[PATCH] use stock embedded timestamp 2015-01-01T0000+0000

[Daniel Kahn Gillmor]

Variant timestamps make some grub platforms produce non-deterministic
core images.  This makes it difficult to use simple tools to audit the
stability of a system with grub installed.

This patch selects a single timestamp to use for these embedded
timestamps so that the core images will be replicable.
---
 util/mkimage.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/util/mkimage.c b/util/mkimage.c
index 7821dc5..adc1706 100644
--- a/util/mkimage.c
+++ b/util/mkimage.c
@@ -55,6 +55,9 @@
 
 #define TARGET_NO_FIELD 0xffffffff
 
+/* use 2015-01-01T00:00:00+0000 as a stock timestamp */
+#define STABLE_EMBEDDING_TIMESTAMP 1420070400
+
 struct grub_install_image_target_desc
 {
   const char *dirname;
@@ -1439,7 +1442,7 @@ grub_install_generate_image (const char *dir, const char 
*prefix,
        c->machine = grub_host_to_target16 (image_target->pe_target);
 
        c->num_sections = grub_host_to_target16 (4);
-       c->time = grub_host_to_target32 (time (0));
+       c->time = grub_host_to_target32 (STABLE_EMBEDDING_TIMESTAMP);
        c->characteristics = grub_host_to_target16 (GRUB_PE32_EXECUTABLE_IMAGE
                                                    | 
GRUB_PE32_LINE_NUMS_STRIPPED
                                                    | 
((image_target->voidp_sizeof == 4)
@@ -1782,7 +1785,7 @@ grub_install_generate_image (const char *dir, const char 
*prefix,
 
       memset (hdr, 0, sizeof (*hdr));
       hdr->ih_magic = grub_cpu_to_be32_compile_time (GRUB_UBOOT_IH_MAGIC);
-      hdr->ih_time = grub_cpu_to_be32 (time (0));
+      hdr->ih_time = grub_cpu_to_be32 (STABLE_EMBEDDING_TIMESTAMP);
       hdr->ih_size = grub_cpu_to_be32 (core_size);
       hdr->ih_load = grub_cpu_to_be32 (image_target->link_addr);
       hdr->ih_ep = grub_cpu_to_be32 (image_target->link_addr);
@@ -1856,7 +1859,7 @@ grub_install_generate_image (const char *dir, const char 
*prefix,
        head->magic = image_target->bigendian ? grub_host_to_target16 (0x160)
          : grub_host_to_target16 (0x166);
        head->nsec = grub_host_to_target16 (1);
-       head->time = grub_host_to_target32 (0);
+       head->time = grub_host_to_target32 (STABLE_EMBEDDING_TIMESTAMP);
        head->opt = grub_host_to_target16 (0x38);
        head->flags = image_target->bigendian
          ? grub_host_to_target16 (0x207)
-- 
2.1.4