diff options
| -rw-r--r-- | _posts/2020-05-20-makefile-escaping.md | 82 |
1 files changed, 57 insertions, 25 deletions
diff --git a/_posts/2020-05-20-makefile-escaping.md b/_posts/2020-05-20-makefile-escaping.md index f393c51..cdad1cc 100644 --- a/_posts/2020-05-20-makefile-escaping.md +++ b/_posts/2020-05-20-makefile-escaping.md @@ -43,11 +43,13 @@ and you're good to go. You can then replace `'$(shell your-command arg1 arg2)'` with `'$(call escape,$(shell your-command arg1 arg2))'`. -* To escape environment variable values, define another helper function: +* To escape environment variable values, redefine them using the `$(value)` +function: - escape_var = $(call escape,$(value $(1))) + test_var ?= Default value + test_var := $(value test_var) - You can then replace `'$(VAR_NAME)'` with `'$(call escape_var,VAR_NAME)'`. + Then use the same `escape` function: `'$(call escape,$(test_var))'`. * Don't override variables using `make var1=value1 var2=value2`, use your shell instead: `var1=value1 var2=value2 make`. @@ -174,33 +176,46 @@ escape = $(subst ','\'',$(1)) cwd := $(shell basename -- "$$( pwd )") export cwd +inner_var := Inner variable +outer_var := Outer variable - $(inner_var) - $(cwd) + echo_cwd := printf '%s\n' '$(call escape,$(cwd))' bash_cwd := bash -c '$(call escape,$(echo_cwd))' +echo_outer_var := printf '%s\n' '$(call escape,$(outer_var))' + .PHONY: test test: @printf '%s\n' '$(call escape,$(cwd))' @printf '%s\n' "$$cwd" @bash -c '$(call escape,$(echo_cwd))' @bash -c '$(call escape,$(bash_cwd))' + @printf '%s\n' '$(call escape,$(outer_var))' + @bash -c '$(call escape,$(echo_outer_var))' $ ( mkdir -p -- "Includes ' quote" && cd -- "Includes ' quote" && make -f ../Makefile test ; ) Includes ' quote Includes ' quote Includes ' quote Includes ' quote +Outer variable - Inner variable - Includes ' quote +Outer variable - Inner variable - Includes ' quote $ ( mkdir -p -- 'Maybe a comment #' && cd -- 'Maybe a comment #' && make -f ../Makefile test ; ) Maybe a comment # Maybe a comment # Maybe a comment # Maybe a comment # +Outer variable - Inner variable - Maybe a comment # +Outer variable - Inner variable - Maybe a comment # $ ( mkdir -p -- 'Variable ${reference}' && cd -- 'Variable ${reference}' && make -f ../Makefile test ; ) Variable ${reference} Variable ${reference} Variable ${reference} Variable ${reference} +Outer variable - Inner variable - Variable ${reference} +Outer variable - Inner variable - Variable ${reference} ``` Environment variables @@ -270,30 +285,37 @@ Turns out, you can do just that using the `value` function in `make`. ``` $ cat > Makefile escape = $(subst ','\'',$(1)) -escape_var = $(call escape,$(value $(1))) test_var ?= This is safe. +test_var := $(value test_var) export test_var -echo_test_var := printf '%s\n' '$(call escape_var,test_var)' -bash_test_var := bash -c '$(call escape_var,echo_test_var)' +inner_var := Inner variable +outer_var := Outer variable - $(inner_var) - $(test_var) + +echo_test_var := printf '%s\n' '$(call escape,$(test_var))' +bash_test_var := bash -c '$(call escape,$(echo_test_var))' + +echo_outer_var := printf '%s\n' '$(call escape,$(outer_var))' .PHONY: test test: - @printf '%s\n' '$(call escape_var,test_var)' + @printf '%s\n' '$(call escape,$(test_var))' @printf '%s\n' "$$test_var" - @bash -c '$(call escape_var,echo_test_var)' - @bash -c '$(call escape_var,bash_test_var)' - -$ test_var='Variable ${reference}' make test -Variable ${reference} -Variable ${reference} -Variable ${reference} -Variable ${reference} + @bash -c '$(call escape,$(echo_test_var))' + @bash -c '$(call escape,$(bash_test_var))' + @printf '%s\n' '$(call escape,$(outer_var))' + @bash -c '$(call escape,$(echo_outer_var))' + +$ test_var="Quote '"' and variable ${reference}' make test +Quote ' and variable ${reference} +Quote ' and variable ${reference} +Quote ' and variable ${reference} +Quote ' and variable ${reference} +Outer variable - Inner variable - Quote ' and variable ${reference} +Outer variable - Inner variable - Quote ' and variable ${reference} ``` -You can still use the original `escape` function to escape `shell` output. - One thing to note is that I couldn't find a way to prevent variable values from being expanded when [overriding variables] on the command line. For example, this doesn't work: @@ -302,18 +324,28 @@ For example, this doesn't work: ``` $ make test test_var='Variable ${reference}' +Makefile:23: warning: undefined variable 'reference' make: warning: undefined variable 'reference' -Variable ${reference} Variable -Variable ${reference} -Variable ${reference} +Variable +Variable +Variable +Outer variable - Inner variable - Variable +Outer variable - Inner variable - Variable +``` + +One way to fix this is to escape the dollar sign using `make` syntax: +``` $ make test test_var='Variable $${reference}' -Variable $${reference} Variable ${reference} -Variable $${reference} -Variable $${reference} +Variable ${reference} +Variable ${reference} +Variable ${reference} +Outer variable - Inner variable - Variable ${reference} +Outer variable - Inner variable - Variable ${reference} ``` -As a workaround, set parameter values using your shell: `var_name=value make -...`. +But that's messy. +An easy workaround would be to set parameter values using your shell: +`var_name=value make ...`. |