pwcache: Fill the user/group caches lazily

Iterating all the users/groups can be expensive, especially with NSS.
Android has so many that it doesn't even return them all from
get{pw,gr}ent() for performance reasons, leading to incorrect behaviour
of -user/-group/etc.

1 files changed, 28 insertions, 24 deletions

diff --git a/src/pwcache.h b/src/pwcache.h
index f1a1db3..6ae8bea 100644
--- a/src/pwcache.h
+++ b/src/pwcache.h
@@ -25,92 +25,96 @@
 #include <pwd.h>
 
 /**
- * The user table.
+ * A user cache.
  */
 struct bfs_users;
 
 /**
- * Parse the user table.
+ * Create a user cache.
  *
  * @return
- *         The parsed user table, or NULL on failure.
+ *         A new user cache, or NULL on failure.
  */
-struct bfs_users *bfs_users_parse(void);
+struct bfs_users *bfs_users_new(void);
 
 /**
  * Get a user entry by name.
  *
  * @param users
- *         The user table.
+ *         The user cache.
  * @param name
  *         The username to look up.
  * @return
- *         The matching user, or NULL if not found.
+ *         The matching user, or NULL if not found (errno == 0) or an error
+ *         occurred (errno != 0).
  */
-const struct passwd *bfs_getpwnam(const struct bfs_users *users, const char *name);
+const struct passwd *bfs_getpwnam(struct bfs_users *users, const char *name);
 
 /**
  * Get a user entry by ID.
  *
  * @param users
- *         The user table.
+ *         The user cache.
  * @param uid
  *         The ID to look up.
  * @return
- *         The matching user, or NULL if not found.
+ *         The matching user, or NULL if not found (errno == 0) or an error
+ *         occurred (errno != 0).
  */
-const struct passwd *bfs_getpwuid(const struct bfs_users *users, uid_t uid);
+const struct passwd *bfs_getpwuid(struct bfs_users *users, uid_t uid);
 
 /**
- * Free a user table.
+ * Free a user cache.
  *
  * @param users
- *         The user table to free.
+ *         The user cache to free.
  */
 void bfs_users_free(struct bfs_users *users);
 
 /**
- * The group table.
+ * A group cache.
  */
 struct bfs_groups;
 
 /**
- * Parse the group table.
+ * Create a group cache.
  *
  * @return
- *         The parsed group table, or NULL on failure.
+ *         A new group cache, or NULL on failure.
  */
-struct bfs_groups *bfs_groups_parse(void);
+struct bfs_groups *bfs_groups_new(void);
 
 /**
  * Get a group entry by name.
  *
  * @param groups
- *         The group table.
+ *         The group cache.
  * @param name
  *         The group name to look up.
  * @return
- *         The matching group, or NULL if not found.
+ *         The matching group, or NULL if not found (errno == 0) or an error
+ *         occurred (errno != 0).
  */
-const struct group *bfs_getgrnam(const struct bfs_groups *groups, const char *name);
+const struct group *bfs_getgrnam(struct bfs_groups *groups, const char *name);
 
 /**
  * Get a group entry by ID.
  *
  * @param groups
- *         The group table.
+ *         The group cache.
  * @param uid
  *         The ID to look up.
  * @return
- *         The matching group, or NULL if not found.
+ *         The matching group, or NULL if not found (errno == 0) or an error
+ *         occurred (errno != 0).
  */
-const struct group *bfs_getgrgid(const struct bfs_groups *groups, gid_t gid);
+const struct group *bfs_getgrgid(struct bfs_groups *groups, gid_t gid);
 
 /**
- * Free a group table.
+ * Free a group cache.
  *
  * @param groups
- *         The group table to free.
+ *         The group cache to free.
  */
 void bfs_groups_free(struct bfs_groups *groups);