From: Karel Zak <kzak@redhat.com>
Date: Wed, 22 Feb 2023 20:22:32 +0000 (+0100)
Subject: libmount: make it possible to define order of hooks
X-Git-Tag: v2.39-rc1~60
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=211bb3c9df0f6764a2ae62753c0c1ed930ca37f0;p=thirdparty%2Futil-linux.git

libmount: make it possible to define order of hooks

In some cases we have more hooks in the same stage and it's necessary
to call some hooks after another.

Signed-off-by: Karel Zak <kzak@redhat.com>
---

diff --git a/libmount/src/hooks.c b/libmount/src/hooks.c
index 2dd795590b..db204ec28e 100644
--- a/libmount/src/hooks.c
+++ b/libmount/src/hooks.c
@@ -66,10 +66,12 @@ struct hookset_hook {
 	const struct libmnt_hookset *hookset;
 	int stage;
 	void *data;
+	const char *after;
 
 	int (*func)(struct libmnt_context *, const struct libmnt_hookset *, void *);
 
 	struct list_head	hooks;
+	unsigned int		executed : 1;
 };
 
 static const char *stagenames[] = {
@@ -88,6 +90,9 @@ static const char *stagenames[] = {
 	[MNT_STAGE_POST] = "post",
 };
 
+static int call_depend_hooks(struct libmnt_context *cxt, const char *name, int stage);
+
+
 int mnt_context_deinit_hooksets(struct libmnt_context *cxt)
 {
 	size_t i;
@@ -188,13 +193,14 @@ void *mnt_context_get_hookset_data(struct libmnt_context *cxt,
 	return hd ? hd->data : NULL;
 }
 
-int mnt_context_append_hook(struct libmnt_context *cxt,
+static int append_hook(struct libmnt_context *cxt,
 			const struct libmnt_hookset *hs,
 			int stage,
 			void *data,
 			int (*func)(struct libmnt_context *,
 				    const struct libmnt_hookset *,
-				    void *))
+				    void *),
+			const char *after)
 {
 	struct hookset_hook *hook;
 
@@ -215,11 +221,35 @@ int mnt_context_append_hook(struct libmnt_context *cxt,
 	hook->data = data;
 	hook->func = func;
 	hook->stage = stage;
+	hook->after = after;
 
 	list_add_tail(&hook->hooks, &cxt->hooksets_hooks);
 	return 0;
 }
 
+int mnt_context_append_hook(struct libmnt_context *cxt,
+			const struct libmnt_hookset *hs,
+			int stage,
+			void *data,
+			int (*func)(struct libmnt_context *,
+				    const struct libmnt_hookset *,
+				    void *))
+{
+	return append_hook(cxt, hs, stage, data, func, NULL);
+}
+
+int mnt_context_insert_hook(struct libmnt_context *cxt,
+			const char *after,
+			const struct libmnt_hookset *hs,
+			int stage,
+			void *data,
+			int (*func)(struct libmnt_context *,
+				    const struct libmnt_hookset *,
+				    void *))
+{
+	return append_hook(cxt, hs, stage, data, func, after);
+}
+
 static struct hookset_hook *get_hookset_hook(struct libmnt_context *cxt,
 					     const struct libmnt_hookset *hs,
 					     int stage,
@@ -277,9 +307,40 @@ int mnt_context_has_hook(struct libmnt_context *cxt,
 	return get_hookset_hook(cxt, hs, stage, data) ? 1 : 0;
 }
 
+static int call_hook(struct libmnt_context *cxt, struct hookset_hook *hook)
+{
+	int rc = hook->func(cxt, hook->hookset, hook->data);
+
+	hook->executed = 1;
+	if (!rc)
+		rc = call_depend_hooks(cxt, hook->hookset->name, hook->stage);
+	return rc;
+}
+
+static int call_depend_hooks(struct libmnt_context *cxt, const char *name, int stage)
+{
+	struct list_head *p = NULL, *next = NULL;
+	int rc = 0;
+
+	list_for_each_safe(p, next, &cxt->hooksets_hooks) {
+		struct hookset_hook *x = list_entry(p, struct hookset_hook, hooks);
+
+		if (x->stage != stage || x->executed ||
+		    x->after == NULL || strcmp(x->after, name) != 0)
+			continue;
+
+		DBG(CXT, ul_debugobj(cxt, "calling %s [after]", x->hookset->name));
+		rc = call_hook(cxt, x);
+		if (rc)
+			break;
+	}
+
+	return rc;
+}
+
 int mnt_context_call_hooks(struct libmnt_context *cxt, int stage)
 {
-	struct list_head *p, *next;
+	struct list_head *p = NULL, *next = NULL;
 	size_t i;
 	int rc = 0;
 
@@ -292,9 +353,11 @@ int mnt_context_call_hooks(struct libmnt_context *cxt, int stage)
 		if (hs->firststage != stage)
 			continue;
 
-		DBG(CXT, ul_debugobj(cxt, "calling %s hook", hs->name));
+		DBG(CXT, ul_debugobj(cxt, "calling %s [first]", hs->name));
 
 		rc = hs->firstcall(cxt, hs, NULL);
+		if (!rc)
+			rc = call_depend_hooks(cxt, hs->name, stage);
 		if (rc < 0)
 			goto done;
 	}
@@ -303,17 +366,26 @@ int mnt_context_call_hooks(struct libmnt_context *cxt, int stage)
 	list_for_each_safe(p, next, &cxt->hooksets_hooks) {
 		struct hookset_hook *x = list_entry(p, struct hookset_hook, hooks);
 
-		if (x->stage != stage)
+		if (x->stage != stage || x->executed)
 			continue;
 
-		DBG(CXT, ul_debugobj(cxt, "calling %s hook", x->hookset->name));
-
-		rc = x->func(cxt, x->hookset, x->data);
+		DBG(CXT, ul_debugobj(cxt, "calling %s [active]", x->hookset->name));
+		rc = call_hook(cxt, x);
 		if (rc < 0)
 			goto done;
 	}
 
 done:
+	/* zeroize status */
+	p = next = NULL;
+	list_for_each_safe(p, next, &cxt->hooksets_hooks) {
+		struct hookset_hook *x = list_entry(p, struct hookset_hook, hooks);
+
+		if (x->stage != stage)
+			continue;
+		x->executed = 0;
+	}
+
 	DBG(CXT, ul_debugobj(cxt, "<--- stage:%s [rc=%d status=%d]",
 				stagenames[stage], rc, cxt->syscall_status));
 	return rc;
diff --git a/libmount/src/mountP.h b/libmount/src/mountP.h
index 38c0a6d512..e390f39b28 100644
--- a/libmount/src/mountP.h
+++ b/libmount/src/mountP.h
@@ -349,6 +349,14 @@ extern int mnt_context_append_hook(struct libmnt_context *cxt,
 			int (*func)(struct libmnt_context *,
 				const struct libmnt_hookset *,
 				void *));
+extern int mnt_context_insert_hook(struct libmnt_context *cxt,
+			const char *after,
+			const struct libmnt_hookset *hs,
+			int stage,
+			void *data,
+			int (*func)(struct libmnt_context *,
+				const struct libmnt_hookset *,
+				void *));
 
 extern int mnt_context_remove_hook(struct libmnt_context *cxt,
 			const struct libmnt_hookset *hs,