[patch] minimal-malloc.patch

minimal-malloc.patch (text/plain), 2.12 KB, created by Ed Catmur on 2007-06-24 18:50:58 UTC

--- src/Makefile.am	2007/03/19 22:15:22	1.1
+++ src/Makefile.am	2007/03/19 22:28:33
@@ -24,6 +24,7 @@ libsandbox_la_SOURCES = \
 	libsandbox.c      \
 	canonicalize.c    \
 	sandbox_utils.c   \
+	mmalloc.c         \
 	$(LOCAL_INCLUDES)
 
 sandbox_CFLAGS = -DOUTSIDE_LIBSANDBOX
--- src/mmalloc.c	2007/03/19 22:15:16	1.1
+++ src/mmalloc.c	2007/03/19 22:29:00
@@ -0,0 +1,79 @@
+/* Minimal mmap-based malloc/free implementation to be used by libsandbox
+ * internal routines, since we can't trust the current process to have a
+ * malloc/free implementation that is sane and available at all times.
+ */
+
+#include <stdlib.h>   /* malloc()/free() prototypes */
+#include <string.h>   /* mem*(), strdup() prototype */
+#include <sys/mman.h> /* mmap() */
+
+#define SB_MALLOC_TO_MMAP(ptr) ((void*)(((size_t*)ptr) - 1))
+#define SB_MMAP_TO_MALLOC(ptr) ((void*)(((size_t*)ptr) + 1))
+#define SB_MALLOC_TO_SIZE(ptr) (*((size_t*)SB_MALLOC_TO_MMAP(ptr)))
+
+void *malloc(size_t size)
+{
+	size_t *ret;
+	size += sizeof(size_t);
+	ret = mmap(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
+	if (ret == MAP_FAILED)
+		return NULL;
+	*ret = size;
+	return SB_MMAP_TO_MALLOC(ret);
+}
+
+void free(void *ptr)
+{
+	if (ptr == NULL)
+		return;
+	munmap(SB_MALLOC_TO_MMAP(ptr), SB_MALLOC_TO_SIZE(ptr));
+}
+
+void *calloc(size_t nmemb, size_t size)
+{
+	void *ret;
+	size_t malloc_size = nmemb * size;
+	ret = malloc(malloc_size); /* dont care about overflow */
+	if (ret == NULL)
+		return NULL;
+	memset(ret, 0x00, malloc_size);
+	return ret;
+}
+
+void *realloc(void *ptr, size_t size)
+{
+	void *ret;
+	size_t old_malloc_size;
+
+	if (ptr == NULL)
+		return malloc(size);
+	if (size == 0) {
+		free(ptr);
+		return ptr;
+	}
+
+	old_malloc_size = SB_MALLOC_TO_SIZE(ptr);
+	ret = malloc(size);
+	if (ret == NULL)
+		return NULL;
+	memcpy(ret, ptr, (size < old_malloc_size ? size : old_malloc_size));
+	free(ptr);
+	return ret;
+}
+
+#ifdef strdup
+#undef strdup
+#endif
+char *strdup(const char *s)
+{
+	size_t len;
+	char *ret;
+
+	if (s == NULL)
+		return NULL;
+	len = strlen(s);
+	ret = malloc(len + 1);
+	if (ret == NULL)
+		return NULL;
+	memcpy(ret, s, len + 1);
+}