From deb2e708cd007a02ffc0f9dd5b65ff55daed38cb Mon Sep 17 00:00:00 2001
From: Drew Galbraith <dgalbraith33@gmail.com>
Date: Sun, 19 Nov 2023 20:35:55 -0800
Subject: [PATCH] [Mammoth] Add a helper method for duplicating memory
 capabilities.

---
 lib/mammoth/include/mammoth/memory_region.h | 3 ++-
 lib/mammoth/src/memory_region.cpp           | 6 ++++++
 sys/victoriafalls/victoriafalls_server.cpp  | 4 +---
 3 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/lib/mammoth/include/mammoth/memory_region.h b/lib/mammoth/include/mammoth/memory_region.h
index de87d6e..c8c1521 100644
--- a/lib/mammoth/include/mammoth/memory_region.h
+++ b/lib/mammoth/include/mammoth/memory_region.h
@@ -53,7 +53,8 @@ class OwnedMemoryRegion {
   uint64_t vaddr() { return vaddr_; }
   uint64_t size() { return size_; }
 
-  uint64_t cap() { return vmmo_cap_; }
+  z_cap_t cap() { return vmmo_cap_; }
+  z_cap_t DuplicateCap();
 
   bool empty() { return vmmo_cap_ != 0; }
   explicit operator bool() { return vmmo_cap_ != 0; }
diff --git a/lib/mammoth/src/memory_region.cpp b/lib/mammoth/src/memory_region.cpp
index e070b03..e4177f8 100644
--- a/lib/mammoth/src/memory_region.cpp
+++ b/lib/mammoth/src/memory_region.cpp
@@ -72,3 +72,9 @@ OwnedMemoryRegion OwnedMemoryRegion::FromCapability(z_cap_t vmmo_cap) {
   // FIXME: get the size here.
   return OwnedMemoryRegion(vmmo_cap, vaddr, size);
 }
+
+z_cap_t OwnedMemoryRegion::DuplicateCap() {
+  z_cap_t cap;
+  check(ZCapDuplicate(vmmo_cap_, kZionPerm_All, &cap));
+  return cap;
+}
diff --git a/sys/victoriafalls/victoriafalls_server.cpp b/sys/victoriafalls/victoriafalls_server.cpp
index 788998c..bf16f2b 100644
--- a/sys/victoriafalls/victoriafalls_server.cpp
+++ b/sys/victoriafalls/victoriafalls_server.cpp
@@ -56,9 +56,7 @@ glcr::ErrorCode VFSServer::HandleOpenFile(const OpenFileRequest& request,
   // FIXME: There isn't really a reason we need to map the file into memory then
   // duplicate the cap. In the future just get the cap from the read then pass
   // it to the caller directly.
-  uint64_t mem_cap;
-  uint64_t cap = ZCapDuplicate(region.cap(), kZionPerm_All, &mem_cap);
-  response.set_memory(mem_cap);
+  response.set_memory(region.DuplicateCap());
   // TODO: Consider folding this up into the actual read call.
   ASSIGN_OR_RETURN(Inode * inode, driver_.GetInode(inode_num));
   // FIXME: This technically only sets the lower 32 bits.