Make GCC respect SOURCE_DATE_EPOCH in __DATE__ and __TIME__ macros.
Patch adapted from upstream source repository:
https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=e3e8c48c4a494d9da741c1c8ea6c4c0b7c4ff934
From e3e8c48c4a494d9da741c1c8ea6c4c0b7c4ff934 Mon Sep 17 00:00:00 2001
From: doko <doko@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Thu, 28 Apr 2016 09:12:05 +0000
Subject: [PATCH] gcc/c-family/ChangeLog:
diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
index 1bf5d080034..6f0898a38d7 100644
--- a/gcc/c-family/c-common.c
+++ b/gcc/c-family/c-common.c
@@ -12318,4 +12318,37 @@ pointer_to_zero_sized_aggr_p (tree t)
return (TYPE_SIZE (t) && integer_zerop (TYPE_SIZE (t)));
}
+/* Read SOURCE_DATE_EPOCH from environment to have a deterministic
+ timestamp to replace embedded current dates to get reproducible
+ results. Returns -1 if SOURCE_DATE_EPOCH is not defined. */
+time_t
+get_source_date_epoch ()
+{
+ char *source_date_epoch;
+ long long epoch;
+ char *endptr;
+
+ source_date_epoch = getenv ("SOURCE_DATE_EPOCH");
+ if (!source_date_epoch)
+ return (time_t) -1;
+
+ errno = 0;
+ epoch = strtoll (source_date_epoch, &endptr, 10);
+ if ((errno == ERANGE && (epoch == LLONG_MAX || epoch == LLONG_MIN))
+ || (errno != 0 && epoch == 0))
+ fatal_error (UNKNOWN_LOCATION, "environment variable $SOURCE_DATE_EPOCH: "
+ "strtoll: %s\n", xstrerror(errno));
+ if (endptr == source_date_epoch)
+ fatal_error (UNKNOWN_LOCATION, "environment variable $SOURCE_DATE_EPOCH: "
+ "no digits were found: %s\n", endptr);
+ if (*endptr != '\0')
+ fatal_error (UNKNOWN_LOCATION, "environment variable $SOURCE_DATE_EPOCH: "
+ "trailing garbage: %s\n", endptr);
+ if (epoch < 0)
+ fatal_error (UNKNOWN_LOCATION, "environment variable $SOURCE_DATE_EPOCH: "
+ "value must be nonnegative: %lld \n", epoch);
+
+ return (time_t) epoch;
+}
+
#include "gt-c-family-c-common.h"
diff --git a/gcc/c-family/c-common.h b/gcc/c-family/c-common.h
index fdb227f85c3..ba0a5d7df50 100644
--- a/gcc/c-family/c-common.h
+++ b/gcc/c-family/c-common.h
@@ -1437,4 +1437,10 @@ extern bool contains_cilk_spawn_stmt (tree);
extern tree cilk_for_number_of_iterations (tree);
extern bool check_no_cilk (tree, const char *, const char *,
location_t loc = UNKNOWN_LOCATION);
+
+/* Read SOURCE_DATE_EPOCH from environment to have a deterministic
+ timestamp to replace embedded current dates to get reproducible
+ results. Returns -1 if SOURCE_DATE_EPOCH is not defined. */
+extern time_t get_source_date_epoch (void);
+
#endif /* ! GCC_C_COMMON_H */
diff --git a/gcc/c-family/c-lex.c b/gcc/c-family/c-lex.c
index bb55be8063e..e68471b9d2b 100644
--- a/gcc/c-family/c-lex.c
+++ b/gcc/c-family/c-lex.c
@@ -402,6 +402,9 @@ c_lex_with_flags (tree *value, location_t *loc, unsigned char *cpp_flags,
enum cpp_ttype type;
unsigned char add_flags = 0;
enum overflow_type overflow = OT_NONE;
+ time_t source_date_epoch = get_source_date_epoch ();
+
+ cpp_init_source_date_epoch (parse_in, source_date_epoch);
timevar_push (TV_CPP);
retry:
diff --git a/gcc/doc/cppenv.texi b/gcc/doc/cppenv.texi
index 100811dc637..3b5317beb53 100644
--- a/gcc/doc/cppenv.texi
+++ b/gcc/doc/cppenv.texi
@@ -79,4 +79,21 @@ main input file is omitted.
@ifclear cppmanual
@xref{Preprocessor Options}.
@end ifclear
+
+@item SOURCE_DATE_EPOCH
+
+If this variable is set, its value specifies a UNIX timestamp to be
+used in replacement of the current date and time in the @code{__DATE__}
+and @code{__TIME__} macros, so that the embedded timestamps become
+reproducible.
+
+The value of @env{SOURCE_DATE_EPOCH} must be a UNIX timestamp,
+defined as the number of seconds (excluding leap seconds) since
+01 Jan 1970 00:00:00 represented in ASCII, identical to the output of
+@samp{@command{date +%s}}.
+
+The value should be a known timestamp such as the last modification
+time of the source or package and it should be set by the build
+process.
+
@end vtable
diff --git a/libcpp/include/cpplib.h b/libcpp/include/cpplib.h
index 1b731d1a3ad..7a5481219be 100644
--- a/libcpp/include/cpplib.h
+++ b/libcpp/include/cpplib.h
@@ -775,6 +775,9 @@ extern void cpp_init_special_builtins (cpp_reader *);
/* Set up built-ins like __FILE__. */
extern void cpp_init_builtins (cpp_reader *, int);
+/* Initialize the source_date_epoch value. */
+extern void cpp_init_source_date_epoch (cpp_reader *, time_t);
+
/* This is called after options have been parsed, and partially
processed. */
extern void cpp_post_options (cpp_reader *);
diff --git a/libcpp/init.c b/libcpp/init.c
index 45a4d13ffa3..a8d00f4628b 100644
--- a/libcpp/init.c
+++ b/libcpp/init.c
@@ -530,6 +530,13 @@ cpp_init_builtins (cpp_reader *pfile, int hosted)
_cpp_define_builtin (pfile, "__OBJC__ 1");
}
+/* Initialize the source_date_epoch value. */
+void
+cpp_init_source_date_epoch (cpp_reader *pfile, time_t source_date_epoch)
+{
+ pfile->source_date_epoch = source_date_epoch;
+}
+
/* Sanity-checks are dependent on command-line options, so it is
called as a subroutine of cpp_read_main_file (). */
#if ENABLE_CHECKING
diff --git a/libcpp/internal.h b/libcpp/internal.h
index c2d08168945..8507eba1747 100644
--- a/libcpp/internal.h
+++ b/libcpp/internal.h
@@ -502,6 +502,10 @@ struct cpp_reader
const unsigned char *date;
const unsigned char *time;
+ /* Externally set timestamp to replace current date and time useful for
+ reproducibility. */
+ time_t source_date_epoch;
+
/* EOF token, and a token forcing paste avoidance. */
cpp_token avoid_paste;
cpp_token eof;
diff --git a/libcpp/macro.c b/libcpp/macro.c
index eb32a6f8c98..3f3b278e97d 100644
--- a/libcpp/macro.c
+++ b/libcpp/macro.c
@@ -350,13 +350,20 @@ _cpp_builtin_macro_text (cpp_reader *pfile, cpp_hashnode *node)
time_t tt;
struct tm *tb = NULL;
- /* (time_t) -1 is a legitimate value for "number of seconds
- since the Epoch", so we have to do a little dance to
- distinguish that from a genuine error. */
- errno = 0;
- tt = time(NULL);
- if (tt != (time_t)-1 || errno == 0)
- tb = localtime (&tt);
+ /* Set a reproducible timestamp for __DATE__ and __TIME__ macro
+ usage if SOURCE_DATE_EPOCH is defined. */
+ if (pfile->source_date_epoch != (time_t) -1)
+ tb = gmtime (&pfile->source_date_epoch);
+ else
+ {
+ /* (time_t) -1 is a legitimate value for "number of seconds
+ since the Epoch", so we have to do a little dance to
+ distinguish that from a genuine error. */
+ errno = 0;
+ tt = time (NULL);
+ if (tt != (time_t)-1 || errno == 0)
+ tb = localtime (&tt);
+ }
if (tb)
{
--
2.11.0
