get_gid_name

SFL
Version 2.11

`get_gid_name`

#include "sfluid.h"
char *
get_gid_name (gid_t gid)

Synopsis

Get group name from group file. We optimise by keeping a table of gids and names in memory. Note that this will cause problems if the program stays running when the group file has been changed. Returns a string containing the translated user name, or "<none>" if the gid could not be translated. Under MS- DOS the gid must be zero. The returned string is in a static area that is _not_ overwritten with each call, but which should be treated as read-only, and unstable: i.e. the value returned by one call to get_gid_name may change as a result of a later call. If you need persistent strings, use strdupl() after each call.

Source Code - (sfluid.c)

{
#   if (defined (DOES_UID))
    static struct gids {                /*  Table of cache'd gids            */
        gid_t id;
        char  *name;
    } cache [GID_CACHE_MAX];
    static int
        cache_size = 0,                 /*  Number of gid's in cache         */
        cache_oldest = 0;               /*  Oldest entry in cache            */
    int
        cache_scan;                     /*  Scan through cache               */
    struct group
        *group_entry;

    /*  First, look for gid in cache                                         */
    for (cache_scan = 0; cache_scan < cache_size; cache_scan++)
        if (cache [cache_scan].id == gid)
            return (cache [cache_scan].name);

    /*  Add new name to cache: if cache was full, kick-out oldest entry      */
    if (cache_size == GID_CACHE_MAX)
      {
        cache_scan = cache_oldest++;
        cache_oldest %= GID_CACHE_MAX;
        free (cache [cache_scan].name);
      }
    else
        cache_scan = cache_size++;

    cache [cache_scan].id = gid;
#   if (defined (__VMS__))
        cache [cache_scan].name = "<none>";
#   else
    if ((group_entry = getgrgid (gid)) == NULL)
        cache [cache_scan].name = "<none>";
    else
        cache [cache_scan].name = strdupl (group_entry-> gr_name);
#   endif

    return (cache [cache_scan].name);

#   elif (defined (__MSDOS__))
    return (gid == 0? "group": "<none>");

#   endif
}

| << | < | > | >>