Portable aligned memory allocation

CMakeLists.txt

@@ -58,6 +58,8 @@ if(SUPPORT_GZIP)
 	endif()
 endif()
 
+set(LIB_SOURCES ${LIB_SOURCES} src/aligned_malloc.c)
+
 option(SUPPORT_NEAR_OPTIMAL_PARSING "Support near optimal parsing (high compression mode)" ON)
 if(SUPPORT_NEAR_OPTIMAL_PARSING)
 	add_definitions(-DSUPPORT_NEAR_OPTIMAL_PARSING=1)

src/aligned_malloc.c

@@ -0,0 +1,36 @@
+/*
+ * aligned_malloc.c
+ *
+ * Aligned memory allocation using only malloc() and free().
+ * Avoids portability problems with posix_memalign(), aligned_alloc(), etc.
+ *
+ * This file has no copyright assigned and is placed in the Public Domain.
+ */
+
+#include "aligned_malloc.h"
+
+#include <stdint.h>
+#include <stdlib.h>
+
+void *
+aligned_malloc(size_t alignment, size_t size)
+{
+	const uintptr_t mask = alignment - 1;
+	char *ptr = NULL;
+	char *raw_ptr;
+
+	raw_ptr = malloc(mask + sizeof(size_t) + size);
+	if (raw_ptr) {
+		ptr = (char *)raw_ptr + sizeof(size_t);
+		ptr = (void *)(((uintptr_t)ptr + mask) & ~mask);
+		*((size_t *)ptr - 1) = ptr - raw_ptr;
+	}
+	return ptr;
+}
+
+void
+aligned_free(void *ptr)
+{
+	if (ptr)
+		free((char *)ptr - *((size_t *)ptr - 1));
+}

src/aligned_malloc.h

@@ -0,0 +1,14 @@
+/*
+ * aligned_malloc.c
+ *
+ * Aligned memory allocation.
+ *
+ * This file has no copyright assigned and is placed in the Public Domain.
+ */
+
+#pragma once
+
+#include <stddef.h>
+
+extern void *aligned_malloc(size_t alignment, size_t size);
+extern void aligned_free(void *ptr);

src/deflate_compress.c

@@ -10,6 +10,7 @@
 
 #include "libdeflate.h"
 
+#include "aligned_malloc.h"
 #include "deflate_compress.h"
 #include "deflate_constants.h"
 #include "unaligned.h"
@@ -2197,7 +2198,7 @@ deflate_alloc_compressor(unsigned int compression_level)
 #endif
 		size = offsetof(struct deflate_compressor, nonoptimal_end);
 
-	c = aligned_alloc(MATCHFINDER_ALIGNMENT, size);
+	c = aligned_malloc(MATCHFINDER_ALIGNMENT, size);
 	if (!c)
 		return NULL;
 
@@ -2313,7 +2314,7 @@ deflate_compress(struct deflate_compressor *c,
 LIBEXPORT void
 deflate_free_compressor(struct deflate_compressor *c)
 {
-	free(c);
+	aligned_free(c);
 }
 
 unsigned int