Allow embedded timestamps by C/C++ macros to be set externally (3)
Dhole
dhole@openmailbox.org
Tue Apr 26 21:29:00 GMT 2016
Hi Bernd,
On 16-04-25 12:15:50, Bernd Schmidt wrote:
> On 04/18/2016 02:26 PM, Dhole wrote:
> >A few months ago I submited a patch to allow the embedded timestamps by
> >C/C++ macros to be set externally [2], which was already an improvement
> >over [1]. I was told to wait until the GCC 7 stage 1 started to send
> >this patch again.
>
> >+/* 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()
>
> Always have a space before open-paren. Maybe this should return time_t. See
> below.
>
> >+/* 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();
>
> Double space after the end of a sentence. Space before open paren.
>
> >+ source_date_epoch = get_source_date_epoch();
> >+ cpp_init_source_date_epoch(parse_in, source_date_epoch);
>
> Spaces.
>
> >+/* Initialize the source_date_epoch value. */
> >+extern void cpp_init_source_date_epoch (cpp_reader *, long long);
>
> Also thinking we should be using time_t here.
>
> > /* Sanity-checks are dependent on command-line options, so it is
> > called as a subroutine of cpp_read_main_file (). */
>
> We don't write () to mark function names.
>
> >+ tb = gmtime ((time_t*) &pfile->source_date_epoch);
>
> Space before the "*". But this cast looks ugly and unreliable (think
> big-endian). This is why I would prefer to move to a time_t representation
> sooner.
>
> >2016-04-18 Eduard Sanou<dhole@openmailbox.org>
> > Matthias Klose<doko@debian.org>
> > * 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.
>
> Add blank lines after the end of the names in ChangeLogs.
Thanks for the review!
I've fixed all the spaces issues. I've also changed the "unsigned long long"
to "time_t" as you suggested. Also, to improve reliability I'm now
using strtoll rather than strtoull, so that negative values can be
detected in SOURCE_DATE_EPOCH, which are treated as errors. This way
the variable pfile->source_date_epoch can't be set to -1 (which is the
default value) when SOURCE_DATE_EPOCH is defined.
I'm attaching the improved patch with the ChangeLog.
Cheers,
--
Dhole
-------------- next part --------------
diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
index f2846bb..6ef63b1 100644
--- a/gcc/c-family/c-common.c
+++ b/gcc/c-family/c-common.c
@@ -12741,4 +12741,37 @@ valid_array_size_p (location_t loc, tree type, tree name)
return true;
}
+/* 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 fa3746c..656bc75 100644
--- a/gcc/c-family/c-common.h
+++ b/gcc/c-family/c-common.h
@@ -1467,4 +1467,9 @@ extern bool reject_gcc_builtin (const_tree, location_t = UNKNOWN_LOCATION);
extern void warn_duplicated_cond_add_or_warn (location_t, tree, vec<tree> **);
extern bool valid_array_size_p (location_t, tree, tree);
+/* 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 96da4fc..753e8b8 100644
--- a/gcc/c-family/c-lex.c
+++ b/gcc/c-family/c-lex.c
@@ -385,6 +385,10 @@ 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;
+ time_t source_date_epoch = (time_t) -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 22c8cb3..e958e93 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 35b0375..4998b3a 100644
--- a/libcpp/include/cpplib.h
+++ b/libcpp/include/cpplib.h
@@ -784,6 +784,9 @@ 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 4343075..f5ff85b 100644
--- a/libcpp/init.c
+++ b/libcpp/init.c
@@ -533,8 +533,15 @@ 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 (). */
+ called as a subroutine of cpp_read_main_file. */
#if CHECKING_P
static void sanity_checks (cpp_reader *);
static void sanity_checks (cpp_reader *pfile)
diff --git a/libcpp/internal.h b/libcpp/internal.h
index 9ce8707..e3eb26b 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 c251553..c2a8376 100644
--- a/libcpp/macro.c
+++ b/libcpp/macro.c
@@ -357,13 +357,20 @@ _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)
{
-------------- next part --------------
gcc/c-family/ChangeLog:
2016-04-26 Eduard Sanou <dhole@openmailbox.org>
Matthias Klose <doko@debian.org>
* 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.
gcc/ChangeLog:
2016-04-26 Eduard Sanou <dhole@openmailbox.org>
Matthias Klose <doko@debian.org>
* doc/cppenv.texi: Document SOURCE_DATE_EPOCH environment variable.
libcpp/ChangeLog:
2016-04-26 Eduard Sanou <dhole@openmailbox.org>
Matthias Klose <doko@debian.org>
* 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.
-------------- next part --------------
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