Android中init.rc文件的解析
本文分析Android中如何解析init.rc文件,重点描述了on action内的解析,并从解析的过程中总结出init.rc的语法规范。
对init.rc的解析是在parse_config(): [system/core/init/init_parser.c]中进行的。解析发生在init全过程中的哪个阶段,参看《Android init进程启动过程分析》。
一、解析过程
1. 扫描init.rc中的token
找到其中的 文件结束EOF/文本TEXT/新行NEWLINE,其中的空格‘ ’、‘\t’、‘\r’会被忽略,#开头的行也被忽略掉;
而对于TEXT,空格‘ ’、‘\t’、‘\r’、‘\n’都是TEXT的结束标志。
2. 对每一个TEXT token,都加入到args[]数组中
3. 当遇到新一行(‘\n’)的时候,用args[0]通过lookup_keyword()检索匹配关键字;
1) 对Section(on和service),调用parse_new_section() 解析:
- 对on section,调用parse_action(),并设置解析函数parse_line为parse_line_action()
- 对service section,调用parse_service(),并设置解析函数parse_line为parse_line_service()
2) 对其他关键字的行(非on或service开头的地方,也就是没有切换section)调用parse_line()
也就是,
- 对于on section内的命令行,调用parse_line_action()解析;
- 对于service section内的命令行,调用parse_line_service()解析。
二、关键数据类型原型及关键数据定义
2.1 Token的定义
[cpp]
#defineT_EOF 0
#defineT_TEXT 1
#defineT_NEWLINE 2
#defineT_EOF 0
#defineT_TEXT 1
#defineT_NEWLINE 2
2.2 关键字定义
[cpp]
KEYWORD(capability, OPTION, 0, 0)
KEYWORD(chdir, COMMAND, 1, do_chdir)
KEYWORD(chroot, COMMAND, 1, do_chroot)
KEYWORD(class, OPTION, 0, 0)
KEYWORD(class_start, COMMAND, 1,do_class_start)
KEYWORD(class_stop, COMMAND, 1, do_class_stop)
KEYWORD(console, OPTION, 0, 0)
KEYWORD(critical, OPTION, 0, 0)
KEYWORD(disabled, OPTION, 0, 0)
KEYWORD(domainname, COMMAND, 1, do_domainname)
KEYWORD(exec, COMMAND, 1, do_exec)
KEYWORD(export, COMMAND, 2, do_export)
KEYWORD(group, OPTION, 0, 0)
KEYWORD(hostname, COMMAND, 1, do_hostname)
KEYWORD(ifup, COMMAND, 1, do_ifup)
KEYWORD(insmod, COMMAND, 1, do_insmod)
KEYWORD(import, COMMAND, 1, do_import)
KEYWORD(keycodes, OPTION, 0, 0)
KEYWORD(mkdir, COMMAND, 1, do_mkdir)
KEYWORD(mount, COMMAND, 3, do_mount)
KEYWORD(on, SECTION, 0, 0)
KEYWORD(oneshot, OPTION, 0, 0)
KEYWORD(onrestart, OPTION, 0, 0)
KEYWORD(restart, COMMAND, 1, do_restart)
KEYWORD(service, SECTION, 0, 0)
KEYWORD(setenv, OPTION, 2, 0)
KEYWORD(setkey, COMMAND, 0, do_setkey)
KEYWORD(setprop, COMMAND, 2, do_setprop)
KEYWORD(setrlimit, COMMAND, 3, do_setrlimit)
KEYWORD(socket, OPTION, 0, 0)
KEYWORD(start, COMMAND, 1, do_start)
KEYWORD(stop, COMMAND, 1, do_stop)
KEYWORD(trigger, COMMAND, 1, do_trigger)
KEYWORD(symlink, COMMAND, 1, do_symlink)
KEYWORD(sysclktz, COMMAND, 1, do_sysclktz)
KEYWORD(user, OPTION, 0, 0)
KEYWORD(wait, COMMAND, 1, do_wait)
KEYWORD(write, COMMAND, 2, do_write)
KEYWORD(copy, COMMAND, 2, do_copy)
KEYWORD(chown, COMMAND, 2, do_chown)
KEYWORD(chmod, COMMAND, 2, do_chmod)
KEYWORD(loglevel, COMMAND, 1, do_loglevel)
KEYWORD(ioprio, OPTION, 0, 0)
KEYWORD(capability, OPTION, 0, 0)
KEYWORD(chdir, COMMAND, 1, do_chdir)
KEYWORD(chroot, COMMAND, 1, do_chroot)
KEYWORD(class, OPTION, 0, 0)
KEYWORD(class_start, COMMAND, 1,do_class_start)
KEYWORD(class_stop, COMMAND, 1, do_class_stop)
KEYWORD(console, OPTION, 0, 0)
KEYWORD(critical, OPTION, 0, 0)
KEYWORD(disabled, OPTION, 0, 0)
KEYWORD(domainname, COMMAND, 1, do_domainname)
KEYWORD(exec, COMMAND, 1, do_exec)
KEYWORD(export, COMMAND, 2, do_export)
KEYWORD(group, OPTION, 0, 0)
KEYWORD(hostname, COMMAND, 1, do_hostname)
KEYWORD(ifup, COMMAND, 1, do_ifup)
KEYWORD(insmod, COMMAND, 1, do_insmod)
KEYWORD(import, COMMAND, 1, do_import)
KEYWORD(keycodes, OPTION, 0, 0)
KEYWORD(mkdir, COMMAND, 1, do_mkdir)
KEYWORD(mount, COMMAND, 3, do_mount)
KEYWORD(on, SECTION, 0, 0)
KEYWORD(oneshot, OPTION, 0, 0)
KEYWORD(onrestart, OPTION, 0, 0)
KEYWORD(restart, COMMAND, 1, do_restart)
KEYWORD(service, SECTION, 0, 0)
KEYWORD(setenv, OPTION, 2, 0)
KEYWORD(setkey, COMMAND, 0, do_setkey)
KEYWORD(setprop, COMMAND, 2, do_setprop)
KEYWORD(setrlimit, COMMAND, 3, do_setrlimit)
KEYWORD(socket, OPTION, 0, 0)
KEYWORD(start, COMMAND, 1, do_start)
KEYWORD(stop,
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