[Bug 1599459] Re: cannot bootstrap from repositories without InRelease files when --debian-installer set

[Sebastian Unger]

I'm also affected by this. The attached patch fixes the problem using
only posix shell mechanisms.

Please note that the paths in the diff are absolute to patch the problem
in-system.


** Patch added: "functions.diff"
   https://bugs.launchpad.net/ubuntu/+source/debootstrap/+bug/1599459/+attachment/4873850/+files/functions.diff

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https://bugs.launchpad.net/bugs/1599459

Title:
  cannot bootstrap from repositories without InRelease files when
  --debian-installer set

Status in debootstrap package in Ubuntu:
  Confirmed
Status in debootstrap package in Debian:
  New

Bug description:
  Version: 1.0.78+nmu1ubuntu1

  I am using debootstrap in my own minimal system bootstrapper, and am
  making use of the progress information reported to FH 3 as enabled by
  the --debian-installer command-line flag.

  Unfortunately, using this flag causes the behaviour of debootstrap to
  change, specifically in its handling of InRelease / Release files.

  During normal operation, debootstrap will first attempt to fetch an
  InRelease file from the repository; if this is unavailable, i.e. the
  fetch fails with 404, then debootstrap will normally fall back to
  fetching a Release file instead.  Indeed, this is the behaviour of
  debootstrap if --debian-installer is not passed on the command-line.

  debootstrap uses the wgetprogress() function to fetch these URLs.  It
  reads:

  wgetprogress () {
          [ ! "$VERBOSE" ] && QSWITCH="-q"
          local ret=0
          if [ "$USE_DEBIANINSTALLER_INTERACTION" ] && [ "$PROGRESS_NEXT" ]; then
                  wget "$@" 2>&1 >/dev/null | $PKGDETAILS "WGET%" $PROGRESS_NOW $PROGRESS_NEXT $PROGRESS_END >&3
                  ret=$?
          else
                  wget $QSWITCH "$@"
                  ret=$?
          fi
          return $ret
  }

  When the --debian-installer command-line flag is set, the first path
  of the if branch will be taken - running the output of wget through a
  pipe, so that the $PKGDETAILS command can be used to parse progress
  information provided by wget and report it to FH 3 in a format usable
  by debian-installer.

  However, if the URL passed to wget returns 404, then while the wget command
  will fail, the $PKGDETAILS command, and thus the pipeline as a whole, does not, and the wgetprocess () function thus erroneously returns success.

  As a consequence, debootstrap does not fall back to fetching and using a
  Release file as it should in this case, and the bootstrapping attempt as a
  whole fails.

  Because this is a POSIX shell-script, I don't believe there is a
  straightforward mechanism to fetch the exit status of the wget command when it is part of a pipeline.  (See: http://cfajohnson.com/shell/cus-faq-2.html#Q11). It might be possible to enhance the code invoked by $PKGDETAILS to return a fatal exit status if it does not definitely see a successful file retrieval?

  A more direct work-around is to modify this function to
  unconditionally use the second code path that does not attempt to
  invoke wget as part of a pipeline. However, this does mean that you
  lose out on intra-file download progress reporting.

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