support/download/git

   1 #!/usr/bin/env bash
   2
   3 # We want to catch any unexpected failure, and exit immediately
   4 set -e
   5
   6 # Download helper for git, to be called from the download wrapper script
   7 #
   8 # Call it as:
   9 #   .../git [-q] [-r] OUT_FILE REPO_URL CSET BASENAME
  10 #
  11 #   -q  Be quiet.
  12 #   -r  Clone and archive sub-modules.
  13 #
  14 # Environment:
  15 #   GIT      : the git command to call
  16
  17 verbose=
  18 recurse=0
  19 while getopts :qr OPT; do
  20     case "${OPT}" in
  21     q)  verbose=-q; exec >/dev/null;;
  22     r)  recurse=1;;
  23     \?) printf "unknown option '%s'\n" "${OPTARG}" >&2; exit 1;;
  24     esac
  25 done
  26 shift $((OPTIND-1))
  27
  28 output="${1}"
  29 repo="${2}"
  30 cset="${3}"
  31 basename="${4}"
  32
  33 shift 4 # Get rid of our options
  34
  35 # Caller needs to single-quote its arguments to prevent them from
  36 # being expanded a second time (in case there are spaces in them)
  37 _git() {
  38     eval ${GIT} "${@}"
  39 }
  40
  41 # Try a shallow clone, since it is faster than a full clone - but that only
  42 # works if the version is a ref (tag or branch). Before trying to do a shallow
  43 # clone we check if ${cset} is in the list provided by git ls-remote. If not
  44 # we fall back on a full clone.
  45 #
  46 # Messages for the type of clone used are provided to ease debugging in case of
  47 # problems
  48 git_done=0
  49 if [ -n "$(_git ls-remote "'${repo}'" "'${cset}'" 2>&1)" ]; then
  50     printf "Doing shallow clone\n"
  51     if _git clone ${verbose} "${@}" --depth 1 -b "'${cset}'" "'${repo}'" "'${basename}'"; then
  52         git_done=1
  53     else
  54         printf "Shallow clone failed, falling back to doing a full clone\n"
  55     fi
  56 fi
  57 if [ ${git_done} -eq 0 ]; then
  58     printf "Doing full clone\n"
  59     _git clone ${verbose} "${@}" "'${repo}'" "'${basename}'"
  60 fi
  61
  62 pushd "${basename}" >/dev/null
  63
  64 # Try to get the special refs exposed by some forges (pull-requests for
  65 # github, changes for gerrit...). There is no easy way to know whether
  66 # the cset the user passed us is such a special ref or a tag or a sha1
  67 # or whatever else. We'll eventually fail at checking out that cset,
  68 # below, if there is an issue anyway. Since most of the cset we're gonna
  69 # have to clone are not such special refs, consign the output to oblivion
  70 # so as not to alarm unsuspecting users, but still trace it as a warning.
  71 if ! _git fetch origin "'${cset}:${cset}'" >/dev/null 2>&1; then
  72     printf "Could not fetch special ref '%s'; assuming it is not special.\n" "${cset}"
  73 fi
  74
  75 # Checkout the required changeset, so that we can update the required
  76 # submodules.
  77 _git checkout -q "'${cset}'"
  78
  79 # Get date of commit to generate a reproducible archive.
  80 # %cD is RFC2822, so it's fully qualified, with TZ and all.
  81 date="$( _git log -1 --pretty=format:%cD )"
  82
  83 # There might be submodules, so fetch them.
  84 if [ ${recurse} -eq 1 ]; then
  85     _git submodule update --init --recursive
  86 fi
  87
  88 # We do not need the .git dir; we keep other .git files, in case they
  89 # are the only files in their directory.
  90 rm -rf .git
  91
  92 popd >/dev/null
  93
  94 # Generate the archive, sort with the C locale so that it is reproducible
  95 find "${basename}" -not -type d >"${basename}.list"
  96 LC_ALL=C sort <"${basename}.list" >"${basename}.list.sorted"
  97 tar cf - --numeric-owner --owner=0 --group=0 --mtime="${date}" \
  98          -T "${basename}.list.sorted" >"${output}.tar"
  99 gzip -n <"${output}.tar" >"${output}"