[LTP] [PATCH v16 1/2] lib: New library function tst_get_free_uid

[Petr Vorel]

Hi Wei,

> +uid_t tst_get_free_uid_(const char *file, const int lineno, uid_t skip);
> +
> +/**
> + * tst_get_free_uid() - Find a UID not assigned to any user.
> + * @skip: UID value to skip (pass 0 to skip none).
> + *
> + * Scans the password database for the first unused UID starting
> + * from 1, skipping @skip. Calls tst_brk(TBROK) if no free UID
> + * is found or a lookup error occurs.
> + *
> + * Return: An unused uid_t value.
> + */
> +#define tst_get_free_uid(skip) tst_get_free_uid_(__FILE__, __LINE__, (skip))
> +
>  /*
>   * Find unassigned gid. The skip argument can be used to ignore e.g. the main
>   * group of a specific user in case it's not listed in the group file. If you
> diff --git a/lib/tst_uid.c b/lib/tst_uid.c
> index b0b087362..47c267bc4 100644
> --- a/lib/tst_uid.c
> +++ b/lib/tst_uid.c
> @@ -5,6 +5,7 @@

>  #include <sys/types.h>
>  #include <grp.h>
> +#include <pwd.h>
>  #include <errno.h>

>  #define TST_NO_DEFAULT_MAIN
> @@ -12,6 +13,33 @@
>  #include "tst_uid.h"

>  #define MAX_GID 32767
> +#define MAX_UID 32767
> +
> +uid_t tst_get_free_uid_(const char *file, const int lineno, uid_t skip)
> +{
> +	uid_t ret;
> +
> +	for (ret = 1; ret < MAX_UID; ret++) {
> +		if (ret == skip)
> +			continue;
> +
> +		errno = 0;
> +		if (getpwuid(ret))
> +			continue;


If you don't mind I'd prefer to use the same approach which is on
tst_get_free_gid_(), e.g. set errno first:

	errno = 0;

	for (ret = 1; ret < MAX_UID; ret++) {
		if (ret == skip || getpwuid(ret))
			continue;

Reviewed-by: Petr Vorel <pvorel@suse.cz>

Other than that LGTM.

Cc Martin in case he wants to add his ack before I merge.

Kind regards,
Petr

> +
> +		if (errno == 0 || errno == ENOENT || errno == ESRCH) {
> +			tst_res_(file, lineno, TINFO,
> +				"Found unused UID %d", (int)ret);
> +			return ret;
> +		}
> +
> +		tst_brk_(file, lineno, TBROK | TERRNO, "User ID lookup failed");
> +		return (uid_t)-1;
> +	}
> +
> +	tst_brk_(file, lineno, TBROK, "No free user ID found");
> +	return (uid_t)-1;
> +}