util.c: fix return type of get_group_id

gr_gid is of type gid_t (not uid_t).  From grp.h(0p) of POSIX.1-2017:

> DESCRIPTION
>
> The <grp.h> header shall declare the group structure, which shall
> include the following members:
>
>    char   *gr_name The name of the group.
>    gid_t   gr_gid  Numerical group ID.
>    char  **gr_mem  Pointer to a null-terminated array of character
>                    pointers to member names.
>
> The <grp.h> header shall define the gid_t and size_t types as
> described in <sys/types.h>.

Note: The callers already store the result in gid_t variables.

First caused by commit dc3564b18 ("fixes", 2016-03-09).

2 files changed, 2 insertions, 2 deletions

diff --git a/src/firejail/firejail.h b/src/firejail/firejail.h
index d29c2a976..c8d35c825 100644
--- a/src/firejail/firejail.h
+++ b/src/firejail/firejail.h
@@ -532,7 +532,7 @@ void update_map(char *mapping, char *map_file);
 void wait_for_other(int fd);
 void notify_other(int fd);
 uid_t pid_get_uid(pid_t pid);
-uid_t get_group_id(const char *group);
+gid_t get_group_id(const char *group);
 void flush_stdin(void);
 int create_empty_dir_as_user(const char *dir, mode_t mode);
 void create_empty_dir_as_root(const char *dir, mode_t mode);
diff --git a/src/firejail/util.c b/src/firejail/util.c
index 1f5665cbc..87ca4c1e7 100644
--- a/src/firejail/util.c
+++ b/src/firejail/util.c
@@ -959,7 +959,7 @@ uid_t pid_get_uid(pid_t pid) {
 }
 
 
-uid_t get_group_id(const char *group) {
+gid_t get_group_id(const char *group) {
         gid_t gid = 0;
         struct group *g = getgrnam(group);
         if (g)