abort() is now called if a heap mapping fails

photon/libc/sys/horizon/heap.c

@@ -1,8 +1,12 @@
 #include <stdint.h>
 #include <stddef.h>
+#include <stdlib.h>
 #include <string.h>
+#include <stdio.h>
 #include <magenta/vmo.h>
 #include <magenta/bootstrap.h>
+#include <magenta/errors.h>
+#include <magenta/misc.h>
 #include <magenta/vmar.h>
 
 #define ROUND_UP(x, b) x += (b) - ((x) % (b))
@@ -56,9 +60,15 @@ void *__crt_heap_extend(size_t sz)
     mx_vmar_bounds(mx_bootstrap_handle_get(MX_B_VMAR_ROOT), &vmar_base, NULL);
     size_t offset = heap_end - vmar_base;
 
-    mx_vmar_map(mx_bootstrap_handle_get(MX_B_VMAR_ROOT),
+    mx_status_t err = mx_vmar_map(mx_bootstrap_handle_get(MX_B_VMAR_ROOT),
             MX_VM_PERM_READ | MX_VM_PERM_WRITE | MX_VM_SPECIFIC,
             offset, heap_vmo, heap_sz, sz, &alloc_base);
+
+    if (err != MX_OK) {
+        printf("cannot map extended heap: %s\n", mx_status_to_string(err));
+        abort();
+    }
+
     heap_sz += sz;
 
     void *out = (void *)heap_end;