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 #include <stdlib.h>
  25 #include <string.h>
  26 #include "UserSettings.h"
  27 #include "io_stream.h"
  28 #include "KeysSetting.h"
  29
  30 ExtraKeysSetting *ExtraKeysSetting::global;
  31
  32 ExtraKeysSetting::ExtraKeysSetting ():
  33   keybuffer (NULL), bufsize (0), numkeys (0)
  34 {
  35   global = this;
  36   const char *p = UserSettings::instance().get ("extrakeys");
  37   if (p)
  38     {
  39       bufsize = strlen (p) + 1; // Include final NUL.
  40       keybuffer = strdup (p);
  41       // Replace final NUL by LF.
  42       keybuffer[bufsize - 1] = 0x0a;
  43       // Calling count_keys gets the count but also sizes the buffer
  44       // correctly, discarding any trailing non-LF-terminated data.
  45       bufsize = count_keys ();
  46     }
  47 }
  48
  49 ExtraKeysSetting::~ExtraKeysSetting ()
  50 {
  51   if (keybuffer)
  52     {
  53       // Replace final LF by NUL.
  54       keybuffer[bufsize - 1] = '\0';
  55       UserSettings::instance().set ("extrakeys", keybuffer);
  56     }
  57 }
  58
  59 void
  60 ExtraKeysSetting::flush (void)
  61 {
  62   if (bufsize)
  63     delete [] keybuffer;
  64   keybuffer = 0;
  65   bufsize = 0;
  66   numkeys = 0;
  67 }
  68
  69 void
  70 ExtraKeysSetting::realloc (size_t newbufsize)
  71 {
  72   char *newbuf = new char[newbufsize];
  73   if (bufsize)
  74     {
  75       memcpy (newbuf, keybuffer, newbufsize < bufsize ? newbufsize : bufsize);
  76       delete [] keybuffer;
  77     }
  78   keybuffer = newbuf;
  79   bufsize = newbufsize;
  80 }
  81
  82 size_t
  83 ExtraKeysSetting::count_keys (void)
  84 {
  85   size_t offs = 0, size = 0;
  86   numkeys = 0;
  87   while (offs < bufsize)
  88     if (keybuffer[offs++] == 0x0a)
  89       {
  90         size = offs;
  91         ++numkeys;
  92       }
  93   return size;
  94 }
  95
  96 size_t
  97 ExtraKeysSetting::num_keys (void)
  98 {
  99   return numkeys;
 100 }
 101
 102 const char *
 103 ExtraKeysSetting::get_key (size_t num, size_t *size)
 104 {
 105   if (!numkeys || (num >= numkeys))
 106     return NULL;
 107
 108   const char *ptr = keybuffer;
 109   while (num--)
 110     while (*ptr++ != 0x0a);
 111
 112   // Count its size if requested.
 113   if (size)
 114     {
 115       const char *ptr2 = ptr;
 116       while (num--)
 117         if (*ptr2 != 0x0a)
 118           ++ptr2;
 119         else
 120           break;
 121       *size = ptr2 - ptr;
 122     }
 123   return ptr;
 124 }
 125
 126 void
 127 ExtraKeysSetting::add_unique_key (const char *key)
 128 {
 129   size_t osize = bufsize;
 130   realloc (bufsize + strlen (key) + 1);
 131   strcpy (keybuffer + osize, key);
 132   keybuffer[bufsize - 1] = 0x0a;
 133   ++numkeys;
 134 }
 135
 136 void
 137 ExtraKeysSetting::add_key (const char *key)
 138 {
 139   /* Only add key if we don't already have it. */
 140   const char *ptr = keybuffer;
 141   size_t remain = bufsize;
 142   size_t keylen = strlen (key);
 143
 144   while (remain >= keylen)
 145     {
 146       if (memcmp (ptr, key, keylen) == 0)
 147         return;
 148
 149       while (remain--)
 150         if (*ptr++ == 0x0a)
 151           break;
 152     }
 153   add_unique_key (key);
 154 }