2.9BSD - /usr/src/ucb/oldcsh/getpwuid.c

   1: /*
   2:  * Modified version of getpwuid which doesn't use stdio.
   3:  * This is done to keep it (and hence csh) small at a small
   4:  * cost in speed.
   5:  */
   6: #include <pwd.h>
   7: #include <whoami.h>
   8: 
   9: #ifdef UCB_PWHASH
  10: #include <sys/pwdtbl.h>
  11: #include <sys/stat.h>
  12: #define pwf _pw_file
  13: 
  14: static char UTBL[] = "/etc/uid_pw_map"; /* name of user id table */
  15: extern int  pwf;                /* pointer to password file */
  16: static int  uf = -1;            /* user id table */
  17: static int  nusers;             /* number of users */
  18: static off_t    uidloc();           /* finds uid from table */
  19: struct stat sbuf;               /* stat buffer */
  20: #endif
  21: 
  22: struct passwd *
  23: getpwuid(uid)
  24: register uid;
  25: {
  26:     register struct passwd *p;
  27:     struct passwd *getpwent();
  28: 
  29: #ifdef UCB_PWHASH
  30:     off_t loc;
  31: #endif
  32: 
  33: #ifdef UCB_PWHASH
  34:     if (pwf == -1)
  35:         setpwent();
  36: 
  37:     loc = uidloc (uid);
  38:     if (loc >= 0)  {
  39:         lseek (pwf,loc,0);
  40:         p = getpwent();
  41:         if (p->pw_uid == uid)
  42:             return (p);
  43:     }
  44: #endif
  45: 
  46:                         /* begin linear search */
  47:     setpwent();
  48:     while( (p = getpwent()) && p->pw_uid != uid );
  49:     endpwent();
  50:     return(p);
  51: }
  52: 
  53: #ifdef UCB_PWHASH
  54: static off_t
  55: uidloc (uid)                /* finds uid from uid->loc table */
  56: register unsigned   uid;
  57: {
  58:     off_t       high;           /* high pointer to file */
  59:     off_t       low;            /* low pointer to file */
  60:     off_t       test;           /* current pointer to file */
  61:     struct pwloc    p;          /* table entry from file */
  62: 
  63:                         /* get status of uid table file
  64: 						 * and open it */
  65:     if (uf == -1)  {
  66:         if (stat (UTBL,&sbuf) || (uf = open (UTBL, 0)) == -1)
  67:             return ((off_t) -1);
  68: 
  69:                         /* compute number of entries */
  70:         nusers = sbuf.st_size/sizeof(struct pwloc);
  71:     }
  72: 
  73:     low = 0;                /* initialize pointers */
  74:     high = nusers;
  75: 
  76: compare:
  77:     test = (high+low+1)/2;          /* find midpoint */
  78:     if (test == high)           /* no valid midpoint */
  79:         return ((off_t) -1);
  80: 
  81:                         /* read table entry */
  82:     lseek (uf, test*sizeof (struct pwloc), 0);
  83:     if (read(uf, &p, sizeof (struct pwloc)) != sizeof (struct pwloc))
  84:         return ((off_t) -1);
  85:     if (p.pwl_uid == uid)           /* return if location found */
  86:         return (p.pwl_loc);
  87: 
  88:     if (p.pwl_uid < uid)            /* adjust pointers */
  89:         low = test;
  90:     else
  91:         high = test;
  92:     goto compare;
  93: }
  94: #endif

Defined functions

Defined variables

Defined macros