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authorGravatar Yann E. MORIN <yann.morin.1998@free.fr>2017-10-21 22:31:02 +0200
committerGravatar Peter Korsgaard <peter@korsgaard.com>2017-10-22 16:10:37 +0200
commit6393b6904b6a2ee429e60cf3a107eb7eb8b7e0c3 (patch)
tree0ba44974e1d5a1ac4473f515a8c9221f4f5db4dc /toolchain
parent4852f05907cd365825f37c283a415a77ba1fcba9 (diff)
downloadbuildroot-6393b6904b6a2ee429e60cf3a107eb7eb8b7e0c3.tar.gz
buildroot-6393b6904b6a2ee429e60cf3a107eb7eb8b7e0c3.tar.bz2
toolchain/wrapper: fake __DATE_ and __TIME__ for older gcc
Starting with version 7, gcc automatically recognises and enforces the environment variable SOURCE_DATE_EPOCH, and fakes __DATE__ and __TIME__ accordingly, to produce reproducible builds (at least in regards to date and time). However, older gcc versions do not offer this feature. So, we use our toolchain wrapper to force-feed __DATE__ and __TIME__ as macros, which will take precedence over those that gcc may compute itself. We compute them according to the specs: https://reproducible-builds.org/specs/source-date-epoch/ https://gcc.gnu.org/onlinedocs/cpp/Standard-Predefined-Macros.html Since we define macros otherwise internal to gcc, we have to tell it not to warn about that. The -Wno-builtin-macro-redefined flag was introduced in gcc-4.4.0. Therefore, we make BR2_REPRODUCIBLE depend on GCC >= 4.4. gcc-7 will ignore SOURCE_DATE_EPOCH when __DATE__ and __TIME__ are user-defined. Anyway, this is of no consequence: whether __DATE__ and __TIME__ or SOURCE_DATE_EPOCH takes precedence, it would yield the exact same end result since we use the same logic to compute it. Note that we didn't copy the code for it from gcc so using the same logic doesn't imply that we're inheriting GPL-3.0. Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr> Cc: Jérôme Pouiller <jezz@sysmic.org> Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com> Cc: Arnout Vandecappelle <arnout@mind.be> Cc: Peter Korsgaard <peter@korsgaard.com> [Arnout: rewrite commit message] Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be> Reviewed-by: "Yann E. MORIN" <yann.morin.1998@free.fr> Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Diffstat (limited to 'toolchain')
-rw-r--r--toolchain/toolchain-wrapper.c75
1 files changed, 73 insertions, 2 deletions
diff --git a/toolchain/toolchain-wrapper.c b/toolchain/toolchain-wrapper.c
index dd77c11131..2928ea42d0 100644
--- a/toolchain/toolchain-wrapper.c
+++ b/toolchain/toolchain-wrapper.c
@@ -22,12 +22,19 @@
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
+#include <time.h>
+#include <stdbool.h>
#ifdef BR_CCACHE
static char ccache_path[PATH_MAX];
#endif
static char path[PATH_MAX];
static char sysroot[PATH_MAX];
+/* As would be defined by gcc:
+ * https://gcc.gnu.org/onlinedocs/cpp/Standard-Predefined-Macros.html
+ * sizeof() on string literals includes the terminating \0. */
+static char _time_[sizeof("-D__TIME__=\"HH:MM:SS\"")];
+static char _date_[sizeof("-D__DATE__=\"MMM DD YYYY\"")];
/**
* GCC errors out with certain combinations of arguments (examples are
@@ -35,12 +42,15 @@ static char sysroot[PATH_MAX];
* that we only pass the predefined one to the real compiler if the inverse
* option isn't in the argument list.
* This specifies the worst case number of extra arguments we might pass
- * Currently, we have:
+ * Currently, we may have:
* -mfloat-abi=
* -march=
* -mcpu=
+ * -D__TIME__=
+ * -D__DATE__=
+ * -Wno-builtin-macro-redefined
*/
-#define EXCLUSIVE_ARGS 3
+#define EXCLUSIVE_ARGS 6
static char *predef_args[] = {
#ifdef BR_CCACHE
@@ -160,6 +170,60 @@ static void check_unsafe_path(const char *arg,
}
}
+/* Returns false if SOURCE_DATE_EPOCH was not defined in the environment.
+ *
+ * Returns true if SOURCE_DATE_EPOCH is in the environment and represent
+ * a valid timestamp, in which case the timestamp is formatted into the
+ * global variables _date_ and _time_.
+ *
+ * Aborts if SOURCE_DATE_EPOCH was set in the environment but did not
+ * contain a valid timestamp.
+ *
+ * Valid values are defined in the spec:
+ * https://reproducible-builds.org/specs/source-date-epoch/
+ * but we further restrict them to be positive or null.
+ */
+bool parse_source_date_epoch_from_env(void)
+{
+ char *epoch_env, *endptr;
+ time_t epoch;
+ struct tm epoch_tm;
+
+ if ((epoch_env = getenv("SOURCE_DATE_EPOCH")) == NULL)
+ return false;
+ errno = 0;
+ epoch = (time_t) strtoll(epoch_env, &endptr, 10);
+ /* We just need to test if it is incorrect, but we do not
+ * care why it is incorrect.
+ */
+ if ((errno != 0) || !*epoch_env || *endptr || (epoch < 0)) {
+ fprintf(stderr, "%s: invalid SOURCE_DATE_EPOCH='%s'\n",
+ program_invocation_short_name,
+ epoch_env);
+ exit(1);
+ }
+ tzset(); /* For localtime_r(), below. */
+ if (localtime_r(&epoch, &epoch_tm) == NULL) {
+ fprintf(stderr, "%s: cannot parse SOURCE_DATE_EPOCH=%s\n",
+ program_invocation_short_name,
+ getenv("SOURCE_DATE_EPOCH"));
+ exit(1);
+ }
+ if (!strftime(_time_, sizeof(_time_), "-D__TIME__=\"%T\"", &epoch_tm)) {
+ fprintf(stderr, "%s: cannot set time from SOURCE_DATE_EPOCH=%s\n",
+ program_invocation_short_name,
+ getenv("SOURCE_DATE_EPOCH"));
+ exit(1);
+ }
+ if (!strftime(_date_, sizeof(_date_), "-D__DATE__=\"%b %e %Y\"", &epoch_tm)) {
+ fprintf(stderr, "%s: cannot set date from SOURCE_DATE_EPOCH=%s\n",
+ program_invocation_short_name,
+ getenv("SOURCE_DATE_EPOCH"));
+ exit(1);
+ }
+ return true;
+}
+
int main(int argc, char **argv)
{
char **args, **cur, **exec_args;
@@ -289,6 +353,13 @@ int main(int argc, char **argv)
}
#endif /* ARCH || CPU */
+ if (parse_source_date_epoch_from_env()) {
+ *cur++ = _time_;
+ *cur++ = _date_;
+ /* This has existed since gcc-4.4.0. */
+ *cur++ = "-Wno-builtin-macro-redefined";
+ }
+
paranoid_wrapper = getenv("BR_COMPILER_PARANOID_UNSAFE_PATH");
if (paranoid_wrapper && strlen(paranoid_wrapper) > 0)
paranoid = 1;