Thanks, I installed that patch.
In thinking about the recipe I noticed that it doesn't talk about
directory timestamps. I installed the attached to address this issue,
and also to document the recipe a bit better.From 68636f0bcb83e83041cf3198b09dbcf138b2ee69 Mon Sep 17 00:00:00 2001
From: Paul Eggert <[email protected]>
Date: Tue, 25 Jul 2023 09:43:16 -0700
Subject: [PATCH] Improve reproducibility recipe
MIME-Version: 1.0
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* doc/tar.texi (Reproducibility): Improve index.
Improve and add comments to recipe. In the recipe,
don’t worry about file names beginning with ‘-’ for simplicity;
don’t use touch -c as it exits with status 0 even when it
does not work; and set directory timestamps too.
---
doc/tar.texi | 28 ++++++++++++++++++++--------
1 file changed, 20 insertions(+), 8 deletions(-)
diff --git a/doc/tar.texi b/doc/tar.texi
index 8319688f..fa9ac2d3 100644
--- a/doc/tar.texi
+++ b/doc/tar.texi
@@ -10307,6 +10307,7 @@ This option is meaningless with @option{--list} (@option{-t}).
@node Portability
@section Making @command{tar} Archives More Portable
+@cindex portable archives
Creating a @command{tar} archive on a particular system that is meant to be
useful later on many other machines and with other versions of @command{tar}
is more challenging than you might think. @command{tar} archive formats
@@ -11182,6 +11183,7 @@ Done
@node Reproducibility
@section Making @command{tar} Archives More Reproducible
+@cindex reproducible archives
Sometimes it is important for an archive to be @dfn{reproducible},
so that one can be easily verify it to have been derived solely from
its input. We call an archive reproducible, if an archive
@@ -11256,11 +11258,23 @@ function get_commit_time() @{
--date=format:%Y-%m-%dT%H:%M:%SZ \
"$@@"
@}
-SOURCE_EPOCH=$(get_commit_time)
+#
+# Set each source file timestamp to that of its latest commit.
git ls-files | while read -r file; do
- commit_time=$(get_commit_time -- "$file") &&
- touch -cmd $commit_time -- "$file"
+ commit_time=$(get_commit_time "$file") &&
+ touch -md $commit_time "$file"
done
+#
+# Set timestamp of each directory under $FILES
+# to the latest timestamp of any descendant.
+find $FILES -depth -type d -exec sh -c \
+ 'touch -r "$0/$(ls -At "$0" | head -n 1)" "$0"' \
+ @{@} ';'
+#
+# Create $ARCHIVE.tgz from $FILES, pretending that
+# the modification time for each newer file
+# is that of the most recent commit of any source file.
+SOURCE_EPOCH=$(get_commit_time)
TARFLAGS="
--sort=name --format=posix
--pax-option=exthdr.name=%d/PaxHeaders/%f
@@ -11269,11 +11283,9 @@ TARFLAGS="
--numeric-owner --owner=0 --group=0
--mode=go+u,go-w
"
-GZIPFLAGS="
- --no-name --best
-"
-LC_ALL=C tar $TARFLAGS -cf - FILES |
- gzip $GZIPFLAGS > ARCHIVE.tgz
+GZIPFLAGS="--no-name --best"
+LC_ALL=C tar $TARFLAGS -cf - $FILES |
+ gzip $GZIPFLAGS > $ARCHIVE.tgz
@end example
@node cpio
--
2.39.2
