->asize = new_size;
+	return 0;
+
+on_oom:
+	git_array_clear(*a);
+	return -1;
+}
+
+#define git_array_alloc(a) \
+	(((a).size < (a).asize || git_array_grow(&(a), sizeof(*(a).ptr)) == 0) ? \
+	&(a).ptr[(a).size++] : (void *)NULL)
+
+#define git_array_last(a) ((a).size ? &(a).ptr[(a).size - 1] : (void *)NULL)
+
+#define git_array_pop(a) ((a).size ? &(a).ptr[--(a).size] : (void *)NULL)
+
+#define git_array_get(a, i) (((i) < (a).size) ? &(a).ptr[(i)] : (void *)NULL)
+
+#define git_array_size(a) (a).size
+
+#define git_array_valid_index(a, i) ((i) < (a).size)
+
+#define git_array_foreach(a, i, element) \
+	for ((i) = 0; (i) < (a).size && ((element) = &(a).ptr[(i)]); (i)++)
+
+GIT_INLINE(int) git_array__search(
+	size_t *out,
+	void *array_ptr,
+	size_t item_size,
+	size_t array_len,
+	int (*compare)(const void *, const void *),
+	const void *key)
+{
+	size_t lim;
+	unsigned char *part, *array = array_ptr, *base = array_ptr;
+	int cmp = -1;
+
+	for (lim = array_len; lim != 0; lim >>= 1) {
+		part = base + (lim >> 1) * item_size;
+		cmp = (*compare)(key, part);
+
+		if (cmp == 0) {
+			base = part;
+			break;
+		}
+		if (cmp > 0) { /* key > p; take right partition */
+			base = part + 1 * item_size;
+			lim--;
+		} /* else take left partition */
+	}
+
+	if (out)
+		*out = (base - array) / item_size;
+
+	return (cmp == 0) ? 0 : GIT_ENOTFOUND;
+}
+
+#define git_array_search(out, a, cmp, key) \
+	git_array__search(out, (a).ptr, sizeof(*(a).ptr), (a).size, \
+		(cmp), (key))
+
+#endif