get_uid_name

SFL
Version 2.11

`get_uid_name`

#include "sfluid.h"
char *
get_uid_name (uid_t uid)

Synopsis

Get user name from passwd file. We optimise by keeping a table of uids and names in memory. Note that this will cause problems if the program stays running when the passwd file has been changed. Returns a string containing the translated user name, or "<none>" if the uid could not be translated. Under MS- DOS the uid 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_uid_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 uids {                /*  Table of cached uids             */
        uid_t id;
        char  *name;
    } cache [UID_CACHE_MAX];
    static int
        cache_size = 0,                 /*  Number of uid's in cache         */
        cache_oldest = 0;               /*  Oldest entry in cache            */
    int
        cache_scan;                     /*  Scan through cache               */
    struct passwd
        *passwd_entry;

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

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

    cache [cache_scan].id = uid;
    if ((passwd_entry = getpwuid (uid)) == NULL)
        cache [cache_scan].name = "<none>";
    else
        cache [cache_scan].name = strdupl (passwd_entry-> pw_name);

    return (cache [cache_scan].name);

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

#   endif
}

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