OSX/sec/SOSCircle/SecureObjectSync/SOSGenCount.c

   1 //
   2 //  SOSGenCount.c
   3 //  sec
   4 //
   5 //  Created by Richard Murphy on 1/29/15.
   6 //
   7 //
   8
   9 #include "SOSGenCount.h"
  10 #include <utilities/SecCFWrappers.h>
  11 #include <CoreFoundation/CFLocale.h>
  12
  13 static CFAbsoluteTime SOSGenerationCountGetDateBits(int64_t genValue) {
  14     return (uint32_t) ((((uint64_t) genValue) >> 32) << 1);
  15 }
  16
  17 void SOSGenerationCountWithDescription(SOSGenCountRef gen, void (^operation)(CFStringRef description)) {
  18     CFStringRef description = SOSGenerationCountCopyDescription(gen);
  19
  20     operation(description);
  21
  22     CFReleaseSafe(description);
  23 }
  24
  25 CFStringRef SOSGenerationCountCopyDescription(SOSGenCountRef gen) {
  26     int64_t value = SOSGetGenerationSint(gen);
  27
  28     CFMutableStringRef gcDecsription = CFStringCreateMutableCopy(kCFAllocatorDefault, 0, CFSTR("["));
  29
  30     withStringOfAbsoluteTime(SOSGenerationCountGetDateBits(value), ^(CFStringRef decription) {
  31         CFStringAppend(gcDecsription, decription);
  32     });
  33
  34     CFStringAppendFormat(gcDecsription, NULL, CFSTR(" %u]"), (uint32_t)(value & 0xFFFFFFFF));
  35
  36     return gcDecsription;
  37 }
  38
  39 int64_t SOSGetGenerationSint(SOSGenCountRef gen) {
  40     int64_t value;
  41     if(!gen) return 0;
  42     CFNumberGetValue(gen, kCFNumberSInt64Type, &value);
  43     return value;
  44 }
  45
  46 static int64_t sosGenerationSetHighBits(int64_t value, int32_t high_31)
  47 {
  48     value &= 0xFFFFFFFF; // Keep the low 32 bits.
  49     value |= ((int64_t) high_31) << 32;
  50
  51     return value;
  52 }
  53
  54 static SOSGenCountRef sosGenerationCreateOrIncrement(SOSGenCountRef gen) {
  55     int64_t value = 0;
  56
  57     if(gen) {
  58         value = SOSGetGenerationSint(gen);
  59     }
  60
  61     if((value >> 32) == 0) {
  62         uint32_t seconds = CFAbsoluteTimeGetCurrent(); // seconds
  63         value = sosGenerationSetHighBits(value, (seconds >> 1));
  64     }
  65
  66     value++;
  67     return CFNumberCreate(NULL, kCFNumberSInt64Type, &value);
  68 }
  69
  70 SOSGenCountRef SOSGenerationCreate() {
  71     return sosGenerationCreateOrIncrement(NULL);
  72 }
  73
  74
  75 // We need this for a circle gencount test
  76 SOSGenCountRef SOSGenerationCreateWithValue(int64_t value) {
  77     return CFNumberCreate(NULL, kCFNumberSInt64Type, &value);
  78 }
  79
  80 SOSGenCountRef SOSGenerationIncrementAndCreate(SOSGenCountRef gen) {
  81     return sosGenerationCreateOrIncrement(gen);
  82 }
  83
  84 SOSGenCountRef SOSGenerationCopy(SOSGenCountRef gen) {
  85     if(!gen) return NULL;
  86     int64_t value = SOSGetGenerationSint(gen);
  87     return CFNumberCreate(NULL, kCFNumberSInt64Type, &value);
  88 }
  89
  90 // Is current older than proposed?
  91 bool SOSGenerationIsOlder(SOSGenCountRef older, SOSGenCountRef newer) {
  92     switch(CFNumberCompare(older, newer, NULL)) {
  93         case kCFCompareLessThan:  return true;
  94         case kCFCompareEqualTo: return false;
  95         case kCFCompareGreaterThan:  return false;
  96     }
  97     return false;
  98 }
  99
 100 // Is current older than proposed?
 101 static bool SOSGenerationIsOlderOrEqual(SOSGenCountRef older, SOSGenCountRef newer) {
 102     switch(CFNumberCompare(older, newer, NULL)) {
 103         case kCFCompareLessThan:  return true;
 104         case kCFCompareEqualTo: return true;
 105         case kCFCompareGreaterThan:  return false;
 106     }
 107     return false;
 108 }
 109
 110
 111 SOSGenCountRef SOSGenerationCreateWithBaseline(SOSGenCountRef reference) {
 112     SOSGenCountRef retval = SOSGenerationCreate();
 113     if(SOSGenerationIsOlderOrEqual(retval, reference)) {
 114         CFReleaseNull(retval);
 115         retval = SOSGenerationIncrementAndCreate(reference);
 116     }
 117     return retval;
 118 }