On Fri, 13 Mar 2015, Dimitrios Apostolou wrote:
I believe my only choice at this point is to forbid "make dist" if tar is detected to be old (less than 1.29), and keep doing --hard-dereference. I open to new ideas though. :-)
The attached patch solves the problem in a more elegant manner IMHO, so I plan to include this modified tar.m4 in my project.
Review is welcome, and feel free to include to upstream automake. Dimitris
From 3672979dc4313da1ec1727eadf3284771e9186f8 Mon Sep 17 00:00:00 2001 From: Dimitrios Apostolou <ji...@gmx.net> Date: Mon, 16 Mar 2015 13:09:06 +0100 Subject: [PATCH 1/1] GNU Tar now uses --hard-dereference when possible Historically "make dist" tries to store only files inside the tarball, avoiding all symlinks/hardlinks in order to bypass limitations of the tar format (for example the "ustar" format allows only 100 characters filenames for symlinks). For that reason -o (i.e. --dereference) has been passed to the tar command. However GNU Tar changed its behaviour since v1.24 and stores symlinks as hardlinks if --dereference is passed. Thus we now need to pass --hard-dereference to make sure no links are stored in the tarball. Unfortunately this option is available since GNU tar v1.28, which means that for versions 1.24-1.28 "make dist" will create tarballs containing hardlinks, with all the limitations of the respective format (see [1]). [1] http://www.gnu.org/software/tar/manual/html_section/tar_68.html --- m4/tar.m4 | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/m4/tar.m4 b/m4/tar.m4 index d8054cb..bca9c3f 100644 --- a/m4/tar.m4 +++ b/m4/tar.m4 @@ -72,18 +72,26 @@ m4_if([$1], [v7], _am_tools=${am_cv_prog_tar_$1-$_am_tools} for _am_tool in $_am_tools; do case $_am_tool in gnutar) for _am_tar in tar gnutar gtar; do AM_RUN_LOG([$_am_tar --version]) && break done - am__tar="$_am_tar --format=m4_if([$1], [pax], [posix], [$1]) -chf - "'"$$tardir"' - am__tar_="$_am_tar --format=m4_if([$1], [pax], [posix], [$1]) -chf - "'"$tardir"' + AC_MSG_CHECKING([if GNU tar supports --hard-dereference]) + AM_RUN_LOG([$_am_tar --hard-dereference]) + # Exit code 64 means unrecognized option + if test "$ac_status" -eq 64; then + am__tar="$_am_tar --format=m4_if([$1], [pax], [posix], [$1]) -chf - "'"$$tardir"' + am__tar_="$_am_tar --format=m4_if([$1], [pax], [posix], [$1]) -chf - "'"$tardir"' + else + am__tar="$_am_tar --format=m4_if([$1], [pax], [posix], [$1]) --hard-dereference -chf - "'"$$tardir"' + am__tar_="$_am_tar --format=m4_if([$1], [pax], [posix], [$1]) --hard-dereference -chf - "'"$tardir"' + fi am__untar="$_am_tar -xf -" ;; plaintar) # Must skip GNU tar: if it does not support --format= it doesn't create # ustar tarball either. (tar --version) >/dev/null 2>&1 && continue am__tar='tar chf - "$$tardir"' am__tar_='tar chf - "$tardir"' -- 1.9.1
