From d6ebbc6ddfb6488a57fc68a9e05dc7542331cb8c Mon Sep 17 00:00:00 2001
From: Michael Tremer <michael.tremer@ipfire.org>
Date: Fri, 18 Oct 2024 14:59:35 +0000
Subject: [PATCH] snapshot: Cleanup old snapshots

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>
---
 src/libpakfire/include/pakfire/snapshot.h |   2 +
 src/libpakfire/pakfire.c                  |   5 +
 src/libpakfire/snapshot.c                 | 125 +++++++++++++++++++++-
 3 files changed, 131 insertions(+), 1 deletion(-)

diff --git a/src/libpakfire/include/pakfire/snapshot.h b/src/libpakfire/include/pakfire/snapshot.h
index 0e540b3cc..e7fa1018b 100644
--- a/src/libpakfire/include/pakfire/snapshot.h
+++ b/src/libpakfire/include/pakfire/snapshot.h
@@ -45,5 +45,7 @@ int pakfire_snapshot_umount(struct pakfire_snapshot* snapshot);
 int pakfire_snapshot_make(struct pakfire_snapshot** snapshot,
 	struct pakfire* pakfire, const char** packages);
 
+int pakfire_snapshot_clean(struct pakfire* pakfire);
+
 #endif /* PAKFIRE_PRIVATE */
 #endif /* PAKFIRE_SNAPSHOT_H */
diff --git a/src/libpakfire/pakfire.c b/src/libpakfire/pakfire.c
index d17176e59..5884d6aac 100644
--- a/src/libpakfire/pakfire.c
+++ b/src/libpakfire/pakfire.c
@@ -1117,6 +1117,11 @@ PAKFIRE_EXPORT int pakfire_clean(struct pakfire* pakfire, int flags) {
 	if (r)
 		return r;
 
+	// Clean all snapshots
+	r = pakfire_snapshot_clean(pakfire);
+	if (r < 0)
+		return r;
+
 	// Clean build environments
 	r = pakfire_build_clean(pakfire, flags);
 	if (r)
diff --git a/src/libpakfire/snapshot.c b/src/libpakfire/snapshot.c
index 80b8b1f11..599936b1f 100644
--- a/src/libpakfire/snapshot.c
+++ b/src/libpakfire/snapshot.c
@@ -19,11 +19,13 @@
 #############################################################################*/
 
 #include <errno.h>
+#include <fts.h>
 #include <dirent.h>
 #include <fcntl.h>
 #include <linux/limits.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <sys/file.h>
 #include <sys/mount.h>
 
 #include <pakfire/logging.h>
@@ -53,6 +55,7 @@ struct pakfire_snapshot {
 		PAKFIRE_SNAPSHOT_INIT = 0,
 		PAKFIRE_SNAPSHOT_MOUNTED,
 		PAKFIRE_SNAPSHOT_UMOUNTED,
+		PAKFIRE_SNAPSHOT_DESTROYED,
 	} state;
 };
 
@@ -96,7 +99,13 @@ int pakfire_snapshot_create(
 		goto ERROR;
 	}
 
-	// XXX Check and lock the snapshot
+	// Lock the snapshot
+	r = flock(s->fd, LOCK_SH);
+	if (r < 0) {
+		CTX_ERROR(s->ctx, "Could not lock %s: %m\n", s->path);
+		r = -errno;
+		goto ERROR;
+	}
 
 	// Return the snapshot
 	*snapshot = pakfire_snapshot_ref(s);
@@ -350,6 +359,53 @@ int pakfire_snapshot_umount(struct pakfire_snapshot* snapshot) {
 	return 0;
 }
 
+static int pakfire_snapshot_destroy(struct pakfire_snapshot* snapshot) {
+	int r;
+
+	// Check if the snapshot is mounted
+	switch (snapshot->state) {
+		case PAKFIRE_SNAPSHOT_MOUNTED:
+			CTX_DEBUG(snapshot->ctx, "Snapshot is mounted\n");
+			return -EBUSY;
+
+		default:
+			break;
+	}
+
+	/*
+		Try to get an exclusive lock on the directory.
+
+		If this fails, another process is using this snapshot.
+	*/
+	r = flock(snapshot->fd, LOCK_EX|LOCK_NB);
+	if (r < 0) {
+		switch (errno) {
+			case EWOULDBLOCK:
+				return -EBUSY;
+
+			default:
+				CTX_DEBUG(snapshot->ctx,
+					"Could not acquire an exclusive lock on %s: %m\n", snapshot->path);
+				break;
+		}
+	}
+
+	CTX_INFO(snapshot->ctx, "Destroying snapshot %s\n", snapshot->path);
+
+	// Remove all files
+	r = pakfire_rmtree(snapshot->path, 0);
+	if (r < 0) {
+		CTX_ERROR(snapshot->ctx, "Could not destroy snapshot %s: %s\n",
+			snapshot->path, strerror(-r));
+		return r;
+	}
+
+	// Mark as destroyed
+	snapshot->state = PAKFIRE_SNAPSHOT_DESTROYED;
+
+	return 0;
+}
+
 static int pakfire_snapshot_install_packages(struct pakfire* pakfire, const char** packages) {
 	struct pakfire_transaction* transaction = NULL;
 	int r;
@@ -465,3 +521,70 @@ ERROR:
 
 	return r;
 }
+
+/*
+	Cleans up any unused snapshots
+*/
+int pakfire_snapshot_clean(struct pakfire* pakfire) {
+	struct pakfire_snapshot* snapshot = NULL;
+	char path[PATH_MAX];
+	FTS* f = NULL;
+	int r;
+
+	struct pakfire_ctx* ctx = pakfire_ctx(pakfire);
+
+	// Make the path
+	r = pakfire_cache_path(pakfire, path, "%s", "snapshots");
+	if (r < 0)
+		return r;
+
+	char* paths[] = {
+		path, NULL,
+	};
+
+	// Open the directory
+	f = fts_open(paths, FTS_PHYSICAL|FTS_NOCHDIR|FTS_NOSTAT, NULL);
+
+	for (;;) {
+		FTSENT* node = fts_read(f);
+		if (!node)
+			break;
+
+		// Skip the main directory
+		if (node->fts_level == 0) {
+			continue;
+
+		// Skip any subdirectories
+		} else if (node->fts_level > 1) {
+			fts_set(f, node, FTS_SKIP);
+			continue;
+		}
+
+		// We only care about directories
+		if (node->fts_info == FTS_D)
+			continue;
+
+		// Open the snapshot
+		r = pakfire_snapshot_create(&snapshot, ctx, node->fts_path);
+		if (r < 0)
+			goto ERROR;
+
+		// Destroy the snapshot
+		r = pakfire_snapshot_destroy(snapshot);
+		if (r < 0)
+			goto ERROR;
+
+		// Free the snapshot
+		snapshot = pakfire_snapshot_unref(snapshot);
+	}
+
+ERROR:
+	if (snapshot)
+		pakfire_snapshot_unref(snapshot);
+	if (ctx)
+		pakfire_ctx_unref(ctx);
+	if (f)
+		fts_close(f);
+
+	return r;
+}
-- 
2.39.5