一、init.rc语法规则
1.init.rc文件的内容主要分类
动作(Action)
命令(Commands)
服务(Services)
选项(Options)
触发(trigger)
2.动作和命令一起使用
on <trigger> <command> <command> <command>
2.1.trigger是触发条件,为真执行命令
trigger有以下几种类型
boot /init.conf加载完毕时触发<name>=<value> 当<name>被设置为<value>时触发 device-added-<path>device-removed-<path> 设备<path>被添加移除时触发service-exited-<name> 当服务<name>退出时触发
3.服务和选项一起使用
service <name> <pathname> [ <argument> ]* <option> <option>
3.1.option选项
criticaldisabledsetenv <name> <value>socket <name> <type> <perm> [ <user> [ <group> ] ]user <username>group <groupname> [ <groupname> ]*oneshotclass <name>onrestart
二、init.rc文件的解析
1.init_parse_config_file
在system/core/init/init.c文件的main函数中调用
init_parse_config_file("/init.rc");函数将init.rc作为参数读取进来
int init_parse_config_file(const char *fn){ char *data; data = read_file(fn, 0); //读取init.rc文件到data中 if (!data) return -1; parse_config(fn, data); //解析配置 DUMP(); return 0;}2.解析配置parse_config
static void parse_config(const char *fn, char *s){ struct parse_state state; char *args[INIT_PARSER_MAXARGS]; int nargs; nargs = 0; state.filename = fn; state.line = 1; state.ptr = s; //指向init.rc的数据 state.nexttoken = 0; state.parse_line = parse_line_no_op; //空操作 for (;;) { switch (next_token(&state)) { //-->3.next_token跳过注释等,筛选需要解析的行 case T_EOF: //文件末尾 state.parse_line(&state, 0, 0); //后面参数为 0, 0所以直接返回 return; case T_NEWLINE: //新行解析 if (nargs) { //有文本参数 int kw = lookup_keyword(args[0]); //解析关键词-->4.lookup_keyword if (kw_is(kw, SECTION)) { //判断是否section类-->5.kw_is state.parse_line(&state, 0, 0); //后面参数为 0, 0所以直接返回 parse_new_section(&state, kw, nargs, args); //6.parse_new_section } else { state.parse_line(&state, nargs, args); //解析前一行parse_line_service或parse_line_action } nargs = 0; //nargs参数个数清0 } break; case T_TEXT: //文本 if (nargs < INIT_PARSER_MAXARGS) { args[nargs++] = state.text; //保存文本参数,nargs++ } break; } }}T_TEXT分支记录参数信息 例如
on early-init
symlink /initlogo.rle.bak /initlogo.rle
则会记录成
args[0]=on, args[1]=early-init -->换行
args[0]=symlink, args[1]=/initlogo.rle.bak, args[2]=/initlogo.rle -->换行
记录完后换新行会进入T_NEWLINE分支,分支会解析上一行的args[0],提取关键字,判断关键字类型做处理
如果是on和service关键词会调用parse_new_section处理,如果不是则调用state.parse_line函数处理,
parse_line函数可以是parse_line_service【service】或parse_line_action【on】
该parse_line函数主要是解析on/service后面带的command/options
正如例子中,on early-init 调用parse_new_section设置parse_line函数为parse_line_action
接着处理【on的command】symlink /initlogo.rle.bak /initlogo.rle的时候则调用parse_line函数parse_line_action
等到所有都处理完了则进入T_EOF分支,T_EOF分支return,跳出循环体
3.next_token
int next_token(struct parse_state *state){ char *x = state->ptr; char *s; if (state->nexttoken) { int t = state->nexttoken; state->nexttoken = 0; return t; } for (;;) { switch (*x) { case 0: //文件结尾 state->ptr = x; return T_EOF; case '\n': //换行 state->line++; //行数++ x++; state->ptr = x; return T_NEWLINE; case ' ': //空格 case '\t': //tab制表 case '\r': //回车 x++; continue; case '#': //注释 while (*x && (*x != '\n')) //跳过注释直到换行 x++; state->line++; //行数++ state->ptr = x; return T_NEWLINE; default: //文本 goto text; } }textdone: state->ptr = x; *s = 0; return T_TEXT;text: state->text = s = x;textresume: for (;;) { switch (*x) { case 0: //文本结束 goto textdone; case ' ': //空格 case '\t': //tab制表 case '\r': //回车 x++; goto textdone; case '\n': //换行 state->nexttoken = T_NEWLINE; x++; goto textdone; case '"': //引号括起 x++; for (;;) { switch (*x) { case 0: state->ptr = x; return T_EOF; case '"': //引号结束 x++; goto textresume; default: //引号括起的内容 *s++ = *x++; } } break; case '\\': //转义字符 x++; switch (*x) { case 0: goto textdone; case 'n': *s++ = '\n'; break; case 'r': *s++ = '\r'; break; case 't': *s++ = '\t'; break; case '\\': *s++ = '\\'; break; case '\r': /* \ <cr> <lf> -> line continuation */ if (x[1] != '\n') { x++; continue; } case '\n': /* \ <lf> -> line continuation */ state->line++; x++; /* eat any extra whitespace */ while((*x == ' ') || (*x == '\t')) x++; continue; default: /* unknown escape -- just copy */ *s++ = *x++; } continue; default: //复制文本到s *s++ = *x++; } } return T_EOF;}4.lookup_keyword
int lookup_keyword(const char *s){ switch (*s++) { case 'c': if (!strcmp(s, "opy")) return K_copy; if (!strcmp(s, "apability")) return K_capability; if (!strcmp(s, "hdir")) return K_chdir; if (!strcmp(s, "hroot")) return K_chroot; if (!strcmp(s, "lass")) return K_class; if (!strcmp(s, "lass_start")) return K_class_start; if (!strcmp(s, "lass_stop")) return K_class_stop; if (!strcmp(s, "onsole")) return K_console; if (!strcmp(s, "hown")) return K_chown; if (!strcmp(s, "hmod")) return K_chmod; if (!strcmp(s, "ritical")) return K_critical; break; case 'd': if (!strcmp(s, "isabled")) return K_disabled; if (!strcmp(s, "omainname")) return K_domainname; break; case 'e': if (!strcmp(s, "xec")) return K_exec; if (!strcmp(s, "xport")) return K_export; break; case 'g': if (!strcmp(s, "roup")) return K_group; break; case 'h': if (!strcmp(s, "ostname")) return K_hostname; break; case 'i': if (!strcmp(s, "oprio")) return K_ioprio; if (!strcmp(s, "fup")) return K_ifup; if (!strcmp(s, "nsmod")) return K_insmod; if (!strcmp(s, "mport")) return K_import; break; case 'k': if (!strcmp(s, "eycodes")) return K_keycodes; break; case 'l': if (!strcmp(s, "oglevel")) return K_loglevel; break; case 'm': if (!strcmp(s, "kdir")) return K_mkdir; if (!strcmp(s, "ount")) return K_mount; break; case 'o': if (!strcmp(s, "n")) return K_on; if (!strcmp(s, "neshot")) return K_oneshot; if (!strcmp(s, "nrestart")) return K_onrestart; break; case 'r': if (!strcmp(s, "estart")) return K_restart; break; case 's': if (!strcmp(s, "ervice")) return K_service; if (!strcmp(s, "etenv")) return K_setenv; if (!strcmp(s, "etkey")) return K_setkey; if (!strcmp(s, "etprop")) return K_setprop; if (!strcmp(s, "etrlimit")) return K_setrlimit; if (!strcmp(s, "ocket")) return K_socket; if (!strcmp(s, "tart")) return K_start; if (!strcmp(s, "top")) return K_stop; if (!strcmp(s, "ymlink")) return K_symlink; if (!strcmp(s, "ysclktz")) return K_sysclktz; break; case 't': if (!strcmp(s, "rigger")) return K_trigger; break; case 'u': if (!strcmp(s, "ser")) return K_user; break; case 'w': if (!strcmp(s, "rite")) return K_write; if (!strcmp(s, "ait")) return K_wait; break; } return K_UNKNOWN;}
5.kw_is
5.1.kw_is宏定义
#define kw_is(kw, type) (keyword_info[kw].flags & (type))
5.2.keyword_info全局数组的定义
struct { const char *name; int (*func)(int nargs, char **args); unsigned char nargs; unsigned char flags;} keyword_info[KEYWORD_COUNT] = { [ K_UNKNOWN ] = { "unknown", 0, 0, 0 },#include "keywords.h"};该数组包含了keywords.h文件
5.3.keywords.h文件内容
#ifndef KEYWORDint do_chroot(int nargs, char **args);int do_chdir(int nargs, char **args);int do_class_start(int nargs, char **args);int do_class_stop(int nargs, char **args);int do_domainname(int nargs, char **args);int do_exec(int nargs, char **args);int do_export(int nargs, char **args);int do_hostname(int nargs, char **args);int do_ifup(int nargs, char **args);int do_insmod(int nargs, char **args);int do_import(int nargs, char **args);int do_mkdir(int nargs, char **args);int do_mount(int nargs, char **args);int do_restart(int nargs, char **args);int do_setkey(int nargs, char **args);int do_setprop(int nargs, char **args);int do_setrlimit(int nargs, char **args);int do_start(int nargs, char **args);int do_stop(int nargs, char **args);int do_trigger(int nargs, char **args);int do_symlink(int nargs, char **args);int do_sysclktz(int nargs, char **args);int do_write(int nargs, char **args);int do_copy(int nargs, char **args);int do_chown(int nargs, char **args);int do_chmod(int nargs, char **args);int do_loglevel(int nargs, char **args);int do_wait(int nargs, char **args);#define __MAKE_KEYWORD_ENUM__#define KEYWORD(symbol, flags, nargs, func) K_##symbol,enum { K_UNKNOWN,#endif 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)#ifdef __MAKE_KEYWORD_ENUM__ KEYWORD_COUNT,};#undef __MAKE_KEYWORD_ENUM__#undef KEYWORD#endif5.4.结合KEYWORD宏拆开全局keyword_info数组可得
struct { const char *name; int (*func)(int nargs, char **args); unsigned char nargs; unsigned char flags;} keyword_info[KEYWORD_COUNT] = {[ K_UNKNOWN ] = { "unknown", 0, 0, 0 },[ K_capability ] = { "capability", 0, 0, OPTION },[ K_chdir ] = { "chdir", do_chdir, 1, COMMAND },[ K_chroot ] = { "chroot", do_chroot, 1, COMMAND },[ K_class ] = { "class", 0, 0, OPTION, },[ K_class_start ] = { "class_start", do_class_start, 1, COMMAND },[ K_class_stop ] = { "class_stop", do_class_stop, 1, COMMAND },[ K_console ] = { "console", 0, 0, OPTION },[ K_critical ] = { "critical", 0, 0, OPTION },[ K_disabled ] = { "disabled", 0, 0, OPTION },[ K_domainname ] = { "domainname", do_domainname, 1, COMMAND },[ K_exec ] = { "exec", do_exec, 1, COMMAND },[ K_export ] = { "export", do_export, 2, COMMAND },[ K_group ] = { "group", 0, 0, OPTION },[ K_hostname ] = { "hostname", do_hostname, 1, COMMAND },[ K_ifup ] = { "ifup", do_ifup, 1 COMMAND },[ K_insmod ] = { "insmod", do_insmod, 1, COMMAND },[ K_import ] = { "import", do_import, 1, COMMAND },[ K_keycodes ] = { "keycodes", 0, 0, OPTION },[ K_mkdir ] = { "mkdir", do_mkdir, 1, COMMAND },[ K_mount ] = { "mount", do_mount, 3, COMMAND },[ K_on ] = { "on", 0, 0, SECTION },///////////////////////[ K_oneshot ] = { "oneshot", 0, 0, OPTION },[ K_onrestart ] = { "onrestart", 0, 0, OPTION },[ K_restart ] = { "restart", do_restart, 1, COMMAND },[ K_service ] = { "service", 0, 0, SECTION },///////////////////////[ K_setenv ] = { "setenv", 0, 2, OPTION },[ K_setkey ] = { "setkey", do_setkey, 0, COMMAND },[ K_setprop ] = { "setprop", do_setprop, 2, COMMAND },[ K_setrlimit ] = { "setrlimit", do_setrlimit , 3, COMMAND },[ K_socket ] = { "socket", 0, 0, OPTION },[ K_start ] = { "start", do_start, 1, COMMAND },[ K_stop ] = { "stop", do_stop, 1, COMMAND },[ K_trigger ] = { "trigger", do_trigger, 1, COMMAND },[ K_symlink ] = { "symlink", do_symlink, 1, COMMAND },[ K_sysclktz ] = { "sysclktz", do_sysclktz, 1, COMMAND },[ K_user ] = { "user", 0, 0, OPTION },[ K_wait ] = { "wait", do_wait, 1, COMMAND },[ K_write ] = { "write", do_write, 2, COMMAND },[ K_copy ] = { "copy", do_copy, 2, COMMAND },[ K_chown ] = { "chown", do_chown, 2, COMMAND },[ K_chmod ] = { "chmod", do_chmod, 2, COMMAND },,[ K_loglevel ] = { "loglevel", do_loglevel, 1, COMMAND },[ K_ioprio ] = { "ioprio", 0, 0 OPTION },}5.5.同理可以理解
#define kw_name(kw) (keyword_info[kw].name) //根据关键词获取名字#define kw_func(kw) (keyword_info[kw].func) //根据关键词获取处理函数指针#define kw_nargs(kw) (keyword_info[kw].nargs) //根据关键词获取参数个数
6.parse_new_section
void parse_new_section(struct parse_state *state, int kw,int nargs, char **args){ printf("[ %s %s ]\n", args[0],nargs > 1 ? args[1] : ""); switch(kw) { case K_service: //service类型-->三、service的处理 state->context = parse_service(state, nargs, args); //解析service if (state->context) { state->parse_line = parse_line_service; //设置parse_line函数,处理options return; } break; case K_on: //on类型 -->四、action的处理 state->context = parse_action(state, nargs, args); //解析action if (state->context) { state->parse_line = parse_line_action; //设置parse_line函数,处理command return; } break; } state->parse_line = parse_line_no_op;}三、service的处理
1.相关结构体
struct service { struct listnode slist; const char *name; const char *classname; unsigned flags; pid_t pid; time_t time_started; time_t time_crashed; int nr_crashed; uid_t uid; gid_t gid; gid_t supp_gids[NR_SVC_SUPP_GIDS]; size_t nr_supp_gids; struct socketinfo *sockets; struct svcenvinfo *envvars; struct action onrestart; int *keycodes; int nkeycodes; int keychord_id; int ioprio_class; int ioprio_pri; int nargs; char *args[1];}2.parse_service解析service
static void *parse_service(struct parse_state *state, int nargs, char **args){ struct service *svc; if (nargs < 3) { //至少要三个service 服务名 应用程序路径 parse_error(state, "services must have a name and a program\n"); return 0; } if (!valid_name(args[1])) { parse_error(state, "invalid service name '%s'\n", args[1]); return 0; } svc = service_find_by_name(args[1]); //根据服务名找到service if (svc) { parse_error(state, "ignored duplicate definition of service '%s'\n", args[1]); return 0; } nargs -= 2; //参数个数调整 svc = calloc(1, sizeof(*svc) + sizeof(char*) * nargs); //分配service和参数内存 if (!svc) { parse_error(state, "out of memory\n"); return 0; } svc->name = args[1]; //服务名 svc->classname = "default"; //默认设置service->classname为"default",在init.rc有一句class_start default memcpy(svc->args, args + 2, sizeof(char*) * nargs); //复制参数,参数中移除argc[0]和argc[1],从argc[2]复制起 svc->args[nargs] = 0; //最后一个参数值为0表示参数结束 svc->nargs = nargs; //设置服务的参数个数为更新后的参数个数 svc->onrestart.name = "onrestart"; list_init(&svc->onrestart.commands); //初始化命令链表 list_add_tail(&service_list, &svc->slist); //添加到全局service_list链表中 return svc;}
3.parse_line_service解析service的选项
static void parse_line_service(struct parse_state *state, int nargs, char **args) //解析service的选项options{ struct service *svc = state->context; struct command *cmd; int i, kw, kw_nargs; if (nargs == 0) { //参数个数为0直接返回 return; } svc->ioprio_class = IoSchedClass_NONE; kw = lookup_keyword(args[0]); //根据参数0获取关键词(选项Options) switch (kw) { case K_capability: //capability break; case K_class: //class if (nargs != 2) { parse_error(state, "class option requires a classname\n"); } else { svc->classname = args[1]; } break; case K_console: //console svc->flags |= SVC_CONSOLE; break; case K_disabled: //disabled svc->flags |= SVC_DISABLED; break; case K_ioprio: //ioprio if (nargs != 3) { parse_error(state, "ioprio optin usage: ioprio <rt|be|idle> <ioprio 0-7>\n"); } else { svc->ioprio_pri = strtoul(args[2], 0, 8); if (svc->ioprio_pri < 0 || svc->ioprio_pri > 7) { parse_error(state, "priority value must be range 0 - 7\n"); break; } if (!strcmp(args[1], "rt")) { svc->ioprio_class = IoSchedClass_RT; } else if (!strcmp(args[1], "be")) { svc->ioprio_class = IoSchedClass_BE; } else if (!strcmp(args[1], "idle")) { svc->ioprio_class = IoSchedClass_IDLE; } else { parse_error(state, "ioprio option usage: ioprio <rt|be|idle> <0-7>\n"); } } break; case K_group: //group if (nargs < 2) { parse_error(state, "group option requires a group id\n"); } else if (nargs > NR_SVC_SUPP_GIDS + 2) { parse_error(state, "group option accepts at most %d supp. groups\n", NR_SVC_SUPP_GIDS); } else { int n; svc->gid = decode_uid(args[1]); for (n = 2; n < nargs; n++) { svc->supp_gids[n-2] = decode_uid(args[n]); } svc->nr_supp_gids = n - 2; } break; case K_keycodes: //keycodes if (nargs < 2) { parse_error(state, "keycodes option requires atleast one keycode\n"); } else { svc->keycodes = malloc((nargs - 1) * sizeof(svc->keycodes[0])); if (!svc->keycodes) { parse_error(state, "could not allocate keycodes\n"); } else { svc->nkeycodes = nargs - 1; for (i = 1; i < nargs; i++) { svc->keycodes[i - 1] = atoi(args[i]); } } } break; case K_oneshot: //oneshot svc->flags |= SVC_ONESHOT; break; case K_onrestart: //onrestart nargs--; args++; kw = lookup_keyword(args[0]); if (!kw_is(kw, COMMAND)) { parse_error(state, "invalid command '%s'\n", args[0]); break; } kw_nargs = kw_nargs(kw); if (nargs < kw_nargs) { parse_error(state, "%s requires %d %s\n", args[0], kw_nargs - 1,kw_nargs > 2 ? "arguments" : "argument"); break; } cmd = malloc(sizeof(*cmd) + sizeof(char*) * nargs); cmd->func = kw_func(kw); cmd->nargs = nargs; memcpy(cmd->args, args, sizeof(char*) * nargs); list_add_tail(&svc->onrestart.commands, &cmd->clist); break; case K_critical: //critical svc->flags |= SVC_CRITICAL; break; case K_setenv: //setenv { /* name value */ struct svcenvinfo *ei; if (nargs < 2) { parse_error(state, "setenv option requires name and value arguments\n"); break; } ei = calloc(1, sizeof(*ei)); if (!ei) { parse_error(state, "out of memory\n"); break; } ei->name = args[1]; ei->value = args[2]; ei->next = svc->envvars; svc->envvars = ei; break; } case K_socket: //socket {/* name type perm [ uid gid ] */ struct socketinfo *si; if (nargs < 4) { parse_error(state, "socket option requires name, type, perm arguments\n"); break; } if (strcmp(args[2],"dgram") && strcmp(args[2],"stream")&& strcmp(args[2],"seqpacket")) { parse_error(state, "socket type must be 'dgram', 'stream' or 'seqpacket'\n"); break; } si = calloc(1, sizeof(*si)); if (!si) { parse_error(state, "out of memory\n"); break; } si->name = args[1]; si->type = args[2]; si->perm = strtoul(args[3], 0, 8); if (nargs > 4) si->uid = decode_uid(args[4]); if (nargs > 5) si->gid = decode_uid(args[5]); si->next = svc->sockets; svc->sockets = si; break; } case K_user: //user if (nargs != 2) { parse_error(state, "user option requires a user id\n"); } else { svc->uid = decode_uid(args[1]); } break; default: parse_error(state, "invalid option '%s'\n", args[0]); }}四、action的处理
1.相关结构体
struct action { struct listnode alist; struct listnode qlist; struct listnode tlist; unsigned hash; const char *name; struct listnode commands; struct command *current;};struct command{ struct listnode clist; int (*func)(int nargs, char **args); int nargs; char *args[1];};2.parse_action解析action
static void *parse_action(struct parse_state *state, int nargs, char **args){ struct action *act; if (nargs < 2) { //on类型的参数必须为2个 args[0]=on,args[1]=触发条件[trigger] parse_error(state, "actions must have a trigger\n"); return 0; } if (nargs > 2) { //多了也不行 parse_error(state, "actions may not have extra parameters\n"); return 0; } act = calloc(1, sizeof(*act)); //分配action结构体内存 act->name = args[1]; list_init(&act->commands) //初始化命令链表; list_add_tail(&action_list, &act->alist); //添加到全局action_list链表中 return act;}3.parse_line_action解析command
static void parse_line_action(struct parse_state* state, int nargs, char **args) //解析command{ struct command *cmd; struct action *act = state->context; int (*func)(int nargs, char **args); int kw, n; if (nargs == 0) { //参数个数为0直接返回 return; } kw = lookup_keyword(args[0]); //根据参数0,查找关键词 if (!kw_is(kw, COMMAND)) { //是否命令类型 parse_error(state, "invalid command '%s'\n", args[0]); return; } n = kw_nargs(kw); //根据命令获取参数个数 if (nargs < n) { parse_error(state, "%s requires %d %s\n", args[0], n - 1,n > 2 ? "arguments" : "argument"); return; } cmd = malloc(sizeof(*cmd) + sizeof(char*) * nargs); //分配命令和参数内存 cmd->func = kw_func(kw); //设置命令对应的函数 cmd->nargs = nargs; //设置参数个数 memcpy(cmd->args, args, sizeof(char*) * nargs); //复制参数 list_add_tail(&act->commands, &cmd->clist); //添加到state->context链表}
五、service和action的执行
前面分析了:init解析init.rc文件并筛选出service和action,分别设置其结构体成员并添加进各自的全局链表service_list和action_list中
接着分析下service和action的执行
在init的main函数中除了解析init.rc(init_parse_config_file("/init.rc");)
还解析了跟硬件相关的
get_hardware_name(hardware, &revision);
snprintf(tmp, sizeof(tmp), "/init.%s.rc", hardware);
init_parse_config_file(tmp);
解析的结果都同样保存在全局链表service_list和action_list中
接着会有以下几行函数
action_for_each_trigger("early-init", action_add_queue_tail);queue_builtin_action(wait_for_coldboot_done_action, "wait_for_coldboot_done");queue_builtin_action(property_init_action, "property_init");queue_builtin_action(keychord_init_action, "keychord_init");queue_builtin_action(console_init_action, "console_init");queue_builtin_action(set_init_properties_action, "set_init_properties");action_for_each_trigger("init", action_add_queue_tail);action_for_each_trigger("early-fs", action_add_queue_tail);action_for_each_trigger("fs", action_add_queue_tail);action_for_each_trigger("post-fs", action_add_queue_tail);queue_builtin_action(property_service_init_action, "property_service_init");queue_builtin_action(signal_init_action, "signal_init");queue_builtin_action(check_startup_action, "check_startup");action_for_each_trigger("early-boot", action_add_queue_tail);action_for_each_trigger("boot", action_add_queue_tail);queue_builtin_action(queue_property_triggers_action, "queue_propety_triggers");1.action_for_each_trigger
void action_for_each_trigger(const char *trigger,void (*func)(struct action *act)){ struct listnode *node; struct action *act; list_for_each(node, &action_list) { //遍历全局action_list act = node_to_item(node, struct action, alist); if (!strcmp(act->name, trigger)) { //比较名字和trigger触发条件 func(act); //符合触发条件,则执行action_add_queue_tail函数 } }}1.1 action_add_queue_tail
void action_add_queue_tail(struct action *act){ list_add_tail(&action_queue, &act->qlist);}综合上面的action_for_each_trigger函数集,可知main函数
依次处理脚本中on标志以 early-init init early-fs fs post-fs early-boot boot的trigger的action
执行action_add_queue_tail函数将action添加到全局action_queue队列链表
2.queue_builtin_action
void queue_builtin_action(int (*func)(int nargs, char **args), char *name){ struct action *act; struct command *cmd; act = calloc(1, sizeof(*act)); //分配action内存 act->name = name; //设置名字 list_init(&act->commands); //初始化command链表 cmd = calloc(1, sizeof(*cmd)); //分配command cmd->func = func; //设置执行函数为传递的第一个参数 cmd->args[0] = name; //设置command的参数0 list_add_tail(&act->commands, &cmd->clist); //添加command到action的commands链表中 list_add_tail(&action_list, &act->alist); //添加action到全局action_list链表中 action_add_queue_tail(act); //添加action到全局action_queue队列链表}
创建以name标记的action,并添加进全局action_list中,同时添加进action_queue队列链表
所以全局action_queue队列链表中的顺序调整为
early-init [wait_for_coldboot_done] [property_init] [keychord_init] [console_init] [set_init_properties]
init early-fs fs post-fs [property_service_init] [signal_init] [check_startup] early-boot boot [queue_propety_triggers]
接着进入main的for(;;)循环体
3.execute_one_command执行一个command
void execute_one_command(void){ int ret; //第一次执行cur_action为0,执行完某个action下的所有command后cur_command为0,条件为真 if (!cur_action || !cur_command || is_last_command(cur_action, cur_command)) { cur_action = action_remove_queue_head(); //获取下一个action cur_command = NULL; if (!cur_action) return; INFO("processing action %p (%s)\n", cur_action, cur_action->name); cur_command = get_first_command(cur_action); //获取action的第一个command } else { //循环执行某个action下的所有command cur_command = get_next_command(cur_action, cur_command); //获取action的下一个command } if (!cur_command) //没有command可取了,则cur_command=0 return; //返回 ret = cur_command->func(cur_command->nargs, cur_command->args); //执行command的处理函数 INFO("command '%s' r=%d\n", cur_command->args[0], ret);}因为execute_one_command套在for(;;)中所以会循环执行action_queue队列链表下的action的command
4.service_list下的服务的执行
4.1service由service_start启动
搜索代码遍历调用service_start的分支:
KEYWORD(class_start, COMMAND, 1, do_class_start)do_class_start->service_for_each_class->service_start_if_not_disabled->service_startKEYWORD(start, COMMAND, 1, do_start)do_start->service_startKEYWORD(restart, COMMAND, 1, do_restart)do_restart->service_startmain[for(;;)]->restart_processes->service_for_each_flags->restart_service_if_needed->service_startmain[for(;;)]->handle_property_set_fd->handle_control_message->msg_start->service_startmain[for(;;)]->handle_keychord->service_start
前三个分支是由处理command是调用的处理函数do_XXX调用的,也就是execute_one_command函数的处理过程会调用到
后三个分支是在init的main函数的循环体中调用
在init.rc中有一句class_start default
作为class_start命令在处理时会调用到do_class_start
int do_class_start(int nargs, char **args) //argc[1]=default{ service_for_each_class(args[1], service_start_if_not_disabled); return 0;}service_for_each_class根据class类名查找service
void service_for_each_class(const char *classname,void (*func)(struct service *svc)){ struct listnode *node; struct service *svc; list_for_each(node, &service_list) { //遍历全局service_list svc = node_to_item(node, struct service, slist); if (!strcmp(svc->classname, classname)) { //在前面parse_service函数中,将svc->classname = "default",所以为真 func(svc); //调用service_start_if_not_disabled } }}service_start_if_not_disabled启动没有禁止启动的service
static void service_start_if_not_disabled(struct service *svc){ if (!(svc->flags & SVC_DISABLED)) { //若没设置SVC_DISABLED标志,也就是init.rc中对应的service的options没有disabled service_start(svc, NULL); //则会启动服务 }}到这里重要的正规的service就已经启动了
5.service_start的简单解析
void service_start(struct service *svc, const char *dynamic_args){ struct stat s; pid_t pid; int needs_console; int n; svc->flags &= (~(SVC_DISABLED|SVC_RESTARTING)); //去掉禁用和重启标志 svc->time_started = 0; if (svc->flags & SVC_RUNNING) { //若已经运行了,则直接返回 return; } needs_console = (svc->flags & SVC_CONSOLE) ? 1 : 0; //需要console if (needs_console && (!have_console)) { //需要但没有console ERROR("service '%s' requires console\n", svc->name); svc->flags |= SVC_DISABLED; return; } if (stat(svc->args[0], &s) != 0) { ERROR("cannot find '%s', disabling '%s'\n", svc->args[0], svc->name); svc->flags |= SVC_DISABLED; return; } if ((!(svc->flags & SVC_ONESHOT)) && dynamic_args) { //没one-shot标志但使用了动态参数 ERROR("service '%s' must be one-shot to use dynamic args, disabling\n",svc->args[0]); svc->flags |= SVC_DISABLED; return; } NOTICE("starting '%s'\n", svc->name); //打印信息 pid = fork(); //创建进程 if (pid == 0) { //子进程 struct socketinfo *si; struct svcenvinfo *ei; char tmp[32]; int fd, sz; if (properties_inited()) { get_property_workspace(&fd, &sz); sprintf(tmp, "%d,%d", dup(fd), sz); add_environment("ANDROID_PROPERTY_WORKSPACE", tmp); } for (ei = svc->envvars; ei; ei = ei->next) add_environment(ei->name, ei->value); for (si = svc->sockets; si; si = si->next) { int socket_type = (!strcmp(si->type, "stream") ? SOCK_STREAM :(!strcmp(si->type, "dgram") ? SOCK_DGRAM : SOCK_SEQPACKET)); int s = create_socket(si->name, socket_type,si->perm, si->uid, si->gid); if (s >= 0) { publish_socket(si->name, s); } } if (svc->ioprio_class != IoSchedClass_NONE) { if (android_set_ioprio(getpid(), svc->ioprio_class, svc->ioprio_pri)) { ERROR("Failed to set pid %d ioprio = %d,%d: %s\n",getpid(), svc->ioprio_class, svc->ioprio_pri, strerror(errno)); } } if (needs_console) { //需要控制台 setsid(); open_console(); //打开控制台 } else { zap_stdio(); } setpgid(0, getpid()); if (svc->gid) { setgid(svc->gid); } if (svc->nr_supp_gids) { setgroups(svc->nr_supp_gids, svc->supp_gids); } if (svc->uid) { setuid(svc->uid); } if (!dynamic_args) { if (execve(svc->args[0], (char**) svc->args, (char**) ENV) < 0) {//service 路径参数对应的应用程序 ERROR("cannot execve('%s'): %s\n", svc->args[0], strerror(errno)); } } else { char *arg_ptrs[INIT_PARSER_MAXARGS+1]; int arg_idx = svc->nargs; char *tmp = strdup(dynamic_args); char *next = tmp; char *bword; /* Copy the static arguments */ memcpy(arg_ptrs, svc->args, (svc->nargs * sizeof(char *))); while((bword = strsep(&next, " "))) { arg_ptrs[arg_idx++] = bword; if (arg_idx == INIT_PARSER_MAXARGS) break; } arg_ptrs[arg_idx] = '\0'; execve(svc->args[0], (char**) arg_ptrs, (char**) ENV); //service 路径参数对应的应用程序 } _exit(127); } if (pid < 0) { ERROR("failed to start '%s'\n", svc->name); svc->pid = 0; return; } svc->time_started = gettime(); //记录service启动时间 svc->pid = pid; //记录service的pid号 svc->flags |= SVC_RUNNING; //添加已运行标志SVC_RUNNING if (properties_inited()) notify_service_state(svc->name, "running");}这里execve(svc->args[0], (char**) arg_ptrs, (char**) ENV)中args[0]是init.rc中service <name> <pathname> [ <argument> ]*的<pathname>,
arg_ptrs指向[ <argument> ]*
例如：service servicemanager /system/bin/servicemanager就会执行execve(/system/bin/servicemanager,...........)