compilers/linux86-0.16.17/unproto/strsave.c

   1 /*++
   2 /* NAME
   3 /*      strsave 3
   4 /* SUMMARY
   5 /*      maintain unique copy of a string
   6 /* SYNOPSIS
   7 /*      char *strsave(string)
   8 /*      char *string;
   9 /* DESCRIPTION
  10 /*      This function returns a pointer to an unique copy of its
  11 /*      argument.
  12 /* DIAGNOSTISC
  13 /*      strsave() calls fatal() when it runs out of memory.
  14 /* AUTHOR(S)
  15 /*      Wietse Venema
  16 /*      Eindhoven University of Technology
  17 /*      Department of Mathematics and Computer Science
  18 /*      Den Dolech 2, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
  19 /* LAST MODIFICATION
  20 /*      92/01/15 21:53:13
  21 /* VERSION/RELEASE
  22 /*      1.1
  23 /*--*/
  24
  25 static char strsave_sccsid[] = "@(#) strsave.c 1.1 92/01/15 21:53:13";
  26
  27 /* C library */
  28
  29 extern char *strcpy();
  30 extern char *malloc();
  31
  32 /* Application-specific stuff */
  33
  34 #include "error.h"
  35
  36 #define STR_TABSIZE     100
  37
  38 struct string {
  39     char   *strval;                     /* unique string copy */
  40     struct string *next;                /* next one in hash chain */
  41 };
  42
  43 static struct string *str_tab[STR_TABSIZE] = {0,};
  44
  45 /* More string stuff. Maybe it should go to an #include file. */
  46
  47 #define STREQ(x,y)      (*(x) == *(y) && strcmp((x),(y)) == 0)
  48
  49 /* strsave - save unique copy of string */
  50
  51 char   *strsave(str)
  52 register char *str;
  53 {
  54     register struct string *s;
  55     register int where = hash(str, STR_TABSIZE);
  56
  57     /* Look for existing entry. */
  58
  59     for (s = str_tab[where]; s; s = s->next)
  60         if (STREQ(str, s->strval))
  61             return (s->strval);
  62
  63     /* Add new entry. */
  64
  65     if ((s = (struct string *) malloc(sizeof(*s))) == 0
  66         || (s->strval = malloc(strlen(str) + 1)) == 0)
  67         fatal("out of memory");
  68     s->next = str_tab[where];
  69     str_tab[where] = s;
  70     return (strcpy(s->strval, str));
  71 }