在adb中有三个模块，分别是adbd，adb server，adb client，如下表所示：
module name | process name | run as |
adbd | adbd | device/emulator |
adb server | windows: adb.exe linux: adb | client |
adb client | such as eclipse, screencast,ddm app…and so on | client |
adb server需要连接到adbd，这个连接叫adbconnect，这时候就可以通过客户端与设备端进行沟通，如下图：
具体的沟通交流层次如下图所示：
adbd是运行在设备端的一个守护进程，具体代码在adb.c中：
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); //adbd的入口
#endif
}其中adb_main 函数是adbd进程的入口，执行“sevice adbd”时从这里开始调用。
在adbd中将会创建一对socket，一个用来控制连接，一个用来连接到adb client，adbd将会接收和发送信息与应用层的程序进行交流，如图所示：
数据结构
struct fdevent
{
fdevent *next;
fdevent *prev;
int fd;
int force_eof;
unsigned short state;
unsigned short events;
fd_func func;
void *arg;
};adb server将会扫描设备的5555到5585的奇数端口号，install_listener将会实施交互监听，如图所示：
adb server和adb client将会通过socket与设备端进行交流，端口号为5037，如下图：
adb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
endif
ifeq ($(HOST_OS),darwin)
USB_SRCS := usb_osx.c
EXTRA_SRCS := get_my_path_darwin.c
LOCAL_LDLIBS += -lpthread -framework CoreFoundation -framework IOKit -framework Carbon
endif
ifeq ($(HOST_OS),freebsd)
USB_SRCS := usb_libusb.c
EXTRA_SRCS := get_my_path_freebsd.c
LOCAL_LDLIBS += -lpthread -lusb
endif
ifeq ($(HOST_OS),windows)
USB_SRCS := usb_windows.c
EXTRA_SRCS := get_my_path_windows.c ../libcutils/list.c
EXTRA_STATIC_LIBS := AdbWinApi
ifneq ($(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/
endif
LOCAL_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) \
$(USB_SRCS) \
utils.c \
usb_vendors.c
LOCAL_C_INCLUDES += external/openssl/include
ifneq ($(USE_SYSDEPS_WIN32),)
LOCAL_SRC_FILES += sysdeps_win32.c
else
LOCAL_SRC_FILES += fdevent.c
endif
LOCAL_CFLAGS += -O2 -g -DADB_HOST=1 -Wall -Wno-unused-parameter
LOCAL_CFLAGS += -D_XOPEN_SOURCE -D_GNU_SOURCE
LOCAL_MODULE := adb
LOCAL_MODULE_TAGS := debug
LOCAL_STATIC_LIBRARIES := libzipfile libunz libcrypto_static $(EXTRA_STATIC_LIBS)
ifeq ($(USE_SYSDEPS_WIN32),)
LOCAL_STATIC_LIBRARIES += libcutils
endif
include $(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 $(CLEAR_VARS)
LOCAL_SRC_FILES := \
adb.c \
backup_service.c \
fdevent.c \
transport.c \
transport_local.c \
transport_usb.c \
adb_auth_client.c \
sockets.c \
services.c \
file_sync_service.c \
jdwp_service.c \
framebuffer_service.c \
remount_service.c \
usb_linux_client.c \
log_service.c \
utils.c
LOCAL_CFLAGS := -O2 -g -DADB_HOST=0 -Wall -Wno-unused-parameter
LOCAL_CFLAGS += -D_XOPEN_SOURCE -D_GNU_SOURCE
ifneq (,$(filter userdebug eng,$(TARGET_BUILD_VARIANT)))
LOCAL_CFLAGS += -DALLOW_ADBD_ROOT=1
endif
LOCAL_MODULE := adbd
LOCAL_FORCE_STATIC_EXECUTABLE := true
LOCAL_MODULE_PATH := $(TARGET_ROOT_OUT_SBIN)
LOCAL_UNSTRIPPED_PATH := $(TARGET_ROOT_OUT_SBIN_UNSTRIPPED)
LOCAL_STATIC_LIBRARIES := libcutils libc libmincrypt
include $(BUILD_EXECUTABLE)
# adb host tool for device-as-host
# =========================================================
ifneq ($(SDK_ONLY),true)
include $(CLEAR_VARS)
LOCAL_LDLIBS := -lrt -ldl -lpthread
LOCAL_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 \
utils.c \
usb_vendors.c \
fdevent.c
LOCAL_CFLAGS := \
-O2 \
-g \
-DADB_HOST=1 \
-DADB_HOST_ON_TARGET=1 \
-Wall \
-Wno-unused-parameter \
-D_XOPEN_SOURCE \
-D_GNU_SOURCE
LOCAL_C_INCLUDES += external/openssl/include
LOCAL_MODULE := adb
LOCAL_STATIC_LIBRARIES := libzipfile libunz libcutils
LOCAL_SHARED_LIBRARIES := libcrypto
include $(BUILD_EXECUTABLE)
endif通过编译，最终会有3个执行文件被生成，adbd和两个adb程序。
adbd是设备终端的守护进程；
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。
其中宏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。
先来看adbd程序，此时宏的设置是ADB_HOST=0。在main函数代码中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);
#endif
atexit(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);
#endif
init_transport_registration();//初始化fevent transport_registration_fde
#if ADB_HOST
HOST = 1;
#ifdef WORKAROUND_BUG6558362
if(is_daemon) adb_set_affinity();
#endif
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, 0)) {
exit(1);
}
#else
property_get("ro.adb.secure", value, "0");//判断系统属性ro.adb.secure，目标板没有设置这个宏
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) { //没有定义环境变量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 */
/*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*/
if (should_drop_privileges()) {
struct __user_cap_header_struct header;
struct __user_cap_data_struct cap[2];
if (prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0) != 0) {
exit(1);
}
drop_capabilities_bounding_set_if_needed();
memset(&header, 0, sizeof(header));
memset(cap, 0, sizeof(cap));
/* set CAP_SYS_BOOT capability, so "adb reboot" will succeed */
header.version = _LINUX_CAPABILITY_VERSION_3;
header.pid = 0;
cap[CAP_TO_INDEX(CAP_SYS_BOOT)].effective |= CAP_TO_MASK(CAP_SYS_BOOT);
cap[CAP_TO_INDEX(CAP_SYS_BOOT)].permitted |= CAP_TO_MASK(CAP_SYS_BOOT);
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, 0)) {
exit(1);
}
}
//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()
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.
//读取属性service.adb.tcp.port或persist.adb.tcp.port,执行local_init()，它内部会创建adb thread
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 {
// listen on default port
local_init(DEFAULT_ADB_LOCAL_TRANSPORT_PORT);
}
D("adb_main(): pre init_jdwp()\n");
init_jdwp();//执行init_jdwp()，jdwp是Java调试体系中的一种
D("adb_main(): post init_jdwp()\n");
#endif
if (is_daemon)
{
// inform our parent that we are up and running.
#ifdef HAVE_WIN32_PROC
DWORD count;
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();//调用fdevent_loop()监听fdevent并处理
usb_cleanup();
return 0;
}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 hint
serial = 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 || server_port > 65535) {
fprintf(stderr,
"adb: Env var ANDROID_ADB_SERVER_PORT must be a positive number less than 65535. 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 if (!strcmp(argv[0],"-a")) {
gListenAll = 1;
} else if(!strncmp(argv[0], "-H", 2)) {
const char *hostname = NULL;
if (argv[0][2] == '\0') {
if (argc < 2) return usage();
hostname = argv[1];
argc--;
argv++;
} else {
hostname = argv[0] + 2;
}
adb_set_tcp_name(hostname);
} else if(!strncmp(argv[0], "-P", 2)) {
if (argv[0][2] == '\0') {
if (argc < 2) return usage();
server_port_str = argv[1];
argc--;
argv++;
} else {
server_port_str = argv[0] + 2;
}
if (strlen(server_port_str) > 0) {
server_port = (int) strtol(server_port_str, NULL, 0);
if (server_port <= 0 || server_port > 65535) {
fprintf(stderr,
"adb: port number must be a positive number less than 65536. Got \"%s\"\n",
server_port_str);
return usage();
}
} else {
fprintf(stderr,
"adb: port number must be a positive number less than 65536. Got empty string.\n");
return usage();
}
} 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 <host>[:<port>]\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 [<host>[:<port>]]\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")) {
char host_prefix[64];
char remove = 0;
char remove_all = 0;
char list = 0;
char no_rebind = 0;
// Parse options here.
while (argc > 1 && argv[1][0] == '-') {
if (!strcmp(argv[1], "--list"))
list = 1;
else if (!strcmp(argv[1], "--remove"))
remove = 1;
else if (!strcmp(argv[1], "--remove-all"))
remove_all = 1;
else if (!strcmp(argv[1], "--no-rebind"))
no_rebind = 1;
else {
return usage();
}
argc--;
argv++;
}
// Ensure we can only use one option at a time.
if (list + remove + remove_all + no_rebind > 1) {
return usage();
}
// Determine the <host-prefix> for this command.
if (serial) {
snprintf(host_prefix, sizeof host_prefix, "host-serial:%s",
serial);
} else if (ttype == kTransportUsb) {
snprintf(host_prefix, sizeof host_prefix, "host-usb");
} else if (ttype == kTransportLocal) {
snprintf(host_prefix, sizeof host_prefix, "host-local");
} else {
snprintf(host_prefix, sizeof host_prefix, "host");
}
// Implement forward --list
if (list) {
if (argc != 1)
return usage();
snprintf(buf, sizeof buf, "%s:list-forward", host_prefix);
char* forwards = adb_query(buf);
if (forwards == NULL) {
fprintf(stderr, "error: %s\n", adb_error());
return 1;
}
printf("%s", forwards);
free(forwards);
return 0;
}
// Implement forward --remove-all
else if (remove_all) {
if (argc != 1)
return usage();
snprintf(buf, sizeof buf, "%s:killforward-all", host_prefix);
}
// Implement forward --remove <local>
else if (remove) {
if (argc != 2)
return usage();
snprintf(buf, sizeof buf, "%s:killforward:%s", host_prefix, argv[1]);
}
// Or implement one of:
// forward <local> <remote>
// forward --no-rebind <local> <remote>
else
{
if (argc != 3)
return usage();
const char* command = no_rebind ? "forward:norebind:" : "forward";
snprintf(buf, sizeof buf, "%s:%s:%s;%s", host_prefix, command, 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")) {
int fd = 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;
}adb_commandline 函数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。
使用usb进行调试，则执行usb_init()，它的代码在usb_linux_client.c 中，如下：
void usb_init()
{
if (access(USB_FFS_ADB_EP0, F_OK) == 0)
usb_ffs_init();
else
usb_adb_init();
}调用usb_adb_init():
static void usb_adb_init()
{
usb_handle *h;
adb_thread_t tid;
int fd;
h = calloc(1, sizeof(usb_handle));
h->write = usb_adb_write;
h->read = usb_adb_read;
h->kick = usb_adb_kick;
h->fd = -1;
adb_cond_init(&h->notify, 0);
adb_mutex_init(&h->lock, 0);
// Open the file /dev/android_adb_enable to trigger
// the enabling of the adb USB function in the kernel.
// We never touch this file again - just leave it open
// indefinitely so the kernel will know when we are running
// and when we are not.
fd = unix_open("/dev/android_adb_enable", O_RDWR);
if (fd < 0) {
D("failed to open /dev/android_adb_enable\n");
} else {
close_on_exec(fd);
}
D("[ usb_init - starting thread ]\n");
if(adb_thread_create(&tid, usb_adb_open_thread, h)){
fatal_errno("cannot create usb thread");
}
}它初始化了usb_handle，并把它作为参数创建usb_adb_open_thread()线程。这里不能打开/dev/android_adb_enable。h->fd的值会在线程usb_adb_open_thread中赋值，并把它做为h->write(), h->read(), h->kick()的文件句柄，h->kick()函数功能是把h->fd置为-1。 usb_adb_open_thread的代码如下：
static void *usb_adb_open_thread(void *x)
{
struct usb_handle *usb = (struct usb_handle *)x;
int fd;
while (1) {
// wait until the USB device needs opening
adb_mutex_lock(&usb->lock);
while (usb->fd != -1)
adb_cond_wait(&usb->notify, &usb->lock);
adb_mutex_unlock(&usb->lock);
D("[ usb_thread - opening device ]\n");
do {
/* XXX use inotify? */
fd = unix_open("/dev/android_adb", O_RDWR);
if (fd < 0) {
// to support older kernels
fd = unix_open("/dev/android", O_RDWR);
}
if (fd < 0) {
adb_sleep_ms(1000);
}
} while (fd < 0);
D("[ opening device succeeded ]\n");
close_on_exec(fd);
usb->fd = fd;
D("[ usb_thread - registering device ]\n");
register_usb_transport(usb, 0, 0, 1);
}
// never gets here
return 0;
}这个线程的作用是一进入立即打开/dev/android_adb或/dev/Android，如果成功，则调用register_usb_transport()后再次循环，并阻塞在以下代码处
while(usb->fd != -1)
adb_cond_wait(&usb->notify, &usb->lock);当usb->kick()调用后fd的值被赋为-1，并发送cond唤醒上面的代码。
adb源码fdevent.c文件中定义了工作时创建、监听和处理读写事件。
static fdevent **fd_table = 0; //fd_table保存的是以fdevent->fd为索引保存的fdevent指针
static int fd_table_max = 0;the_fdevent的值等于fd_table[the_fdevent->fd]
static void fdevent_register(fdevent *fde)
{
if(fde->fd < 0) {
FATAL("bogus negative fd (%d)\n", fde->fd);
}
if(fde->fd >= fd_table_max) { //初始化或自动增长fd_table
int oldmax = fd_table_max;
if(fde->fd > 32000) {
FATAL("bogus huuuuge fd (%d)\n", fde->fd);
}
if(fd_table_max == 0) {
fdevent_init();
fd_table_max = 256;
}
while(fd_table_max <= fde->fd) {
fd_table_max *= 2;
}
fd_table = realloc(fd_table, sizeof(fdevent*) * fd_table_max);
if(fd_table == 0) {
FATAL("could not expand fd_table to %d entries\n", fd_table_max);
}
memset(fd_table + oldmax, 0, sizeof(int) * (fd_table_max - oldmax));
}
fd_table[fde->fd] = fde; //将fde添加到fd_table
}
static void fdevent_unregister(fdevent *fde) //这个函数即将fde从fd_table中删除
{
if((fde->fd < 0) || (fde->fd >= fd_table_max)) {
FATAL("fd out of range (%d)\n", fde->fd);
}
if(fd_table[fde->fd] != fde) {
FATAL("fd_table out of sync [%d]\n", fde->fd);
}
fd_table[fde->fd] = 0;
if(!(fde->state & FDE_DONT_CLOSE)) { //如果fde->fd打开了并没有关闭，需要执行关闭操作
dump_fde(fde, "close");
adb_close(fde->fd);
}
}其中fdevent是代码处理事件的载体，结构体定义如下
struct fdevent
{
fdevent *next;
fdevent *prev; //表明是循环链表
int fd;
int force_eof;
unsigned short state; //低8位表示事件，高8位表示状态
unsigned short events; //需要处理的事件
fd_func func; //事件处理回调函数
void *arg; //参数
};其中事件可以是：
/* events that may be observed */
#define FDE_READ 0x0001
#define FDE_WRITE 0x0002
#define FDE_ERROR 0x0004
#define FDE_TIMEOUT 0x0008
/* features that may be set (via the events set/add/del interface) */
#define FDE_DONT_CLOSE 0x0080状态可以是：
#define FDE_ACTIVE 0x0100
#define FDE_PENDING 0x0200
#define FDE_CREATED 0x0400时间和状态的掩码分别为：
#define FDE_EVENTMASK 0x00ff
#define FDE_STATEMASK 0xff00注意，这些状态是可以同时存在的。
当调用fdevent_create()后，FDE_CREATED标志被设置，当调用fdevent_install()后， FDE_CREATED标志被设置，但在fdevent_create()内部调用了fdevent_install()，所以调用fdevent_create()都被设置了。
当有事件在调用select发生后，相应的事件state会设置为FDE_PENDING，当事件处理完后这个标志又被删除。相应的代码是：
void fdevent_loop()
{
fdevent *fde;
fdevent_subproc_setup();
for(;;) {
D("--- ---- waiting for events\n");
fdevent_process();///在这个函数中调用select，当有事件发生时，state被设置为FDE_PENDING，event也会被设置。所有的pending事件都会被保存在全局变量list_pending中。
while((fde = fdevent_plist_dequeue())) { //处理list_pending变量的事件
fdevent_call_fdfunc(fde);
}
}
}其中list_pending的相关代码：
//变量定义和初始化
static fdevent list_pending = {
.next = &list_pending,
.prev = &list_pending,
};
//添加一个元素
static void fdevent_plist_enqueue(fdevent *node)
{
fdevent *list = &list_pending;
node->next = list;
node->prev = list->prev;
node->prev->next = node;
list->prev = node;
}
//删除一个指定元素
static void fdevent_plist_remove(fdevent *node)
{
node->prev->next = node->next;
node->next->prev = node->prev;
node->next = 0;
node->prev = 0;
}
//从list中取出一个元素
static fdevent *fdevent_plist_dequeue(void)
{
fdevent *list = &list_pending;
fdevent *node = list->next;
if(node == list) return 0;
list->next = node->next;
list->next->prev = list;
node->next = 0;
node->prev = 0;
return node;
}事件的处理是阻塞方式的，可以有两种代码实现方法。定义宏CRAPTASTIC表示使用epoll的方式，否则使用select方式。这里只列举select的处理方式：
static fd_set read_fds; //读事件集合
static fd_set write_fds; //写事件集合
static fd_set error_fds; //发生错误事件集合
static int select_n = 0;
static void fdevent_init(void) //初始化
{
FD_ZERO(&read_fds);
FD_ZERO(&write_fds);
FD_ZERO(&error_fds);
}
static void fdevent_connect(fdevent *fde) //添加
{
if(fde->fd >= select_n) {
select_n = fde->fd + 1;
}
}
static void fdevent_disconnect(fdevent *fde) //从所有事件集合删除fde
{
int i, n;
FD_CLR(fde->fd, &read_fds);
FD_CLR(fde->fd, &write_fds);
FD_CLR(fde->fd, &error_fds);
for(n = 0, i = 0; i < select_n; i++) {
if(fd_table[i] != 0) n = i;
}
select_n = n + 1;
}
static void fdevent_update(fdevent *fde, unsigned events)//根据events设置事件集合
{
if(events & FDE_READ) {
FD_SET(fde->fd, &read_fds);
} else {
FD_CLR(fde->fd, &read_fds);
}
if(events & FDE_WRITE) {
FD_SET(fde->fd, &write_fds);
} else {
FD_CLR(fde->fd, &write_fds);
}
if(events & FDE_ERROR) {
FD_SET(fde->fd, &error_fds);
} else {
FD_CLR(fde->fd, &error_fds);
}
fde->state = (fde->state & FDE_STATEMASK) | events;
}
/* Looks at fd_table[] for bad FDs and sets bit in fds.
** Returns the number of bad FDs.
*/
static int fdevent_fd_check(fd_set *fds) //通过调用fcntl来判断是否是一个有效的fdevent
{
int i, n = 0;
fdevent *fde;
for(i = 0; i < select_n; i++) {
fde = fd_table[i];
if(fde == 0) continue;
if(fcntl(i, F_GETFL, NULL) < 0) {
FD_SET(i, fds);
n++;
// fde->state |= FDE_DONT_CLOSE;
}
}
return n;
}transport的原理是使用了fevent机制进行数据传输，atransport结构体的定义如下
struct atransport
{
atransport *next;
atransport *prev;
int (*read_from_remote)(apacket *p, atransport *t);
int (*write_to_remote)(apacket *p, atransport *t);
void (*close)(atransport *t);
void (*kick)(atransport *t);
int fd;
int transport_socket;
fdevent transport_fde;
int ref_count;
unsigned sync_token;
int connection_state;
int online;
transport_type type;
/* usb handle or socket fd as needed */
usb_handle *usb;
int sfd;
/* used to identify transports for clients */
char *serial;
char *product;
char *model;
char *device;
char *devpath;
int adb_port; // Use for emulators (local transport)
/* a list of adisconnect callbacks called when the transport is kicked */
int kicked;
adisconnect disconnects;
void *key;
unsigned char token[TOKEN_SIZE];
fdevent auth_fde;
unsigned failed_auth_attempts;
};它是一个双向链表，所有的实体都保存在全局数据transport_list中：
static atransport transport_list = {
.next = &transport_list,
.prev = &transport_list,
};atransport的数据传输的两个函数是：
static int
read_packet(int fd, const char* name, apacket** ppacket)
{
char *p = (char*)ppacket; /* really read a packet address */
int r;
int len = sizeof(*ppacket);
char buff[8];
if (!name) {
snprintf(buff, sizeof buff, "fd=%d", fd);
name = buff;
}
while(len > 0) {
r = adb_read(fd, p, len);
if(r > 0) {
len -= r;
p += r;
} else {
D("%s: read_packet (fd=%d), error ret=%d errno=%d: %s\n", name, fd, r, errno, strerror(errno));
if((r < 0) && (errno == EINTR)) continue;
return -1;
}
}
#if ADB_TRACE
if (ADB_TRACING) {
dump_packet(name, "from remote", *ppacket);
}
#endif
return 0;
}
static int
write_packet(int fd, const char* name, apacket** ppacket)
{
char *p = (char*) ppacket; /* we really write the packet address */
int r, len = sizeof(ppacket);
char buff[8];
if (!name) {
snprintf(buff, sizeof buff, "fd=%d", fd);
name = buff;
}
#if ADB_TRACE
if (ADB_TRACING) {
dump_packet(name, "to remote", *ppacket);
}
#endif
len = sizeof(ppacket);
while(len > 0) {
r = adb_write(fd, p, len);
if(r > 0) {
len -= r;
p += r;
} else {
D("%s: write_packet (fd=%d) error ret=%d errno=%d: %s\n", name, fd, r, errno, strerror(errno));
if((r < 0) && (errno == EINTR)) continue;
return -1;
}
}
return 0;
}这是它的内部传输接口，注意传输的是apacket的数据内部。
外部接口的数据传输接口是：
static void transport_socket_events(int fd, unsigned events, void *_t)
{
atransport *t = _t;
D("transport_socket_events(fd=%d, events=%04x,...)\n", fd, events);
if(events & FDE_READ){
apacket *p = 0;
if(read_packet(fd, t->serial, &p)){
D("%s: failed to read packet from transport socket on fd %d\n", t->serial, fd);
} else {
handle_packet(p, (atransport *) _t);
}
}
}
void send_packet(apacket *p, atransport *t)
{
unsigned char *x;
unsigned sum;
unsigned count;
p->msg.magic = p->msg.command ^ 0xffffffff;
count = p->msg.data_length;
x = (unsigned char *) p->data;
sum = 0;
while(count-- > 0){
sum += *x++;
}
p->msg.data_check = sum;
print_packet("send", p);
if (t == NULL) {
D("Transport is null \n");
// Zap errno because print_packet() and other stuff have errno effect.
errno = 0;
fatal_errno("Transport is null");
}
if(write_packet(t->transport_socket, t->serial, &p)){
fatal_errno("cannot enqueue packet on transport socket");
}
}物理接口到atransport的接口是：
/* The transport is opened by transport_register_func before
** the input and output threads are started.
**
** The output thread issues a SYNC(1, token) message to let
** the input thread know to start things up. In the event
** of transport IO failure, the output thread will post a
** SYNC(0,0) message to ensure shutdown.
**
** The transport will not actually be closed until both
** threads exit, but the input thread will kick the transport
** on its way out to disconnect the underlying device.
*/
static void *output_thread(void *_t)
{
atransport *t = _t;
apacket *p;
D("%s: starting transport output thread on fd %d, SYNC online (%d)\n",
t->serial, t->fd, t->sync_token + 1);
p = get_apacket();
p->msg.command = A_SYNC;
p->msg.arg0 = 1;
p->msg.arg1 = ++(t->sync_token);
p->msg.magic = A_SYNC ^ 0xffffffff;
if(write_packet(t->fd, t->serial, &p)) {
put_apacket(p);
D("%s: failed to write SYNC packet\n", t->serial);
goto oops;
}
D("%s: data pump started\n", t->serial);
for(;;) {
p = get_apacket();
if(t->read_from_remote(p, t) == 0){
D("%s: received remote packet, sending to transport\n",
t->serial);
if(write_packet(t->fd, t->serial, &p)){
put_apacket(p);
D("%s: failed to write apacket to transport\n", t->serial);
goto oops;
}
} else {
D("%s: remote read failed for transport\n", t->serial);
put_apacket(p);
break;
}
}
D("%s: SYNC offline for transport\n", t->serial);
p = get_apacket();
p->msg.command = A_SYNC;
p->msg.arg0 = 0;
p->msg.arg1 = 0;
p->msg.magic = A_SYNC ^ 0xffffffff;
if(write_packet(t->fd, t->serial, &p)) {
put_apacket(p);
D("%s: failed to write SYNC apacket to transport", t->serial);
}
oops:
D("%s: transport output thread is exiting\n", t->serial);
kick_transport(t);
transport_unref(t);
return 0;
}这里做了一个物理到抽象的转换。最上层还有一层是tmsg的传输 , tmsg的作用是用于atransport的管理
void init_transport_registration(void)
{
int s[2];
if(adb_socketpair(s)){
fatal_errno("cannot open transport registration socketpair");
}
transport_registration_send = s[0];
transport_registration_recv = s[1];
fdevent_install(&transport_registration_fde,
transport_registration_recv,
transport_registration_func,
0);
fdevent_set(&transport_registration_fde, FDE_READ);
}
/* the fdevent select pump is single threaded */
static void register_transport(atransport *transport)
{
tmsg m;
m.transport = transport;
m.action = 1;
D("transport: %s registered\n", transport->serial);
if(transport_write_action(transport_registration_send, &m)) {
fatal_errno("cannot write transport registration socket\n");
}
}
static void remove_transport(atransport *transport)
{
tmsg m;
m.transport = transport;
m.action = 0;
D("transport: %s removed\n", transport->serial);
if(transport_write_action(transport_registration_send, &m)) {
fatal_errno("cannot write transport registration socket\n");
}
}未完待续。。。
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