2.9BSD - /usr/src/lib/c/stdio/getmap.c

   1: /*	@(#)getmap.c	2.1	SCCS id keyword	*/
   2: #include <whoami.h>
   3: #include <sys/types.h>
   4: #include <pwtable.h>
   5: #define NAMSIZ  8
   6: 
   7: static int  tbf = -1;           /* table file */
   8: static char TBL[] = UCB_PWHASH; /* name of map table */
   9: static unsigned nusers;             /* number of users */
  10: 
  11: long    lseek();
  12: 
  13: static struct pwtable   mapentry;       /* table entry from file */
  14: 
  15: static
  16: setmapent()
  17: {
  18:     if (tbf == -1) {
  19:         if ((tbf = open (TBL, 0)) < 0)
  20:             return (0);
  21:                         /* compute number of entries */
  22:         nusers = lseek(tbf, 0L, 2) / (2 * sizeof(struct pwtable));
  23:     }
  24:     return(1);
  25: }
  26: 
  27: endmapent()
  28: {
  29:     if (tbf >= 0) {
  30:         close(tbf);
  31:         tbf = -1;
  32:     }
  33: }
  34: 
  35: struct pwtable *
  36: getmapuid(uid)
  37: register uid;
  38: {
  39:     unsigned        high;           /* high offset to file */
  40:     unsigned        low;            /* low offset to file */
  41:     unsigned        test;           /* current offset to file */
  42: 
  43:     if (!setmapent())
  44:         return(0);
  45:     low = 0;                /* initialize pointers */
  46:     high = nusers;
  47: 
  48:     do {
  49:         test = (low + high) / 2;            /* find midpoint */
  50:         lseek (tbf, (long) test * sizeof (struct pwtable), 0);
  51:         if (read(tbf, &mapentry, sizeof (struct pwtable)) !=
  52:             sizeof (struct pwtable))
  53:             return (0);
  54:         if (mapentry.pwt_uid == uid)
  55:             return (&mapentry);
  56:         if (mapentry.pwt_uid < uid)
  57:             low = test + 1;
  58:         else
  59:             high = test;
  60:     } while (low != high);
  61:     return(0);
  62: }
  63: 
  64: struct pwtable *
  65: getmapnam(name)
  66: char *name;
  67: {
  68:     unsigned        high;           /* high offset to file */
  69:     unsigned        low;            /* low offset to file */
  70:     unsigned        test;           /* current offset to file */
  71:     int differ;
  72: 
  73:     if (!setmapent())
  74:         return(0);
  75:     low = 0;                /* initialize pointer */
  76:     high = nusers;
  77: 
  78:     do {
  79:         test = (low + high) / 2;            /* find midpoint */
  80:         lseek (tbf, ((long) test + nusers) * sizeof (struct pwtable), 0);
  81:         if (read(tbf, &mapentry, sizeof (struct pwtable)) !=
  82:             sizeof (struct pwtable))
  83:             return (0);
  84: 
  85:         if ((differ = strncmp (mapentry.pwt_name,name,NAMSIZ)) == 0)
  86:             return (&mapentry);
  87: 
  88:         if (differ < 0)             /* adjust pointers */
  89:             low = test + 1;
  90:         else
  91:             high = test;
  92:     } while (low != high);
  93:     return(0);
  94: }

Defined functions

Defined variables

Defined macros