dpkg-genbuildinfo: Add Build-Date field

This records the time the build happened. This might be useful when
there is a need to track down problems caused by external time-based
events not visible from inside the build system. Things like hardware,
software deployment or other such failures.

debian/changelog

@@ -7,6 +7,7 @@ dpkg (1.18.15) UNRELEASED; urgency=medium
       Proposed by Szabolcs Nagy <nsz@port70.net>. Closes: #843714
   * On source builds add 'source' to the Architecture field in the
     .buildinfo file in dpkg-genbuildinfo.
+  * Add new Build-Date field to .buildinfo files.
   * Perl modules:
     - Validate architecture arguments in Dpkg::Deps deps_parse().
       Prompted by Johannes Schauer <josch@debian.org>.

man/deb-buildinfo.man

@@ -130,6 +130,11 @@ The name of the distribution this package is originating from.
 The Debian architecture for the installation the packages is being built in.
 Common architectures are \fBamd64\fP, \fBarmel\fP, \fBi386\fP, etc.
 .TP
+.BR Build\-Date: " \fIbuild-date\fP"
+The date the package was built.
+It must be in the same format as the date in a \fBdeb\-changelog\fP(5)
+entry.
+.TP
 .BR Build\-Path: " \fIbuild-path\fP"
 The absolute build path, which correspond to the unpacked source tree.
 This field is only going to be present if the vendor has whitelisted it

scripts/Dpkg/Control/FieldsCore.pm

@@ -115,6 +115,9 @@ our %FIELDS = (
         dependency => 'union',
         dep_order => 6,
     },
+    'Build-Date' => {
+        allowed => CTRL_FILE_BUILDINFO,
+    },
     'Build-Depends' => {
         allowed => ALL_SRC,
         separator => FIELD_SEP_COMMA,
@@ -472,7 +475,7 @@ our %FIELD_ORDER = (
         qw(Format Source Binary Architecture Version
         Binary-Only-Changes),
         @checksum_fields,
-        qw(Build-Origin Build-Architecture Build-Path
+        qw(Build-Origin Build-Architecture Build-Date Build-Path
            Installed-Build-Depends Environment),
     ],
     CTRL_FILE_CHANGES() => [

scripts/dpkg-genbuildinfo.pl

@@ -27,7 +27,7 @@ use warnings;
 
 use Cwd;
 use File::Basename;
-use POSIX qw(:fcntl_h strftime);
+use POSIX qw(:fcntl_h :locale_h strftime);
 
 use Dpkg ();
 use Dpkg::Gettext;
@@ -69,6 +69,16 @@ my $checksums = Dpkg::Checksums->new();
 my %archadded;
 my @archvalues;
 
+sub get_build_date {
+    my $date;
+
+    setlocale(LC_TIME, 'C');
+    $date = strftime('%a, %d %b %Y %T %z', localtime);
+    setlocale(LC_TIME, '');
+
+    return $date;
+}
+
 # There is almost the same function in dpkg-checkbuilddeps, they probably
 # should be factored out.
 sub parse_status {
@@ -394,8 +404,8 @@ if ($changelog->{'Binary-Only'}) {
 }
 
 $fields->{'Build-Origin'} = get_current_vendor();
-
 $fields->{'Build-Architecture'} = get_build_arch();
+$fields->{'Build-Date'} = get_build_date();
 
 my $cwd = cwd();
 if ($always_include_path) {