From d0bc096b4a4b94cc62ce00541afb74860392df9c Mon Sep 17 00:00:00 2001
From: Thomas Van Lenten <thomasvl@google.com>
Date: Thu, 12 Jan 2017 17:13:10 -0500
Subject: Timestamp helper fix, Duration helper cleanup.

- The Timestamp proto does not allow for negative nanos fields, so the seconds
  must be shifted and a positive nanos then applied.
- Tweak the helpers on Duration to make it clear there is no "base" time
  involved.
- Update the unittests for duration and timestamp to cover positive and
  negative NSTimeIntervals and what their impact is on the protos.
---
 objectivec/GPBWellKnownTypes.m | 52 ++++++++++++++++++++++++++++++------------
 1 file changed, 37 insertions(+), 15 deletions(-)

(limited to 'objectivec/GPBWellKnownTypes.m')

diff --git a/objectivec/GPBWellKnownTypes.m b/objectivec/GPBWellKnownTypes.m
index ed798a2e..2808afeb 100644
--- a/objectivec/GPBWellKnownTypes.m
+++ b/objectivec/GPBWellKnownTypes.m
@@ -41,15 +41,25 @@ NSString *const GPBWellKnownTypesErrorDomain =
 
 static NSString *kTypePrefixGoogleApisCom = @"type.googleapis.com/";
 
-static NSTimeInterval TimeIntervalSince1970FromSecondsAndNanos(int64_t seconds,
-                                                               int32_t nanos) {
+static NSTimeInterval TimeIntervalFromSecondsAndNanos(int64_t seconds,
+                                                      int32_t nanos) {
   return seconds + (NSTimeInterval)nanos / 1e9;
 }
 
-static int32_t SecondsAndNanosFromTimeIntervalSince1970(NSTimeInterval time,
-                                                        int64_t *outSeconds) {
+static int32_t SecondsAndNanosFromTimeInterval(NSTimeInterval time,
+                                               int64_t *outSeconds,
+                                               BOOL nanosMustBePositive) {
   NSTimeInterval seconds;
   NSTimeInterval nanos = modf(time, &seconds);
+
+  if (nanosMustBePositive && (nanos < 0)) {
+    // Per Timestamp.proto, nanos is non-negative and "Negative second values with
+    // fractions must still have non-negative nanos values that count forward in
+    // time. Must be from 0 to 999,999,999 inclusive."
+    --seconds;
+    nanos = 1.0 + nanos;
+  }
+
   nanos *= 1e9;
   *outSeconds = (int64_t)seconds;
   return (int32_t)nanos;
@@ -88,8 +98,8 @@ static NSString *ParseTypeFromURL(NSString *typeURLString) {
 - (instancetype)initWithTimeIntervalSince1970:(NSTimeInterval)timeIntervalSince1970 {
   if ((self = [super init])) {
     int64_t seconds;
-    int32_t nanos = SecondsAndNanosFromTimeIntervalSince1970(
-        timeIntervalSince1970, &seconds);
+    int32_t nanos = SecondsAndNanosFromTimeInterval(
+        timeIntervalSince1970, &seconds, YES);
     self.seconds = seconds;
     self.nanos = nanos;
   }
@@ -105,13 +115,13 @@ static NSString *ParseTypeFromURL(NSString *typeURLString) {
 }
 
 - (NSTimeInterval)timeIntervalSince1970 {
-  return TimeIntervalSince1970FromSecondsAndNanos(self.seconds, self.nanos);
+  return TimeIntervalFromSecondsAndNanos(self.seconds, self.nanos);
 }
 
 - (void)setTimeIntervalSince1970:(NSTimeInterval)timeIntervalSince1970 {
   int64_t seconds;
   int32_t nanos =
-      SecondsAndNanosFromTimeIntervalSince1970(timeIntervalSince1970, &seconds);
+      SecondsAndNanosFromTimeInterval(timeIntervalSince1970, &seconds, YES);
   self.seconds = seconds;
   self.nanos = nanos;
 }
@@ -122,29 +132,41 @@ static NSString *ParseTypeFromURL(NSString *typeURLString) {
 
 @implementation GPBDuration (GBPWellKnownTypes)
 
-- (instancetype)initWithTimeIntervalSince1970:(NSTimeInterval)timeIntervalSince1970 {
+- (instancetype)initWithTimeInterval:(NSTimeInterval)timeInterval {
   if ((self = [super init])) {
     int64_t seconds;
-    int32_t nanos = SecondsAndNanosFromTimeIntervalSince1970(
-        timeIntervalSince1970, &seconds);
+    int32_t nanos = SecondsAndNanosFromTimeInterval(
+        timeInterval, &seconds, NO);
     self.seconds = seconds;
     self.nanos = nanos;
   }
   return self;
 }
 
-- (NSTimeInterval)timeIntervalSince1970 {
-  return TimeIntervalSince1970FromSecondsAndNanos(self.seconds, self.nanos);
+- (instancetype)initWithTimeIntervalSince1970:(NSTimeInterval)timeIntervalSince1970 {
+  return [self initWithTimeInterval:timeIntervalSince1970];
 }
 
-- (void)setTimeIntervalSince1970:(NSTimeInterval)timeIntervalSince1970 {
+- (NSTimeInterval)timeInterval {
+  return TimeIntervalFromSecondsAndNanos(self.seconds, self.nanos);
+}
+
+- (void)setTimeInterval:(NSTimeInterval)timeInterval {
   int64_t seconds;
   int32_t nanos =
-      SecondsAndNanosFromTimeIntervalSince1970(timeIntervalSince1970, &seconds);
+      SecondsAndNanosFromTimeInterval(timeInterval, &seconds, NO);
   self.seconds = seconds;
   self.nanos = nanos;
 }
 
+- (NSTimeInterval)timeIntervalSince1970 {
+  return self.timeInterval;
+}
+
+- (void)setTimeIntervalSince1970:(NSTimeInterval)timeIntervalSince1970 {
+  self.timeInterval = timeIntervalSince1970;
+}
+
 @end
 
 #pragma mark - GPBAny
-- 
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