Android编译中m、mm、mmm 详解

Android 完成编译的时候先执行 source build/envsetup.sh。在这个shell 脚本中定义了 help, croot, m, mm, mmm 等 function之后在当前目录下执行help 可以发现它给出的信息和此前见过linux 下面help 的信息不一样了：[plain]view plaincopyprint?Invoke

江海细流

3790人浏览 · 2014-11-07 19:52:45

江海细流 · 2014-11-07 19:52:45 发布

转载于：http://blog.csdn.net/yajun0601/article/details/7309010

Android 完成编译的时候先执行 source build/envsetup.sh。在这个shell 脚本中定义了 help, croot, m, mm, mmm 等 function

之后在当前目录下执行help 可以发现它给出的信息和此前见过linux 下面help 的信息不一样了：

[plain] view plain copy print ?

Invoke ". build/envsetup.sh" from your shell to add the following functions to your environment:
- croot: Changes directory to the top of the tree.
- m: Makes from the top of the tree.
- mm: Builds all of the modules in the current directory.
- mmm: Builds all of the modules in the supplied directories.
- cgrep: Greps on all local C/C++ files.
- jgrep: Greps on all local Java files.
- resgrep: Greps on all local res/*.xml files.
- godir: Go to the directory containing a file.

Invoke ". build/envsetup.sh" from your shell to add the following functions to your environment:
- croot:   Changes directory to the top of the tree.
- m:       Makes from the top of the tree.
- mm:      Builds all of the modules in the current directory.
- mmm:     Builds all of the modules in the supplied directories.
- cgrep:   Greps on all local C/C++ files.
- jgrep:   Greps on all local Java files.
- resgrep: Greps on all local res/*.xml files.
- godir:   Go to the directory containing a file.

关于source

source 命令会把对应脚本中的内容读取到当前的bash 解释器中，在当前的执行环境中执行；其中定义的 function 以及通过 export 声明的变量等在 source 执行结束之后依然存在于当前的bash 环境中。比如我们常用的 source .bashrc 或者 source .profile 等目的是为了引用刚刚改动过的环境变量。

m 的解释

m 的定义如下：

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561 function m()
562 {
563 T=$(gettop)
564 if [ "$T" ]; then
565 make -C $T $@
566 else
567 echo "Couldn't locate the top of the tree. Try setting TOP."
568 fi
569 }
570

 561 function m()
 562 {
 563     T=$(gettop)
 564     if [ "$T" ]; then
 565         make -C $T $@
 566     else
 567         echo "Couldn't locate the top of the tree.  Try setting TOP."
 568     fi
 569 }
 570

当你在任何一个目录下打 m 的时候，它会执行上面的function.

gettop 返回源码的顶层目录，如果这个目录存在，比如在我的机器上是：

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~/Android/an403/external/webkit/Source/WebKit/android/jni/test$ gettop
/home/mypc/Android/an403

~/Android/an403/external/webkit/Source/WebKit/android/jni/test$ gettop
/home/mypc/Android/an403

$@ 返回调用这个脚本时传入的参数
比如我们执行 m showcommands -d

经过 function m 的翻译后就执行

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make -C /home/yajun/Android/an403 showcommands -d

make -C /home/yajun/Android/an403 showcommands -d

当然如果当前的目录不在源码树里面，gettop 就返回空，这样 m 的结果就时

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~$ m
Couldn't locate the top of the tree. Try setting TOP.

~$ m
Couldn't locate the top of the tree.  Try setting TOP.

下面主要讲解mm

mm 的定义如下，功能是 Builds all of the modules in the current directory.

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591 function mm()
592 {
593 # If we're sitting in the root of the build tree, just do a
594 # normal make.
595 if [ -f build/core/envsetup.mk -a -f Makefile ]; then
596 make $@
597 else
598 # Find the closest Android.mk file.
599 T=$(gettop)
600 local M=$(findmakefile)
601 # Remove the path to top as the makefilepath needs to be relative
602 local M=`echo $M|sed 's:'$T'/::'`
603 if [ ! "$T" ]; then
604 echo "Couldn't locate the top of the tree. Try setting TOP."
605 elif [ ! "$M" ]; then
606 echo "Couldn't locate a makefile from the current directory."
607 else
608 ONE_SHOT_MAKEFILE=$M make -C $T all_modules $@
609 fi
610 fi
611 }

 591 function mm()
 592 {
 593     # If we're sitting in the root of the build tree, just do a
 594     # normal make.
 595     if [ -f build/core/envsetup.mk -a -f Makefile ]; then
 596         make $@
 597     else
 598         # Find the closest Android.mk file.
 599         T=$(gettop)
 600         local M=$(findmakefile)
 601         # Remove the path to top as the makefilepath needs to be relative
 602         local M=`echo $M|sed 's:'$T'/::'`
 603         if [ ! "$T" ]; then
 604             echo "Couldn't locate the top of the tree.  Try setting TOP."
 605         elif [ ! "$M" ]; then
 606             echo "Couldn't locate a makefile from the current directory."
 607         else
 608             ONE_SHOT_MAKEFILE=$M make -C $T all_modules $@
 609         fi
 610     fi
 611 }

从它的注释可以看出，当你在某个目录下执行 mm 的时候，

它首先现判断当前目录是不是 TOP 目录，如果是，就直接开始make 了～

如果不是，就调用findmakefile 寻找 Android.mk , 搜索的路径是当前目录-> 父目录 -> 父目录 -> ... -> 到根目录

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571 function findmakefile()
572 {
573 TOPFILE=build/core/envsetup.mk
574 # We redirect cd to /dev/null in case it's aliased to
575 # a command that prints something as a side-effect
576 # (like pushd)
577 local HERE=$PWD
578 T=
579 while [ $ ! \( -f $TOPFILE $ \) -a $ $PWD != "/" $ ]; do
580 T=$PWD
581 if [ -f "$T/Android.mk" ]; then
582 echo $T/Android.mk
583 cd $HERE > /dev/null
584 return
585 fi
586 cd .. > /dev/null
587 done
588 cd $HERE > /dev/null
589 }

 571 function findmakefile()
 572 {
 573     TOPFILE=build/core/envsetup.mk
 574     # We redirect cd to /dev/null in case it's aliased to
 575     # a command that prints something as a side-effect
 576     # (like pushd)
 577     local HERE=$PWD
 578     T= 
 579     while [ \( ! \( -f $TOPFILE \) \) -a \( $PWD != "/" \) ]; do
 580         T=$PWD
 581         if [ -f "$T/Android.mk" ]; then
 582             echo $T/Android.mk
 583             cd $HERE > /dev/null
 584             return
 585         fi
 586         cd .. > /dev/null
 587     done
 588     cd $HERE > /dev/null
 589 }

文章写到一半 CSDN 挂了。。。

当在某个目录下找到Android.mk后，就把它echo 出来。然后 cd $HERE 返回调用 findmakefile 的目录。
以我在 /home/yajun/Android/an403/external/webkit/Source/WebKit/android/benchmark/ 下执行 mm 为例

findmakefile 的返回结果是 /home/yajun/Android/an403/external/webkit/Source/WebKit/android/benchmark/Android.mk

而 gettop 的返回结果是 /home/yajun/Android/an403

所以执行local M=`echo $M|sed 's:'$T'/::'` 之后， M =external/webkit/Source/WebKit/android/benchmark/Android.mk

ONE_SHOT_MAKEFILE=$M make -C $T all_modules $@ 展开后就是
ONE_SHOT_MAKEFILE=external/webkit/Source/WebKit/android/benchmark/Android.mk make -C /home/yajun/Android/an403 all_modules

到后面怎么make 的？（）

上面的执行就可以看作是：

make -C /home/yajun/Android/an403 all_modules ONE_SHOT_MAKEFILE=external/webkit/Source/WebKit/android/benchmark/Android.mk

接下来的执行会进入到 build/core/main.mk 中，在这里会 include external/webkit/Source/WebKit/android/benchmark/Android.mk