qgetgrnam_r.3

NAME

qgetgrnam, qgetgrnam_r, qgetgrgid, qgetgrgid_r - get group file entry

SYNOPSIS

#include <sys/types.h>
#include <qgetpwgr.h>

struct group *qgetgrnam(const char *name);

struct group *qgetgrgid(gid_t gid);

int qgetgrnam_r(const char *name, struct group *grp,
 char *buf, size_t buflen, struct group **result);

int qgetgrgid_r(gid_t gid, struct group *grp,
 char *buf, size_t buflen, struct group **result);

DESCRIPTION

The qgetgrnam() function returns a pointer to a structure containing the broken-out fields of the record in the group database (e.g., the local group file /etc/group, ) that matches the group name name.

The qgetgrgid() function returns a pointer to a structure containing the broken-out fields of the record in the group database that matches the group ID gid.

The group structure is defined in <grp.h> as follows:

struct group {
    char   *gr_name;        /* group name */
    char   *gr_passwd;      /* group password */
    gid_t   gr_gid;         /* group ID */
    char  **gr_mem;         /* NULL-terminated array of pointers
                               to names of group members */
};

For more information about the fields of this structure, see group(5).

The qgetgrnam_r() and qgetgrgid_r() functions obtain the same information as qgetgrnam() and qgetgrgid(), but store the retrieved group structure in the space pointed to by grp. The string fields pointed to by the members of the group structure are stored in the buffer buf of size buflen. A pointer to the result (in case of success) or NULL (in case no entry was found or an error occurred) is stored in *result.

The call

sysconf(_SC_GETGR_R_SIZE_MAX)

returns either -1, without changing errno, or an initial suggested size for buf. (If this size is too small, the call fails with ERANGE, in which case the caller can retry with a larger buffer.)

RETURN VALUE

The qgetgrnam() and qgetgrgid() functions return a pointer to a group structure, or NULL if the matching entry is not found or an error occurs. If an error occurs, errno is set appropriately. If one wants to check errno after the call, it should be set to zero before the call.

The return value may point to a static area, and may be overwritten by subsequent calls to qgetgrent(3), qgetgrgid(), or qgetgrnam(). (Do not pass the returned pointer to free(3).)

On success, qgetgrnam_r() and qgetgrgid_r() return zero, and set *result to grp. If no matching group record was found, these functions return 0 and store NULL in *result. In case of error, an error number is returned, and NULL is stored in *result.

ERRORS

0 or ENOENT
The given name or gid was not found.

EINTR
A signal was caught; see signal(7).

ENOMEM
Insufficient memory to allocate group structure.

ERANGE
Insufficient buffer space supplied.

ETXTBUSY
Temporary error happened.

FILES

/etc/group
local group database file

SEE ALSO

qgetgrent(3), qsetgrent(3), qendgrent(3), grpscan(3), group(5)