477a0dbd5e
Having randomly generated bytes in the binary output breaks reproducible builds. Since build timestamps are usually the source of irreproducibility there is a standard which defines an environment variable SOURCE_DATE_EPOCH to be used when set for build timestamps. According to the standard [1], the value of SOURCE_DATE_EPOCH is a base-10 integer of the number of seconds since the UNIX epoch. Currently, this is a 10 digit number that fits into 32-bits, but will not shortly after the year 2100. So to be future-proof only use the least significant 32-bits. On 64-bit architectures, where the canary is also 64-bits, there is an extra 32-bits that can be filled to provide more entropy. The first byte is NUL to filter out string buffer overflow attacks and the remaining 24-bits are set to static random bytes. [1] https://reproducible-builds.org/specs/source-date-epoch Signed-off-by: Glenn Washburn <development@efficientek.com> Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
This is GRUB 2, the second version of the GRand Unified Bootloader. GRUB 2 is rewritten from scratch to make GNU GRUB cleaner, safer, more robust, more powerful, and more portable. See the file NEWS for a description of recent changes to GRUB 2. See the file INSTALL for instructions on how to build and install the GRUB 2 data and program files. See the file MAINTAINERS for information about the GRUB maintainers, etc. If you found a security vulnerability in the GRUB please check the SECURITY file to get more information how to properly report this kind of bugs to the maintainers. Please visit the official web page of GRUB 2, for more information. The URL is <http://www.gnu.org/software/grub/grub.html>. More extensive documentation is available in the Info manual, accessible using 'info grub' after building and installing GRUB 2. There are a number of important user-visible differences from the first version of GRUB, now known as GRUB Legacy. For a summary, please see: info grub Introduction 'Changes from GRUB Legacy'