tools/mkimage: backport SOURCE_DATE_EPOCH for reproducible builds

[openwrt/staging/rmilecki.git] / tools / mkimage / patches / 090-reproducible-SOURCE_DATE_EPOCH.patch

diff --git a/tools/mkimage/patches/090-reproducible-SOURCE_DATE_EPOCH.patch b/tools/mkimage/patches/090-reproducible-SOURCE_DATE_EPOCH.patch
new file mode 100644 (file)
index 0000000..c238fd6
--- /dev/null
+++ b/tools/mkimage/patches/090-reproducible-SOURCE_DATE_EPOCH.patch
@@ -0,0 +1,82 @@
+From f3f431a712729a1af94d01bd1bfde17a252ff02c Mon Sep 17 00:00:00 2001
+From: Paul Kocialkowski <contact@paulk.fr>
+Date: Sun, 26 Jul 2015 18:48:15 +0200
+Subject: [PATCH] Reproducible U-Boot build support, using SOURCE_DATE_EPOCH
+
+In order to achieve reproducible builds in U-Boot, timestamps that are defined
+at build-time have to be somewhat eliminated. The SOURCE_DATE_EPOCH environment
+variable allows setting a fixed value for those timestamps.
+
+Simply by setting SOURCE_DATE_EPOCH to a fixed value, a number of targets can be
+built reproducibly. This is the case for e.g. sunxi devices.
+
+However, some other devices might need some more tweaks, especially regarding
+the image generation tools.
+
+Signed-off-by: Paul Kocialkowski <contact@paulk.fr>
+---
+ Makefile              |  7 ++++---
+ README                | 12 ++++++++++++
+ tools/default_image.c | 21 ++++++++++++++++++++-
+ 3 files changed, 36 insertions(+), 4 deletions(-)
+
+--- a/README
++++ b/README
+@@ -4928,6 +4928,18 @@ within that device.
+       normal addressable memory via the LBC. CONFIG_SYS_LS_MC_FW_ADDR is the
+       virtual address in NOR flash.
+ 
++Reproducible builds
++-------------------
++
++In order to achieve reproducible builds, timestamps used in the U-Boot build
++process have to be set to a fixed value.
++
++This is done using the SOURCE_DATE_EPOCH environment variable.
++SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
++option for U-Boot or an environment variable in U-Boot.
++
++SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
++
+ Building the Software:
+ ======================
+ 
+--- a/tools/default_image.c
++++ b/tools/default_image.c
+@@ -89,6 +89,9 @@ static void image_set_header(void *ptr,
+                               struct image_tool_params *params)
+ {
+       uint32_t checksum;
++      char *source_date_epoch;
++      struct tm *time_universal;
++      time_t time;
+ 
+       image_header_t * hdr = (image_header_t *)ptr;
+ 
+@@ -97,9 +100,25 @@ static void image_set_header(void *ptr,
+                               sizeof(image_header_t)),
+                       sbuf->st_size - sizeof(image_header_t));
+ 
++      source_date_epoch = getenv("SOURCE_DATE_EPOCH");
++      if (source_date_epoch != NULL) {
++              time = (time_t) strtol(source_date_epoch, NULL, 10);
++
++              time_universal = gmtime(&time);
++              if (time_universal == NULL) {
++                      fprintf(stderr, "%s: SOURCE_DATE_EPOCH is not valid\n",
++                              __func__);
++                      time = 0;
++              } else {
++                      time = mktime(time_universal);
++              }
++      } else {
++              time = sbuf->st_mtime;
++      }
++
+       /* Build new header */
+       image_set_magic(hdr, params->magic);
+-      image_set_time(hdr, sbuf->st_mtime);
++      image_set_time(hdr, time);
+       image_set_size(hdr, sbuf->st_size - sizeof(image_header_t));
+       image_set_load(hdr, params->addr);
+       image_set_ep(hdr, params->ep);