Currently the code relies on __DATE__ and __TIME__ macros.
This prevents to have reproducible build because these values changes every
time we compile.
To achieve reproducible builds, make use of SOURCE_DATE_EPOCH as proposed
on https://reproducible-builds.org
See:
- https://reproducible-builds.org/docs/
- https://reproducible-builds.org/docs/source-date-epoch/
This could be achieved another way if you accept to replace the __DATE__ and __TIME__ macros by something "reproducible".
--- a/FreeFileSync/Source/Makefile
+++ b/FreeFileSync/Source/Makefile
@@ -39,6 +39,10 @@
LDFLAGS += `$(PKG_CONFIG) --libs libselinux`
endif
+ifneq ($(SOURCE_DATE_EPOCH),)
+cxxFlags += -DSOURCE_DATE_EPOCH=$(SOURCE_DATE_EPOCH)
+endif
+
cppFiles=
cppFiles+=application.cpp
cppFiles+=base_tools.cpp
--- a/FreeFileSync/Source/RealTimeSync/Makefile
+++ b/FreeFileSync/Source/RealTimeSync/Makefile
@@ -16,6 +16,10 @@
#treat as system headers so that warnings are hidden:
CXXFLAGS += -isystem/usr/include/gtk-3.0
+ifneq ($(SOURCE_DATE_EPOCH),)
+cxxFlags += -DSOURCE_DATE_EPOCH=$(SOURCE_DATE_EPOCH)
+endif
+
cppFiles=
cppFiles+=application.cpp
cppFiles+=config.cpp
--- a/zen/time.h
+++ b/zen/time.h
@@ -251,8 +251,16 @@
inline
TimeComp getCompileTime()
{
+#ifdef SOURCE_DATE_EPOCH
+ time_t build_date = SOURCE_DATE_EPOCH;
+ tm *ltm = std::localtime(&build_date);
+ char compileTime[100];
+ std::strftime(compileTime, 100, "%b %d %Y %T", ltm); //e.g. "Aug 1 2017 01:32:26"
+#else
//https://gcc.gnu.org/onlinedocs/cpp/Standard-Predefined-Macros.html
char compileTime[] = __DATE__ " " __TIME__; //e.g. "Aug 1 2017 01:32:26"
+#endif
+
if (compileTime[4] == ' ') //day is space-padded, but %d expects zero-padding
compileTime[4] = '0';
