Allow an optional "override clock" for deterministic timestamps

When trying to achieve a fully reproducible build process for an
OS image timestamps are a major source of variance. The RPM
database contains two fields in package header records that
are relevant here:

- RPMTAG_INSTALLTIME which is an explicit timestamp indicating
  when the package was installed.
- RPMTAG_INSTALLTID which is an opaque value represending the
  transaction ID under which a package was installed but in terms
  of internal implementation is also a timestamp.

This change allows the presence of the SOURCE_DATE_EPOCH
environment variable, commonly used to override timestamps in
build systems, to institute an "override time" mode in which
values for RPMTAG_INSTALLTID and RPMTAG_INSTALLTIME become
predicatble.

1 files changed, 5 insertions, 0 deletions

diff --git a/lib/rpmts_internal.h b/lib/rpmts_internal.h
index e69ef2584..fc6e15883 100644
--- a/lib/rpmts_internal.h
+++ b/lib/rpmts_internal.h
@@ -91,6 +91,8 @@ struct rpmts_s {
     rpmtriggers trigs2run;   /*!< Transaction file triggers */
 
     int min_writes;             /*!< macro minimize_writes used */
+
+    time_t overrideTime;	/*!< Time value used when overriding system clock. */
 };
 
 #ifdef __cplusplus
@@ -131,6 +133,9 @@ rpmRC runScript(rpmts ts, rpmte te, Header h, ARGV_const_t prefixes,
 RPM_GNUC_INTERNAL
 int rpmtsNotifyChange(rpmts ts, int event, rpmte te, rpmte other);
 
+RPM_GNUC_INTERNAL
+rpm_time_t rpmtsGetTime(rpmts ts, time_t step);
+
 #ifdef __cplusplus
 }
 #endif