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179 lines
5.2 KiB
179 lines
5.2 KiB
# This allows us to work with the newline character: |
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define newline |
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endef |
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newline := $(newline) |
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# nl-escape |
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# |
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# Usage: escape = $(call nl-escape[,escape]) |
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# |
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# This is used as the common way to specify |
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# what should replace a newline when escaping |
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# newlines; the default is a bizarre string. |
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# |
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nl-escape = $(if $(1),$(1),m822df3020w6a44id34bt574ctac44eb9f4n) |
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# escape-nl |
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# |
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# Usage: escaped-text = $(call escape-nl,text[,escape]) |
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# |
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# GNU make's $(shell ...) function converts to a |
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# single space each newline character in the output |
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# produced during the expansion; this may not be |
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# desirable. |
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# |
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# The only solution is to change each newline into |
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# something that won't be converted, so that the |
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# information can be recovered later with |
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# $(call unescape-nl...) |
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# |
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escape-nl = $(subst $(newline),$(call nl-escape,$(2)),$(1)) |
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# unescape-nl |
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# |
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# Usage: text = $(call unescape-nl,escaped-text[,escape]) |
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# |
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# See escape-nl. |
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# |
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unescape-nl = $(subst $(call nl-escape,$(2)),$(newline),$(1)) |
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# shell-escape-nl |
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# |
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# Usage: $(shell some-command | $(call shell-escape-nl[,escape])) |
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# |
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# Use this to escape newlines from within a shell call; |
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# the default escape is a bizarre string. |
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# |
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# NOTE: The escape is used directly as a string constant |
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# in an `awk' program that is delimited by shell |
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# single-quotes, so be wary of the characters |
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# that are chosen. |
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# |
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define shell-escape-nl |
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awk 'NR==1 {t=$$0} NR>1 {t=t "$(nl-escape)" $$0} END {printf t}' |
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endef |
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# shell-unescape-nl |
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# |
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# Usage: $(shell some-command | $(call shell-unescape-nl[,escape])) |
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# |
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# Use this to unescape newlines from within a shell call; |
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# the default escape is a bizarre string. |
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# |
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# NOTE: The escape is used directly as an extended regular |
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# expression constant in an `awk' program that is |
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# delimited by shell single-quotes, so be wary |
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# of the characters that are chosen. |
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# |
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# (The bash shell has a bug where `{gsub(...),...}' is |
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# misinterpreted as a brace expansion; this can be |
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# overcome by putting a space between `{' and `gsub'). |
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# |
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define shell-unescape-nl |
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awk 'NR==1 {t=$$0} NR>1 {t=t "\n" $$0} END { gsub(/$(nl-escape)/,"\n",t); printf t }' |
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endef |
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# escape-for-shell-sq |
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# |
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# Usage: embeddable-text = $(call escape-for-shell-sq,text) |
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# |
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# This function produces text that is suitable for |
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# embedding in a shell string that is delimited by |
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# single-quotes. |
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# |
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escape-for-shell-sq = $(subst ','\'',$(1)) |
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# shell-sq |
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# |
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# Usage: single-quoted-and-escaped-text = $(call shell-sq,text) |
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# |
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shell-sq = '$(escape-for-shell-sq)' |
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# shell-wordify |
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# |
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# Usage: wordified-text = $(call shell-wordify,text) |
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# |
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# For instance: |
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# |
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# |define text |
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# |hello |
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# |world |
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# |endef |
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# | |
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# |target: |
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# | echo $(call shell-wordify,$(text)) |
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# |
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# At least GNU make gets confused by expanding a newline |
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# within the context of a command line of a makefile rule |
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# (this is in constrast to a `$(shell ...)' function call, |
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# which can handle it just fine). |
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# |
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# This function avoids the problem by producing a string |
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# that works as a shell word, regardless of whether or |
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# not it contains a newline. |
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# |
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# If the text to be wordified contains a newline, then |
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# an intrictate shell command substitution is constructed |
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# to render the text as a single line; when the shell |
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# processes the resulting escaped text, it transforms |
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# it into the original unescaped text. |
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# |
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# If the text does not contain a newline, then this function |
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# produces the same results as the `$(shell-sq)' function. |
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# |
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shell-wordify = $(if $(findstring $(newline),$(1)),$(_sw-esc-nl),$(shell-sq)) |
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define _sw-esc-nl |
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"$$(echo $(call escape-nl,$(shell-sq),$(2)) | $(call shell-unescape-nl,$(2)))" |
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endef |
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# is-absolute |
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# |
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# Usage: bool-value = $(call is-absolute,path) |
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# |
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is-absolute = $(shell echo $(shell-sq) | grep -q ^/ && echo y) |
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# lookup |
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# |
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# Usage: absolute-executable-path-or-empty = $(call lookup,path) |
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# |
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# (It's necessary to use `sh -c' because GNU make messes up by |
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# trying too hard and getting things wrong). |
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# |
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lookup = $(call unescape-nl,$(shell sh -c $(_l-sh))) |
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_l-sh = $(call shell-sq,command -v $(shell-sq) | $(call shell-escape-nl,)) |
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# is-executable |
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# |
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# Usage: bool-value = $(call is-executable,path) |
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# |
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# (It's necessary to use `sh -c' because GNU make messes up by |
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# trying too hard and getting things wrong). |
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# |
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is-executable = $(call _is-executable-helper,$(shell-sq)) |
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_is-executable-helper = $(shell sh -c $(_is-executable-sh)) |
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_is-executable-sh = $(call shell-sq,test -f $(1) -a -x $(1) && echo y) |
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# get-executable |
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# |
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# Usage: absolute-executable-path-or-empty = $(call get-executable,path) |
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# |
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# The goal is to get an absolute path for an executable; |
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# the `command -v' is defined by POSIX, but it's not |
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# necessarily very portable, so it's only used if |
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# relative path resolution is requested, as determined |
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# by the presence of a leading `/'. |
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# |
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get-executable = $(if $(1),$(if $(is-absolute),$(_ge-abspath),$(lookup))) |
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_ge-abspath = $(if $(is-executable),$(1)) |
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# get-supplied-or-default-executable |
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# |
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# Usage: absolute-executable-path-or-empty = $(call get-executable-or-default,variable,default) |
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# |
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define get-executable-or-default |
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$(if $($(1)),$(call _ge_attempt,$($(1)),$(1)),$(call _ge_attempt,$(2))) |
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endef |
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_ge_attempt = $(if $(get-executable),$(get-executable),$(call _gea_err,$(2))) |
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_gea_err = $(if $(1),$(error Please set '$(1)' appropriately))
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