Port most syscalls to VFS2.

pipe and pipe2 aren't ported, pending a slight rework of pipe FDs for VFS2.
mount and umount2 aren't ported out of temporary laziness. access and faccessat
need additional FSImpl methods to implement properly, but are stubbed to
prevent googletest from CHECK-failing. Other syscalls require additional
plumbing.

Updates #1623

PiperOrigin-RevId: 297188448

1 files changed, 8 insertions, 0 deletions

diff --git a/pkg/fspath/builder.go b/pkg/fspath/builder.go
index 7ddb36826..6318d3874 100644
--- a/pkg/fspath/builder.go
+++ b/pkg/fspath/builder.go
@@ -16,6 +16,8 @@ package fspath
 
 import (
 	"fmt"
+
+	"gvisor.dev/gvisor/pkg/gohacks"
 )
 
 // Builder is similar to strings.Builder, but is used to produce pathnames
@@ -102,3 +104,9 @@ func (b *Builder) AppendString(str string) {
 	copy(b.buf[b.start:], b.buf[oldStart:])
 	copy(b.buf[len(b.buf)-len(str):], str)
 }
+
+// String returns the accumulated string. No other methods should be called
+// after String.
+func (b *Builder) String() string {
+	return gohacks.StringFromImmutableBytes(b.buf[b.start:])
+}