system: isolate app/system into generic implementation

This improves maintainability and extensibility of system operations, makes writing tests for them possible, and operations now apply and revert in order, instead of being bunched up into their own categories.

Signed-off-by: Ophestra Umiker <cat@ophivana.moe>

1 files changed, 82 insertions, 0 deletions

diff --git a/internal/system/mkdir.go b/internal/system/mkdir.go
new file mode 100644
index 00000000..2c303630
--- /dev/null
+++ b/internal/system/mkdir.go
@@ -0,0 +1,82 @@
+package system
+
+import (
+	"errors"
+	"fmt"
+	"os"
+
+	"git.ophivana.moe/cat/fortify/internal/fmsg"
+	"git.ophivana.moe/cat/fortify/internal/state"
+	"git.ophivana.moe/cat/fortify/internal/verbose"
+)
+
+// Ensure the existence and mode of a directory.
+func (sys *I) Ensure(name string, perm os.FileMode) {
+	sys.lock.Lock()
+	defer sys.lock.Unlock()
+
+	sys.ops = append(sys.ops, &Mkdir{User, name, perm, false})
+}
+
+// Ephemeral ensures the temporary existence and mode of a directory through the life of et.
+func (sys *I) Ephemeral(et state.Enablement, name string, perm os.FileMode) {
+	sys.lock.Lock()
+	defer sys.lock.Unlock()
+
+	sys.ops = append(sys.ops, &Mkdir{et, name, perm, true})
+}
+
+type Mkdir struct {
+	et        state.Enablement
+	path      string
+	perm      os.FileMode
+	ephemeral bool
+}
+
+func (m *Mkdir) Type() state.Enablement {
+	return m.et
+}
+
+func (m *Mkdir) apply(_ *I) error {
+	verbose.Println("ensuring directory", m)
+
+	// create directory
+	err := os.Mkdir(m.path, m.perm)
+	if !errors.Is(err, os.ErrExist) {
+		return fmsg.WrapErrorSuffix(err,
+			fmt.Sprintf("cannot create directory %q:", m.path))
+	}
+
+	// directory exists, ensure mode
+	return fmsg.WrapErrorSuffix(os.Chmod(m.path, m.perm),
+		fmt.Sprintf("cannot change mode of %q to %s:", m.path, m.perm))
+}
+
+func (m *Mkdir) revert(_ *I, ec *Criteria) error {
+	if !m.ephemeral {
+		// skip non-ephemeral dir and do not log anything
+		return nil
+	}
+
+	if ec.hasType(m) {
+		verbose.Println("destroying ephemeral directory", m)
+		return fmsg.WrapErrorSuffix(os.Remove(m.path),
+			fmt.Sprintf("cannot remove ephemeral directory %q:", m.path))
+	} else {
+		verbose.Println("skipping ephemeral directory", m)
+		return nil
+	}
+}
+
+func (m *Mkdir) Is(o Op) bool {
+	m0, ok := o.(*Mkdir)
+	return ok && m0 != nil && *m == *m0
+}
+
+func (m *Mkdir) Path() string {
+	return m.path
+}
+
+func (m *Mkdir) String() string {
+	return fmt.Sprintf("mode: %s path: %q", m.perm.String(), m.path)
+}