On 11/17/2015 12:26 AM, Joseph Myers wrote:
> fprintf to stderr is never appropriate. All diagnostics should go through
> a diagnostic function that properly causes the message to be translated.
>
> If you want a fatal error (exit immediately after giving the message
> rather than continuing compilation), use the fatal_error function, which
> takes an explicit location. You can use UNKNOWN_LOCATION to avoid an
> input file being named, (...)
Thanks for the advise! I've applied the change in the patch.
> Also, this environment variable needs documenting in cppenv.texi.
I have added the documentation as required, it's included in the
attached patch.
Regarding the copyright assignment process, it's in progress :)
Best regards,
Dhole
gcc/c-family/ChangeLog:
2015-11-18 Eduard Sanou <[email protected]>
Matthias Klose <[email protected]>
* c-common.c (get_source_date_epoch): New function, gets the environment
variable SOURCE_DATE_EPOCH and parses it as long long with error
handling.
* c-common.h (get_source_date_epoch): Prototype.
* c-lex.c (c_lex_with_flags): set parse_in->source_date_epoch.
libcpp/ChangeLog:
2015-11-18 Eduard Sanou <[email protected]>
Matthias Klose <[email protected]>
* doc/cppenv.texi: Document SOURCE_DATE_EPOCH environment variable.
2015-11-18 Eduard Sanou <[email protected]>
Matthias Klose <[email protected]>
* include/cpplib.h (cpp_init_source_date_epoch): Prototype.
* init.c (cpp_init_source_date_epoch): New function.
* internal.h: Added source_date_epoch variable to struct
cpp_reader to store a reproducible date.
* macro.c (_cpp_builtin_macro_text): Set pfile->date timestamp from
pfile->source_date_epoch instead of localtime if source_date_epoch is
set, to be used for __DATE__ and __TIME__ macros to help reproducible
builds.
diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
index 7fe7fa6..dbf9fb0 100644
--- a/gcc/c-family/c-common.c
+++ b/gcc/c-family/c-common.c
@@ -12318,4 +12318,38 @@ 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. */
+long long
+get_source_date_epoch()
+{
+ char *source_date_epoch;
+ unsigned long long epoch;
+ char *endptr;
+
+ source_date_epoch = getenv ("SOURCE_DATE_EPOCH");
+ if (!source_date_epoch)
+ return -1;
+
+ errno = 0;
+ epoch = strtoull (source_date_epoch, &endptr, 10);
+ if ((errno == ERANGE && (epoch == ULLONG_MAX || epoch == 0))
+ || (errno != 0 && epoch == 0))
+ fatal_error (UNKNOWN_LOCATION, "environment variable $SOURCE_DATE_EPOCH: "
+ "strtoull: %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 > ULONG_MAX)
+ fatal_error (UNKNOWN_LOCATION, "environment variable $SOURCE_DATE_EPOCH: "
+ "value must be smaller than or equal to: %lu but was found to "
+ "be: %llu \n", ULONG_MAX, epoch);
+
+ return (long long) 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 cabf452..4b55277 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 long long get_source_date_epoch();
+
#endif /* ! GCC_C_COMMON_H */
diff --git a/gcc/c-family/c-lex.c b/gcc/c-family/c-lex.c
index bb55be8..9344f66 100644
--- a/gcc/c-family/c-lex.c
+++ b/gcc/c-family/c-lex.c
@@ -402,6 +402,10 @@ 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;
+ long long source_date_epoch = -1;
+
+ 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 100811d..3b5317b 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 5e08014..9eee80f 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 *, long long);
+
/* 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 45a4d13..dfde0a1 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, long long 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 c2d0816..4363d96 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. */
+ long long 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 1e0a0b5..42beb9c 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 != -1)
+ tb = gmtime ((time_t*) &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)
{
