lib/config

# lib/config - Configuration file manipulation functions

# These functions have no external dependencies and the following side-effects:
#
# CONFIG_AWK_CMD is defined, default is ``awk``

# Meta-config files contain multiple INI-style configuration files
# using a specific new section header to delimit them:
#
#   [[group-name|file-name]]
#
# group-name refers to the group of configuration file changes to be processed
# at a particular time.  These are called phases in ``stack.sh`` but
# group here as these functions are not DevStack-specific.
#
# file-name is the destination of the config file

# Save trace setting
C_XTRACE=$(set +o | grep xtrace)
set +o xtrace


# Allow the awk command to be overridden on legacy platforms
CONFIG_AWK_CMD=${CONFIG_AWK_CMD:-awk}

# Get the section for the specific group and config file
# get_meta_section infile group configfile
function get_meta_section {
    local file=$1
    local matchgroup=$2
    local configfile=$3

    [[ -r $file ]] || return 0
    [[ -z $configfile ]] && return 0

    $CONFIG_AWK_CMD -v matchgroup=$matchgroup -v configfile=$configfile '
        BEGIN { group = "" }
        /^\[\[.+\|.*\]\]/ {
            if (group == "") {
                gsub("[][]", "", $1);
                split($1, a, "|");
                if (a[1] == matchgroup && a[2] == configfile) {
                    group=a[1]
                }
            } else {
                group=""
            }
            next
        }
        {
            if (group != "")
                print $0
        }
    ' $file
}


# Get a list of config files for a specific group
# get_meta_section_files infile group
function get_meta_section_files {
    local file=$1
    local matchgroup=$2

    [[ -r $file ]] || return 0

    $CONFIG_AWK_CMD -v matchgroup=$matchgroup '
        /^\[\[.+\|.*\]\]/ {
            gsub("[][]", "", $1);
            split($1, a, "|");
            if (a[1] == matchgroup)
                print a[2]
        }
    ' $file
}


# Merge the contents of a meta-config file into its destination config file
# If configfile does not exist it will be created.
# merge_config_file infile group configfile
function merge_config_file {
    local file=$1
    local matchgroup=$2
    local configfile=$3

    # note in the awk below, \x27 is ascii for ' -- this avoids
    # having to do nasty quoting games
    get_meta_section $file $matchgroup $configfile | \
    $CONFIG_AWK_CMD -v configfile=$configfile '
        BEGIN { section = "" }
        /^\[.+\]/ {
            gsub("[][]", "", $1);
            section=$1
            next
        }
        /^ *\#/ {
            next
        }
        /^[^ \t]+/ {
            # get offset of first '=' in $0
            eq_idx = index($0, "=")
            # extract attr & value from $0
            attr = substr($0, 1, eq_idx - 1)
            value = substr($0, eq_idx + 1)
            # only need to strip trailing whitespace from attr
            sub(/[ \t]*$/, "", attr)
            # need to strip leading & trailing whitespace from value
            sub(/^[ \t]*/, "", value)
            sub(/[ \t]*$/, "", value)
            print "iniset " configfile " " section " " attr " \x27" value "\x27"
        }
    ' | while read a; do eval "$a"; done

}


# Merge all of the files specified by group
# merge_config_group infile group [group ...]
function merge_config_group {
    local localfile=$1; shift
    local matchgroups=$@

    [[ -r $localfile ]] || return 0

    local configfile group
    for group in $matchgroups; do
        for configfile in $(get_meta_section_files $localfile $group); do
            if [[ -d $(dirname $(eval "echo $configfile")) ]]; then
                merge_config_file $localfile $group $configfile
            fi
        done
    done
}


# Restore xtrace
$C_XTRACE

# Local variables:
# mode: shell-script
# End: