copy mempattern files from Knot DNS as they are

It seems just easier than having the copies in the current way.
I don't think the `static inline` were helping us anyway,
except for avoiding KR_EXPORT in some cases.

Still, differences when copying:
 - we use plain memset() in the implementation
   (no motivation here to use the complex memzero() approach)
 - we expose mm_malloc(), as we've been referring to it
 - we KR_EXPORT some of the functions (for lua and modules)

3 files changed, 177 insertions, 0 deletions

diff --git a/contrib/mempattern.c b/contrib/mempattern.c
new file mode 100644
index 00000000..96715c9e
--- /dev/null
+++ b/contrib/mempattern.c
@@ -0,0 +1,121 @@
+/*  Copyright (C) 2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program 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, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <stdlib.h>
+
+#include "contrib/mempattern.h"
+#include "contrib/ucw/mempool.h"
+
+static void mm_nofree(void *p)
+{
+	/* nop */
+}
+
+void *mm_malloc(void *ctx, size_t n)
+{
+	(void)ctx;
+	return malloc(n);
+}
+
+void *mm_alloc(knot_mm_t *mm, size_t size)
+{
+	if (mm) {
+		return mm->alloc(mm->ctx, size);
+	} else {
+		return malloc(size);
+	}
+}
+
+void *mm_calloc(knot_mm_t *mm, size_t nmemb, size_t size)
+{
+	if (nmemb == 0 || size == 0) {
+		return NULL;
+	}
+	if (mm) {
+		size_t total_size = nmemb * size;
+		if (total_size / nmemb != size) { // Overflow check
+			return NULL;
+		}
+		void *mem = mm_alloc(mm, total_size);
+		if (mem == NULL) {
+			return NULL;
+		}
+		return memset(mem, 0, total_size);
+	} else {
+		return calloc(nmemb, size);
+	}
+}
+
+void *mm_realloc(knot_mm_t *mm, void *what, size_t size, size_t prev_size)
+{
+	if (mm) {
+		void *p = mm->alloc(mm->ctx, size);
+		if (p == NULL) {
+			return NULL;
+		} else {
+			if (what) {
+				memcpy(p, what,
+				       prev_size < size ? prev_size : size);
+			}
+			mm_free(mm, what);
+			return p;
+		}
+	} else {
+		return realloc(what, size);
+	}
+}
+
+char *mm_strdup(knot_mm_t *mm, const char *s)
+{
+	if (s == NULL) {
+		return NULL;
+	}
+	if (mm) {
+		size_t len = strlen(s) + 1;
+		void *mem = mm_alloc(mm, len);
+		if (mem == NULL) {
+			return NULL;
+		}
+		return memcpy(mem, s, len);
+	} else {
+		return strdup(s);
+	}
+}
+
+void mm_free(knot_mm_t *mm, void *what)
+{
+	if (mm) {
+		if (mm->free) {
+			mm->free(what);
+		}
+	} else {
+		free(what);
+	}
+}
+
+void mm_ctx_init(knot_mm_t *mm)
+{
+	mm->ctx = NULL;
+	mm->alloc = mm_malloc;
+	mm->free = free;
+}
+
+void mm_ctx_mempool(knot_mm_t *mm, size_t chunk_size)
+{
+	mm->ctx = mp_new(chunk_size);
+	mm->alloc = (knot_mm_alloc_t)mp_alloc;
+	mm->free = mm_nofree;
+}
diff --git a/contrib/mempattern.h b/contrib/mempattern.h
new file mode 100644
index 00000000..f8ed5c45
--- /dev/null
+++ b/contrib/mempattern.h
@@ -0,0 +1,55 @@
+/*  Copyright (C) 2018 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program 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, see <https://www.gnu.org/licenses/>.
+ */
+
+/*!
+ * \brief Memory allocation related functions.
+ */
+
+#pragma once
+
+#include <libknot/mm_ctx.h>
+#include "lib/defines.h"
+
+/*! \brief Default memory block size. */
+#define MM_DEFAULT_BLKSIZE 4096
+
+/*! \brief Allocs using 'mm' if any, uses system malloc() otherwise. */
+KR_EXPORT
+void *mm_alloc(knot_mm_t *mm, size_t size);
+
+/*! \brief Callocs using 'mm' if any, uses system calloc() otherwise. */
+void *mm_calloc(knot_mm_t *mm, size_t nmemb, size_t size);
+
+/*! \brief Reallocs using 'mm' if any, uses system realloc() otherwise. */
+KR_EXPORT
+void *mm_realloc(knot_mm_t *mm, void *what, size_t size, size_t prev_size);
+
+/*! \brief Strdups using 'mm' if any, uses system strdup() otherwise. */
+char *mm_strdup(knot_mm_t *mm, const char *s);
+
+/*! \brief Free using 'mm' if any, uses system free() otherwise. */
+KR_EXPORT
+void mm_free(knot_mm_t *mm, void *what);
+
+/*! \brief Initialize default memory allocation context. */
+void mm_ctx_init(knot_mm_t *mm);
+
+/*! \brief Memory pool context. */
+void mm_ctx_mempool(knot_mm_t *mm, size_t chunk_size);
+
+/*! \brief Simple malloc wrapper.  Not exposed in knot's mempattern. */
+void *mm_malloc(void *ctx, size_t n);
+
diff --git a/contrib/meson.build b/contrib/meson.build
index effbafda..5d97e889 100644
--- a/contrib/meson.build
+++ b/contrib/meson.build
@@ -6,6 +6,7 @@ contrib_src = files([
   'ccan/json/json.c',
   'ucw/mempool.c',
   'ucw/mempool-fmt.c',
+  'mempattern.c',
   'murmurhash3/murmurhash3.c',
   'base32hex.c',
   'base64.c',