1 files changed, 98 insertions, 0 deletions
diff --git a/libkpod/hooks.go b/libkpod/hooks.go
new file mode 100644
index 000000000..f353cdcde
--- /dev/null
+++ b/libkpod/hooks.go
@@ -0,0 +1,98 @@
+package libkpod
+
+import (
+	"encoding/json"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"regexp"
+	"strings"
+	"syscall"
+
+	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
+)
+
+const (
+	// DefaultHooksDirPath Default directory containing hooks config files
+	DefaultHooksDirPath = "/usr/share/containers/oci/hooks.d"
+	// OverrideHooksDirPath Directory where admin can override the default configuration
+	OverrideHooksDirPath = "/etc/containers/oci/hooks.d"
+)
+
+// HookParams is the structure returned from read the hooks configuration
+type HookParams struct {
+	Hook          string   `json:"hook"`
+	Stage         []string `json:"stage"`
+	Cmds          []string `json:"cmd"`
+	Annotations   []string `json:"annotation"`
+	HasBindMounts bool     `json:"hasbindmounts"`
+}
+
+// readHook reads hooks json files, verifies it and returns the json config
+func readHook(hookPath string) (HookParams, error) {
+	var hook HookParams
+	raw, err := ioutil.ReadFile(hookPath)
+	if err != nil {
+		return hook, errors.Wrapf(err, "error Reading hook %q", hookPath)
+	}
+	if err := json.Unmarshal(raw, &hook); err != nil {
+		return hook, errors.Wrapf(err, "error Unmarshalling JSON for %q", hookPath)
+	}
+	if _, err := os.Stat(hook.Hook); err != nil {
+		return hook, errors.Wrapf(err, "unable to stat hook %q in hook config %q", hook.Hook, hookPath)
+	}
+	validStage := map[string]bool{"prestart": true, "poststart": true, "poststop": true}
+	for _, cmd := range hook.Cmds {
+		if _, err = regexp.Compile(cmd); err != nil {
+			return hook, errors.Wrapf(err, "invalid cmd regular expression %q defined in hook config %q", cmd, hookPath)
+		}
+	}
+	for _, cmd := range hook.Annotations {
+		if _, err = regexp.Compile(cmd); err != nil {
+			return hook, errors.Wrapf(err, "invalid cmd regular expression %q defined in hook config %q", cmd, hookPath)
+		}
+	}
+	for _, stage := range hook.Stage {
+		if !validStage[stage] {
+			return hook, errors.Wrapf(err, "unknown stage %q defined in hook config %q", stage, hookPath)
+		}
+	}
+	return hook, nil
+}
+
+// readHooks reads hooks json files in directory to setup OCI Hooks
+// adding hooks to the passedin hooks map.
+func readHooks(hooksPath string, hooks map[string]HookParams) error {
+	if _, err := os.Stat(hooksPath); err != nil {
+		if os.IsNotExist(err) {
+			logrus.Warnf("hooks path: %q does not exist", hooksPath)
+			return nil
+		}
+		return errors.Wrapf(err, "unable to stat hooks path %q", hooksPath)
+	}
+
+	files, err := ioutil.ReadDir(hooksPath)
+	if err != nil {
+		return err
+	}
+
+	for _, file := range files {
+		if !strings.HasSuffix(file.Name(), ".json") {
+			continue
+		}
+		hook, err := readHook(filepath.Join(hooksPath, file.Name()))
+		if err != nil {
+			return err
+		}
+		for key, h := range hooks {
+			// hook.Hook can only be defined in one hook file, unless it has the
+			// same name in the override path.
+			if hook.Hook == h.Hook && key != file.Name() {
+				return errors.Wrapf(syscall.EINVAL, "duplicate path,  hook %q from %q already defined in %q", hook.Hook, hooksPath, key)
+			}
+		}
+		hooks[file.Name()] = hook
+	}
+	return nil
+}