Add hooks for building reproducible images

examples/hooks/reproducible/1000-reproducible-function-uuid_generate_random.hook.chroot

@@ -0,0 +1,63 @@
+#!/bin/sh
+set -e
+
+# util-linux creates random UUIDs when uuid_generate_random is called
+# Use LD_PRELOAD to replace uuid_generate_random with a less random version
+
+# Don't run if gcc is not installed
+if [ ! -e /usr/bin/cc ];
+then
+  exit 0
+fi
+
+cat > unrandomize_uuid_generate_random.c << END_OF_SOURCE
+#include <stdlib.h>
+#include <stdio.h>
+
+#define SEQUENCE_FILENAME "/var/cache/unrandomize_uuid_generate_random.sequence_number"
+
+/* https://tools.ietf.org/html/rfc4122 */
+typedef unsigned char uuid_t[16];
+
+/* Our pseudo-random version */
+void uuid_generate_random(uuid_t out)
+{
+  /* Nil UUID */
+  for (int i=0;i<16;i++) {
+    out[i] = 0x00;
+  }
+  out[6]=0x40; /* UUID version 4 means randomly generated */
+  out[8]=0x80; /* bit7=1,bit6=0 */
+
+  /* The file doesn't need to exist yet */
+  FILE *f = fopen(SEQUENCE_FILENAME, "rb");
+  if (f) {
+    fread(out+12, 4, 1, f);
+    fclose(f);
+  }
+  /* Use the next number. Endianness is not important */
+  (*(unsigned long*)(out+12))++;
+
+  unsigned long long epoch;
+  /* Use SOURCE_DATE_EPOCH when provided */
+  char *date = getenv("SOURCE_DATE_EPOCH");
+  if (date) {
+    epoch = strtoll(date, NULL, 10);
+  } else {
+    epoch = 0ll;
+  }
+  out[0] = (epoch & 0xFF000000) >> 24;
+  out[1] = (epoch & 0x00FF0000) >> 16;
+  out[2] = (epoch & 0x0000FF00) >>  8;
+  out[3] = (epoch & 0x000000FF);
+
+  /* Write the sequence number */
+  f = fopen(SEQUENCE_FILENAME, "wb");
+  if (f) {
+    fwrite(out+12, 4, 1, f);
+    fclose(f);
+  }
+}
+END_OF_SOURCE
+/usr/bin/cc -shared -fPIC unrandomize_uuid_generate_random.c -Wall --pedantic -o /usr/lib/unrandomize_uuid_generate_random.so
+rm -f unrandomize_uuid_generate_random.c

examples/hooks/reproducible/1001-reproducible-fontconfig.hook.chroot

@@ -0,0 +1,25 @@
+#!/bin/sh
+set -e
+
+# fontconfig creates non-reproducible files with UUIDs
+# See https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=864082
+#
+# Because the UUIDs should not be deleted, the proposed work-around is:
+# * Use LD_PRELOAD to replace uuid_generate_random with a less random version
+
+# Don't run if fontconfig is not installed
+if [ ! -e /usr/bin/fc-cache ];
+then
+  exit 0
+fi
+
+# Don't run if the LD_PRELOAD module is not compiled
+if [ ! -e /usr/lib/unrandomize_uuid_generate_random.so ];
+then
+  echo "P: $(basename $0) Reproducible hook inactive: The UUID module was not found"
+  exit 0
+fi
+
+LD_PRELOAD=/usr/lib/unrandomize_uuid_generate_random.so /usr/bin/fc-cache --force --really-force --system-only --verbose
+
+echo "P: $(basename $0) Reproducible hook has been applied"

examples/hooks/reproducible/1002-reproducible-mdadm.hook.chroot

@@ -0,0 +1,21 @@
+#!/bin/sh
+set -e
+
+# mkconf of mdadm creates a file with a timestamp
+# A bug report with patch is available at https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=982607
+# This script duplicates that patch
+
+# Don't run if mdadm is not installed
+if [ ! -e /usr/share/mdadm/mkconf ];
+then
+  exit 0
+fi
+
+# If mkconf already contains references to SOURCE_DATE_EPOCH, there is no need to patch the file
+if grep -q SOURCE_DATE_EPOCH /usr/share/mdadm/mkconf;
+then
+  exit 0
+fi
+sed -i -e '/# This configuration was auto-generated on/cif [ -z $SOURCE_DATE_EPOCH ]; then\n  echo "# This configuration was auto-generated on $(date -R) by mkconf"\nelse\n  echo "# This configuration was auto-generated on $(date -R --utc -d@$SOURCE_DATE_EPOCH) by mkconf"\nfi' /usr/share/mdadm/mkconf
+
+echo "P: $(basename $0) Reproducible hook has been applied"

examples/hooks/reproducible/1003-reproducible-plymouth.hook.chroot

@@ -0,0 +1,27 @@
+#!/bin/sh
+set -e
+
+# The hook of plymouth in update-initramfs calls fc-cache
+
+# Don't run if plymouth is not installed
+if [ ! -e /usr/share/initramfs-tools/hooks/plymouth ];
+then
+  exit 0
+fi
+
+# If the hook already contains references to LD_PRELOAD, there is no need to patch the file
+if grep -q LD_PRELOAD /usr/share/initramfs-tools/hooks/plymouth;
+then
+  exit 0
+fi
+
+# Don't patch if the LD_PRELOAD module is not compiled
+if [ ! -e /usr/lib/unrandomize_uuid_generate_random.so ];
+then
+  echo "P: $(basename $0) Reproducible hook inactive: The UUID module was not found"
+  exit 0
+fi
+
+sed -i -e 's|fc-cache -s|LD_PRELOAD=/usr/lib/unrandomize_uuid_generate_random.so fc-cache|' /usr/share/initramfs-tools/hooks/plymouth
+
+echo "P: $(basename $0) Reproducible hook has been applied"

examples/hooks/reproducible/1004-reproducible-libxml-sax-perl.hook.chroot

@@ -0,0 +1,28 @@
+#!/bin/sh
+set -e
+
+# update-perl-sax-parsers of libxml-sax-perl creates a file with a random order of its lines
+# A bug report with patch is available at https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=993444
+# This script duplicates that patch
+
+# Don't run if libxml-sax-perl is not installed
+if [ ! -e /usr/bin/update-perl-sax-parsers ];
+then
+  exit 0
+fi
+
+# If Debian.pm already contains a sort line, there is no need to patch the file
+if grep -q sort /usr/share/perl5/XML/SAX/Debian.pm;
+then
+  exit 0
+fi
+
+# Patch the Perl script
+sed -i -e '/foreach my $key/s/keys/sort keys/' /usr/share/perl5/XML/SAX/Debian.pm
+
+# Regenerate the file that has more than one key-value pair
+update-perl-sax-parsers --remove XML::SAX::Expat
+update-perl-sax-parsers --add XML::SAX::Expat --priority 50
+update-perl-sax-parsers --update
+
+echo "P: $(basename $0) Reproducible hook has been applied"

examples/hooks/reproducible/9000-cleanup-ucf-backup-files.hook.chroot

@@ -0,0 +1,7 @@
+#!/bin/sh
+set -e
+
+# Delete all older backups of ucf files
+# The current files are /var/lib/ucf/hashfile and /var/lib/ucf/registry
+rm -f /var/lib/ucf/hashfile.*
+rm -f /var/lib/ucf/registry.* 

examples/hooks/reproducible/9900-reproducible-cleanup-uuid_generate_random.hook.chroot

@@ -0,0 +1,6 @@
+#!/bin/sh
+set -e
+
+# Remove the module and its data file
+rm -f /usr/lib/unrandomize_uuid_generate_random.so
+rm -f /var/cache/unrandomize_uuid_generate_random.sequence_number

examples/hooks/reproducible/README

@@ -0,0 +1,11 @@
+Use these scripts to generate reproducible images.
+
+See the generic Wiki page: https://wiki.debian.org/ReproducibleInstalls/LiveImages
+
+After 'lb config' and before 'lb build' you should copy these hooks:
+
+cp /usr/share/doc/live-build/examples/hooks/reproducible/* config/hooks/normal
+
+or (when using the latest git version):
+
+cp $LIVE_BUILD/examples/hooks/reproducible/* config/hooks/normal