bash.common

#!/bin/bash

# Don't re-run installs or downloads unless MINAGE seconds have passed since last time
MAXAGE=604800

TS_NOW=$( date '+%s' )


function die() {
    echo "FATAL ERROR: $*" >&2
    exit 1
}


###
# If path exists and mtime is less than maxage, return 0
# Otherwise, return 1
# PARAMS:
# 1. path   - path to dir or file
# 2. maxage - maximum age in secs to be considered recent
###
function is_recent() {
    [[ $DEBUG -eq 1 ]] && set -x
    local path=$1
    local maxage=$2
    local rv=1
    local age
    if [[ -e $path ]] ; then
        ts=$( stat -c '%Y' $path )
        let "age = $TS_NOW - $ts"
        if [[ $age -lt $maxage ]] ; then
            rv=0
        fi
    fi
  return $rv
}


###
#  Return 0 if current user is root, return 1 otherwise
###
function assert_root() {
    [[ $(id -u) -eq 0 ]]
}



###
#  Recursively sync files from SRCDIR to TGTDIR
#  Perform a chown on each file changed in TGTDIR
###
function copy_files() {
    [[ $DEBUG -eq 1 ]] && set -x
    local srcdir="$1"
    local tgtdir="$2"
    local usr_grp=$( stat -c '%u:%g' "$tgtdir" )
    chown -R $usr_grp $srcdir/
    local rsync_verbose=''
    [[ $VERBOSE -eq 1 ]] && rsync_verbose='-v'
    rsync -rog $rsync_verbose "$srcdir/" "$tgtdir/"
    # Verify copied files are identical
    diff_verbose='-q'
    [[ $VERBOSE -eq 1 ]] && diff_verbose='-s'
    find "$srcdir" -type f \
    | while read; do
        tgt_fn=$tgtdir/${REPLY#$srcdir/} 
        diff $diff_verbose $REPLY $tgt_fn || die "Copied file mismatch: $REPLY $tgt_fn"
    done
}


###
#  Update apt libraries if they are older than one day
#  If apt libraries are younger than one day, do nothing
###
function apt_update() {
    [[ $DEBUG -eq 1 ]] && set -x
    is_recent '/var/lib/apt/lists' 86400 \
    || sudo apt -yqq update
}