1# This allows us to work with the newline character: 2define newline 3 4 5endef 6newline := $(newline) 7 8# nl-escape 9# 10# Usage: escape = $(call nl-escape[,escape]) 11# 12# This is used as the common way to specify 13# what should replace a newline when escaping 14# newlines; the default is a bizarre string. 15# 16nl-escape = $(if $(1),$(1),m822df3020w6a44id34bt574ctac44eb9f4n) 17 18# escape-nl 19# 20# Usage: escaped-text = $(call escape-nl,text[,escape]) 21# 22# GNU make's $(shell ...) function converts to a 23# single space each newline character in the output 24# produced during the expansion; this may not be 25# desirable. 26# 27# The only solution is to change each newline into 28# something that won't be converted, so that the 29# information can be recovered later with 30# $(call unescape-nl...) 31# 32escape-nl = $(subst $(newline),$(call nl-escape,$(2)),$(1)) 33 34# unescape-nl 35# 36# Usage: text = $(call unescape-nl,escaped-text[,escape]) 37# 38# See escape-nl. 39# 40unescape-nl = $(subst $(call nl-escape,$(2)),$(newline),$(1)) 41 42# shell-escape-nl 43# 44# Usage: $(shell some-command | $(call shell-escape-nl[,escape])) 45# 46# Use this to escape newlines from within a shell call; 47# the default escape is a bizarre string. 48# 49# NOTE: The escape is used directly as a string constant 50# in an `awk' program that is delimited by shell 51# single-quotes, so be wary of the characters 52# that are chosen. 53# 54define shell-escape-nl 55awk 'NR==1 {t=$$0} NR>1 {t=t "$(nl-escape)" $$0} END {printf t}' 56endef 57 58# shell-unescape-nl 59# 60# Usage: $(shell some-command | $(call shell-unescape-nl[,escape])) 61# 62# Use this to unescape newlines from within a shell call; 63# the default escape is a bizarre string. 64# 65# NOTE: The escape is used directly as an extended regular 66# expression constant in an `awk' program that is 67# delimited by shell single-quotes, so be wary 68# of the characters that are chosen. 69# 70# (The bash shell has a bug where `{gsub(...),...}' is 71# misinterpreted as a brace expansion; this can be 72# overcome by putting a space between `{' and `gsub'). 73# 74define shell-unescape-nl 75awk 'NR==1 {t=$$0} NR>1 {t=t "\n" $$0} END { gsub(/$(nl-escape)/,"\n",t); printf t }' 76endef 77 78# escape-for-shell-sq 79# 80# Usage: embeddable-text = $(call escape-for-shell-sq,text) 81# 82# This function produces text that is suitable for 83# embedding in a shell string that is delimited by 84# single-quotes. 85# 86escape-for-shell-sq = $(subst ','\'',$(1)) 87 88# shell-sq 89# 90# Usage: single-quoted-and-escaped-text = $(call shell-sq,text) 91# 92shell-sq = '$(escape-for-shell-sq)' 93 94# shell-wordify 95# 96# Usage: wordified-text = $(call shell-wordify,text) 97# 98# For instance: 99# 100# |define text 101# |hello 102# |world 103# |endef 104# | 105# |target: 106# | echo $(call shell-wordify,$(text)) 107# 108# At least GNU make gets confused by expanding a newline 109# within the context of a command line of a makefile rule 110# (this is in constrast to a `$(shell ...)' function call, 111# which can handle it just fine). 112# 113# This function avoids the problem by producing a string 114# that works as a shell word, regardless of whether or 115# not it contains a newline. 116# 117# If the text to be wordified contains a newline, then 118# an intrictate shell command substitution is constructed 119# to render the text as a single line; when the shell 120# processes the resulting escaped text, it transforms 121# it into the original unescaped text. 122# 123# If the text does not contain a newline, then this function 124# produces the same results as the `$(shell-sq)' function. 125# 126shell-wordify = $(if $(findstring $(newline),$(1)),$(_sw-esc-nl),$(shell-sq)) 127define _sw-esc-nl 128"$$(echo $(call escape-nl,$(shell-sq),$(2)) | $(call shell-unescape-nl,$(2)))" 129endef 130 131# is-absolute 132# 133# Usage: bool-value = $(call is-absolute,path) 134# 135is-absolute = $(shell echo $(shell-sq) | grep -q ^/ && echo y) 136 137# lookup 138# 139# Usage: absolute-executable-path-or-empty = $(call lookup,path) 140# 141# (It's necessary to use `sh -c' because GNU make messes up by 142# trying too hard and getting things wrong). 143# 144lookup = $(call unescape-nl,$(shell sh -c $(_l-sh))) 145_l-sh = $(call shell-sq,command -v $(shell-sq) | $(call shell-escape-nl,)) 146 147# is-executable 148# 149# Usage: bool-value = $(call is-executable,path) 150# 151# (It's necessary to use `sh -c' because GNU make messes up by 152# trying too hard and getting things wrong). 153# 154is-executable = $(call _is-executable-helper,$(shell-sq)) 155_is-executable-helper = $(shell sh -c $(_is-executable-sh)) 156_is-executable-sh = $(call shell-sq,test -f $(1) -a -x $(1) && echo y) 157 158# get-executable 159# 160# Usage: absolute-executable-path-or-empty = $(call get-executable,path) 161# 162# The goal is to get an absolute path for an executable; 163# the `command -v' is defined by POSIX, but it's not 164# necessarily very portable, so it's only used if 165# relative path resolution is requested, as determined 166# by the presence of a leading `/'. 167# 168get-executable = $(if $(1),$(if $(is-absolute),$(_ge-abspath),$(lookup))) 169_ge-abspath = $(if $(is-executable),$(1)) 170 171# get-supplied-or-default-executable 172# 173# Usage: absolute-executable-path-or-empty = $(call get-executable-or-default,variable,default) 174# 175define get-executable-or-default 176$(if $($(1)),$(call _ge_attempt,$($(1)),$(1)),$(call _ge_attempt,$(2))) 177endef 178_ge_attempt = $(if $(get-executable),$(get-executable),$(call _gea_err,$(2))) 179_gea_err = $(if $(1),$(error Please set '$(1)' appropriately)) 180