Clever Geek Handbook

Debugging the Makefile / part 1 /

Men-debug makefile  adalah sihir hitam. Sayangnya, tidak ada yang namanya makefile debugger untuk memeriksa kemajuan aturan tertentu atau bagaimana variabel diperluas. Sebagian besar debugging dapat dilakukan dengan cetakan biasa dan memeriksa makefile . Tentu saja, GNU make sedikit membantu dengan metode bawaan dan opsi baris perintah. Salah satu teknik terbaik untuk men -debug makefile adalah dengan menambahkan hook debug dan menggunakan teknik pemrograman yang aman untuk bersandar pada saat terjadi kesalahan. Berikut ini adalah beberapa teknik debugging dasar dan praktik pemrograman aman yang menurut saya akan paling berguna.





Kemampuan debugging dari make

Sebuah sangat berguna  fungsi untuk debugging makefile yang tidak bekerja warning



. Karena fungsi warning



diperluas menjadi string kosong, ia dapat digunakan di mana saja di makefile : di tingkat atas, di nama target, di daftar dependensi, dan di skrip perintah. Ini memungkinkan nilai variabel dicetak di tempat yang paling tepat untuk memeriksanya. Sebagai contoh:





$(warning A top-level warning)
FOO := $(warning Right-hand side of a simple variable)bar
BAZ = $(warning Right-hand side of a recursive variable)boo
$(warning A target)target: $(warning In a prerequisite list)makefile $(BAZ)
   $(warning In a command script)
   ls
$(BAZ):

Memberikan keluaran:





$ make
makefile:1: A top-level warning
makefile:2: Right-hand side of a simple variable
makefile:5: A target
makefile:5: In a prerequisite list
makefile:5: Right-hand side of a recursive variable
makefile:8: Right-hand side of a recursive variable
makefile:6: In a command script
ls
makefile

Perhatikan bahwa eksekusi fungsi warning



mengikuti aliran normal algoritme make



untuk penghitungan langsung dan yang ditangguhkan. Selain itu, tugas untuk BAZ



memuat warning



dan pesan tidak dicetak hingga BAZ



diperluas ke daftar ketergantungan.





Kemampuan untuk memasukkan warning



panggilan di mana saja menjadikannya alat debugging yang sangat berguna.





Opsi baris perintah

: --just-print (-n)



, --print-data-base (-p)



--warn-undefined-variables



.





--just-print

makefile — make



--just-print (-n)



. make



makefile , . , GNU make



(@



) - .





. , . make



, shell



, . :





REQUIRED_DIRS = ...
_MKDIRS := $(shell for d in $(REQUIRED_DIRS); \
             do                               \
                [[ -d $$d ]] || mkdir -p $$d; \
             done)

$(objects) : $(sources)

_MKDIRS



. --just-print



, makefile. , make



( ) $(objects)



.





--print-data-base

, . , "" makefile, make



. : , , , , ( ) vpath . .





Variables :





# automatic
<D = $(patsubst %/,%,$(dir $<))
# environment
EMACS_DIR = C:/usr/emacs-21.3.50.7
# default
CWEAVE = cweave
# makefile (from `../mp3_player/makefile', line 35)
CPPFLAGS = $(addprefix -I ,$(include_dirs))
# makefile (from `../ch07-separate-binaries/makefile', line 44)
RM := rm -f
# makefile (from `../mp3_player/makefile', line 14)
define make-library
 libraries += $1
 sources += $2
 $1: $(call source-to-object,$2)
 $(AR) $(ARFLAGS) $$@ $$^
endef

- , , , , $(<D)



. origin



(. make manual). , . . .





Directories make



, make



. make, SCCS RCS -, , . : , inode .





Implicit rules make



. , , , :





%.c %.h: %.y
# commands to execute (from `../mp3_player/makefile', line 73):
   $(YACC.y) --defines $<
   $(MV) y.tab.c $*.c
   $(MV) y.tab.h $*.h
%: %.c
# commands to execute (built-in):
   $(LINK.c) $^ $(LOADLIBES) $(LDLIBS) -o $@
%.o: %.c
# commands to execute (built-in):
   $(COMPILE.c) $(OUTPUT_OPTION) $<

make



. , . , Files, .





makefile.  — , . , :





%.c %.h: YYLEXFLAG := -d
%.c %.h: %.y
 $(YACC.y) --defines $<
 $(MV) y.tab.c $*.c
 $(MV) y.tab.h $*.h

:





# Pattern-specific variable values

%.c :
# makefile (from `Makefile', line 1)
# YYLEXFLAG := -d
# variable set hash-table stats:
# Load=1/16=6%, Rehash=0, Collisions=0/1=0%
%.h :
# makefile (from `Makefile', line 1)
# YYLEXFLAG := -d
# variable set hash-table stats:
# Load=1/16=6%, Rehash=0, Collisions=0/1=0%

# 2 pattern-specific variable values

Files , - , :





# Not a target:
.p.o:
# Implicit rule search has not been done.
# Modification time never checked.
# File has not been updated.
# commands to execute (built-in):
 $(COMPILE.p) $(OUTPUT_OPTION) $<
lib/ui/libui.a: lib/ui/ui.o
# Implicit rule search has not been done.
# Last modified 2004-04-01 22:04:09.515625
# File has been updated.
# Successfully updated.
# commands to execute (from `../mp3_player/lib/ui/module.mk', line 3):
 ar rv $@ $^
lib/codec/codec.o: ../mp3_player/lib/codec/codec.c ../mp3_player/lib/codec/codec.c ..
/mp3_player/include/codec/codec.h
# Implicit rule search has been done.
# Implicit/static pattern stem: `lib/codec/codec'
# Last modified 2004-04-01 22:04:08.40625
# File has been updated.
# Successfully updated.
# commands to execute (built-in):
 $(COMPILE.c) $(OUTPUT_OPTION) $<

- "Not a target";  — . , make



. , vpath , .





VPATH Search Paths VPATH



vpath



.





makefile', eval



, - , .





--warn-undefined-variables

make



. , , . , , . make



, makefile' , :





$ make --warn-undefined-variables -n
makefile:35: warning: undefined variable MAKECMDGOALS
makefile:45: warning: undefined variable CFLAGS
makefile:45: warning: undefined variable TARGET_ARCH
...
makefile:35: warning: undefined variable MAKECMDGOALS
make: warning: undefined variable CFLAGS
make: warning: undefined variable TARGET_ARCH
make: warning: undefined variable CFLAGS
make: warning: undefined variable TARGET_ARCH
...
make: warning: undefined variable LDFLAGS
make: warning: undefined variable TARGET_ARCH
make: warning: undefined variable LOADLIBES
make: warning: undefined variable LDLIBS

, .





--debug

make



, --debug



. . : basic



, verbose



, implicit



, jobs



, all



, makefile



, .





--debug



, basic



- . -d



, all



. : --debug=option1,option2



, option



( , make ):





  • basic





    . , make



    , .





  • verbose





    basic



    , .





  • implicit





    basic



    , .





  • jobs





    make



    ' . basic



    .





  • all





    -d



    .





  • makefile





    , , makefile . , . make



    makefile' . basic



    , all



    .





,

, makefile , . , makefile , .





, , , . , , , . makefile, . , makefile . , - , , , .





«KISS» — . makefile , , . . , , .





, makefile' , , - , , C++ Java. make



! , .





makefile . , make



, makefile , :





do:
   cd i-dont-exist; \
   echo *.c

makefile , :





$ make
cd i-dont-exist; \
echo *.c
/bin/sh: line 1: cd: i-dont-exist: No such file or directory
*.c

, .c



, . . -, :





SHELL = /bin/bash
do:
   cd i-dont-exist && \
   shopt -s nullglob &&
   echo *.c

cd



make



, echo



make



. , nullglob



bash



. (, .)





$ make
cd i-dont-exist && \
echo *.c
/bin/sh: line 1: cd: i-dont-exist: No such file or directory
make: *** [do] Error 1

. makefile' , , . ?





_MKDIRS := $(shell for d in $(REQUIRED_DIRS); do [[ -d $$d \
]] || mkdir -p $$d; done)

:





_MKDIRS := $(shell                           \
             for d in $(REQUIRED_DIRS);      \
             do                              \
               [[ -d $$d ]] || mkdir -p $$d; \
             done)

, , , . . , - , , , .





, . , :





TAGS:
        cd src \
        ctags --recurse

disk_free:
        echo "Checking free disk space..." \
        df . | awk '{ print $$4 }'

. . , strip



. . , , .





. , .  — make . « » .





,  — if



, , assert



, , , ( ), , , make



.





 — . make — 3.80:





NEED_VERSION := 3.80
$(if $(filter $(NEED_VERSION),$(MAKE_VERSION)),,             \
 $(error You must be running make version $(NEED_VERSION).))

Java CLASSPATH



.





- .





assert



, :





# $(call assert,condition,message)
define assert
   $(if $1,,$(error Assertion failed: $2))
endef
# $(call assert-file-exists,wildcard-pattern)
define assert-file-exists
   $(call assert,$(wildcard $1),$1 does not exist)
endef
# $(call assert-not-null,make-variable)
define assert-not-null
   $(call assert,$($1),The variable "$1" is null)
endef

assert



makefile , .





:





# $(debug-enter)
debug-enter = $(if $(debug_trace),\
                $(warning Entering $0($(echo-args))))

# $(debug-leave)
debug-leave = $(if $(debug_trace),$(warning Leaving $0))
comma := ,
echo-args = $(subst ' ','$(comma) ',\
              $(foreach a,1 2 3 4 5 6 7 8 9,'$($a)'))

, . debug_trace



:





$ make debug_trace=1

@



, , :





QUIET := @
…
target:
   $(QUIET) some command

:





$ make QUIET=







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