terom@583: #!/bin/bash
terom@575: # vim: set ft=sh :
terom@575: #
terom@575: # Dependency-based updates + utils
terom@575: 
terom@575: ## Compare the given output file with all given source files:
terom@575: #
terom@575: #   check_update $out ${deps[@]} && do_update $out ... || ...
terom@575: #
terom@575: # Returns true if the output file needs to be updated.
terom@575: function check_update {
terom@575:     # target
terom@575:     local out=$1; shift
terom@575: 
terom@575:     debug "$out"
terom@575: 
terom@575:     # need update?
terom@575:     local update=
terom@575: 
terom@575:     if [ ${#@} == 0 ]; then
terom@575:         debug "  update: unknown deps"
terom@575:         update=y
terom@575: 
terom@575:     elif [ ! -e $out ]; then
terom@575:         debug "  update: dest missing"
terom@575:         update=y
terom@575:         
terom@575:     elif [ $UPDATE_FORCE ]; then
terom@575:         debug "  update: forced"
terom@575:         update=y
terom@575:     fi
terom@575: 
terom@575:     # check deps
terom@575:     for dep in "$@"; do
terom@575:         # don't bother checking if already figured out
terom@575:         [ $update ] && continue
terom@575: 
terom@575:         # check
terom@575:         if [ ! -e $ROOT/$dep ]; then
terom@590:             fail "$out: Missing source: $dep"
terom@575: 
terom@575:         elif [ $ROOT/$out -ot $ROOT/$dep ]; then
terom@575:             debug "  update: $dep"
terom@575:             update=y
terom@575:         else
terom@575:             debug "  check: $dep"
terom@575:         fi
terom@575:     done
terom@575: 
terom@575:     [ ! $update ] && debug "  up-to-date"
terom@575: 
terom@575:     # return
terom@575:     [ $update ]
terom@575: }
terom@575: 
terom@575: ## Generate updated output file from given command's stdout:
terom@575: #
terom@575: #   do_update $out $BIN/cmd --args
terom@575: #
terom@575: # Writes output to a temporary .new file, optionally shows a diff of changes, and commits
terom@575: # the new version to $out (unless noop'd).
terom@575: function do_update {
terom@575:     local out=$1; shift
terom@575:     local tmp=$out.new
terom@575: 
terom@575:     debug "$out"
terom@575:     cmd "$@" > $ROOT/$tmp
terom@575: 
terom@575:     # compare
terom@575:     if [ -e $ROOT/$out ] && [ $UPDATE_DIFF ]; then
terom@575:         debug "  changes:"
terom@575: 
terom@575:         # terse
terom@575:         indent "        " diff --unified=1 $ROOT/$out $ROOT/$tmp || true
terom@575:     fi
terom@575:     
terom@575:     # deploy
terom@575:     if [ $UPDATE_NOOP ]; then
terom@575:         # cleanup
terom@575:         debug "  no-op"
terom@575: 
terom@575:         cmd rm $ROOT/$tmp
terom@575:     else
terom@575:         # commit
terom@575:         debug "  deploy"
terom@575: 
terom@575:         cmd mv $ROOT/$tmp $ROOT/$out
terom@575:     fi
terom@575: }
terom@575: 
terom@575: ## Look for a link target:
terom@575: #
terom@575: #   find_link   $lnk    $tgt...
terom@575: #
terom@575: # Outputs the first given target to exist, skipping any that are the same as the given $lnk.
terom@575: # If no $tgt matches, outputs the last one, or '-'.
terom@575: function choose_link {
terom@575:     local lnk=$1; shift
terom@575:     local tgt=-
terom@575: 
terom@575:     for tgt in "$@"; do
terom@575:         [ $tgt != $out ] && [ -e $ROOT/$tgt ] && break
terom@575:     done
terom@575:     
terom@575:     echo $tgt
terom@575: }
terom@575: 
terom@575: 
terom@575: ## Compare symlink to target:
terom@575: #
terom@575: #   check_link $lnk $tgt && do_link $lnk $tgt || ...
terom@575: #
terom@575: # Tests if the symlink exists, and the target matches.
terom@575: # Fails if the target does not exist.
terom@575: function check_link {
terom@575:     local lnk=$1
terom@575:     local tgt=$2
terom@575: 
terom@575:     [ ! -e $ROOT/$tgt ] && fail "$tgt: target does not exist"
terom@575:     
terom@575:     [ ! -e $ROOT/$lnk ] || [ $(readlink $ROOT/$lnk) != $ROOT/$tgt ]
terom@575: }
terom@575: 
terom@575: ## Update symlink to point to target:
terom@575: #
terom@575: #   do_link $lnk $tgt
terom@575: #
terom@575: function do_link {
terom@575:     local lnk=$1
terom@575:     local tgt=$2
terom@575: 
terom@575:     cmd ln -sf $ROOT/$tgt $ROOT/$lnk
terom@575: }
terom@575: