split out low-level memory mapping wrappers

Makefile

@@ -2,12 +2,13 @@ CPPFLAGS := -D_GNU_SOURCE
 CFLAGS := -std=c11 -Wall -Wextra -O2 -flto -fPIC -fvisibility=hidden -pedantic
 LDFLAGS := -Wl,--as-needed,-z,defs,-z,relro,-z,now
 LDLIBS := -lpthread
-OBJECTS := chacha.o malloc.o random.o util.o
+OBJECTS := chacha.o malloc.o memory.o random.o util.o
 
 hardened_malloc.so: $(OBJECTS)
 	$(CC) $(CFLAGS) $(LDFLAGS) -shared $^ $(LDLIBS) -o $@
 
-malloc.o: malloc.c malloc.h random.h util.h
+malloc.o: malloc.c malloc.h memory.h random.h util.h
+memory.o: memory.c memory.h util.h
 random.o: random.c random.h chacha.h util.h
 util.o: util.c util.h
 chacha.o: chacha.c chacha.h

malloc.c

@@ -15,6 +15,7 @@
 #include "libdivide.h"
 
 #include "malloc.h"
+#include "memory.h"
 #include "random.h"
 #include "util.h"
 
@@ -28,33 +29,6 @@ static_assert(sizeof(void *) == 8, "64-bit only");
 #define MIN_ALIGN 16
 #define ALIGNMENT_CEILING(s, alignment) (((s) + (alignment - 1)) & ((~(alignment)) + 1))
 
-static void *memory_map(size_t size) {
-    void *p = mmap(NULL, size, PROT_NONE, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
-    if (unlikely(p == MAP_FAILED)) {
-        if (errno != ENOMEM) {
-            fatal_error("non-ENOMEM mmap failure");
-        }
-        return NULL;
-    }
-    return p;
-}
-
-static int memory_unmap(void *ptr, size_t size) {
-    int ret = munmap(ptr, size);
-    if (unlikely(ret) && errno != ENOMEM) {
-        fatal_error("non-ENOMEM munmap failure");
-    }
-    return ret;
-}
-
-static int memory_protect(void *ptr, size_t size, int prot) {
-    int ret = mprotect(ptr, size, prot);
-    if (unlikely(ret) && errno != ENOMEM) {
-        fatal_error("non-ENOMEM mprotect failure");
-    }
-    return ret;
-}
-
 static void *allocate_pages(size_t usable_size, size_t guard_size, bool unprotect) {
     usable_size = PAGE_CEILING(usable_size);
 

memory.c

@@ -0,0 +1,33 @@
+#include <errno.h>
+
+#include <sys/mman.h>
+
+#include "memory.h"
+#include "util.h"
+
+void *memory_map(size_t size) {
+    void *p = mmap(NULL, size, PROT_NONE, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
+    if (unlikely(p == MAP_FAILED)) {
+        if (errno != ENOMEM) {
+            fatal_error("non-ENOMEM mmap failure");
+        }
+        return NULL;
+    }
+    return p;
+}
+
+int memory_unmap(void *ptr, size_t size) {
+    int ret = munmap(ptr, size);
+    if (unlikely(ret) && errno != ENOMEM) {
+        fatal_error("non-ENOMEM munmap failure");
+    }
+    return ret;
+}
+
+int memory_protect(void *ptr, size_t size, int prot) {
+    int ret = mprotect(ptr, size, prot);
+    if (unlikely(ret) && errno != ENOMEM) {
+        fatal_error("non-ENOMEM mprotect failure");
+    }
+    return ret;
+}

memory.h

@@ -0,0 +1,10 @@
+#ifndef MEMORY_H
+#define MEMORY_H
+
+#include <stddef.h>
+
+void *memory_map(size_t size);
+int memory_unmap(void *ptr, size_t size);
+int memory_protect(void *ptr, size_t size, int prot);
+
+#endif