1 # Mage Build Tool by Matt McCutchen
2 # http://www.kepreon.com/~matt/mage/
4 # Remember the original default goal so we can restore it at the end of mage.mk.
5 mg-orig-default-goal := $(.DEFAULT_GOAL)
14 # Shell-quote: a'b => 'a'\''b'
15 sq = '$(subst ','\'',$1)'
16 # Make-quote: a$\nb => a$$$(nl)b
17 # This is enough to assign the value, *but not to use it as an argument!*
18 mqas = $(subst $(nl),$$(nl),$(subst $$,$$$$,$1))
19 # Return nonempty if the strings are equal, empty otherwise.
20 # If the strings have only nice characters, you can do $(filter x$1,x$2).
21 streq = $(findstring x$1,$(findstring x$2,x$1))
23 # $(call fmt-make-assignment,foo,bar)
24 # Output a make assignment that stores bar in variable foo.
25 # The result is like `foo:=bar' but handles leading spaces, $, and
26 # newlines appearing in bar safely.
27 fmt-make-assignment = $1:=$$(empty)$(call mqas,$2)
29 # We use second-expansion heavily to dynamically compute prerequisites when they
30 # are needed. Second-expansion lets us follow make's implicit rule search
31 # instead of trying to anticipate which prerequisites it will need in advance.
36 # Mage uses two kinds of "obfuscated targets" (those that are not the simple
37 # names of real files):
38 # - An always-exists target like /.//. is used as a prerequisite of an implicit
39 # rule. Since it exists, make doesn't second-expand its own prerequisites
40 # until it is actually run. This way, a target's prerequisites can depend on
41 # the results of previous command scripts.
42 # - An alternative-name target like /.//./proc/self/cwd/bar is used to check the
43 # mtime of a file without actually building it or introducing a circular
46 # $(newoid) allocates and returns a new obfuscation ID (oid). Example:
48 # You can then refer to target $x or $x$(aname)bar (for any file bar).
49 # Prerequisites and commands come from $($x@opr) and $($x@ocmd).
50 # Target-specific variables $(oid) and $(otgt) (if alternate-name) are
54 # TODO If the system doesn't support /proc/self/cwd, use something else.
55 aname:=/proc/self/cwd/
57 newoid=$(nextoid)$(eval nextoid:=$(subst /.//////,//./,$(patsubst /.//////%,/././%,$(nextoid:.=/.))))
59 # High-priority implicit rule for obfuscated targets. Works for both always-
60 # exists and alternate-name targets.
61 $(opfx)%: oid=$(word 1,$(subst $(aname), ,$@))
62 $(opfx)%: otgt=$(word 2,$(subst $(aname), ,$@))
63 $(opfx)%: $$($$(oid)@opr)
69 # bar@cmd:=cat foo >bar.tmp
70 # bar@warnings:=$(empty)yikes!
71 # And if dependency-logging:
72 # List of filename@revision, revision is x for exists and empty for doesn't
73 # exist. Later perhaps x will be the mtime.
74 # bar@deps:=included@x oops@
75 # If bar is overridden, we clear all three variables.
78 # Make sure foo.o's genfile, if any, has been loaded.
80 $(if $($1@gloaded),,$(eval
89 # $(call mg-translate-cmd,touch $$@)
90 # Translates $@, $<, $^, $+, $* to Mage-ized variables if necessary.
91 # We won't support $%, $?, $|.
92 # There might be false matches, e.g., $$@ => $$(mg@) ;
93 # to prevent that, do $$$(empty)@ .
94 define mg-translate-cmd
95 $(subst $$@,$$(mg@),$(subst $$<,$$(mg<),$(subst $$^,$$(mg^),$(subst $$+,$$(mg+),$1))))
98 # $(call mg-define-rule,target,prerequisite,cmd)
100 # If cmd uses $@, quote if necessary so this function sees $@, etc.
102 # When we generate bar from foo using a Mage rule:
104 # - "bar.g: foo" generates bar if necessary.
105 # - "bar: bar.g" loads new genfile and replays warnings if bar.g was
106 # already up to date.
108 # - bar is managed and up to date => replay
109 # - bar doesn't exist or is managed and out of date => generate
110 # - bar is unmanaged => warn about override
113 mg-scout-oid:=$(newoid)
114 define mg-define-rule
117 # Define some target-specific variables.
118 # It might look like we could use $*, but $1 most likely isn't %.
119 $1.g: target = $$(@:.g=)
120 $1.g: cmd = $(call mg-translate-cmd,$3)
121 $1.g: mg@ = $$(target).tmp
122 $1.g: mg^ = $$(filter-out MG-% $$(opfx)%,$$^)
123 $1.g: mg+ = $$(filter-out MG-% $$(opfx)%,$$+)
124 $1.g: mg< = $$(firstword $$(mg^))
126 # Rule for the genfile. Evidently all the prerequisites we want second-expanded
127 # have to go on the same rule.
128 $1.g: $2 $$$$(mg-scout-target) MG-FORCE
131 $(mg-file-from-genfile)
135 define mg-file-from-genfile
136 # If the file was regenerated, load the new genfile.
137 # If not, replay any warnings.
138 # HMMM Maybe errors should go to stderr???
141 $$(if $$($$@@warnings),$$(if $$($$@@built),,$$(info $$($$@@cmd) # warning replay)$$(info $$($$@@warnings))),)
144 # If the target is unmanaged, we must run the rule; we'll see that the
145 # obfuscated target is in $? and complain.
146 mg-scout-target=$(if $(wildcard $(target)),$(mg-scout-oid)$(aname)$(target),)
148 # If the command changed, we must regenerate.
149 mg-check-cmd=$(if $(call streq,$(cmd),$($(target)@cmd)),,x)
151 # Just add additional prerequisites.
152 # I don't think this can add patterns to implicit rules, but it should be able
153 # to add specific prerequisites to uses of implicit rules.
154 define mg-define-prereq
160 # Procedure to generate bar. Remember, $@ is bar.g.
162 # 1. Complain. (Should we stop "`bar' is up to date" using @:; ?)
163 # 2. Clear out the warnings so we don't replay them.
164 # Otherwise, check prereqs, command, and nonexistence to decide whether bar
165 # needs to be regenerated. If so:
166 # 1. Set a flag so Mage knows to reread the genfile when make runs target
168 # 2. Echo the command being run.
169 # On error, skip to 8:
170 # 3. Open the new genfile bar.g.tmp for writing.
171 # 4. Store the command in bar.g.tmp.
172 # 5. Run the command to bar.tmp, storing warnings in bar.g.tmp.
173 # 6. If bar.tmp differs from bar:
174 # a. Clear and touch bar.g (so bar doesn't become an override if we're
175 # killed between steps 6b and 7).
176 # b. Move in the new bar.
177 # 7. Now that bar is known to be up to date, move in the new bar.g.
178 # 8. Defensively remove both temporary files and exit with the exit code
179 # from before the removal. (trap EXIT)
181 $(call gload,$(target))\
182 $(if $(filter $(mg-scout-oid)$(aname)$(target),$?),\
183 $(info mage: warning: Manually created/modified file at $(target) overrides rule.)\
184 $(eval $(target)@cmd:=)$(eval $(target)@warnings:=)$(eval $(target)@deps:=)\
186 $(if $?$(if $(wildcard $(target)),,x)$(mg-check-cmd),\
187 $(eval $(target)@gloaded:=)$(eval $(target)@built:=1)$(info $(cmd))\
188 @trap 'rm -f $(target).tmp $@.tmp' EXIT &&\
189 exec 3>$@.tmp && $(mg-assign-cmd) >&3 &&\
190 set -o pipefail && { $(mg-run-cmd) | tee /dev/fd/4 | $(mg-wrap-warnings) >&3; } 4>&1 &&\
191 $(mg-maybe-move-target) && mv -f $@.tmp $@\
195 # Pieces of mg-generate that I factored out to make mg-generate more readable.
196 mg-assign-cmd=echo $(call sq,$(call fmt-make-assignment,$(target)@cmd,$(cmd)))
197 mg-run-cmd={ ($(cmd)) 2>&1 && { [ -r $(target).tmp ] || { echo 'mage: error: Command for $(target) succeeded without creating it!'; false; }; }; }
198 mg-wrap-warnings=sed -re '1s/^/$(target)@warnings:=$$(empty)/; 1!s/^/$(target)@warnings+=$$(nl)/'
199 mg-maybe-move-target={ cmp -s $(target) $(target).tmp || echo >$@ && mv -f $(target).tmp $(target); }
203 # We don't want anything we defined to become the default goal.
204 .DEFAULT_GOAL := $(mg-orig-default-goal)