venvpatch

#!/bin/sh
# venvpatch (part of ossobv/vcutil) // wdoekes/2014-2015 // Public Domain
#
# Automatically applies one or more patches to the current python environment.
#
# Use this to apply a set of patches to a python virtualenv and optionally the
# system packages. Group the patches you want to apply in a single directory
# and venvpatch will apply all unapplied ones at once. Specify --apply to
# actually do it.
#
# Usage:
#
#     venvpatch PATH_WITH_PATCH_FILES [--apply]
#     venvpatch SINGLE_PATCH_FILE [--apply]
#
# Common python project deployment workflow goes like this:
#
# - Create a virtual environment:
#   $ mkvirtualenv PROJECT
# - Install the requirements:
#   $ pip install -r requirements.txt
# - Apply a set of patches to the requirements:
#   $ cdsitepackages
#   $ patch -p1 < /path/to/project/patches/somepatch.patch
#   $ patch -p0 < /path/to/project/patches/anotherpatch.patch
#
# The venvpatch utility will take care of:
#
# - Applying multiple patch files at once.
# - Checking whether a patch is applied already, and ignoring it otherwise.
# - Autodetecting -p0 and -p1.
# - Autodetecting the destination path, be it in the virtualenv site-packages
#   or in the system-global-packages.
#
# In the following example, the first patch has been applied already:
#
#     # ls ./docs/patches/1.4/
#     issue16211+14029-query-expression-extra-operators-1.4.patch
#     pisa3-reportlab-version.patch
#
#     # venvpatch ./docs/patches/1.4/
#     source = /srv/django-projects/test/docs/patches/1.4/
#      [X] issue16211+14029-query-expression-extra-operators-1.4.patch => \
#            /srv/virtualenvs/test/lib/python2.7/site-packages
#      [ ] pisa3-reportlab-version.patch => /usr/lib/pymodules/python2.7
#
#     # venvpatch ./docs/patches/1.4/ --apply
#     source = /srv/django-projects/test/docs/patches/1.4/
#      [X] issue16211+14029-query-expression-extra-operators-1.4.patch => \
#            /srv/virtualenvs/test/lib/python2.7/site-packages
#      [N] pisa3-reportlab-version.patch => /usr/lib/pymodules/python2.7
#     patching file sx/pisa3/pisa_util.py
#
# A re-run of venvpatch would now show [X] next to both patches. In case of
# errors, an [E] would be shown.
#
patchpath="$1"
test -z "$patchpath" &&
    echo "venvpatch: Need SOURCE_PATCH_PATH as first argument" >&2 &&
    exit 1
apply="$2"


# Init globals.
local_packages=$(
    python -c 'import distutils;print(distutils.sysconfig.get_python_lib())' \
      2>/dev/null)
other_packages=$(python -c 'import sys; print(" ".join(sys.path))')
cwd=$(pwd)/
patchpath=$(echo "$patchpath" | sed -e 's#^\([^/]\)#'$cwd'\1#')

# Fetch patch arguments.
patchver=$(patch --version | sed -e '1!d;s/.* //')
if test $(printf '%s\n2.7\n' $patchver | sort -V | head -n1) = 2.7; then
    patchargs="--follow-symlinks --forward"
else
    patchargs="--forward"
fi


# Echo source path so manual intervention is eased.
if test -f "$patchpath"; then
    echo "source = $(dirname "$patchpath")"
else
    echo "source = $patchpath"
fi


# Collect possible patches, and loop over them:
ret=0
find "$patchpath" -maxdepth 1 -type f -name '*.patch' | sort |
while read patch; do
    patch_basename=$(basename "$patch")

    # Get the first file to be patched.
    path1=$(grep ^+++ "$patch" | head -n1 | awk '{print $2}')

    # Does it begin with a/ or b/ ? Then we should check the second path
    # element instead.
    # NOTE: $dir may turn out to be a plain file.
    if echo "$path1" | grep -q '^[ab]/'; then
        dir=$(echo "$path1" | sed -e 's#^[ab]/\([^/]*\)/.*#\1#')
        level=1
    else
        dir=$(echo "$path1" | sed -e 's#^\([^/]*\)/.*#\1#')
        level=0
    fi

    # Where do we patch? In VIRTUAL_ENV or in global?
    dest=
    for path in $local_packages $other_packages; do
        if test -d "$path/$dir" || test -r "$path/$dir"; then
            dest="$path"
            break
        fi
    done
    if test -z "$dest"; then
        cat >&2 <<EOF
venvpatch: No sensible patch location found for '$dir' in $patch
venvpatch: Forgot to enable virtualenv?
EOF
        exit 1
    fi

    # Very well. Let's see what a dry-run does. And if --apply is
    # passed as arg2, let's rock.
    cd "$dest"
    output=$(patch -p$level -i$patch --dry-run $patchargs \
      </dev/null 2>&1)
    if test $? -eq 0; then
        if test "$apply" = "--apply"; then
            echo " [N] $patch_basename => $dest"
            patch -p$level -i$patch $patchargs || exit 1
        else
            echo " [ ] $patch_basename => $dest"
        fi
    elif echo "$output" | grep -q ^Reversed; then
        echo " [X] $patch_basename => $dest"
    else
        echo " [E] $patch_basename => $dest"
        echo "     Output: "
        echo "$output" | sed -e 's/^/        /'
        echo "     Permission issue? Try:"
        echo "        sudo env PATH=\$PATH $0 $patch"
        ret=1
    fi

    test $ret = 0  # set status code
done

# vim: set ts=8 sw=4 sts=4 et ai tw=79: