db: fix database reading without scripts or triggers

Most notably this happens after blank database is initialized with --initdb,
but can happen also in other conditions.

The error checking changes modified behaviour if the file does not exist.
Explicitly check for ENOENT and ignore it. But the behaviour is improved
from earlier as now e.g. EPERM will be detected and reported correctly.

Fixes #10679

Fixes: 6da3e8eb "istream, archive, db: convert db and tar function to use istream"

src/database.c

@@ -1118,14 +1118,14 @@ static void apk_db_triggers_write(struct apk_database *db, struct apk_ostream *o
 	}
 }
 
-static void apk_db_triggers_read(struct apk_database *db, struct apk_istream *is)
+static int apk_db_triggers_read(struct apk_database *db, struct apk_istream *is)
 {
 	struct apk_checksum csum;
 	struct apk_package *pkg;
 	struct apk_installed_package *ipkg;
 	apk_blob_t l;
 
-	if (IS_ERR_OR_NULL(is)) return;
+	if (IS_ERR(is)) return PTR_ERR(is);
 
 	while (!APK_BLOB_IS_NULL(l = apk_istream_get_delim(is, APK_BLOB_STR("\n")))) {
 		apk_blob_pull_csum(&l, &csum);
@@ -1143,6 +1143,8 @@ static void apk_db_triggers_read(struct apk_database *db, struct apk_istream *is
 				      &db->installed.triggers);
 	}
 	apk_istream_close(is);
+
+	return 0;
 }
 
 static int apk_db_read_state(struct apk_database *db, int flags)
@@ -1166,13 +1168,15 @@ static int apk_db_read_state(struct apk_database *db, int flags)
 
 	if (!(flags & APK_OPENF_NO_INSTALLED)) {
 		r = apk_db_index_read(db, apk_istream_from_file(db->root_fd, apk_installed_file), -1);
-		if (r != 0) return -1;
-		apk_db_triggers_read(db, apk_istream_from_file(db->root_fd, apk_triggers_file));
+		if (r && r != -ENOENT) return r;
+		r = apk_db_triggers_read(db, apk_istream_from_file(db->root_fd, apk_triggers_file));
+		if (r && r != -ENOENT) return r;
 	}
 
 	if (!(flags & APK_OPENF_NO_SCRIPTS)) {
-		apk_tar_parse(apk_istream_from_file(db->root_fd, apk_scripts_file),
-			      apk_read_script_archive_entry, db, &db->id_cache);
+		r = apk_tar_parse(apk_istream_from_file(db->root_fd, apk_scripts_file),
+				  apk_read_script_archive_entry, db, &db->id_cache);
+		if (r && r != -ENOENT) return r;
 	}
 
 	return 0;