1 files changed, 141 insertions, 0 deletions
diff --git a/internal/system/tmpfiles.go b/internal/system/tmpfiles.go
new file mode 100644
index 00000000..2a9f724a
--- /dev/null
+++ b/internal/system/tmpfiles.go
@@ -0,0 +1,141 @@
+package system
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"strconv"
+
+	"git.ophivana.moe/cat/fortify/acl"
+	"git.ophivana.moe/cat/fortify/internal/fmsg"
+	"git.ophivana.moe/cat/fortify/internal/state"
+	"git.ophivana.moe/cat/fortify/internal/verbose"
+)
+
+// CopyFile registers an Op that copies path dst from src.
+func (sys *I) CopyFile(dst, src string) {
+	sys.CopyFileType(Process, dst, src)
+}
+
+// CopyFileType registers a file copying Op labelled with type et.
+func (sys *I) CopyFileType(et state.Enablement, dst, src string) {
+	sys.lock.Lock()
+	sys.ops = append(sys.ops, &Tmpfile{et, tmpfileCopy, dst, src})
+	sys.lock.Unlock()
+
+	sys.UpdatePermType(et, dst, acl.Read)
+}
+
+// Link registers an Op that links dst to src.
+func (sys *I) Link(oldname, newname string) {
+	sys.LinkFileType(Process, oldname, newname)
+}
+
+// LinkFileType registers a file linking Op labelled with type et.
+func (sys *I) LinkFileType(et state.Enablement, oldname, newname string) {
+	sys.lock.Lock()
+	defer sys.lock.Unlock()
+
+	sys.ops = append(sys.ops, &Tmpfile{et, tmpfileLink, newname, oldname})
+}
+
+// Write registers an Op that writes dst with the contents of src.
+func (sys *I) Write(dst, src string) {
+	sys.WriteType(Process, dst, src)
+}
+
+// WriteType registers a file writing Op labelled with type et.
+func (sys *I) WriteType(et state.Enablement, dst, src string) {
+	sys.lock.Lock()
+	sys.ops = append(sys.ops, &Tmpfile{et, tmpfileWrite, dst, src})
+	sys.lock.Unlock()
+
+	sys.UpdatePermType(et, dst, acl.Read)
+}
+
+const (
+	tmpfileCopy uint8 = iota
+	tmpfileLink
+	tmpfileWrite
+)
+
+type Tmpfile struct {
+	et       state.Enablement
+	method   uint8
+	dst, src string
+}
+
+func (t *Tmpfile) Type() state.Enablement {
+	return t.et
+}
+
+func (t *Tmpfile) apply(_ *I) error {
+	switch t.method {
+	case tmpfileCopy:
+		verbose.Printf("publishing tmpfile %s\n", t)
+		return fmsg.WrapErrorSuffix(copyFile(t.dst, t.src),
+			fmt.Sprintf("cannot copy tmpfile %q:", t.dst))
+	case tmpfileLink:
+		verbose.Printf("linking tmpfile %s\n", t)
+		return fmsg.WrapErrorSuffix(os.Link(t.src, t.dst),
+			fmt.Sprintf("cannot link tmpfile %q:", t.dst))
+	case tmpfileWrite:
+		verbose.Printf("writing %s\n", t)
+		return fmsg.WrapErrorSuffix(os.WriteFile(t.dst, []byte(t.src), 0600),
+			fmt.Sprintf("cannot write tmpfile %q:", t.dst))
+	default:
+		panic("invalid tmpfile method " + strconv.Itoa(int(t.method)))
+	}
+}
+
+func (t *Tmpfile) revert(_ *I, ec *Criteria) error {
+	if ec.hasType(t) {
+		verbose.Printf("removing tmpfile %q\n", t.dst)
+		return fmsg.WrapErrorSuffix(os.Remove(t.dst),
+			fmt.Sprintf("cannot remove tmpfile %q:", t.dst))
+	} else {
+		verbose.Printf("skipping tmpfile %q\n", t.dst)
+		return nil
+	}
+}
+
+func (t *Tmpfile) Is(o Op) bool {
+	t0, ok := o.(*Tmpfile)
+	return ok && t0 != nil && *t == *t0
+}
+
+func (t *Tmpfile) Path() string {
+	if t.method == tmpfileWrite {
+		return fmt.Sprintf("(%d bytes of data)", len(t.src))
+	}
+	return t.src
+}
+
+func (t *Tmpfile) String() string {
+	switch t.method {
+	case tmpfileCopy:
+		return fmt.Sprintf("%q from %q", t.dst, t.src)
+	case tmpfileLink:
+		return fmt.Sprintf("%q from %q", t.dst, t.src)
+	case tmpfileWrite:
+		return fmt.Sprintf("%d bytes of data to %q", len(t.src), t.dst)
+	default:
+		panic("invalid tmpfile method " + strconv.Itoa(int(t.method)))
+	}
+}
+
+func copyFile(dst, src string) error {
+	dstD, err := os.OpenFile(dst, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
+	if err != nil {
+		return err
+	}
+
+	srcD, err := os.Open(src)
+	if err != nil {
+		return errors.Join(err, dstD.Close())
+	}
+
+	_, err = io.Copy(dstD, srcD)
+	return errors.Join(err, dstD.Close(), srcD.Close())
+}