/* key-gen.c --- manufacturing sequential keys for some db tables * * ==================================================================== * Copyright (c) 2000-2004 CollabNet.  All rights reserved. * * This software is licensed as described in the file COPYING, which * you should have received as part of this distribution.  The terms * are also available at http://subversion.tigris.org/license-1.html. * If newer versions of this license are posted there, you may use a * newer version instead, at your option. * * This software consists of voluntary contributions made by many * individuals.  For exact contribution history, see the revision * history and logs, available at http://subversion.tigris.org/. * ==================================================================== */#include <assert.h>#include <string.h>#include <stdlib.h>#include <apr.h>#include "key-gen.h"/*** Keys for reps and strings. ***/voidsvn_fs_fs__add_keys(const char *key1, const char *key2, char *result){  int i1 = strlen(key1) - 1;  int i2 = strlen(key2) - 1;  int i3 = 0;  int val;  int carry = 0;  char buf[MAX_KEY_SIZE + 2];  while ((i1 >= 0) || (i2 >= 0) || (carry > 0))    {      val = carry;      if (i1>=0)        val += (key1[i1] <= '9') ? (key1[i1] - '0') : (key1[i1] - 'a' + 10);      if (i2>=0)        val += (key2[i2] <= '9') ? (key2[i2] - '0') : (key2[i2] - 'a' + 10);      carry = val / 36;      val = val % 36;            buf[i3++] = (val <= 9) ? (val + '0') : (val - 10 + 'a');      if (i1>=0)        i1--;      if (i2>=0)        i2--;    }  /* Now reverse the resulting string and NULL terminate it. */  for (i1 = 0; i1 < i3; i1++)    result[i1] = buf[i3 - i1 - 1];  result[i1] = '\0';}voidsvn_fs_fs__next_key(const char *this, apr_size_t *len, char *next){  apr_size_t olen = *len;     /* remember the first length */  int i = olen - 1;           /* initial index; we work backwards */  char c;                     /* current char */  svn_boolean_t carry = TRUE; /* boolean: do we have a carry or not?                                 We start with a carry, because we're                                 incrementing the number, after all. */    /* Leading zeros are not allowed, except for the string "0". */  if ((*len > 1) && (this[0] == '0'))    {      *len = 0;      return;    }    for (i = (olen - 1); i >= 0; i--)    {      c = this[i];      /* Validate as we go. */      if (! (((c >= '0') && (c <= '9')) || ((c >= 'a') && (c <= 'z'))))        {          *len = 0;          return;        }      if (carry)        {          if (c == 'z')            next[i] = '0';          else            {              carry = FALSE;                            if (c == '9')                next[i] = 'a';              else                next[i] = c + 1;            }        }      else        next[i] = c;    }  /* The new length is OLEN, plus 1 if there's a carry out of the     leftmost digit. */  *len = olen + (carry ? 1 : 0);  /* Ensure that we haven't overrun the (ludicrous) bound on key length.     Note that MAX_KEY_SIZE is a bound on the size *including*     the trailing null byte. */  assert(*len < MAX_KEY_SIZE);  /* Now we know it's safe to add the null terminator. */  next[*len] = '\0';  /* Handle any leftover carry. */  if (carry)    {      memmove(next+1, next, olen);      next[0] = '1';    }}intsvn_fs_fs__key_compare(const char *a, const char *b){  int a_len = strlen(a);  int b_len = strlen(b);  int cmp;  if (a_len > b_len)    return 1;  if (b_len > a_len)    return -1;  cmp = strcmp(a, b);  return (cmp ? (cmp / abs(cmp)) : 0);}