external/ibm-public/postfix/dist/src/util/nvtable.c

   1 /*      $NetBSD$        */
   2
   3 /*++
   4 /* NAME
   5 /*      nvtable 3
   6 /* SUMMARY
   7 /*      attribute list manager
   8 /* SYNOPSIS
   9 /*      #include <nvtable.h>
  10 /*
  11 /*      typedef struct {
  12 /* .in +4
  13 /*              char    *key;
  14 /*              char    *value;
  15 /*              /* private fields... */
  16 /* .in -4
  17 /*      } NVTABLE_INFO;
  18 /*
  19 /*      NVTABLE *nvtable_create(size)
  20 /*      int     size;
  21 /*
  22 /*      NVTABLE_INFO *nvtable_update(table, key, value)
  23 /*      NVTABLE *table;
  24 /*      const char *key;
  25 /*      const char *value;
  26 /*
  27 /*      char    *nvtable_find(table, key)
  28 /*      NVTABLE *table;
  29 /*      const char *key;
  30 /*
  31 /*      NVTABLE_INFO *nvtable_locate(table, key)
  32 /*      NVTABLE *table;
  33 /*      const char *key;
  34 /*
  35 /*      void    nvtable_delete(table, key)
  36 /*      NVTABLE *table;
  37 /*      const char *key;
  38 /*
  39 /*      void    nvtable_free(table)
  40 /*      NVTABLE *table;
  41 /*
  42 /*      void    nvtable_walk(table, action, ptr)
  43 /*      NVTABLE *table;
  44 /*      void    (*action)(NVTABLE_INFO *, char *ptr);
  45 /*      char    *ptr;
  46 /*
  47 /*      NVTABLE_INFO **nvtable_list(table)
  48 /*      NVTABLE *table;
  49 /* DESCRIPTION
  50 /*      This module maintains one or more attribute lists. It provides a
  51 /*      more convenient interface than hash tables, although it uses the
  52 /*      same underlying implementation. Each attribute list entry consists
  53 /*      of a unique string-valued lookup key and a string value.
  54 /*
  55 /*      nvtable_create() creates a table of the specified size and returns a
  56 /*      pointer to the result.
  57 /*
  58 /*      nvtable_update() stores or updates a (key, value) pair in the specified
  59 /*      table and returns a pointer to the resulting entry. The key and the
  60 /*      value are copied.
  61 /*
  62 /*      nvtable_find() returns the value that was stored under the given key,
  63 /*      or a null pointer if it was not found. In order to distinguish
  64 /*      a null value from a non-existent value, use nvtable_locate().
  65 /*
  66 /*      nvtable_locate() returns a pointer to the entry that was stored
  67 /*      for the given key, or a null pointer if it was not found.
  68 /*
  69 /*      nvtable_delete() removes one entry that was stored under the given key.
  70 /*
  71 /*      nvtable_free() destroys a hash table, including contents.
  72 /*
  73 /*      nvtable_walk() invokes the action function for each table entry, with
  74 /*      a pointer to the entry as its argument. The ptr argument is passed
  75 /*      on to the action function.
  76 /*
  77 /*      nvtable_list() returns a null-terminated list of pointers to
  78 /*      all elements in the named table. The list should be passed to
  79 /*      myfree().
  80 /* RESTRICTIONS
  81 /*      A callback function should not modify the attribute list that is
  82 /*      specified to its caller.
  83 /* DIAGNOSTICS
  84 /*      The following conditions are reported and cause the program to
  85 /*      terminate immediately: memory allocation failure; an attempt
  86 /*      to delete a non-existent entry.
  87 /* SEE ALSO
  88 /*      mymalloc(3) memory management wrapper
  89 /*      htable(3) hash table manager
  90 /* LICENSE
  91 /* .ad
  92 /* .fi
  93 /*      The Secure Mailer license must be distributed with this software.
  94 /* AUTHOR(S)
  95 /*      Wietse Venema
  96 /*      IBM T.J. Watson Research
  97 /*      P.O. Box 704
  98 /*      Yorktown Heights, NY 10598, USA
  99 /*--*/
 100
 101 /* C library */
 102
 103 #include <sys_defs.h>
 104
 105 /* Utility library. */
 106
 107 #include <mymalloc.h>
 108 #include <htable.h>
 109 #include <nvtable.h>
 110
 111 /* nvtable_update - update or enter (key, value) pair */
 112
 113 NVTABLE_INFO *nvtable_update(NVTABLE * table, const char *key, const char *value)
 114 {
 115     NVTABLE_INFO *ht;
 116
 117     if ((ht = htable_locate(table, key)) != 0) {
 118         myfree(ht->value);
 119     } else {
 120         ht = htable_enter(table, key, (char *) 0);
 121     }
 122     ht->value = mystrdup(value);
 123     return (ht);
 124 }