system/tmpfiles: do not fail for smaller files

The limit is meant to be an upper bound. Handle EOF and print verbose message for it instead of failing.

Signed-off-by: Ophestra <cat@gensokyo.uk>

4 files changed, 218 insertions, 42 deletions

diff --git a/system/dispatcher.go b/system/dispatcher.go
index 038231bb..502c8e92 100644
--- a/system/dispatcher.go
+++ b/system/dispatcher.go
@@ -1,12 +1,20 @@
 package system
 
 import (
+	"io"
+	"io/fs"
 	"os"
 
 	"hakurei.app/system/acl"
 	"hakurei.app/system/dbus"
 )
 
+type osFile interface {
+	Name() string
+	io.Writer
+	fs.File
+}
+
 // syscallDispatcher provides methods that make state-dependent system calls as part of their behaviour.
 // syscallDispatcher is embedded in [I], so all methods must be unexported.
 type syscallDispatcher interface {
@@ -15,6 +23,10 @@ type syscallDispatcher interface {
 	// just synchronising access is not enough, as this is for test instrumentation.
 	new(f func(k syscallDispatcher))
 
+	// stat provides os.Stat.
+	stat(name string) (os.FileInfo, error)
+	// open provides [os.Open].
+	open(name string) (osFile, error)
 	// mkdir provides os.Mkdir.
 	mkdir(name string, perm os.FileMode) error
 	// chmod provides os.Chmod.
@@ -48,6 +60,8 @@ type direct struct{}
 
 func (k direct) new(f func(k syscallDispatcher)) { go f(k) }
 
+func (k direct) stat(name string) (os.FileInfo, error)     { return os.Stat(name) }
+func (k direct) open(name string) (osFile, error)          { return os.Open(name) }
 func (k direct) mkdir(name string, perm os.FileMode) error { return os.Mkdir(name, perm) }
 func (k direct) chmod(name string, mode os.FileMode) error { return os.Chmod(name, mode) }
 func (k direct) link(oldname, newname string) error        { return os.Link(oldname, newname) }
diff --git a/system/dispatcher_test.go b/system/dispatcher_test.go
index 34973879..f798047c 100644
--- a/system/dispatcher_test.go
+++ b/system/dispatcher_test.go
@@ -1,10 +1,13 @@
 package system
 
 import (
+	"io"
+	"io/fs"
 	"os"
 	"reflect"
 	"slices"
 	"testing"
+	"time"
 	"unsafe"
 
 	"hakurei.app/container/stub"
@@ -180,6 +183,34 @@ func checkOpMeta(t *testing.T, testCases []opMetaTestCase) {
 	})
 }
 
+type stubFi struct {
+	size  int64
+	isDir bool
+}
+
+func (stubFi) Name() string       { panic("unreachable") }
+func (fi stubFi) Size() int64     { return fi.size }
+func (stubFi) Mode() fs.FileMode  { panic("unreachable") }
+func (stubFi) ModTime() time.Time { panic("unreachable") }
+func (fi stubFi) IsDir() bool     { return fi.isDir }
+func (stubFi) Sys() any           { panic("unreachable") }
+
+type readerOsFile struct {
+	closed bool
+	io.Reader
+}
+
+func (*readerOsFile) Name() string               { panic("unreachable") }
+func (*readerOsFile) Write([]byte) (int, error)  { panic("unreachable") }
+func (*readerOsFile) Stat() (fs.FileInfo, error) { panic("unreachable") }
+func (r *readerOsFile) Close() error {
+	if r.closed {
+		return os.ErrClosed
+	}
+	r.closed = true
+	return nil
+}
+
 // InternalNew initialises [I] with a stub syscallDispatcher.
 func InternalNew(t *testing.T, want stub.Expect, uid int) (*I, *stub.Stub[syscallDispatcher]) {
 	k := stub.New(t, func(s *stub.Stub[syscallDispatcher]) syscallDispatcher { return &kstub{s} }, want)
@@ -192,6 +223,28 @@ type kstub struct{ *stub.Stub[syscallDispatcher] }
 
 func (k *kstub) new(f func(k syscallDispatcher)) { k.Helper(); k.New(f) }
 
+func (k *kstub) stat(name string) (fi os.FileInfo, err error) {
+	k.Helper()
+	expect := k.Expects("stat")
+	err = expect.Error(
+		stub.CheckArg(k.Stub, "name", name, 0))
+	if err == nil {
+		fi = expect.Ret.(os.FileInfo)
+	}
+	return
+}
+
+func (k *kstub) open(name string) (f osFile, err error) {
+	k.Helper()
+	expect := k.Expects("open")
+	err = expect.Error(
+		stub.CheckArg(k.Stub, "name", name, 0))
+	if err == nil {
+		f = expect.Ret.(osFile)
+	}
+	return
+}
+
 func (k *kstub) mkdir(name string, perm os.FileMode) error {
 	k.Helper()
 	return k.Expects("mkdir").Error(
diff --git a/system/tmpfiles.go b/system/tmpfiles.go
index bd865d44..d2a6c93a 100644
--- a/system/tmpfiles.go
+++ b/system/tmpfiles.go
@@ -28,15 +28,15 @@ type tmpfileOp struct {
 
 func (t *tmpfileOp) Type() Enablement { return Process }
 
-func (t *tmpfileOp) apply(*I) error {
-	msg.Verbose("copying", t)
-
+func (t *tmpfileOp) apply(sys *I) error {
 	if t.payload == nil {
-		// this is a misuse of the API; do not return an error message
+		// this is a misuse of the API; do not return a wrapped error
 		return errors.New("invalid payload")
 	}
 
-	if b, err := os.Stat(t.src); err != nil {
+	sys.verbose("copying", t)
+
+	if b, err := sys.stat(t.src); err != nil {
 		return newOpError("tmpfile", err, false)
 	} else {
 		if b.IsDir() {
@@ -47,9 +47,20 @@ func (t *tmpfileOp) apply(*I) error {
 		}
 	}
 
-	if f, err := os.Open(t.src); err != nil {
+	var r io.ReadCloser
+	if f, err := sys.open(t.src); err != nil {
 		return newOpError("tmpfile", err, false)
-	} else if _, err = io.CopyN(t.buf, f, t.n); err != nil {
+	} else {
+		r = f
+	}
+	if n, err := io.CopyN(t.buf, r, t.n); err != nil {
+		if !errors.Is(err, io.EOF) {
+			_ = r.Close()
+			return newOpError("tmpfile", err, false)
+		}
+		sys.verbosef("copied %d bytes from %q", n, t.src)
+	}
+	if err := r.Close(); err != nil {
 		return newOpError("tmpfile", err, false)
 	}
 
diff --git a/system/tmpfiles_test.go b/system/tmpfiles_test.go
index a06242ee..5ee5e0d1 100644
--- a/system/tmpfiles_test.go
+++ b/system/tmpfiles_test.go
@@ -1,44 +1,142 @@
 package system
 
 import (
-	"strconv"
+	"bytes"
+	"errors"
+	"os"
+	"strings"
+	"syscall"
 	"testing"
+
+	"hakurei.app/container/stub"
 )
 
-func TestCopyFile(t *testing.T) {
-	testCases := []struct {
-		tcOp
-		cap int
-		n   int64
-	}{
-		{tcOp{Process, "/home/ophestra/xdg/config/pulse/cookie"}, 256, 256},
-	}
-	for _, tc := range testCases {
-		t.Run("copy file "+tc.path+" with cap = "+strconv.Itoa(tc.cap)+" n = "+strconv.Itoa(int(tc.n)), func(t *testing.T) {
-			sys := New(t.Context(), 150)
-			sys.CopyFile(new([]byte), tc.path, tc.cap, tc.n)
-			tc.test(t, sys.ops, []Op{
-				&tmpfileOp{nil, tc.path, tc.n, nil},
-			}, "CopyFile")
-		})
-	}
-}
+type errorReader struct{}
 
-func TestTmpfile_String(t *testing.T) {
-	testCases := []struct {
-		src  string
-		n    int64
-		want string
-	}{
-		{"/home/ophestra/xdg/config/pulse/cookie", 256,
-			`up to 256 bytes from "/home/ophestra/xdg/config/pulse/cookie"`},
-	}
+func (errorReader) Read([]byte) (int, error) { return 0, stub.UniqueError(0xdeadbeef) }
+
+func TestTmpfileOp(t *testing.T) {
+	// 255 bytes
+	const paSample = "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
+
+	checkOpBehaviour(t, []opBehaviourTestCase{
+		{"payload", 0xdead, 0xff, &tmpfileOp{
+			nil, "/home/ophestra/xdg/config/pulse/cookie", 1 << 8,
+			func() *bytes.Buffer { buf := new(bytes.Buffer); buf.Grow(1 << 8); return buf }(),
+		}, nil, errors.New("invalid payload"), nil, nil},
+
+		{"stat", 0xdead, 0xff, &tmpfileOp{
+			new([]byte), "/home/ophestra/xdg/config/pulse/cookie", 1 << 8,
+			func() *bytes.Buffer { buf := new(bytes.Buffer); buf.Grow(1 << 8); return buf }(),
+		}, []stub.Call{
+			call("verbose", stub.ExpectArgs{[]any{"copying", &tmpfileOp{new([]byte), "/home/ophestra/xdg/config/pulse/cookie", 1 << 8, func() *bytes.Buffer { buf := new(bytes.Buffer); buf.Grow(1 << 8); return buf }()}}}, nil, nil),
+			call("stat", stub.ExpectArgs{"/home/ophestra/xdg/config/pulse/cookie"}, nil, stub.UniqueError(1)),
+		}, &OpError{Op: "tmpfile", Err: stub.UniqueError(1)}, nil, nil},
+
+		{"stat EISDIR", 0xdead, 0xff, &tmpfileOp{
+			new([]byte), "/home/ophestra/xdg/config/pulse/cookie", 1 << 8,
+			func() *bytes.Buffer { buf := new(bytes.Buffer); buf.Grow(1 << 8); return buf }(),
+		}, []stub.Call{
+			call("verbose", stub.ExpectArgs{[]any{"copying", &tmpfileOp{new([]byte), "/home/ophestra/xdg/config/pulse/cookie", 1 << 8, func() *bytes.Buffer { buf := new(bytes.Buffer); buf.Grow(1 << 8); return buf }()}}}, nil, nil),
+			call("stat", stub.ExpectArgs{"/home/ophestra/xdg/config/pulse/cookie"}, stubFi{1 << 8, true}, nil),
+		}, &OpError{Op: "tmpfile", Err: &os.PathError{Op: "stat", Path: "/home/ophestra/xdg/config/pulse/cookie", Err: syscall.EISDIR}}, nil, nil},
+
+		{"stat ENOMEM", 0xdead, 0xff, &tmpfileOp{
+			new([]byte), "/home/ophestra/xdg/config/pulse/cookie", 1 << 8,
+			func() *bytes.Buffer { buf := new(bytes.Buffer); buf.Grow(1 << 8); return buf }(),
+		}, []stub.Call{
+			call("verbose", stub.ExpectArgs{[]any{"copying", &tmpfileOp{new([]byte), "/home/ophestra/xdg/config/pulse/cookie", 1 << 8, func() *bytes.Buffer { buf := new(bytes.Buffer); buf.Grow(1 << 8); return buf }()}}}, nil, nil),
+			call("stat", stub.ExpectArgs{"/home/ophestra/xdg/config/pulse/cookie"}, stubFi{1<<8 + 1, false}, nil),
+		}, &OpError{Op: "tmpfile", Err: &os.PathError{Op: "stat", Path: "/home/ophestra/xdg/config/pulse/cookie", Err: syscall.ENOMEM}}, nil, nil},
+
+		{"open", 0xdead, 0xff, &tmpfileOp{
+			new([]byte), "/home/ophestra/xdg/config/pulse/cookie", 1 << 8,
+			func() *bytes.Buffer { buf := new(bytes.Buffer); buf.Grow(1 << 8); return buf }(),
+		}, []stub.Call{
+			call("verbose", stub.ExpectArgs{[]any{"copying", &tmpfileOp{new([]byte), "/home/ophestra/xdg/config/pulse/cookie", 1 << 8, func() *bytes.Buffer { buf := new(bytes.Buffer); buf.Grow(1 << 8); return buf }()}}}, nil, nil),
+			call("stat", stub.ExpectArgs{"/home/ophestra/xdg/config/pulse/cookie"}, stubFi{1 << 8, false}, nil),
+			call("open", stub.ExpectArgs{"/home/ophestra/xdg/config/pulse/cookie"}, nil, stub.UniqueError(0)),
+		}, &OpError{Op: "tmpfile", Err: stub.UniqueError(0)}, nil, nil},
+
+		{"reader", 0xdead, 0xff, &tmpfileOp{
+			new([]byte), "/home/ophestra/xdg/config/pulse/cookie", 1 << 8,
+			func() *bytes.Buffer { buf := new(bytes.Buffer); buf.Grow(1 << 8); return buf }(),
+		}, []stub.Call{
+			call("verbose", stub.ExpectArgs{[]any{"copying", &tmpfileOp{new([]byte), "/home/ophestra/xdg/config/pulse/cookie", 1 << 8, func() *bytes.Buffer { buf := new(bytes.Buffer); buf.Grow(1 << 8); return buf }()}}}, nil, nil),
+			call("stat", stub.ExpectArgs{"/home/ophestra/xdg/config/pulse/cookie"}, stubFi{1 << 8, false}, nil),
+			call("open", stub.ExpectArgs{"/home/ophestra/xdg/config/pulse/cookie"}, &readerOsFile{true, errorReader{}}, nil),
+		}, &OpError{Op: "tmpfile", Err: stub.UniqueError(0xdeadbeef)}, nil, nil},
 
-	for _, tc := range testCases {
-		t.Run(tc.want, func(t *testing.T) {
-			if got := (&tmpfileOp{src: tc.src, n: tc.n}).String(); got != tc.want {
-				t.Errorf("String() = %v, want %v", got, tc.want)
-			}
-		})
-	}
+		{"closed", 0xdead, 0xff, &tmpfileOp{
+			new([]byte), "/home/ophestra/xdg/config/pulse/cookie", 1 << 8,
+			func() *bytes.Buffer { buf := new(bytes.Buffer); buf.Grow(1 << 8); return buf }(),
+		}, []stub.Call{
+			call("verbose", stub.ExpectArgs{[]any{"copying", &tmpfileOp{new([]byte), "/home/ophestra/xdg/config/pulse/cookie", 1 << 8, func() *bytes.Buffer { buf := new(bytes.Buffer); buf.Grow(1 << 8); return buf }()}}}, nil, nil),
+			call("stat", stub.ExpectArgs{"/home/ophestra/xdg/config/pulse/cookie"}, stubFi{1 << 8, false}, nil),
+			call("open", stub.ExpectArgs{"/home/ophestra/xdg/config/pulse/cookie"}, &readerOsFile{true, strings.NewReader(paSample + "=")}, nil),
+		}, &OpError{Op: "tmpfile", Err: os.ErrClosed}, nil, nil},
+
+		{"success full", 0xdead, 0xff, &tmpfileOp{
+			new([]byte), "/home/ophestra/xdg/config/pulse/cookie", 1 << 8,
+			func() *bytes.Buffer { buf := new(bytes.Buffer); buf.Grow(1 << 8); return buf }(),
+		}, []stub.Call{
+			call("verbose", stub.ExpectArgs{[]any{"copying", &tmpfileOp{new([]byte), "/home/ophestra/xdg/config/pulse/cookie", 1 << 8, func() *bytes.Buffer { buf := new(bytes.Buffer); buf.Grow(1 << 8); return buf }()}}}, nil, nil),
+			call("stat", stub.ExpectArgs{"/home/ophestra/xdg/config/pulse/cookie"}, stubFi{1 << 8, false}, nil),
+			call("open", stub.ExpectArgs{"/home/ophestra/xdg/config/pulse/cookie"}, &readerOsFile{false, strings.NewReader(paSample + "=")}, nil),
+		}, nil, nil, nil},
+
+		{"success", 0xdead, 0xff, &tmpfileOp{
+			new([]byte), "/home/ophestra/xdg/config/pulse/cookie", 1 << 8,
+			func() *bytes.Buffer { buf := new(bytes.Buffer); buf.Grow(1 << 8); return buf }(),
+		}, []stub.Call{
+			call("verbose", stub.ExpectArgs{[]any{"copying", &tmpfileOp{new([]byte), "/home/ophestra/xdg/config/pulse/cookie", 1 << 8, func() *bytes.Buffer { buf := new(bytes.Buffer); buf.Grow(1 << 8); return buf }()}}}, nil, nil),
+			call("stat", stub.ExpectArgs{"/home/ophestra/xdg/config/pulse/cookie"}, stubFi{1 << 8, false}, nil),
+			call("open", stub.ExpectArgs{"/home/ophestra/xdg/config/pulse/cookie"}, &readerOsFile{false, strings.NewReader(paSample)}, nil),
+			call("verbosef", stub.ExpectArgs{"copied %d bytes from %q", []any{int64(1<<8 - 1), "/home/ophestra/xdg/config/pulse/cookie"}}, nil, nil),
+		}, nil, nil, nil},
+	})
+
+	checkOpsBuilder(t, "CopyFile", []opsBuilderTestCase{
+		{"pulse", 0xcafebabe, func(_ *testing.T, sys *I) {
+			sys.CopyFile(new([]byte), "/home/ophestra/xdg/config/pulse/cookie", 1<<8, 1<<8)
+		}, []Op{&tmpfileOp{
+			new([]byte), "/home/ophestra/xdg/config/pulse/cookie", 1 << 8,
+			func() *bytes.Buffer { buf := new(bytes.Buffer); buf.Grow(1 << 8); return buf }(),
+		}}, stub.Expect{}},
+	})
+
+	checkOpIs(t, []opIsTestCase{
+		{"nil", (*tmpfileOp)(nil), (*tmpfileOp)(nil), false},
+		{"zero", new(tmpfileOp), new(tmpfileOp), true},
+
+		{"n differs", &tmpfileOp{
+			src: "/home/ophestra/xdg/config/pulse/cookie",
+			n:   1 << 7,
+		}, &tmpfileOp{
+			src: "/home/ophestra/xdg/config/pulse/cookie",
+			n:   1 << 8,
+		}, false},
+
+		{"src differs", &tmpfileOp{
+			src: "/home/ophestra/xdg/config/pulse",
+			n:   1 << 8,
+		}, &tmpfileOp{
+			src: "/home/ophestra/xdg/config/pulse/cookie",
+			n:   1 << 8,
+		}, false},
+
+		{"equals", &tmpfileOp{
+			src: "/home/ophestra/xdg/config/pulse/cookie",
+			n:   1 << 8,
+		}, &tmpfileOp{
+			src: "/home/ophestra/xdg/config/pulse/cookie",
+			n:   1 << 8,
+		}, true},
+	})
+
+	checkOpMeta(t, []opMetaTestCase{
+		{"pulse", &tmpfileOp{nil, "/home/ophestra/xdg/config/pulse/cookie", 1 << 8, nil},
+			Process, "/home/ophestra/xdg/config/pulse/cookie",
+			`up to 256 bytes from "/home/ophestra/xdg/config/pulse/cookie"`},
+	})
 }