rk3188--1.mkimage.sh及cpio打包过程分析

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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    fifi

//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.imgcp -a rkst/Image/pcba_small_misc.img rockdev/Image/pcba_small_misc.imgcp -a rkst/Image/pcba_whole_misc.img rockdev/Image/pcba_whole_misc.imgecho "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 || trueelse    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.imgfiecho "done."

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

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