| 1 | # Mage Build Tool by Matt McCutchen |
| 2 | # http://www.kepreon.com/~matt/mage/ |
| 3 | |
| 4 | # Remember the original default goal so we can restore it at the end of mage.mk. |
| 5 | mg-orig-default-goal:=$(.DEFAULT_GOAL) |
| 6 | |
| 7 | # We use second-expansion heavily to dynamically compute prerequisites when they |
| 8 | # are needed. Second-expansion lets us follow make's implicit rule search |
| 9 | # instead of trying to anticipate which prerequisites it will need in advance. |
| 10 | .SECONDEXPANSION: |
| 11 | |
| 12 | |
| 13 | # TEXT UTILITIES |
| 14 | empty:= |
| 15 | bs:=\$(empty) |
| 16 | pct:=% |
| 17 | define nl |
| 18 | |
| 19 | |
| 20 | endef |
| 21 | # Shell-quote: a'b => 'a'\''b' |
| 22 | sq='$(subst ','\'',$1)' |
| 23 | # Make-quote: a$\nb => a$$$(nl)b |
| 24 | # This is enough to assign the value, *but not to use it as an argument!* |
| 25 | mqas=$(subst $(nl),$$(nl),$(subst $$,$$$$,$1)) |
| 26 | # Return nonempty if the strings are equal, empty otherwise. |
| 27 | # If the strings have only nice characters, you can do $(filter x$1,x$2). |
| 28 | streq=$(findstring x$1,$(findstring x$2,x$1)) |
| 29 | |
| 30 | # $(call fmt-make-assignment,foo,bar) |
| 31 | # Output a make assignment that stores bar in variable foo. |
| 32 | # The result is like `foo:=bar' but handles leading spaces, $, and |
| 33 | # newlines appearing in bar safely. |
| 34 | fmt-make-assignment=$1:=$$(empty)$(call mqas,$2) |
| 35 | |
| 36 | |
| 37 | # TARGET OBFUSCATION |
| 38 | |
| 39 | # Mage uses two kinds of "obfuscated targets" (those that are not the simple |
| 40 | # names of real files): |
| 41 | # - An always-exists target like /.//. is used as a prerequisite of an implicit |
| 42 | # rule. Since it exists, make doesn't second-expand its own prerequisites |
| 43 | # until it is actually run. This way, a target's prerequisites can depend on |
| 44 | # the results of previous command scripts. |
| 45 | # - An alternative-name target like /.//./proc/self/cwd/bar is used to check the |
| 46 | # mtime of a file without actually building it or introducing a circular |
| 47 | # dependency. |
| 48 | |
| 49 | # $(newoid) allocates and returns a new obfuscation ID (oid). Example: |
| 50 | # x:=$(newoid) |
| 51 | # You can then refer to target $x or $x$(aname)bar (for any file bar). |
| 52 | # Prerequisites and commands come from $($x@opr) and $($x@ocmd). |
| 53 | # Target-specific variables $(oid) and $(otgt) (if alternate-name) are |
| 54 | # available. |
| 55 | |
| 56 | opfx:=/./ |
| 57 | # TODO If the system doesn't support /proc/self/cwd, use something else. |
| 58 | aname:=/proc/self/cwd/ |
| 59 | nextoid:=/./. |
| 60 | newoid=$(nextoid)$(eval nextoid:=$(subst /.//////,//./,$(patsubst /.//////%,/././%,$(nextoid:.=/.)))) |
| 61 | |
| 62 | # Target-specific variables for obfuscated targets. |
| 63 | $(opfx)%: oid=$(word 1,$(subst $(aname), ,$@)) |
| 64 | $(opfx)%: otgt=$(word 2,$(subst $(aname), ,$@)) |
| 65 | |
| 66 | # High-priority implicit rule for obfuscated targets. Works for both always- |
| 67 | # exists and alternate-name targets. |
| 68 | $(opfx)%: $$($$(oid)@opr) |
| 69 | $($(oid)@ocmd) |
| 70 | |
| 71 | # Make won't use the same implicit rule more than once on its stack, so provide |
| 72 | # a second copy of the rule to allow two obfuscated targets on the stack. |
| 73 | # Needed for $(mg-genfile-oid)$(aname)bar.g <- $(mg-scout-oid)$(aname)bar . |
| 74 | # The prerequisites must look different before second-expansion so the second |
| 75 | # rule isn't discarded as a duplicate. |
| 76 | $(opfx)%: $$(empty) $$($$(oid)@opr) |
| 77 | $($(oid)@ocmd) |
| 78 | |
| 79 | # MAIN BUILD LOGIC |
| 80 | |
| 81 | # DESIGN: |
| 82 | # |
| 83 | # - To each generated file bar corresponds a "genfile" bar.g that contains some |
| 84 | # information about how bar was generated, including the command (for rebuild on |
| 85 | # command change) and the warnings (for replay). |
| 86 | # |
| 87 | # - bar.g's mtime is the last time Mage verified that bar was up to date. bar |
| 88 | # needs to be regenerated iff a prerequisite is newer than *bar.g* (not bar). |
| 89 | # If a prerequisite changes but the command gives the same contents for bar, |
| 90 | # bar.g is touched but bar itself is not touched because files that depend on it |
| 91 | # need not be regenerated. |
| 92 | # |
| 93 | # - If bar is newer than bar.g, the user has overridden it, and we should leave |
| 94 | # the override in place but warn the user about it. |
| 95 | # |
| 96 | # - The user's Makefile defines Mage rules by calling mg-define-rule. Each Mage |
| 97 | # rule becomes one underlying make rule with the same target and a little extra |
| 98 | # magic. This is important so that all implicit rule competition takes place at |
| 99 | # the same target. Additionally, the prerequisites are passed to an obfuscated |
| 100 | # target for bar.g to see if any are newer than bar.g. This is done by the |
| 101 | # single obfuscated implicit rule, keeping the number of implicit rules low. |
| 102 | # Then the command script for bar checks for overrides, command change, |
| 103 | # prerequisite change, etc. and acts accordingly. |
| 104 | # |
| 105 | # Target metadata variables for bar: (* means stored in bar.g) |
| 106 | # |
| 107 | # bar@cmd:=cat foo >bar.tmp |
| 108 | # Generation command as given to the shell.* |
| 109 | # |
| 110 | # bar@warnings:=$(empty)yikes! |
| 111 | # Data that the command printed to stdout or stderr, presumably warnings.* |
| 112 | # |
| 113 | # bar@deps:=included@x oops@ |
| 114 | # If dependency-logging, list of filename@revision used. Revision is x for |
| 115 | # exists and empty for doesn't exist. Later perhaps x will be the mtime.* |
| 116 | # |
| 117 | # bar@gloaded:=1 |
| 118 | # Set if Mage has loaded bar.g and hasn't changed it since then. |
| 119 | # |
| 120 | # bar@gdeps:=foo |
| 121 | # Static dependencies of bar, for checking by bar.g. |
| 122 | # |
| 123 | # bar@gq:=foo $(mg-scout-oid)$(aname)bar |
| 124 | # $? from the rule for bar.g; used by the rule for bar. |
| 125 | # |
| 126 | # bar@checked:=1 |
| 127 | # Set when Mage determines that a file is up to date or depends on it being |
| 128 | # so determined. Used to decide which prerequisite to check next for a |
| 129 | # dependency-logging command. |
| 130 | # |
| 131 | # bar@dlc-ran:=1 |
| 132 | # Indicates that Mage is in the middle of building bar using a dependency- |
| 133 | # logging command. Means that bar.g.tmp, not bar.g, is the most current |
| 134 | # genfile. |
| 135 | # |
| 136 | ## If the rule for bar is overridden, we clear the information from bar.g so |
| 137 | ## that it is as if bar.g didn't exist. -- Not currently needed |
| 138 | # |
| 139 | # Some make features with which Mage's compatibility has not been investigated: |
| 140 | # - Command-line options (especially --dry-run, --question, --touch, |
| 141 | # --always-make, --keep-going, --jobs, --assume-old, and --assume-new) |
| 142 | # - Static pattern rules |
| 143 | # - Vpath |
| 144 | |
| 145 | # $(call gload,foo.o) |
| 146 | # Make sure foo.o's genfile, if any, has been loaded. |
| 147 | define gload |
| 148 | $(if $($1@gloaded),,$(eval |
| 149 | $1@cmd:= |
| 150 | $1@warnings:= |
| 151 | $1@deps:= |
| 152 | -include $1.g |
| 153 | $1@gloaded:=1 |
| 154 | )) |
| 155 | endef |
| 156 | |
| 157 | # bar.g: scout bar and its dependencies and store $?. When implicit rules |
| 158 | # compete for bar, we depend on the rule make uses being the last one it |
| 159 | # second-expands so that $(bar@gdeps) is still correct. |
| 160 | mg-genfile-oid:=$(newoid) |
| 161 | mg-scout-oid:=$(newoid) |
| 162 | $(mg-genfile-oid)@opr=$($(otgt:.g=)@gdeps) $(if $(wildcard $(otgt:.g=)),$(mg-scout-oid)$(aname)$(otgt:.g=),) |
| 163 | $(mg-genfile-oid)@ocmd=$(eval $(otgt:.g=)@gq:=$?) |
| 164 | |
| 165 | # Mage-ized automatic variables. |
| 166 | # $@: needs no translation |
| 167 | # NOTE: $(mg@) is *eventual* target. Commands must write to temp file, $t . |
| 168 | # $%: haven't thought about it much, but probably needs no translation |
| 169 | mg< = $(firstword $(mg^)) |
| 170 | mg? = $(filter-out $(opfx)%,$($@@gq)) |
| 171 | mg^ = $(filter-out MG-% $(opfx)%,$^) |
| 172 | mg+ = $(filter-out MG-% $(opfx)%,$+) |
| 173 | # $|: needs no translation |
| 174 | # $*: needs no translation |
| 175 | |
| 176 | # $(call mg-translate-cmd,cat $$< >$$t) |
| 177 | # Replaces references to automatic variables with references to their Mage-ized |
| 178 | # counterparts. There might be false matches, e.g., $$@ => $$(mg@) ; |
| 179 | # to prevent that, write $$$(empty)@ instead. (c.f. autoconf empty quadrigraph) |
| 180 | define mg-translate-cmd |
| 181 | $(subst $$?,$$(mg?),$(subst $$<,$$(mg<),$(subst $$^,$$(mg^),$(subst $$+,$$(mg+),$1)))) |
| 182 | endef |
| 183 | |
| 184 | # $(call prereq-predict,target,prerequisites) |
| 185 | # Expands to code that does the following at second-expansion time: |
| 186 | # 1. Computes the actual prerequisites from the given prerequisite patterns by |
| 187 | # translating % to $* and prepending a directory if appropriate. |
| 188 | # 2. Saves both existing ($+) and newly computed prerequisites to $(bar@gdeps) |
| 189 | # where the rule for bar.g can get them. |
| 190 | # Factor out set-gdeps because make gets confused if the macro for the |
| 191 | # prerequisites has a colon. Make replaces the first % with the stem *before |
| 192 | # expansion*, so use $(pct) to protect some %s. |
| 193 | set-gdeps=$(eval $@@gdeps:=$1) |
| 194 | prereq-predict=$$$$(call set-gdeps,$$$$+ $(if $(findstring /,$1),$$$$(subst $$$$(pct),$$$*,$2),$$$$(addprefix $$$$(dir $$$$@),$$$$(subst $$$$(pct),$$$$*,$2)))) |
| 195 | |
| 196 | # Used to make the rule for bar always run so we can act based on $(bar@gdeps) |
| 197 | # and check for command change. |
| 198 | MG-FORCE: |
| 199 | .PHONY: MG-FORCE |
| 200 | |
| 201 | # $(call mg-define-rule,target,prerequisites,cmd) |
| 202 | # Defines a rule. cmd is expanded again when it is run, at which time |
| 203 | # Mage-ized automatic variables are available. |
| 204 | define mg-define-rule |
| 205 | $(eval |
| 206 | |
| 207 | # Store the new command. |
| 208 | $1: cmd=$(call mg-translate-cmd,$3) |
| 209 | # Provide variable for the temporary file. FIX |
| 210 | $1: t=$$@.tmp |
| 211 | |
| 212 | # Rule for the target. Set $(bar@gdeps) to all prerequisites. Apply the new |
| 213 | # prerequisites. The command script always runs. Depend on bar.g to get |
| 214 | # $(bar@gq). |
| 215 | $1: $(call prereq-predict,$1,$2) $2 MG-FORCE $(mg-genfile-oid)$(aname)$$$$@.g |
| 216 | $$(mg-rule-cmd) |
| 217 | ) |
| 218 | endef |
| 219 | |
| 220 | # TODO Provide a way to define static pattern rules. |
| 221 | |
| 222 | # Procedure to generate bar. Remember, $@ is bar.g. |
| 223 | # If an override: |
| 224 | # 1. Complain. (Should we stop "`bar' is up to date" using @:; ?) |
| 225 | # 2. Clear out the warnings so we don't replay them. |
| 226 | # Otherwise, check prereqs, command, and nonexistence to decide whether bar |
| 227 | # needs to be regenerated. If so: |
| 228 | # 1. Set a flag so Mage knows to reread the genfile when make runs target |
| 229 | # "bar". |
| 230 | # 2. Echo the command being run. |
| 231 | # On error, skip to 8: |
| 232 | # 3. Open the new genfile bar.g.tmp for writing. |
| 233 | # 4. Store the command in bar.g.tmp. |
| 234 | # 5. Run the command to bar.tmp, storing warnings in bar.g.tmp. |
| 235 | # 6. If bar.tmp differs from bar: |
| 236 | # a. Clear and touch bar.g (so bar doesn't become an override if we're |
| 237 | # killed between steps 6b and 7). |
| 238 | # b. Move in the new bar. |
| 239 | # 7. Now that bar is known to be up to date, move in the new bar.g. |
| 240 | # 8. Defensively remove both temporary files and exit with the exit code |
| 241 | # from before the removal. (trap EXIT) |
| 242 | # If not: |
| 243 | # 1. If there were warnings, replay them. (HMMM To stderr?) |
| 244 | # HMMM .tmp in displayed command looks ugly |
| 245 | define mg-rule-cmd |
| 246 | $(foreach x,$@ $(mg+),$(eval $x@checked:=1)) |
| 247 | $(if $(filter $(mg-scout-oid)$(aname)$@,$($@@gq)),\ |
| 248 | $(info Mage: warning: Manually created/modified file at $@ overrides rule.)\ |
| 249 | ,$(call gload,$@)$(if $($@@gq)$(if $(wildcard $@),,x)$(mg-check-cmd),\ |
| 250 | $(eval $@@gloaded:=)$(info $(cmd))\ |
| 251 | @trap 'rm -f $@.tmp $@.g.tmp' EXIT &&\ |
| 252 | exec 3>$@.g.tmp && $(mg-assign-cmd) >&3 &&\ |
| 253 | set -o pipefail && { $(mg-run-cmd) | tee /dev/fd/4 | $(mg-wrap-warnings) >&3; } 4>&1 &&\ |
| 254 | $(mg-maybe-move-target) && mv -f $@.g.tmp $@.g\ |
| 255 | ,$(if $($@@warnings),\ |
| 256 | $(info $($@@cmd) # Mage warning replay$(nl)$($@@warnings))\ |
| 257 | ))) |
| 258 | endef |
| 259 | |
| 260 | # If the command changed, we must regenerate. |
| 261 | mg-check-cmd=$(if $(call streq,$(cmd),$($@@cmd)),,x) |
| 262 | |
| 263 | # Pieces of mg-generate that I factored out to make mg-generate more readable. |
| 264 | mg-assign-cmd=echo $(call sq,$(call fmt-make-assignment,$@@cmd,$(cmd))) |
| 265 | mg-run-cmd={ ($(cmd)) 2>&1 && { [ -r $@.tmp ] || { echo 'Mage: error: Command for $@ succeeded without creating it!'; false; }; }; } |
| 266 | mg-wrap-warnings=sed -re '1s/^/$@@warnings:=$$(empty)/; 1!s/^/$@@warnings+=$$(nl)/' |
| 267 | mg-maybe-move-target={ cmp -s $@ $@.tmp || echo >$@.g && mv -f $@.tmp $@; } |
| 268 | |
| 269 | # Just add additional prerequisites. This cannot add prerequisite patterns to |
| 270 | # an implicit rule, but it can add specific prerequisites to an individual use |
| 271 | # of an implicit rule. Currently, Mage picks up the target's prerequisites from |
| 272 | # make, so this just attaches the given prerequisites to the target, but the |
| 273 | # implementation might change in the future. |
| 274 | define mg-define-prereq |
| 275 | $(eval $1: $2) |
| 276 | endef |
| 277 | |
| 278 | # END |
| 279 | |
| 280 | # We don't want anything we defined to become the default goal. |
| 281 | .DEFAULT_GOAL := $(mg-orig-default-goal) |