KeysSetting.cc

   1 /*
   2  * Copyright (c) 2008, Dave Korn.
   3  *
   4  *     This program is free software; you can redistribute it and/or modify
   5  *     it under the terms of the GNU General Public License as published by
   6  *     the Free Software Foundation; either version 2 of the License, or
   7  *     (at your option) any later version.
   8  *
   9  *     A copy of the GNU General Public License can be found at
  10  *     http://www.gnu.org/
  11  *
  12  *  This implements the ExtraKeysSetting class, which persists and reads
  13  * in (and saves) extra public DSA signing keys for the verification process.
  14  * It stores them all in a contiguous memory buffer.  Each is one line of
  15  * ASCII text terminated by LF.  THERE IS NO NUL-TERMINATION HERE, TAKE CARE!
  16  * The buffer is sized to the exact size of the content including the terminating
  17  * LF of the last entry.  There is no zero after it.  After reading the file,
  18  * any partial last line is truncated.
  19  *
  20  * Written by Dave Korn <dave.korn.cygwin@gmail.com>
  21  *
  22  */
  23
  24 #if 0
  25 static const char *cvsid =
  26   "\n%%% $Id$\n";
  27 #endif
  28
  29 #include <stdlib.h>
  30 #include <string.h>
  31 #include "UserSettings.h"
  32 #include "io_stream.h"
  33 #include "KeysSetting.h"
  34
  35 ExtraKeysSetting *ExtraKeysSetting::global;
  36
  37 ExtraKeysSetting::ExtraKeysSetting ():
  38   keybuffer (NULL), bufsize (0), numkeys (0)
  39 {
  40   global = this;
  41   const char *p = UserSettings::instance().get ("extrakeys");
  42   if (p)
  43     {
  44       keybuffer = strdup (p);
  45       // Calling count_keys gets the count but also sizes the buffer
  46       // correctly, discarding any trailing non-LF-terminated data.
  47       bufsize = count_keys ();
  48     }
  49 }
  50
  51 ExtraKeysSetting::~ExtraKeysSetting ()
  52 {
  53   if (keybuffer)
  54     UserSettings::instance().set ("extrakeys", keybuffer);
  55 }
  56
  57 void
  58 ExtraKeysSetting::flush (void)
  59 {
  60   if (bufsize)
  61     delete [] keybuffer;
  62   keybuffer = 0;
  63   bufsize = 0;
  64   numkeys = 0;
  65 }
  66
  67 void
  68 ExtraKeysSetting::realloc (size_t newbufsize)
  69 {
  70   char *newbuf = new char[newbufsize];
  71   if (bufsize)
  72     {
  73       memcpy (newbuf, keybuffer, newbufsize < bufsize ? newbufsize : bufsize);
  74       delete [] keybuffer;
  75     }
  76   keybuffer = newbuf;
  77   bufsize = newbufsize;
  78 }
  79
  80 size_t
  81 ExtraKeysSetting::count_keys (void)
  82 {
  83   size_t offs = 0, size = 0;
  84   numkeys = 0;
  85   while (offs < bufsize)
  86     if (keybuffer[offs++] == 0x0a)
  87       {
  88         size = offs;
  89         ++numkeys;
  90       }
  91   return size;
  92 }
  93
  94 size_t
  95 ExtraKeysSetting::num_keys (void)
  96 {
  97   return numkeys;
  98 }
  99
 100 const char *
 101 ExtraKeysSetting::get_key (size_t num, size_t *size)
 102 {
 103   if (!numkeys || (num >= numkeys))
 104     return NULL;
 105
 106   const char *ptr = keybuffer;
 107   while (num--)
 108     while (*ptr++ != 0x0a);
 109
 110   // Count its size if requested.
 111   if (size)
 112     {
 113       const char *ptr2 = ptr;
 114       while (num--)
 115         if (*ptr2 != 0x0a)
 116           ++ptr2;
 117         else
 118           break;
 119       *size = ptr2 - ptr;
 120     }
 121   return ptr;
 122 }
 123
 124 void
 125 ExtraKeysSetting::add_unique_key (const char *key)
 126 {
 127   size_t osize = bufsize;
 128   realloc (bufsize + strlen (key) + 1);
 129   strcpy (keybuffer + osize, key);
 130   keybuffer[bufsize - 1] = 0x0a;
 131   ++numkeys;
 132 }
 133
 134 void
 135 ExtraKeysSetting::add_key (const char *key)
 136 {
 137   /* Only add key if we don't already have it. */
 138   const char *ptr = keybuffer;
 139   size_t remain = bufsize;
 140   size_t keylen = strlen (key);
 141
 142   while (remain >= keylen)
 143     {
 144       if (memcmp (ptr, key, keylen) == 0)
 145         return;
 146
 147       while (remain--)
 148         if (*ptr++ == 0x0a)
 149           break;
 150     }
 151   add_unique_key (key);
 152 }