Merge release-20200622.1-78-gefa2615eb (automated)

1 files changed, 12 insertions, 3 deletions

diff --git a/pkg/sentry/loader/elf.go b/pkg/sentry/loader/elf.go
index 616fafa2c..ddeaff3db 100644
--- a/pkg/sentry/loader/elf.go
+++ b/pkg/sentry/loader/elf.go
@@ -90,14 +90,23 @@ type elfInfo struct {
 	sharedObject bool
 }
 
+// fullReader interface extracts the ReadFull method from fsbridge.File so that
+// client code does not need to define an entire fsbridge.File when only read
+// functionality is needed.
+//
+// TODO(gvisor.dev/issue/1035): Once VFS2 ships, rewrite this to wrap
+// vfs.FileDescription's PRead/Read instead.
+type fullReader interface {
+	// ReadFull is the same as fsbridge.File.ReadFull.
+	ReadFull(ctx context.Context, dst usermem.IOSequence, offset int64) (int64, error)
+}
+
 // parseHeader parse the ELF header, verifying that this is a supported ELF
 // file and returning the ELF program headers.
 //
 // This is similar to elf.NewFile, except that it is more strict about what it
 // accepts from the ELF, and it doesn't parse unnecessary parts of the file.
-//
-// ctx may be nil if f does not need it.
-func parseHeader(ctx context.Context, f fsbridge.File) (elfInfo, error) {
+func parseHeader(ctx context.Context, f fullReader) (elfInfo, error) {
 	// Check ident first; it will tell us the endianness of the rest of the
 	// structs.
 	var ident [elf.EI_NIDENT]byte