Re: [Minios-devel] [UNIKRAFT PATCH v2 3/3] lib/posix-user: Add more group file related functions

[Simon Kuenzer <simon.kuenzer@xxxxxxxxx>]

Thanks!

Reviewed-by: Simon Kuenzer <simon.kuenzer@xxxxxxxxx>

On 17.12.19 08:43, Costin Lupu wrote:
> This patch introduces the changes needed for iterating through the
> "/etc/groups" file. But because we currently provide only a single hardcoded
> group, we will return just one single entry. This can be extended easily,
> either by adding more hardcoded groups or by using the actual "/etc/groups".
> However, the latter option is subject to future work, when we will need a more
> consistent analysis regarding user management and permissions on Unikraft.
>
> The groups iterator is thread safe, therefore we also introduce the `__uk_tls`,
> qualifier which depends on `CONFIG_HAVE_SCHED`, and mark the users iterator as
> TLS as well. Another minor change revisits this library constructor by marking
> it as a Unikraft constructor.
>
> Signed-off-by: Costin Lupu <costin.lupu@xxxxxxxxx>
> ---
>   include/uk/essentials.h |  6 ++++
>   lib/posix-user/user.c   | 70 +++++++++++++++++++++++++++++++++++++++--
>   2 files changed, 74 insertions(+), 2 deletions(-)
>
> diff --git a/include/uk/essentials.h b/include/uk/essentials.h
> index e8264c5f..a6d969e7 100644
> --- a/include/uk/essentials.h
> +++ b/include/uk/essentials.h
> @@ -124,6 +124,12 @@ extern "C" {
>   #define __constructor_prio(lvl) __attribute__ ((constructor (lvl)))
>   #endif
>   
> +#ifdef CONFIG_HAVE_SCHED
> +#define __uk_tls __thread
> +#else
> +#define __uk_tls
> +#endif
> +
>   #else
>   /* TO BE DEFINED */
>   #endif /* __GNUC__ */
> diff --git a/lib/posix-user/user.c b/lib/posix-user/user.c
> index 0d6ca3fb..ba01ab74 100644
> --- a/lib/posix-user/user.c
> +++ b/lib/posix-user/user.c
> @@ -41,6 +41,7 @@
>   #include <sys/types.h>
>   #include <uk/essentials.h>
>   #include <uk/list.h>
> +#include <uk/ctors.h>
>   #include <uk/print.h>
>   #include <uk/user.h>
>   
> @@ -50,7 +51,7 @@
>   #define UK_DEFAULT_GROUP  "root"
>   #define UK_DEFAULT_PASS   "x"
>   
> -static struct passwd_entry {
> +static __uk_tls struct passwd_entry {
>         struct passwd *passwd;
>   
>   	UK_SLIST_ENTRY(struct passwd_entry) entries;
> @@ -60,7 +61,13 @@ UK_SLIST_HEAD(uk_entry_list, struct passwd_entry);
>   
>   static struct uk_entry_list passwds;
>   
> -void __constructor init_ukunistd()
> +static void init_groups(void);
> +
> +/*
> + * TODO make passwd management consistent with group management
> + */
> +
> +static void init_posix_user()
checkpatch complains that `void` is missing within the parantheses.
Since the rest looks fine, I will fix this while upstreaming.

>   {
>         static struct passwd_entry p1;
>         static struct passwd passwd = {
> @@ -77,7 +84,10 @@ void __constructor init_ukunistd()
>   
>   	UK_SLIST_INIT(&passwds);
>         UK_SLIST_INSERT_HEAD(&passwds, &p1, entries);
> +
> +       init_groups();
>   }
> +UK_CTOR_FUNC(2, init_posix_user);
>   
>   uid_t getuid(void)
>   {
> @@ -328,3 +338,59 @@ int getgrnam_r(const char *name, struct group *grp,
>   
>   	return 0;
>   }
> +
> +struct group *getgrgid(gid_t gid)
> +{
> +       struct group *res;
> +
> +       if (gid == g__.gr_gid)
> +               res = &g__;
> +       else {
> +               res = NULL;
> +               errno = ENOENT;
> +       }
> +
> +       return res;
> +}
> +
> +static __uk_tls struct group_entry {
> +       struct group *group;
> +       UK_SLIST_ENTRY(struct group_entry) entries;
> +} *groups_iter;
> +
> +UK_SLIST_HEAD(uk_group_entry_list, struct group_entry);
> +
> +static struct uk_group_entry_list groups;
> +
> +static void init_groups(void)
> +{
> +       static struct group_entry ge;
> +
> +       ge.group = &g__;
> +       UK_SLIST_INIT(&groups);
> +       UK_SLIST_INSERT_HEAD(&groups, &ge, entries);
> +}
> +
> +void setgrent(void)
> +{
> +       groups_iter = UK_SLIST_FIRST(&groups);
> +}
> +
> +void endgrent(void)
> +{
> +       setgrent();
> +}
> +
> +struct group *getgrent(void)
> +{
> +       struct group *res;
> +
> +       if (groups_iter) {
> +               res = groups_iter->group;
> +               groups_iter = UK_SLIST_NEXT(groups_iter, entries);
> +       } else
> +               res = NULL;
> +
> +       return res;
> +
> +}
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