[android|android adb源码分析(1)

ADB是Android debug bridge的缩写,它使用PC机可以通过USB或网络与android设备通讯。
adb的源码位于system/core/adb目录下,先来看下编译脚本Android.mk:

# Copyright 2005 The Android Open Source Project # # Android.mk for adb #LOCAL_PATH:= $(call my-dir)# adb host tool # ========================================================= include $(CLEAR_VARS)# Default to a virtual (sockets) usb interface USB_SRCS := EXTRA_SRCS :=ifeq ($(HOST_OS),linux) USB_SRCS := usb_linux.c EXTRA_SRCS := get_my_path_linux.c LOCAL_LDLIBS += -lrt -ldl -lpthread LOCAL_CFLAGS += -DWORKAROUND_BUG6558362 endififeq ($(HOST_OS),darwin) USB_SRCS := usb_osx.c EXTRA_SRCS := get_my_path_darwin.c LOCAL_LDLIBS += -lpthread -framework CoreFoundation -framework IOKit -framework Carbon endififeq ($(HOST_OS),freebsd) USB_SRCS := usb_libusb.c EXTRA_SRCS := get_my_path_freebsd.c LOCAL_LDLIBS += -lpthread -lusb endififeq ($(HOST_OS),windows) USB_SRCS := usb_windows.c EXTRA_SRCS := get_my_path_windows.c ../libcutils/list.c EXTRA_STATIC_LIBS := AdbWinApi ifneq ($(strip $(USE_CYGWIN)),) # Pure cygwin case LOCAL_LDLIBS += -lpthread -lgdi32 LOCAL_C_INCLUDES += /usr/include/w32api/ddk endif ifneq ($(strip $(USE_MINGW)),) # MinGW under Linux case LOCAL_LDLIBS += -lws2_32 -lgdi32 USE_SYSDEPS_WIN32 := 1 LOCAL_C_INCLUDES += /usr/i586-mingw32msvc/include/ddk endif LOCAL_C_INCLUDES += development/host/windows/usb/api/ endifLOCAL_SRC_FILES := \ adb.c \ console.c \ transport.c \ transport_local.c \ transport_usb.c \ commandline.c \ adb_client.c \ adb_auth_host.c \ sockets.c \ services.c \ file_sync_client.c \ $(EXTRA_SRCS) \ $(USB_SRCS) \ usb_vendors.cLOCAL_C_INCLUDES += external/openssl/includeifneq ($(USE_SYSDEPS_WIN32),) LOCAL_SRC_FILES += sysdeps_win32.c else LOCAL_SRC_FILES += fdevent.c endifLOCAL_CFLAGS += -O2 -g -DADB_HOST=1-Wall -Wno-unused-parameter LOCAL_CFLAGS += -D_XOPEN_SOURCE -D_GNU_SOURCE LOCAL_MODULE := adb LOCAL_MODULE_TAGS := debugLOCAL_STATIC_LIBRARIES := libzipfile libunz libcrypto_static $(EXTRA_STATIC_LIBS) ifeq ($(USE_SYSDEPS_WIN32),) LOCAL_STATIC_LIBRARIES += libcutils endifinclude $(BUILD_HOST_EXECUTABLE)$(call dist-for-goals,dist_files sdk,$(LOCAL_BUILT_MODULE))ifeq ($(HOST_OS),windows) $(LOCAL_INSTALLED_MODULE): \ $(HOST_OUT_EXECUTABLES)/AdbWinApi.dll \ $(HOST_OUT_EXECUTABLES)/AdbWinUsbApi.dll endif# adbd device daemon # =========================================================include $(CLEAR_VARS)LOCAL_SRC_FILES := \ adb.c \ backup_service.c \ fdevent.c \ transport.c \ transport_local.c \ transport_usb.c \ adb_auth_client.c \ sockets.c \ services.c \ file_sync_service.c \ jdwp_service.c \ framebuffer_service.c \ remount_service.c \ usb_linux_client.c \ log_service.cLOCAL_CFLAGS := -O2 -g -DADB_HOST=0 -Wall -Wno-unused-parameter LOCAL_CFLAGS += -D_XOPEN_SOURCE -D_GNU_SOURCEifneq (,$(filter userdebug eng,$(TARGET_BUILD_VARIANT))) LOCAL_CFLAGS += -DALLOW_ADBD_ROOT=1 endifLOCAL_MODULE := adbdLOCAL_FORCE_STATIC_EXECUTABLE := true LOCAL_MODULE_PATH := $(TARGET_ROOT_OUT_SBIN) LOCAL_UNSTRIPPED_PATH := $(TARGET_ROOT_OUT_SBIN_UNSTRIPPED)LOCAL_STATIC_LIBRARIES := liblog libcutils libc libmincrypt include $(BUILD_EXECUTABLE)# adb host tool for device-as-host # ========================================================= ifneq ($(SDK_ONLY),true) include $(CLEAR_VARS)LOCAL_LDLIBS := -lrt -ldl -lpthreadLOCAL_SRC_FILES := \ adb.c \ console.c \ transport.c \ transport_local.c \ transport_usb.c \ commandline.c \ adb_client.c \ adb_auth_host.c \ sockets.c \ services.c \ file_sync_client.c \ get_my_path_linux.c \ usb_linux.c \ usb_vendors.c \ fdevent.cLOCAL_CFLAGS := \ -O2 \ -g \ -DADB_HOST=1 \ -DADB_HOST_ON_TARGET=1 \ -Wall \ -Wno-unused-parameter \ -D_XOPEN_SOURCE \ -D_GNU_SOURCELOCAL_C_INCLUDES += external/openssl/includeLOCAL_MODULE := adbLOCAL_STATIC_LIBRARIES := libzipfile libunz libcutilsLOCAL_SHARED_LIBRARIES := libcryptoinclude $(BUILD_EXECUTABLE) endif


可以看到,最终会有3个执行文件被生成,adbd和两个adb程序。adbd是手机终的守护进程;adb一个是windows、linux、darwin或freebsd运行的程序,另一个是目标机上运行的程序。
宏ADB_HOST用于区分是PC端程序还是目标机端的程序。宏ADB_HOST_ON_TARGET用于区分adb程序是否是在目标机上运行。这3个程序使用的是同一份源码,在内部,使用这些宏来区别不同的程序。
程序的入口在adb.c的main()函数:

int main(int argc, char **argv) { #if ADB_HOST adb_sysdeps_init(); adb_trace_init(); D("Handling commandline()\n"); return adb_commandline(argc - 1, argv + 1); #else /* If adbd runs inside the emulator this will enable adb tracing via * adb-debug qemud service in the emulator. */ adb_qemu_trace_init(); if((argc > 1) && (!strcmp(argv[1],"recovery"))) { adb_device_banner = "recovery"; recovery_mode = 1; }start_device_log(); D("Handling main()\n"); return adb_main(0, DEFAULT_ADB_PORT); #endif }


先来看adbd程序,此时宏的设置是ADB_HOST=0。上面代码中start_device_log()是log的初始化操作,可以重定向输出的log信息,接着进入adb_main()函数。先来看下它的参数DEFAULT_ADB_PORT:

#if ADB_HOST_ON_TARGET /* adb and adbd are coexisting on the target, so use 5038 for adb * to avoid conflicting with adbd's usage of 5037 */ #define DEFAULT_ADB_PORT 5038 #else #define DEFAULT_ADB_PORT 5037 #endif

如果是目标机程序,它的值是5038,否则它的值是5037。这里没有定义ADB_HOST_ON_TARGET, 所以它是5037。
adb_main()的源代码如下:

int adb_main(int is_daemon, int server_port) { #if !ADB_HOST int port; char value[PROPERTY_VALUE_MAX]; umask(000); #endifatexit(adb_cleanup); #ifdef HAVE_WIN32_PROC SetConsoleCtrlHandler( ctrlc_handler, TRUE ); #elif defined(HAVE_FORKEXEC) // No SIGCHLD. Let the service subproc handle its children. signal(SIGPIPE, SIG_IGN); #endifinit_transport_registration(); #if ADB_HOST HOST = 1; usb_vendors_init(); usb_init(); local_init(DEFAULT_ADB_LOCAL_TRANSPORT_PORT); adb_auth_init(); char local_name[30]; build_local_name(local_name, sizeof(local_name), server_port); if(install_listener(local_name, "*smartsocket*", NULL)) { exit(1); } #else property_get("ro.adb.secure", value, "0"); auth_enabled = !strcmp(value, "1"); if (auth_enabled) adb_auth_init(); // Our external storage path may be different than apps, since // we aren't able to bind mount after dropping root. const char* adb_external_storage = getenv("ADB_EXTERNAL_STORAGE"); if (NULL != adb_external_storage) { setenv("EXTERNAL_STORAGE", adb_external_storage, 1); } else { D("Warning: ADB_EXTERNAL_STORAGE is not set.Leaving EXTERNAL_STORAGE" " unchanged.\n"); }/* don't listen on a port (default 5037) if running in secure mode */ /* don't run as root if we are running in secure mode */ if (should_drop_privileges()) { struct __user_cap_header_struct header; struct __user_cap_data_struct cap; if (prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0) != 0) { exit(1); }/* add extra groups: ** AID_ADB to access the USB driver ** AID_LOG to read system logs (adb logcat) ** AID_INPUT to diagnose input issues (getevent) ** AID_INET to diagnose network issues (netcfg, ping) ** AID_GRAPHICS to access the frame buffer ** AID_NET_BT and AID_NET_BT_ADMIN to diagnose bluetooth (hcidump) ** AID_SDCARD_R to allow reading from the SD card ** AID_SDCARD_RW to allow writing to the SD card ** AID_MOUNT to allow unmounting the SD card before rebooting ** AID_NET_BW_STATS to read out qtaguid statistics */ gid_t groups[] = { AID_ADB, AID_LOG, AID_INPUT, AID_INET, AID_GRAPHICS, AID_NET_BT, AID_NET_BT_ADMIN, AID_SDCARD_R, AID_SDCARD_RW, AID_MOUNT, AID_NET_BW_STATS }; if (setgroups(sizeof(groups)/sizeof(groups[0]), groups) != 0) { exit(1); }/* then switch user and group to "shell" */ if (setgid(AID_SHELL) != 0) { exit(1); } if (setuid(AID_SHELL) != 0) { exit(1); }/* set CAP_SYS_BOOT capability, so "adb reboot" will succeed */ header.version = _LINUX_CAPABILITY_VERSION; header.pid = 0; cap.effective = cap.permitted = (1 << CAP_SYS_BOOT); cap.inheritable = 0; capset(&header, &cap); D("Local port disabled\n"); } else { char local_name[30]; build_local_name(local_name, sizeof(local_name), server_port); if(install_listener(local_name, "*smartsocket*", NULL)) { exit(1); } }int usb = 0; if (access(USB_ADB_PATH, F_OK) == 0 || access(USB_FFS_ADB_EP0, F_OK) == 0) { // listen on USB usb_init(); usb = 1; }// If one of these properties is set, also listen on that port // If one of the properties isn't set and we couldn't listen on usb, // listen on the default port. property_get("service.adb.tcp.port", value, ""); if (!value[0]) { property_get("persist.adb.tcp.port", value, ""); } if (sscanf(value, "%d", &port) == 1 && port > 0) { printf("using port=%d\n", port); // listen on TCP port specified by service.adb.tcp.port property local_init(port); } else if (!usb) { // listen on default port local_init(DEFAULT_ADB_LOCAL_TRANSPORT_PORT); }D("adb_main(): pre init_jdwp()\n"); init_jdwp(); D("adb_main(): post init_jdwp()\n"); #endifif (is_daemon) { // inform our parent that we are up and running. #ifdef HAVE_WIN32_PROC DWORDcount; WriteFile( GetStdHandle( STD_OUTPUT_HANDLE ), "OK\n", 3, &count, NULL ); #elif defined(HAVE_FORKEXEC) fprintf(stderr, "OK\n"); #endif start_logging(); } D("Event loop starting\n"); fdevent_loop(); usb_cleanup(); return 0; }


(1) init_transport_registration()初始化fevent transport_registration_fde;
(2) 判断系统属性ro.adb.secure,目标板没有设置这个宏;
(3) 没有定义环境变量adb_external_storage;
(4) should_drop_privileges()根据android编译环境should_drop_privileges返回不同的值,如果它的值是userdebug或eng,宏ALLOW_ADBD_ROOT的值被定义为1,执行install_listener(),否则不会定义,这种情况下,由于adbd运行在root下,为保证它的安全性,它需要降级运行;
(5) 判断是否存在设备文件USB_ADB_PATH或USB_FFS_ADB_EP0,存在则执行usb_init();
(6) 读取属性service.adb.tcp.port或persist.adb.tcp.port(目标板均未定义),执行local_init(),它内部会创建adb thread;
(7) 执行init_jdwp(),jdwp是java调试体系中的一种,具体可百度;
(8) 调用fdevent_loop()监听fdevent并处理;
(9) 程序结束。


再来看adb程序的执行:
在main()中调用return adb_commandline(argc - 1, argv + 1):

int adb_commandline(int argc, char **argv) { char buf[4096]; int no_daemon = 0; int is_daemon = 0; int is_server = 0; int persist = 0; int r; int quote; transport_type ttype = kTransportAny; char* serial = NULL; char* server_port_str = NULL; /* If defined, this should be an absolute path to * the directory containing all of the various system images * for a particular product.If not defined, and the adb * command requires this information, then the user must * specify the path using "-p". */ gProductOutPath = getenv("ANDROID_PRODUCT_OUT"); if (gProductOutPath == NULL || gProductOutPath[0] == '\0') { gProductOutPath = NULL; } // TODO: also try TARGET_PRODUCT/TARGET_DEVICE as a hintserial = getenv("ANDROID_SERIAL"); /* Validate and assign the server port */ server_port_str = getenv("ANDROID_ADB_SERVER_PORT"); int server_port = DEFAULT_ADB_PORT; if (server_port_str && strlen(server_port_str) > 0) { server_port = (int) strtol(server_port_str, NULL, 0); if (server_port <= 0) { fprintf(stderr, "adb: Env var ANDROID_ADB_SERVER_PORT must be a positive number. Got \"%s\"\n", server_port_str); return usage(); } }/* modifiers and flags */ while(argc > 0) { if(!strcmp(argv[0],"server")) { is_server = 1; } else if(!strcmp(argv[0],"nodaemon")) { no_daemon = 1; } else if (!strcmp(argv[0], "fork-server")) { /* this is a special flag used only when the ADB client launches the ADB Server */ is_daemon = 1; } else if(!strcmp(argv[0],"persist")) { persist = 1; } else if(!strncmp(argv[0], "-p", 2)) { const char *product = NULL; if (argv[0][2] == '\0') { if (argc < 2) return usage(); product = argv[1]; argc--; argv++; } else { product = argv[0] + 2; } gProductOutPath = find_product_out_path(product); if (gProductOutPath == NULL) { fprintf(stderr, "adb: could not resolve \"-p %s\"\n", product); return usage(); } } else if (argv[0][0]=='-' && argv[0][1]=='s') { if (isdigit(argv[0][2])) { serial = argv[0] + 2; } else { if(argc < 2 || argv[0][2] != '\0') return usage(); serial = argv[1]; argc--; argv++; } } else if (!strcmp(argv[0],"-d")) { ttype = kTransportUsb; } else if (!strcmp(argv[0],"-e")) { ttype = kTransportLocal; } else { /* out of recognized modifiers and flags */ break; } argc--; argv++; }adb_set_transport(ttype, serial); adb_set_tcp_specifics(server_port); if (is_server) { if (no_daemon || is_daemon) { r = adb_main(is_daemon, server_port); } else { r = launch_server(server_port); } if(r) { fprintf(stderr,"* could not start server *\n"); } return r; }top: if(argc == 0) { return usage(); }/* adb_connect() commands */if(!strcmp(argv[0], "devices")) { char *tmp; char *listopt; if (argc < 2) listopt = ""; else if (argc == 2 && !strcmp(argv[1], "-l")) listopt = argv[1]; else { fprintf(stderr, "Usage: adb devices [-l]\n"); return 1; } snprintf(buf, sizeof buf, "host:%s%s", argv[0], listopt); tmp = adb_query(buf); if(tmp) { printf("List of devices attached \n"); printf("%s\n", tmp); return 0; } else { return 1; } }if(!strcmp(argv[0], "connect")) { char *tmp; if (argc != 2) { fprintf(stderr, "Usage: adb connect [:]\n"); return 1; } snprintf(buf, sizeof buf, "host:connect:%s", argv[1]); tmp = adb_query(buf); if(tmp) { printf("%s\n", tmp); return 0; } else { return 1; } }if(!strcmp(argv[0], "disconnect")) { char *tmp; if (argc > 2) { fprintf(stderr, "Usage: adb disconnect [[:]]\n"); return 1; } if (argc == 2) { snprintf(buf, sizeof buf, "host:disconnect:%s", argv[1]); } else { snprintf(buf, sizeof buf, "host:disconnect:"); } tmp = adb_query(buf); if(tmp) { printf("%s\n", tmp); return 0; } else { return 1; } }if (!strcmp(argv[0], "emu")) { return adb_send_emulator_command(argc, argv); }if(!strcmp(argv[0], "shell") || !strcmp(argv[0], "hell")) { int r; int fd; char h = (argv[0][0] == 'h'); if (h) { printf("\x1b[41; 33m"); fflush(stdout); }if(argc < 2) { D("starting interactive shell\n"); r = interactive_shell(); if (h) { printf("\x1b[0m"); fflush(stdout); } return r; }snprintf(buf, sizeof buf, "shell:%s", argv[1]); argc -= 2; argv += 2; while(argc-- > 0) { strcat(buf, " "); /* quote empty strings and strings with spaces */ quote = (**argv == 0 || strchr(*argv, ' ')); if (quote) strcat(buf, "\""); strcat(buf, *argv++); if (quote) strcat(buf, "\""); }for(; ; ) { D("interactive shell loop. buff=%s\n", buf); fd = adb_connect(buf); if(fd >= 0) { D("about to read_and_dump(fd=%d)\n", fd); read_and_dump(fd); D("read_and_dump() done.\n"); adb_close(fd); r = 0; } else { fprintf(stderr,"error: %s\n", adb_error()); r = -1; }if(persist) { fprintf(stderr,"\n- waiting for device -\n"); adb_sleep_ms(1000); do_cmd(ttype, serial, "wait-for-device", 0); } else { if (h) { printf("\x1b[0m"); fflush(stdout); } D("interactive shell loop. return r=%d\n", r); return r; } } }if(!strcmp(argv[0], "kill-server")) { int fd; fd = _adb_connect("host:kill"); if(fd == -1) { fprintf(stderr,"* server not running *\n"); return 1; } return 0; }if(!strcmp(argv[0], "sideload")) { if(argc != 2) return usage(); if(adb_download("sideload", argv[1], 1)) { return 1; } else { return 0; } }if(!strcmp(argv[0], "remount") || !strcmp(argv[0], "reboot") || !strcmp(argv[0], "reboot-bootloader") || !strcmp(argv[0], "tcpip") || !strcmp(argv[0], "usb") || !strcmp(argv[0], "root")) { char command[100]; if (!strcmp(argv[0], "reboot-bootloader")) snprintf(command, sizeof(command), "reboot:bootloader"); else if (argc > 1) snprintf(command, sizeof(command), "%s:%s", argv[0], argv[1]); else snprintf(command, sizeof(command), "%s:", argv[0]); int fd = adb_connect(command); if(fd >= 0) { read_and_dump(fd); adb_close(fd); return 0; } fprintf(stderr,"error: %s\n", adb_error()); return 1; }if(!strcmp(argv[0], "bugreport")) { if (argc != 1) return usage(); do_cmd(ttype, serial, "shell", "bugreport", 0); return 0; }/* adb_command() wrapper commands */if(!strncmp(argv[0], "wait-for-", strlen("wait-for-"))) { char* service = argv[0]; if (!strncmp(service, "wait-for-device", strlen("wait-for-device"))) { if (ttype == kTransportUsb) { service = "wait-for-usb"; } else if (ttype == kTransportLocal) { service = "wait-for-local"; } else { service = "wait-for-any"; } }format_host_command(buf, sizeof buf, service, ttype, serial); if (adb_command(buf)) { D("failure: %s *\n",adb_error()); fprintf(stderr,"error: %s\n", adb_error()); return 1; }/* Allow a command to be run after wait-for-device, * e.g. 'adb wait-for-device shell'. */ if(argc > 1) { argc--; argv++; goto top; } return 0; }if(!strcmp(argv[0], "forward")) { if(argc != 3) return usage(); if (serial) { snprintf(buf, sizeof buf, "host-serial:%s:forward:%s; %s",serial, argv[1], argv[2]); } else if (ttype == kTransportUsb) { snprintf(buf, sizeof buf, "host-usb:forward:%s; %s", argv[1], argv[2]); } else if (ttype == kTransportLocal) { snprintf(buf, sizeof buf, "host-local:forward:%s; %s", argv[1], argv[2]); } else { snprintf(buf, sizeof buf, "host:forward:%s; %s", argv[1], argv[2]); } if(adb_command(buf)) { fprintf(stderr,"error: %s\n", adb_error()); return 1; } return 0; }/* do_sync_*() commands */if(!strcmp(argv[0], "ls")) { if(argc != 2) return usage(); return do_sync_ls(argv[1]); }if(!strcmp(argv[0], "push")) { if(argc != 3) return usage(); return do_sync_push(argv[1], argv[2], 0 /* no verify APK */); }if(!strcmp(argv[0], "pull")) { if (argc == 2) { return do_sync_pull(argv[1], "."); } else if (argc == 3) { return do_sync_pull(argv[1], argv[2]); } else { return usage(); } }if(!strcmp(argv[0], "install")) { if (argc < 2) return usage(); return install_app(ttype, serial, argc, argv); }if(!strcmp(argv[0], "uninstall")) { if (argc < 2) return usage(); return uninstall_app(ttype, serial, argc, argv); }if(!strcmp(argv[0], "sync")) { char *srcarg, *android_srcpath, *data_srcpath; int listonly = 0; int ret; if(argc < 2) { /* No local path was specified. */ srcarg = NULL; } else if (argc >= 2 && strcmp(argv[1], "-l") == 0) { listonly = 1; if (argc == 3) { srcarg = argv[2]; } else { srcarg = NULL; } } else if(argc == 2) { /* A local path or "android"/"data" arg was specified. */ srcarg = argv[1]; } else { return usage(); } ret = find_sync_dirs(srcarg, &android_srcpath, &data_srcpath); if(ret != 0) return usage(); if(android_srcpath != NULL) ret = do_sync_sync(android_srcpath, "/system", listonly); if(ret == 0 && data_srcpath != NULL) ret = do_sync_sync(data_srcpath, "/data", listonly); free(android_srcpath); free(data_srcpath); return ret; }/* passthrough commands */if(!strcmp(argv[0],"get-state") || !strcmp(argv[0],"get-serialno") || !strcmp(argv[0],"get-devpath")) { char *tmp; format_host_command(buf, sizeof buf, argv[0], ttype, serial); tmp = adb_query(buf); if(tmp) { printf("%s\n", tmp); return 0; } else { return 1; } }/* other commands */if(!strcmp(argv[0],"status-window")) { status_window(ttype, serial); return 0; }if(!strcmp(argv[0],"logcat") || !strcmp(argv[0],"lolcat") || !strcmp(argv[0],"longcat")) { return logcat(ttype, serial, argc, argv); }if(!strcmp(argv[0],"ppp")) { return ppp(argc, argv); }if (!strcmp(argv[0], "start-server")) { return adb_connect("host:start-server"); }if (!strcmp(argv[0], "backup")) { return backup(argc, argv); }if (!strcmp(argv[0], "restore")) { return restore(argc, argv); }if (!strcmp(argv[0], "jdwp")) { intfd = adb_connect("jdwp"); if (fd >= 0) { read_and_dump(fd); adb_close(fd); return 0; } else { fprintf(stderr, "error: %s\n", adb_error()); return -1; } }/* "adb /?" is a common idiom under Windows */ if(!strcmp(argv[0], "help") || !strcmp(argv[0], "/?")) { help(); return 0; }if(!strcmp(argv[0], "version")) { version(stdout); return 0; }usage(); return 1; }


它的代码有点长,但可以很容易看明白它根据命令的参数执行不同的功能。adb程序可能以服务的方式或命令行客户端的方式运行。
【[android|android adb源码分析(1)】
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以上就是main()函数的执行过程,后续将分析其中的细节内容。




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