kumquat-buildroot/support/dependencies/check-host-tar.sh
Peter Korsgaard cdac332d20 check-host-tar.sh: bump minimum tar version to 1.27 for reproducible tar files with long paths
Fixes:
http://autobuild.buildroot.net/results/b18/b187e64a61918f17f69588e2355a03286bc5808e

tar 1.27 subtly changed the tar format when a GNU long link entry is added
(which is done for path elements > 100 characters).  The code used to set
the permission mode of the link entry to 0:

  header = start_private_header ("././@LongLink", size, time (NULL));
  FILL (header->header.mtime, '0');
  FILL (header->header.mode, '0');
  FILL (header->header.uid, '0');
  FILL (header->header.gid, '0');
  FILL (header->header.devmajor, 0);
  FILL (header->header.devminor, 0);

This got dropped in 1.27 by commit df7b55a8f6354e3 (Fix some problems with
negative and out-of-range integers), so the settings from
start_private_header() are used directly - Which are:

  TIME_TO_CHARS (t < 0 ? 0 : min (t, MAX_OCTAL_VAL (header->header.mtime)),
		 header->header.mtime);
  MODE_TO_CHARS (S_IFREG|S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH, header->header.mode);
  UID_TO_CHARS (0, header->header.uid);
  GID_TO_CHARS (0, header->header.gid);

The end result is that tar >= 1.27 sets mode to 644.

The consequence of this is that we create different tar files when long path
names are encountered (which often happens when a package downloads a
specific sha1 from a git repo) depending on the host tar version used,
causing hash mismatches.

As a workaround, bump our minimum tar version to 1.27.  It would be nicer to
only do this if we have packages from bzr/git/hg enabled, but that is an
exercise for later.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Acked-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
2018-04-02 14:46:52 +02:00

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#!/bin/sh
candidate="$1"
tar=`which $candidate`
if [ ! -x "$tar" ]; then
tar=`which tar`
if [ ! -x "$tar" ]; then
# echo nothing: no suitable tar found
exit 1
fi
fi
# Output of 'tar --version' examples:
# tar (GNU tar) 1.15.1
# tar (GNU tar) 1.25
# bsdtar 2.8.3 - libarchive 2.8.3
version=`$tar --version | head -n 1 | sed 's/^.*\s\([0-9]\+\.\S\+\).*$/\1/'`
major=`echo "$version" | cut -d. -f1`
minor=`echo "$version" | cut -d. -f2`
bugfix=`echo "$version" | cut -d. -f3`
version_bsd=`$tar --version | grep 'bsdtar'`
if [ ! -z "${version_bsd}" ] ; then
# mark as invalid version - not all command line options are available
major=0
minor=0
fi
# Minimal version = 1.27 (previous versions do not correctly unpack archives
# containing hard-links if the --strip-components option is used or create
# different gnu long link headers for path elements > 100 characters).
major_min=1
minor_min=27
# Maximal version = 1.29 (1.30 changed --numeric-owner output for
# filenames > 100 characters). This is really a fix for a bug in
# earlier tar versions regarding deterministic output so it is
# unlikely to be reverted in later versions.
major_max=1
minor_max=29
if [ $major -lt $major_min -o $major -gt $major_max ]; then
# echo nothing: no suitable tar found
exit 1
fi
if [ $major -eq $major_min -a $minor -lt $minor_min ]; then
# echo nothing: no suitable tar found
exit 1
fi
if [ $major -eq $major_max -a $minor -gt $minor_max ]; then
# echo nothing: no suitable tar found
exit 1
fi
# valid
echo $tar