Clarify the platform.File interface.

- Redefine some memmap.Mappable, platform.File, and platform.Memory
semantics in terms of File reference counts (no functional change).

- Make AddressSpace.MapFile take a platform.File instead of a raw FD,
and replace platform.File.MapInto with platform.File.FD. This allows
kvm.AddressSpace.MapFile to always use platform.File.MapInternal instead
of maintaining its own (redundant) cache of file mappings in the sentry
address space.

PiperOrigin-RevId: 238044504
Change-Id: Ib73a11e4275c0da0126d0194aa6c6017a9cef64f

1 files changed, 2 insertions, 2 deletions

diff --git a/pkg/sentry/platform/ptrace/subprocess.go b/pkg/sentry/platform/ptrace/subprocess.go
index a9d083f5a..82f125073 100644
--- a/pkg/sentry/platform/ptrace/subprocess.go
+++ b/pkg/sentry/platform/ptrace/subprocess.go
@@ -563,7 +563,7 @@ func (s *subprocess) syscall(sysno uintptr, args ...arch.SyscallArgument) (uintp
 }
 
 // MapFile implements platform.AddressSpace.MapFile.
-func (s *subprocess) MapFile(addr usermem.Addr, fd int, fr platform.FileRange, at usermem.AccessType, precommit bool) error {
+func (s *subprocess) MapFile(addr usermem.Addr, f platform.File, fr platform.FileRange, at usermem.AccessType, precommit bool) error {
 	var flags int
 	if precommit {
 		flags |= syscall.MAP_POPULATE
@@ -574,7 +574,7 @@ func (s *subprocess) MapFile(addr usermem.Addr, fd int, fr platform.FileRange, a
 		arch.SyscallArgument{Value: uintptr(fr.Length())},
 		arch.SyscallArgument{Value: uintptr(at.Prot())},
 		arch.SyscallArgument{Value: uintptr(flags | syscall.MAP_SHARED | syscall.MAP_FIXED)},
-		arch.SyscallArgument{Value: uintptr(fd)},
+		arch.SyscallArgument{Value: uintptr(f.FD())},
 		arch.SyscallArgument{Value: uintptr(fr.Start)})
 	return err
 }