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shared/unit-file: make sure the old hashmaps and sets are freed upon replacement

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Possibly fixes #15220. (There might be another leak. I'm still investigating.)

The leak would occur when the path cache was rebuilt. So in normal circumstances
it wouldn't be too bad, since usually the path cache is not rebuilt too often. But
the case in #15220, where new unit files are created in a loop and started, the leak
occurs once for each unit file:

$ for i in {1..300}; do cp ~/.config/systemd/user/test0001.service ~/.config/systemd/user/test$(printf %04d $i).service; systemctl --user start test$(printf %04d $i).service;done
This commit is contained in:
Zbigniew Jędrzejewski-Szmek
2020-05-28 18:51:52 +02:00
parent db868d45f9
commit 3fb2326f3e
6 changed files with 33 additions and 12 deletions
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src/shared/unit-file.c
+13 -11
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@@ -229,9 +229,9 @@ static bool lookup_paths_mtime_good(const LookupPaths *lp, usec_t mtime) {
int unit_file_build_name_map(
const LookupPaths *lp,
usec_t *cache_mtime,
Hashmap **ret_unit_ids_map,
Hashmap **ret_unit_names_map,
Set **ret_path_cache) {
Hashmap **unit_ids_map,
Hashmap **unit_names_map,
Set **path_cache) {
/* Build two mappings: any name → main unit (i.e. the end result of symlink resolution), unit name →
* all aliases (i.e. the entry for a given key is a a list of all names which point to this key). The
@@ -239,7 +239,8 @@ int unit_file_build_name_map(
* have a key, but it is not present in the value for itself, there was an alias pointing to it, but
* the unit itself is not loadable.
*
* At the same, build a cache of paths where to find units.
* At the same, build a cache of paths where to find units. The non-const parameters are for input
* and output. Existing contents will be freed before the new contents are stored.
*/
_cleanup_hashmap_free_ Hashmap *ids = NULL, *names = NULL;
@@ -253,8 +254,8 @@ int unit_file_build_name_map(
if (cache_mtime && *cache_mtime > 0 && lookup_paths_mtime_good(lp, *cache_mtime))
return 0;
if (ret_path_cache) {
paths = set_new(&path_hash_ops);
if (path_cache) {
paths = set_new(&path_hash_ops_free);
if (!paths)
return log_oom();
}
@@ -296,7 +297,7 @@ int unit_file_build_name_map(
if (!filename)
return log_oom();
if (ret_path_cache) {
if (paths) {
r = set_consume(paths, filename);
if (r < 0)
return log_oom();
@@ -418,10 +419,11 @@ int unit_file_build_name_map(
if (cache_mtime)
*cache_mtime = mtime;
*ret_unit_ids_map = TAKE_PTR(ids);
*ret_unit_names_map = TAKE_PTR(names);
if (ret_path_cache)
*ret_path_cache = TAKE_PTR(paths);
hashmap_free_and_replace(*unit_ids_map, ids);
hashmap_free_and_replace(*unit_names_map, names);
if (path_cache)
set_free_and_replace(*path_cache, paths);
return 1;
}