[Reproducible-builds] Bug#828756: python-reportlab: please make the build reproducible

[Reiner Herrmann]

Source: python-reportlab
Version: 3.3.0-1
Severity: wishlist
Tags: patch
User: reproducible-builds at lists.alioth.debian.org
Usertags: timestamps
X-Debbugs-Cc: reproducible-builds at lists.alioth.debian.org

Hi!

While working on the "reproducible builds" effort [1], we have noticed
that python-reportlab could not be built reproducibly.
It embeds timestamps into metadata of generated PDF files.

The attached patch adds support for SOURCE_DATE_EPOCH [2], so that a
deterministic timestamp is used if it is available.
It also removes an additional timestamp in the content of the user
guide.

Regards,
 Reiner

[1]: https://wiki.debian.org/ReproducibleBuilds
[2]: https://reproducible-builds.org/specs/source-date-epoch/
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diff --git a/debian/patches/reproducible-build.patch b/debian/patches/reproducible-build.patch
new file mode 100644
index 0000000..1b88790
--- /dev/null
+++ b/debian/patches/reproducible-build.patch
@@ -0,0 +1,55 @@
+Description: Enable reproducible building
+ - Remove timestamp from documentation
+ - When generating PDF files, honour SOURCE_DATE_EPOCH for timestamps in
+   metadata: https://reproducible-builds.org/specs/source-date-epoch/
+ - Interpret timestamps in generated PDF files as UTC.
+
+--- a/docs/userguide/ch1_intro.py
++++ b/docs/userguide/ch1_intro.py
+@@ -10,7 +10,6 @@
+ title("ReportLab PDF Library")
+ title("User Guide")
+ centred('ReportLab Version ' + reportlab.Version)
+-centred((datetime(2000,1,1,0,0,0) if invariant else datetime.now()).strftime('Document generated on %Y/%m/%d %H:%M:%S %Z'))
+ 
+ nextTemplate("TOC")
+ 
+--- a/src/reportlab/pdfbase/pdfdoc.py
++++ b/src/reportlab/pdfbase/pdfdoc.py
+@@ -1731,7 +1731,9 @@
+     global _NOWT
+     if not _NOWT:
+         import time
+-        _NOWT = time.time()
++        import os
++        import datetime
++        _NOWT = int(os.environ.get('SOURCE_DATE_EPOCH', time.time()))
+     return _NOWT
+ 
+ class PDFDate(PDFObject):
+@@ -1739,22 +1741,17 @@
+     def __init__(self, invariant=rl_config.invariant, dateFormatter=None):
+         if invariant:
+             now = (2000,1,1,0,0,0,0)
+-            self.dhh = 0
+-            self.dmm = 0
+         else:
+             import time
+-            now = tuple(time.localtime(_getTimeStamp())[:6])
+-            from time import timezone
+-            self.dhh = int(timezone / (3600.0))
+-            self.dmm = (timezone % 3600) % 60
++            now = tuple(time.gmtime(_getTimeStamp())[:6])
+         self.date = now[:6]
+         self.dateFormatter = dateFormatter
+ 
+     def format(self, doc):
+         dfmt = self.dateFormatter or (
+                 lambda yyyy,mm,dd,hh,m,s:
+-                    "D:%04d%02d%02d%02d%02d%02d%+03d'%02d'"
+-                        % (yyyy,mm,dd,hh,m,s,self.dhh,self.dmm))
++                    "D:%04d%02d%02d%02d%02d%02d+00'00'"
++                        % (yyyy,mm,dd,hh,m,s))
+         return format(PDFString(dfmt(*self.date)), doc)
+ 
+ class Destination(PDFObject):
diff --git a/debian/patches/series b/debian/patches/series
index 79de88c..0f5a457 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -1 +1,2 @@
 gsfonts.diff
+reproducible-build.patch
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