#!/bin/sh

#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#
# Copyright (c) Calvin Smith
#
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in the
#    documentation and/or other materials provided with the distribution.
# 3. Neither the name of the author nor the names of his contributors
#    may be used to endorse or promote products derived from this software
#    without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
# SUCH DAMAGE.
#
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

# History:
#
#  2008-05-15: added filename to grep output if more than 1 file is searched.
#  2008-05-08: initial version, with edit, append, and grep functionality.
#

PROG="$(basename $0)"
PORT_CONF_DIR="/etc/portage"

usage() {
    cat <<EOF
NAME

    $PROG

LICENSE

    BSD3

SYNOPSIS

    $PROG -h | --help
    $PROG -e | --edit FILENAME+
    $PROG -a | --append "configuration line" FILENAME+
    $PROG -g | --grep "REGEX" FILENAME*

DESCRIPTION

    $PROG allows non-root admin users to edit and search the portage
    configuration files in $PORT_CONF_DIR.

OPTIONS

    -h, --help
        Display this help message.

    -e, --edit FILENAME+
        Edit one or more portage configuration files in $PORT_CONF_DIR.

    -a, --append CONFIG_LINE FILENAME+
        Append a single line of configuration text to one or more
        portage configuration files in $PORT_CONF_DIR.
        Be careful to quote CONFIG_LINE if necessary.

    -g, --grep REGEX FILENAME*
        Perform a search for the given extended regular expression in each
        FILENAME given. If no FILENAME is given, the search is performed
        on all files in the $PORT_CONF_DIR directory.
        Be careful to quote REGEX if necessary.

    FILENAME is always the name of a file in the $PORT_CONF_DIR
    configuration directory, NOT the full path to the file.

    If you use the append option, a backup of the file is made before
    appending to it. The backups go in $PORT_CONF_DIR/bak, which is created
    if necessary, and the file will have the same name with an additional
    extension of .old (e.g., $PORT_CONF_DIR/package.keywords will be backed up
    to $PORT_CONF_DIR/bak/package.keywords.old).

EXAMPLES

    $PROG -e package.keywords
        Edit the package.keywords file.

    $PROG -e package.unmask package.keywords
        Edit the package.unmask and package.keywords files.

    $PROG -a "=app-portage/vim-7.1.285" package.keywords
        Append "=app-portage/vim-7.1.285" to the package.keywords file.

    $PROG -a "x11-libs/cairo" package.unmask package.keywords
        Append "x11-libs/cairo" to both package.unmask and package.keywords.

    $PROG -g "cairo"
        Search all files in $PORT_CONF_DIR for the literal 'cairo'.

    $PROG -g "gcc|glibc" package.unmask package.keywords
        Search package.unmask and package.keywords for the given
        extended regex, which matches each line that contains either
        'gcc' or 'glibc'.

NOTES

    The purpose of this script is to make it easy to edit portage conf
    files in a reasonably secure manner as a non-root admin user via sudo.

    The root user can do things like

    $ echo 'x11-libs/cairo' >> $PORT_CONF_DIR/package.keywords

    in order to easily add a line to a portage configuration file, but
    non-root users can't do this, and you can't give sudo privileges for
    echo to a user without allowing them to overwrite anything (effectively
    making them root). Thus this script!

    The script should be saved somewhere that is on the PATH of all users,
    like /usr/local/bin, and it should have 755 permissions, so that no-one
    but the root user can edit it but all users can execute it.

    Using the --grep option works for all users and requires no further
    configuration.

    Using the --append option requires that you give the invoking user
    sudo privileges for this script.

    Using the --edit option requires that you additionally give the invoking
    user sudoedit privileges for each of the files in $PORT_CONF_DIR.

    For example, use the following (removing leading whitespace on the first line)
    to allow only appending to files by any user in the wheel group (without
    entering a password):

        %wheel          ALL=NOPASSWD: /usr/local/bin/$PROG

    And use the following to allow any user in the wheel group to both append
    to or edit portage configuration files:

        %wheel          ALL=NOPASSWD: /usr/local/bin/$PROG, \\
                                      sudoedit $PORT_CONF_DIR/package.keywords, \\
                                      sudoedit $PORT_CONF_DIR/package.use, \\
                                      sudoedit $PORT_CONF_DIR/package.unmask, \\
                                      sudoedit $PORT_CONF_DIR/package.mask

ALIASES

    You may find it helpful to define the following aliases for the user that
    will use this script:

    alias pa="sudo $PROG --append"
    alias pe="sudo $PROG --edit"
    alias pg="sudo $PROG --grep"
    alias ph="sudo $PROG --help"

    Unmasking and adding a package to package.keywords is then as simple as:

    pa x11-libs/cairo package.unmask package.keywords

SHORTCUTS

    This script also understands some shortcuts for filenames. On each of the
    following lines, the term on the left side can be used instead of the
    term on the right side:

    keywords  ->  package.keywords
    use       ->  package.use
    unmask    ->  package.unmask
    mask      ->  package.mask

EOF
}

# Print an error message to stderr.
err() {
    echo "$*" 1>&2
}

# Expand one or more filenames into the full path to that
# file in $PORT_CONF_DIR, failing if any path contains a slash,
# returning 0 on success and 1 on failure.
expandportageconfpaths() {
    if [ $# -eq 0 ]; then
        echo ""
        return 0
    fi
    conf_dir="$PORT_CONF_DIR"
    fullpaths=""
    for filename in $@
    do
        if expr match "$filename" ".*\/.*" > /dev/null ; then
            err "Invalid filename (contains '/'): $filename"
            err "File arg should be something like 'package.keywords'"
            return 1
        fi
        case "$filename" in
            keywords) full_filename="package.keywords" ;;
            use)      full_filename="package.use"      ;;
            unmask)   full_filename="package.unmask"   ;;
            mask)     full_filename="package.mask"     ;;
            *)        full_filename="$filename"        ;;
        esac
        fullpaths="$fullpaths $conf_dir/$full_filename"
    done
    # return the fullpaths without the extra initial space
    echo "$fullpaths" | cut -c 2-
    return 0
}

# Edit the configuration file(s) in $PORT_CONF_DIR given by the arguments
# using sudoedit. The arguments given should be just the filename,
# like "package.keywords", rather than the full path.
editconfs() {
    if [ $# -lt 1 ]; then
        err "Usage: editconfs FILENAME+"
        return 1
    fi
    filepaths="$(expandportageconfpaths $@)"
    if [ $? -ne 0 ]; then
        err "Error expanding filenames. Exiting."
        return 1
    fi
    # Open and edit the files one at a time, because I'm not sure that all
    # editors will be able to open multiple files in one process correctly.
    for filepath in $filepaths
    do
        # Run sudoedit via su as the SUDO_USER so that it is SUDO_USER
        # that is required to have edit privileges on the file rather
        # the root user that we are currently running as.
        su -c "sudoedit '$filepath'" ${SUDO_USER}
    done
    return 0
}

# Append a line given by $1 to the configuration file(s) in
# $PORT_CONF_DIR given the arguments after $1. The filename arguments
# should include just the filename, like "package.keywords",
# rather than the full path. The line to be added does not need to
# be terminated with a newline character, as it will be added automatically.
#
# Before appending to a file, the file will be backed up to a file with the same
# name plus ".old" in  $PORT_CONF_DIR/bak, which will be created if necessary.
appendconfs() {
    if [ $# -lt 2 ]; then
        err "Usage appendconfs \"line of conf text\" FILENAME+"
        return 1
    fi
    bak_dir="$PORT_CONF_DIR/bak"
    appendline="$1"
    shift
    filepaths="$(expandportageconfpaths $@)"
    if [ $? -ne 0 ]; then
        err "Error expanding filenames. Exiting."
        return 1
    fi
    [ -d "$bak_dir" ] || mkdir -p "$bak_dir"
    if [ $? -ne 0 ]; then
        err "Unable to create backup dir. Exiting."
        return 1
    fi
    for filepath in $filepaths
    do
        if [ -f "$filepath" ]; then
            bak_path="$bak_dir/$(basename $filepath).old"
            cp -f "$filepath" "$bak_path"
        fi
        echo "$appendline" >> $filepath
    done
    return 0
}

grepconfs() {
    if [ $# -lt 1 ]; then
        err "Usage: grepconfs REGEX FILENAME+"
        return 1
    fi
    grep_pat="$1"
    shift
    case $# in
        0)  # search all: include filename in results
            grep -H -E --color=always "$grep_pat" $PORT_CONF_DIR/package.*
            ;;
        1)  # search just the one file: no filename in results
            grep -h -E --color=always "$grep_pat" $(expandportageconfpaths $@)
            ;;
        *)  # search multiple filepaths: include filename in results
            grep -H -E --color=always "$grep_pat" $(expandportageconfpaths $@)
            ;;
    esac
    return $?
}

if [ $# -eq 0 ]; then
    usage
    exit 1
fi

case "$1" in
-h | --help)
    usage
    exit 0
    ;;
-a | --append)
    shift 1
    appendconfs $@
    exit $?
    ;;
-e | --edit)
    shift 1
    editconfs $@
    exit $?
    ;;
-g | --grep)
    shift 1
    grepconfs $@
    exit $?
    ;;
*)
    usage
    exit 1
    ;;
esac