1 # This allows us to work with the newline character: 2 define newline 3 4 5 endef 6 newline := $(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 # 16 nl-escape = $(or $(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 # 32 escape-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 # 40 unescape-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 # 54 define shell-escape-nl 55 awk 'NR==1 {t=$$0} NR>1 {t=t "$(nl-escape)" $$0} END {printf t}' 56 endef 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 # 74 define shell-unescape-nl 75 awk 'NR==1 {t=$$0} NR>1 {t=t "\n" $$0} END { gsub(/$(nl-escape)/,"\n",t); printf t }' 76 endef 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 # 86 escape-for-shell-sq = $(subst ','\'',$(1)) 87 88 # shell-sq 89 # 90 # Usage: single-quoted-and-escaped-text = $(call shell-sq,text) 91 # 92 shell-sq = '$(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 # 126 shell-wordify = $(if $(findstring $(newline),$(1)),$(_sw-esc-nl),$(shell-sq)) 127 define _sw-esc-nl 128 "$$(echo $(call escape-nl,$(shell-sq),$(2)) | $(call shell-unescape-nl,$(2)))" 129 endef 130 131 # is-absolute 132 # 133 # Usage: bool-value = $(call is-absolute,path) 134 # 135 is-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 # 144 lookup = $(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 # 154 is-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 # 168 get-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 # 175 define get-executable-or-default 176 $(if $($(1)),$(call _ge_attempt,$($(1)),$(1)),$(call _ge_attempt,$(2))) 177 endef 178 _ge_attempt = $(or $(get-executable),$(_gea_warn),$(call _gea_err,$(2))) 179 _gea_warn = $(warning The path '$(1)' is not executable.) 180 _gea_err = $(if $(1),$(error Please set '$(1)' appropriately)) 181 182 # try-cc 183 # Usage: option = $(call try-cc, source-to-build, cc-options) 184 try-cc = $(shell sh -c \ 185 'TMP="$(OUTPUT)$(TMPOUT).$$$$"; \ 186 echo "$(1)" | \ 187 $(CC) -x c - $(2) -o "$$TMP" > /dev/null 2>&1 && echo y; \ 188 rm -f "$$TMP"') 189
