From 7db196c4dbb33562dbfaa28a9476c590f356b2b5 Mon Sep 17 00:00:00 2001
From: Dean Deng <deandeng@google.com>
Date: Fri, 19 Jun 2020 11:48:24 -0700
Subject: Port fadvise64 to vfs2.

Like vfs1, we have a trivial implementation that ignores all valid advice.

Updates #2923.

PiperOrigin-RevId: 317349505
---
 pkg/sentry/syscalls/linux/vfs2/fd.go | 38 ++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

(limited to 'pkg/sentry/syscalls/linux/vfs2/fd.go')

diff --git a/pkg/sentry/syscalls/linux/vfs2/fd.go b/pkg/sentry/syscalls/linux/vfs2/fd.go
index f5eaa076b..e68b20bed 100644
--- a/pkg/sentry/syscalls/linux/vfs2/fd.go
+++ b/pkg/sentry/syscalls/linux/vfs2/fd.go
@@ -210,3 +210,41 @@ func posixLock(t *kernel.Task, args arch.SyscallArguments, file *vfs.FileDescrip
 		return syserror.EINVAL
 	}
 }
+
+// Fadvise64 implements fadvise64(2).
+// This implementation currently ignores the provided advice.
+func Fadvise64(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	fd := args[0].Int()
+	length := args[2].Int64()
+	advice := args[3].Int()
+
+	// Note: offset is allowed to be negative.
+	if length < 0 {
+		return 0, nil, syserror.EINVAL
+	}
+
+	file := t.GetFileVFS2(fd)
+	if file == nil {
+		return 0, nil, syserror.EBADF
+	}
+	defer file.DecRef()
+
+	// If the FD refers to a pipe or FIFO, return error.
+	if _, isPipe := file.Impl().(*pipe.VFSPipeFD); isPipe {
+		return 0, nil, syserror.ESPIPE
+	}
+
+	switch advice {
+	case linux.POSIX_FADV_NORMAL:
+	case linux.POSIX_FADV_RANDOM:
+	case linux.POSIX_FADV_SEQUENTIAL:
+	case linux.POSIX_FADV_WILLNEED:
+	case linux.POSIX_FADV_DONTNEED:
+	case linux.POSIX_FADV_NOREUSE:
+	default:
+		return 0, nil, syserror.EINVAL
+	}
+
+	// Sure, whatever.
+	return 0, nil, nil
+}
-- 
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