split out low-level memory mapping wrappers

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;
+}