git.distorted.org.uk Git - u/mdw/catacomb/blob - key-fetch.c

   1 /* -*-c-*-
   2  *
   3  * $Id$
   4  *
   5  * Higher-level key unpacking
   6  *
   7  * (c) 2000 Straylight/Edgeware
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of Catacomb.
  13  *
  14  * Catacomb is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU Library General Public License as
  16  * published by the Free Software Foundation; either version 2 of the
  17  * License, or (at your option) any later version.
  18  *
  19  * Catacomb is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU Library General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU Library General Public
  25  * License along with Catacomb; if not, write to the Free
  26  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  27  * MA 02111-1307, USA.
  28  */
  29
  30 /*----- Header files ------------------------------------------------------*/
  31
  32 #include <mLib/dstr.h>
  33
  34 #include "key.h"
  35 #include "key-data.h"
  36
  37 /*----- Main code ---------------------------------------------------------*/
  38
  39 /* --- @key_fetchinit@ --- *
  40  *
  41  * Arguments:   @const key_fetchdef *kf@ = pointer to base definition
  42  *              @key_packstruct *kps@ = pointer to destination packing def
  43  *              @void *p@ = pointer to destination block
  44  *
  45  * Returns:     Pointer to packing definition.
  46  *
  47  * Use:         Initializes a packing definition (@key_packdef@ structure).
  48  *              If @kps@ is null on entry, an appropriately sized block is
  49  *              allocated automatically.  Otherwise it must be large enough.
  50  */
  51
  52 static size_t kfcount(const key_fetchdef *kf)
  53 {
  54   size_t n = 1;
  55   while (kf->name) {
  56     n++;
  57     if (kf->kf)
  58       n += kfcount(kf->kf);
  59     kf++;
  60   }
  61   return (n);
  62 }
  63
  64 key_packdef *key_fetchinit(const key_fetchdef *kf,
  65                            key_packstruct *kp, void *p)
  66 {
  67   size_t n = 1 + kfcount(kf);
  68   key_packdef *kpd;
  69   key_packstruct *kps;
  70   char *cp = p;
  71
  72   /* --- If @kps@ is null, count the entries and allocate --- */
  73
  74   if (kp)
  75     kp->name = 0;
  76   else {
  77     kp = xmalloc(n * sizeof(*kp));
  78     kp->name = (char *)kp;
  79   }
  80
  81   /* --- Fill in the top part --- */
  82
  83   kp->kp.e = KENC_STRUCT;
  84   kp->kp.p = &kp[1];
  85   kp->kp.kd = 0;
  86   kpd = &kp->kp;
  87
  88   /* --- Initialize for the main loop --- */
  89
  90   kps = kp + n;
  91   n = 0;
  92   kp++;
  93
  94   /* --- Iterate over the entries in the table --- *
  95    *
  96    * The end of the target block is used as a stack to record where
  97    * substructure is meant to occur.  The integer @n@ is the depth of the
  98    * stack; @kps@ is a full descending stack pointer.  The @kp.p@ member of a
  99    * stack element points back to an entry with substructure, the @kp.p@
 100    * member of which refers to the @kf@ table for the substructure.
 101    *
 102    * This should all be about as clear as mud.
 103    */
 104
 105   for (;;) {
 106
 107     /* --- Blat out a level's worth --- */
 108
 109     while (kf->name) {
 110       kp->name = kf->name;
 111       kp->kp.e = kf->e;
 112       kp->kp.kd = 0;
 113       if ((kf->e & KF_ENCMASK) != KENC_STRUCT)
 114         kp->kp.p = cp + kf->off;
 115       else {
 116         (--kps)->kp.p = kp;
 117         kp->kp.p = (void *)kf->kf;
 118         n++;
 119       }
 120       kf++;
 121       kp++;
 122     }
 123     (kp++)->name = 0;
 124     if (!n)
 125       break;
 126
 127     /* --- Pop an entry from the stack --- */
 128
 129     {
 130       key_packstruct *kkp = (kps++)->kp.p;
 131       kf = kkp->kp.p;
 132       kkp->kp.p = kp;
 133       n--;
 134     }
 135   }
 136
 137   /* --- We're done --- */
 138
 139   return (kpd);
 140 }
 141
 142 /* --- @key_fetch@ --- *
 143  *
 144  * Arguments:   @key_packdef *kp@ = pointer to packing structure
 145  *              @key *k@ = key file containing desired key
 146  *
 147  * Returns:     Error code, or zero.
 148  *
 149  * Use:         Fetches an unpacked key from a packed one.
 150  */
 151
 152 int key_fetch(key_packdef *kp, key *k)
 153 {
 154   dstr d = DSTR_INIT;
 155   int e;
 156
 157   key_fulltag(k, &d);
 158   e = key_unpack(kp, k->k, &d);
 159   dstr_destroy(&d);
 160   return (e);
 161 }
 162
 163 /* --- @key_fetchbyname@ --- *
 164  *
 165  * Arguments:   @key_packdef *kp@ = pointer to packing structure
 166  *              @key_file *kf@ = key file containing desired key
 167  *              @const char *tag@ = user's tag describing the key
 168  *
 169  * Returns:     Error code, or zero.
 170  *
 171  * Use:         Fetches a named key from a key file and unpacks it
 172  *              conveniently.
 173  */
 174
 175 int key_fetchbyname(key_packdef *kp, key_file *kf, const char *tag)
 176 {
 177   dstr d = DSTR_INIT;
 178   key_data **kd;
 179   int e;
 180
 181   if (key_qtag(kf, tag, &d, 0, &kd))
 182     e = KERR_NOTFOUND;
 183   else
 184     e = key_unpack(kp, *kd, &d);
 185   dstr_destroy(&d);
 186   return (e);
 187 }
 188
 189 /* --- @key_fetchdone@ --- *
 190  *
 191  * Arguments:   @key_packdef *kp@ = pointer to packing structure
 192  *
 193  * Returns:     ---
 194  *
 195  * Use:         Frees a packing structure.  If the structure was allocated by
 196  *              @key_fetchinit@ then it is freed.
 197  */
 198
 199 void key_fetchdone(key_packdef *kp)
 200 {
 201   key_packstruct *kps =
 202     (key_packstruct *)(((char *)kp) - offsetof(key_packstruct, kp));
 203   key_unpackdone(kp);
 204   if (kps->name)
 205     xfree(kps);
 206 }
 207
 208 /*----- That's all, folks -------------------------------------------------*/