rk3188--1.mkimage.sh及cpio打包过程分析

一. mkimage.sh

1. android目录下的mkimage.sh

!/bin/bash

set -e

. build/envsetup.sh >/dev/null && setpaths

export PATH=ANDROIDBUILDPATHS:PATH

TARGET=”withoutkernel”

if [ “1”x!=“”x];thenTARGET=1

fi

rm -rf rockdev/Image

mkdir -p rockdev/Image

//在init.rk30board.rc中搜索字符串mtd@system,发现其分区类型为ext4

FSTYPE=

grep 'mtd@system' $OUT/root/init.rk30board.rc | head -n 1 | awk '{ print $2 }'

if [ “$FSTYPE” = “” ]; then

FSTYPE=

grep 'mtd@system' $OUT/root/init.rc | head -n 1 | awk '{ print $2 }'

fi

echo system filesysystem is $FSTYPE

BOARD_CONFIG=device/rockchip/rk30sdk/device.mk

//KERNLE_SRC_PATH为空

KERNEL_SRC_PATH=

grep TARGET_PREBUILT_KERNEL ${BOARD_CONFIG} |grep "^\s*TARGET_PREBUILT_KERNEL *:= *[\w]*\s" |awk '{print $3}'

[ $(id -u) -eq 0 ] || FAKEROOT=fakeroot

BOOT_OTA=”ota”

echo “TARGET=TARGET”[TARGET != BOOTOTA−aTARGET != "withoutkernel" ] && echo "unknow target[${TARGET}],exit!” && exit 0

if [ ! -f $OUT/kernel ]   //这个文件存在不执行以下
then
echo "kernel image not fount![$OUT/kernel] "
read -p "copy kernel from TARGET_PREBUILT_KERNEL[$KERNEL_SRC_PATH] (y/n) n to exit?"
if [ "$REPLY" == "y" ]
then
[ -f $KERNEL_SRC_PATH ] || \
echo -n "fatal! TARGET_PREBUILT_KERNEL not eixit! " || \
echo -n "check you configuration in [${BOARD_CONFIG}] " || exit 0

cp ${KERNEL_SRC_PATH} $OUT/kernel

else
exit 0
fi
fi

//1.boot.img的生成过程

if [ TARGET==BOOT_OTA ] //TARGET=withoutkernel, BOOT_OTA=ota不相等,执行else

then

echo “make ota images… ”

echo -n “create boot.img with kernel… ”

[ -d OUT/root ] && \
mkbootfsOUT/root | minigzip > OUT/ramdisk.img && \
mkbootimg –kernelOUT/kernel --ramdisk OUT/ramdisk.img–outputOUT/boot.img && \

cp -a OUT/boot.imgrockdev/Image/echo“done.”elseecho−n“createboot.imgwithoutkernel…”[−dOUT/root ] && \ //目录out/target/product/rk30sdk/root存在

mkbootfs OUT/root|minigzip>OUT/ramdisk.img && \ //1.将root下的每个文件加上cpio头+每个文件的内容,打包成cpios格式

rkst/mkkrnlimg OUT/ramdisk.imgrockdev/Image/boot.img//2.将这个cpio文件用gzip压缩后写到文件ramdisk.img中echo“done.”//3.mkkrnlimg会对ramdisk.img加上8个字节的头标志,尾部加上4个字字fi//2.recovery.img的生成过程echo−n“createrecovery.imgwithkernel…”[−dOUT/recovery/root ] && \

mkbootfs OUT/recovery/root|minigzip>OUT/ramdisk-recovery.img && \

mkbootimg –kernel OUT/kernel−−ramdiskOUT/ramdisk-recovery.img –output OUT/recovery.img && \
cp -aOUT/recovery.img rockdev/Image/

echo “done.”

echo -n "create misc.img.... "
cp -a rkst/Image/misc.img rockdev/Image/misc.img
cp -a rkst/Image/pcba_small_misc.img rockdev/Image/pcba_small_misc.img
cp -a rkst/Image/pcba_whole_misc.img rockdev/Image/pcba_whole_misc.img
echo "done."

//3.system.img的生成过程

if [ -d OUT/system]thenecho−n“createsystem.img…”if[“FSTYPE” = “cramfs” ]

then

chmod -R 777 OUT/systemFAKEROOT mkfs.cramfs OUT/systemrockdev/Image/system.imgelif[“FSTYPE” = “squashfs” ]

then

chmod -R 777 OUT/systemmksquashfsOUT/system rockdev/Image/system.img -all-root >/dev/null

elif [ “FSTYPE"="ext3"]||["FSTYPE” = “ext4” ]

then //ext3或ext4的生成过程

delta=5120

num_blocks=

du -sk $OUT/system | tail -n1 | awk '{print $1;}'

num_blocks=((num_blocks + $delta))

num_inodes=`find $OUT/system | wc -l`
num_inodes=$(($num_inodes + 500))

ok=0
while [ "$ok" = "0" ]; do
genext2fs -a -d $OUT/system -b $num_blocks -N $num_inodes -m 0 rockdev/Image/system.img >/dev/null 2>&1 && \
tune2fs -j -L system -c -1 -i 0 rockdev/Image/system.img >/dev/null 2>&1 && \
ok=1 || num_blocks=$(($num_blocks + $delta))
done
e2fsck -fy rockdev/Image/system.img >/dev/null 2>&1 || true

delta=1024
num_blocks=`resize2fs -P rockdev/Image/system.img 2>&1 | tail -n1 | awk '{print $7;}'`
rm -f rockdev/Image/system.img
ok=0
while [ "$ok" = "0" ]; do
genext2fs -a -d $OUT/system -b $num_blocks -N $num_inodes -m 0 rockdev/Image/system.img >/dev/null 2>&1 && \
tune2fs -O dir_index,filetype,sparse_super -j -L system -c -1 -i 0 rockdev/Image/system.img >/dev/null 2>&1 && \
ok=1 || num_blocks=$(($num_blocks + $delta))
done
e2fsck -fyD rockdev/Image/system.img >/dev/null 2>&1 || true
else
mkdir -p rockdev/Image/2k rockdev/Image/4k
mkyaffs2image -c 2032 -s 16 -f $OUT/system rockdev/Image/2k/system.img
mkyaffs2image -c 4080 -s 16 -f $OUT/system rockdev/Image/4k/system.img
fi
echo "done."

fi

chmod a+r -R rockdev/Image/

2. mkbootfs分析

mkbootfs在system/core/cpio/mkbootfs.c中

mkbootfs $OUT/root

main

–> archive(*argv, x); //*argv 要打包的源文件路径, x是打包后的文件路径

–> _archive_dir(in, out, strlen(in), strlen(out)); //in要打包的源文件路径, out是打包后的文件路径

static void _archive_dir(char *in, char *out, int ilen, int olen)

{

int i, t;

DIR *d;

struct dirent *de;

DIR* d = opendir(in); //打开目录

int size = 32;
int entries = 0;
char** names = malloc(size * sizeof(char*)); //每次分配32个文件名的内存
//将./out/target/product/rk30sdk/root目录下所有的文件名存在name数组中
while((de = readdir(d)) != 0){
if(de->d_name[0] == '.') continue;       //跳过.目录
if(!strcmp(de->d_name, "root")) continue; //排除root,这是为了什么?
if (entries >= size) {
size *= 2;                 //如果超出32个文件名,则再多分配32*2个,依次类推
names = realloc(names, size * sizeof(char*));  //realloc,又学习了一招
}
names[entries] = strdup(de->d_name);   //strdup可以分配内存并复制
++entries;
}
//对name数组中的文件名进行排序
qsort(names, entries, sizeof(char*), compare);

for (i = 0; i < entries; ++i) {
t = strlen(names[i]);
in[ilen] = '/';
memcpy(in + ilen + 1, names[i], t + 1);

if(olen > 0) {                  //out为空
out[olen] = '/';
memcpy(out + olen + 1, names[i], t + 1);
_archive(in, out, ilen + t + 1, olen + t + 1);
} else {
memcpy(out, names[i], t + 1);       //将文件名复制到out中
_archive(in, out, ilen + t + 1, t); //将这个文件打包到ramdisk.img中
}

in[ilen] = 0;
out[olen] = 0;

free(names[i]);
}
free(names);

}

mkbootfs $OUT/root

main

–> archive(*argv, x); //*argv 要打包的源文件路径, x是打包后的文件路径

–> _archive_dir(in, out, strlen(in), strlen(out)); //in要打包的源文件路径, out是打包后的文件路径

–> _archive //对普通文件 目录 链接分开处理

static void _archive(char *in, char *out, int ilen, int olen)

{

struct stat s;

if(S_ISREG(s.st_mode)){ //1.对普通文件的处理

int fd = open(in, O_RDONLY);

char* tmp = (char*) malloc(s.st_size);

read(fd, tmp, s.st_size);

_eject(&s, out, olen, tmp, s.st_size);

free(tmp);

close(fd);

} else if(S_ISDIR(s.st_mode)) { //2.对目录的处理

_eject(&s, out, olen, 0, 0);

_archive_dir(in, out, ilen, olen);

} else if(S_ISLNK(s.st_mode)) { //3.对链接文件的处理

char buf[1024];

int size;

size = readlink(in, buf, 1024); //调用readlink读符号链接的大小及内容

_eject(&s, out, olen, buf, size);

} else {

die(“Unknown ‘%s’ (mode %d)?\n”, in, s.st_mode);

}

}

注: 符号链接

假设有这样的符号连接

ln -s /home/cong/Desktop/record.txt link

则调用readlink后,buf=”/home/cong/Desktop/record.txt”, size=sizeof(“/home/cong/Desktop/record.txt”);

即realink所读到的就是link所指向的路径的内容及长度

函数的作用是:把文件的信息与文件的内容写到ramdisk.img中去

mkbootfs $OUT/root

main

–> archive(*argv, x); //*argv 要打包的源文件路径, x是打包后的文件路径

–> _archive_dir(in, out, strlen(in), strlen(out)); //in要打包的源文件路径, out是打包后的文件路径

–> _archive //对普通文件 目录 链接分开处理

–> _eject //将文件信息与内容写入到ramdisk.img中去

static void _eject(struct stat *s, char *out, int olen, char *data, unsigned datasize)

{

static unsigned next_inode = 300000;

while(total_size & 3) {
total_size++;
putchar(0);
}

fix_stat(out, s);
//这儿的printf实际上是要写入到ramdisk.img中去的
printf("%06x%08x%08x%08x%08x%08x%08x"
"%08x%08x%08x%08x%08x%08x%08x%s%c",
0x070701,                   <<<<---   标志
next_inode++, // s.st_ino,    //inode_number
s->st_mode,                   //mode
0, // s.st_uid,               //uid
0, // s.st_gid,               //gid
1, // s.st_nlink,             //链接数
0, // s.st_mtime,             //最后修改时间
datasize,                     //文件长度
0, // volmajor                //主号
0, // volminor                //次号
0, // devmajor                //主设备号
0, // devminor,               //次设备号
olen + 1,                     //name_len名字长度
0,                         --->>>>
out,
0
);

total_size += 6 + 8*13 + olen + 1;

while(total_size & 3) {
total_size++;
putchar(0);
}

if(datasize) {
fwrite(data, datasize, 1, stdout);   //这是文件的内容
total_size += datasize;
}

}

最后写入一个结束标志:

static void _eject_trailer()

{

struct stat s;

memset(&s, 0, sizeof(s));

_eject(&s, “TRAILER!!!”, 10, 0, 0);

while(total_size & 0xff) {
total_size++;
putchar(0);
}

}

注: CPIO 的结构包括:

110字节的Head(6 + 8*13)

不定长的文件名(文件名的长度是olen)

结束字符 \0

文件的内容

…. //重复上面4个

最后的文件名是一个 TRAILER!!!

附1. ramdisk.img的解压过程

cong@ubuntu:/tmp/testfile./bak/ramdisk.img./bak/ramdisk.img:gzipcompresseddata,fromUnixcong@ubuntu:/tmp/test cp ./bak/ramdisk.img ./bak/ramdisk.img_bak.gz //重新copy一份

cong@ubuntu:/tmp/testgunzip./bak/ramdisk.imgbak.gz//gunzip解压缩cong@ubuntu:/tmp/test ls ./bak/

ramdisk.img ramdisk.img_bak ramdisk.img.gz

cong@ubuntu:/tmp/testfile./bak/ramdisk.imgbak//解压后的文件就是cpio格式的./bak/ramdisk.imgbak:ASCIIcpioarchive(SVR4withnoCRC)cong@ubuntu:/tmp/test cpio -i -F ./bak/ramdisk.img_bak //解压cpio格式

463 blocks

cong@ubuntu:/tmp/testls//这就能看到所有文件了bakdatadefault.propdevforlinx.rcinitinit.goldfish.rcinit.rclinuxrcprocsbinsyssystemueventd.goldfish.rcueventd.rccong@ubuntu:/tmp/test