support "sideload over ADB" mode

Rather than depending on the existence of some place to store a file
that is accessible to users on an an unbootable device (eg, a physical
sdcard, external USB drive, etc.), add support for sideloading
packages sent to the device with adb.

This change adds a "minimal adbd" which supports nothing but receiving
a package over adb (with the "adb sideload" command) and storing it to
a fixed filename in the /tmp ramdisk, from where it can be verified
and sideloaded in the usual way.  This should be leave available even
on locked user-build devices.

The user can select "apply package from ADB" from the recovery menu,
which starts minimal-adb mode (shutting down any real adbd that may be
running).  Once minimal-adb has received a package it exits
(restarting real adbd if appropriate) and then verification and
installation of the received package proceeds.

Change-Id: I6fe13161ca064a98d06fa32104e1f432826582f5

1 files changed, 1151 insertions, 0 deletions

diff --git a/minadbd/adb.c b/minadbd/adb.c
new file mode 100644
index 0000000..d1e97b3
--- /dev/null
+++ b/minadbd/adb.c
@@ -0,0 +1,1151 @@
+/*
+ * Copyright (C) 2007 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define  TRACE_TAG   TRACE_ADB
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <ctype.h>
+#include <stdarg.h>
+#include <errno.h>
+#include <string.h>
+#include <time.h>
+#include <sys/time.h>
+
+#include "sysdeps.h"
+#include "adb.h"
+
+#if !ADB_HOST
+#include <private/android_filesystem_config.h>
+#include <linux/capability.h>
+#include <linux/prctl.h>
+#else
+#include "usb_vendors.h"
+#endif
+
+#if ADB_TRACE
+ADB_MUTEX_DEFINE( D_lock );
+#endif
+
+int HOST = 0;
+
+static const char *adb_device_banner = "sideload";
+
+void fatal(const char *fmt, ...)
+{
+    va_list ap;
+    va_start(ap, fmt);
+    fprintf(stderr, "error: ");
+    vfprintf(stderr, fmt, ap);
+    fprintf(stderr, "\n");
+    va_end(ap);
+    exit(-1);
+}
+
+void fatal_errno(const char *fmt, ...)
+{
+    va_list ap;
+    va_start(ap, fmt);
+    fprintf(stderr, "error: %s: ", strerror(errno));
+    vfprintf(stderr, fmt, ap);
+    fprintf(stderr, "\n");
+    va_end(ap);
+    exit(-1);
+}
+
+int   adb_trace_mask;
+
+/* read a comma/space/colum/semi-column separated list of tags
+ * from the ADB_TRACE environment variable and build the trace
+ * mask from it. note that '1' and 'all' are special cases to
+ * enable all tracing
+ */
+void  adb_trace_init(void)
+{
+    const char*  p = getenv("ADB_TRACE");
+    const char*  q;
+
+    static const struct {
+        const char*  tag;
+        int           flag;
+    } tags[] = {
+        { "1", 0 },
+        { "all", 0 },
+        { "adb", TRACE_ADB },
+        { "sockets", TRACE_SOCKETS },
+        { "packets", TRACE_PACKETS },
+        { "rwx", TRACE_RWX },
+        { "usb", TRACE_USB },
+        { "sync", TRACE_SYNC },
+        { "sysdeps", TRACE_SYSDEPS },
+        { "transport", TRACE_TRANSPORT },
+        { "jdwp", TRACE_JDWP },
+        { "services", TRACE_SERVICES },
+        { NULL, 0 }
+    };
+
+    if (p == NULL)
+            return;
+
+    /* use a comma/column/semi-colum/space separated list */
+    while (*p) {
+        int  len, tagn;
+
+        q = strpbrk(p, " ,:;");
+        if (q == NULL) {
+            q = p + strlen(p);
+        }
+        len = q - p;
+
+        for (tagn = 0; tags[tagn].tag != NULL; tagn++)
+        {
+            int  taglen = strlen(tags[tagn].tag);
+
+            if (len == taglen && !memcmp(tags[tagn].tag, p, len) )
+            {
+                int  flag = tags[tagn].flag;
+                if (flag == 0) {
+                    adb_trace_mask = ~0;
+                    return;
+                }
+                adb_trace_mask |= (1 << flag);
+                break;
+            }
+        }
+        p = q;
+        if (*p)
+            p++;
+    }
+}
+
+
+apacket *get_apacket(void)
+{
+    apacket *p = malloc(sizeof(apacket));
+    if(p == 0) fatal("failed to allocate an apacket");
+    memset(p, 0, sizeof(apacket) - MAX_PAYLOAD);
+    return p;
+}
+
+void put_apacket(apacket *p)
+{
+    free(p);
+}
+
+void handle_online(void)
+{
+    D("adb: online\n");
+}
+
+void handle_offline(atransport *t)
+{
+    D("adb: offline\n");
+    //Close the associated usb
+    run_transport_disconnects(t);
+}
+
+#if TRACE_PACKETS
+#define DUMPMAX 32
+void print_packet(const char *label, apacket *p)
+{
+    char *tag;
+    char *x;
+    unsigned count;
+
+    switch(p->msg.command){
+    case A_SYNC: tag = "SYNC"; break;
+    case A_CNXN: tag = "CNXN" ; break;
+    case A_OPEN: tag = "OPEN"; break;
+    case A_OKAY: tag = "OKAY"; break;
+    case A_CLSE: tag = "CLSE"; break;
+    case A_WRTE: tag = "WRTE"; break;
+    default: tag = "????"; break;
+    }
+
+    fprintf(stderr, "%s: %s %08x %08x %04x \"",
+            label, tag, p->msg.arg0, p->msg.arg1, p->msg.data_length);
+    count = p->msg.data_length;
+    x = (char*) p->data;
+    if(count > DUMPMAX) {
+        count = DUMPMAX;
+        tag = "\n";
+    } else {
+        tag = "\"\n";
+    }
+    while(count-- > 0){
+        if((*x >= ' ') && (*x < 127)) {
+            fputc(*x, stderr);
+        } else {
+            fputc('.', stderr);
+        }
+        x++;
+    }
+    fprintf(stderr, tag);
+}
+#endif
+
+static void send_ready(unsigned local, unsigned remote, atransport *t)
+{
+    D("Calling send_ready \n");
+    apacket *p = get_apacket();
+    p->msg.command = A_OKAY;
+    p->msg.arg0 = local;
+    p->msg.arg1 = remote;
+    send_packet(p, t);
+}
+
+static void send_close(unsigned local, unsigned remote, atransport *t)
+{
+    D("Calling send_close \n");
+    apacket *p = get_apacket();
+    p->msg.command = A_CLSE;
+    p->msg.arg0 = local;
+    p->msg.arg1 = remote;
+    send_packet(p, t);
+}
+
+static void send_connect(atransport *t)
+{
+    D("Calling send_connect \n");
+    apacket *cp = get_apacket();
+    cp->msg.command = A_CNXN;
+    cp->msg.arg0 = A_VERSION;
+    cp->msg.arg1 = MAX_PAYLOAD;
+    snprintf((char*) cp->data, sizeof cp->data, "%s::",
+            HOST ? "host" : adb_device_banner);
+    cp->msg.data_length = strlen((char*) cp->data) + 1;
+    send_packet(cp, t);
+#if ADB_HOST
+        /* XXX why sleep here? */
+    // allow the device some time to respond to the connect message
+    adb_sleep_ms(1000);
+#endif
+}
+
+static char *connection_state_name(atransport *t)
+{
+    if (t == NULL) {
+        return "unknown";
+    }
+
+    switch(t->connection_state) {
+    case CS_BOOTLOADER:
+        return "bootloader";
+    case CS_DEVICE:
+        return "device";
+    case CS_OFFLINE:
+        return "offline";
+    default:
+        return "unknown";
+    }
+}
+
+void parse_banner(char *banner, atransport *t)
+{
+    char *type, *product, *end;
+
+    D("parse_banner: %s\n", banner);
+    type = banner;
+    product = strchr(type, ':');
+    if(product) {
+        *product++ = 0;
+    } else {
+        product = "";
+    }
+
+        /* remove trailing ':' */
+    end = strchr(product, ':');
+    if(end) *end = 0;
+
+        /* save product name in device structure */
+    if (t->product == NULL) {
+        t->product = strdup(product);
+    } else if (strcmp(product, t->product) != 0) {
+        free(t->product);
+        t->product = strdup(product);
+    }
+
+    if(!strcmp(type, "bootloader")){
+        D("setting connection_state to CS_BOOTLOADER\n");
+        t->connection_state = CS_BOOTLOADER;
+        update_transports();
+        return;
+    }
+
+    if(!strcmp(type, "device")) {
+        D("setting connection_state to CS_DEVICE\n");
+        t->connection_state = CS_DEVICE;
+        update_transports();
+        return;
+    }
+
+    if(!strcmp(type, "recovery")) {
+        D("setting connection_state to CS_RECOVERY\n");
+        t->connection_state = CS_RECOVERY;
+        update_transports();
+        return;
+    }
+
+    if(!strcmp(type, "sideload")) {
+        D("setting connection_state to CS_SIDELOAD\n");
+        t->connection_state = CS_SIDELOAD;
+        update_transports();
+        return;
+    }
+
+    t->connection_state = CS_HOST;
+}
+
+void handle_packet(apacket *p, atransport *t)
+{
+    asocket *s;
+
+    D("handle_packet() %c%c%c%c\n", ((char*) (&(p->msg.command)))[0],
+            ((char*) (&(p->msg.command)))[1],
+            ((char*) (&(p->msg.command)))[2],
+            ((char*) (&(p->msg.command)))[3]);
+    print_packet("recv", p);
+
+    switch(p->msg.command){
+    case A_SYNC:
+        if(p->msg.arg0){
+            send_packet(p, t);
+            if(HOST) send_connect(t);
+        } else {
+            t->connection_state = CS_OFFLINE;
+            handle_offline(t);
+            send_packet(p, t);
+        }
+        return;
+
+    case A_CNXN: /* CONNECT(version, maxdata, "system-id-string") */
+            /* XXX verify version, etc */
+        if(t->connection_state != CS_OFFLINE) {
+            t->connection_state = CS_OFFLINE;
+            handle_offline(t);
+        }
+        parse_banner((char*) p->data, t);
+        handle_online();
+        if(!HOST) send_connect(t);
+        break;
+
+    case A_OPEN: /* OPEN(local-id, 0, "destination") */
+        if(t->connection_state != CS_OFFLINE) {
+            char *name = (char*) p->data;
+            name[p->msg.data_length > 0 ? p->msg.data_length - 1 : 0] = 0;
+            s = create_local_service_socket(name);
+            if(s == 0) {
+                send_close(0, p->msg.arg0, t);
+            } else {
+                s->peer = create_remote_socket(p->msg.arg0, t);
+                s->peer->peer = s;
+                send_ready(s->id, s->peer->id, t);
+                s->ready(s);
+            }
+        }
+        break;
+
+    case A_OKAY: /* READY(local-id, remote-id, "") */
+        if(t->connection_state != CS_OFFLINE) {
+            if((s = find_local_socket(p->msg.arg1))) {
+                if(s->peer == 0) {
+                    s->peer = create_remote_socket(p->msg.arg0, t);
+                    s->peer->peer = s;
+                }
+                s->ready(s);
+            }
+        }
+        break;
+
+    case A_CLSE: /* CLOSE(local-id, remote-id, "") */
+        if(t->connection_state != CS_OFFLINE) {
+            if((s = find_local_socket(p->msg.arg1))) {
+                s->close(s);
+            }
+        }
+        break;
+
+    case A_WRTE:
+        if(t->connection_state != CS_OFFLINE) {
+            if((s = find_local_socket(p->msg.arg1))) {
+                unsigned rid = p->msg.arg0;
+                p->len = p->msg.data_length;
+
+                if(s->enqueue(s, p) == 0) {
+                    D("Enqueue the socket\n");
+                    send_ready(s->id, rid, t);
+                }
+                return;
+            }
+        }
+        break;
+
+    default:
+        printf("handle_packet: what is %08x?!\n", p->msg.command);
+    }
+
+    put_apacket(p);
+}
+
+alistener listener_list = {
+    .next = &listener_list,
+    .prev = &listener_list,
+};
+
+static void ss_listener_event_func(int _fd, unsigned ev, void *_l)
+{
+    asocket *s;
+
+    if(ev & FDE_READ) {
+        struct sockaddr addr;
+        socklen_t alen;
+        int fd;
+
+        alen = sizeof(addr);
+        fd = adb_socket_accept(_fd, &addr, &alen);
+        if(fd < 0) return;
+
+        adb_socket_setbufsize(fd, CHUNK_SIZE);
+
+        s = create_local_socket(fd);
+        if(s) {
+            connect_to_smartsocket(s);
+            return;
+        }
+
+        adb_close(fd);
+    }
+}
+
+static void listener_event_func(int _fd, unsigned ev, void *_l)
+{
+    alistener *l = _l;
+    asocket *s;
+
+    if(ev & FDE_READ) {
+        struct sockaddr addr;
+        socklen_t alen;
+        int fd;
+
+        alen = sizeof(addr);
+        fd = adb_socket_accept(_fd, &addr, &alen);
+        if(fd < 0) return;
+
+        s = create_local_socket(fd);
+        if(s) {
+            s->transport = l->transport;
+            connect_to_remote(s, l->connect_to);
+            return;
+        }
+
+        adb_close(fd);
+    }
+}
+
+static void  free_listener(alistener*  l)
+{
+    if (l->next) {
+        l->next->prev = l->prev;
+        l->prev->next = l->next;
+        l->next = l->prev = l;
+    }
+
+    // closes the corresponding fd
+    fdevent_remove(&l->fde);
+
+    if (l->local_name)
+        free((char*)l->local_name);
+
+    if (l->connect_to)
+        free((char*)l->connect_to);
+
+    if (l->transport) {
+        remove_transport_disconnect(l->transport, &l->disconnect);
+    }
+    free(l);
+}
+
+static void listener_disconnect(void*  _l, atransport*  t)
+{
+    alistener*  l = _l;
+
+    free_listener(l);
+}
+
+int local_name_to_fd(const char *name)
+{
+    int port;
+
+    if(!strncmp("tcp:", name, 4)){
+        int  ret;
+        port = atoi(name + 4);
+        ret = socket_loopback_server(port, SOCK_STREAM);
+        return ret;
+    }
+#ifndef HAVE_WIN32_IPC  /* no Unix-domain sockets on Win32 */
+    // It's non-sensical to support the "reserved" space on the adb host side
+    if(!strncmp(name, "local:", 6)) {
+        return socket_local_server(name + 6,
+                ANDROID_SOCKET_NAMESPACE_ABSTRACT, SOCK_STREAM);
+    } else if(!strncmp(name, "localabstract:", 14)) {
+        return socket_local_server(name + 14,
+                ANDROID_SOCKET_NAMESPACE_ABSTRACT, SOCK_STREAM);
+    } else if(!strncmp(name, "localfilesystem:", 16)) {
+        return socket_local_server(name + 16,
+                ANDROID_SOCKET_NAMESPACE_FILESYSTEM, SOCK_STREAM);
+    }
+
+#endif
+    printf("unknown local portname '%s'\n", name);
+    return -1;
+}
+
+static int remove_listener(const char *local_name, const char *connect_to, atransport* transport)
+{
+    alistener *l;
+
+    for (l = listener_list.next; l != &listener_list; l = l->next) {
+        if (!strcmp(local_name, l->local_name) &&
+            !strcmp(connect_to, l->connect_to) &&
+            l->transport && l->transport == transport) {
+
+            listener_disconnect(l, transport);
+            return 0;
+        }
+    }
+
+    return -1;
+}
+
+static int install_listener(const char *local_name, const char *connect_to, atransport* transport)
+{
+    alistener *l;
+
+    //printf("install_listener('%s','%s')\n", local_name, connect_to);
+
+    for(l = listener_list.next; l != &listener_list; l = l->next){
+        if(strcmp(local_name, l->local_name) == 0) {
+            char *cto;
+
+                /* can't repurpose a smartsocket */
+            if(l->connect_to[0] == '*') {
+                return -1;
+            }
+
+            cto = strdup(connect_to);
+            if(cto == 0) {
+                return -1;
+            }
+
+            //printf("rebinding '%s' to '%s'\n", local_name, connect_to);
+            free((void*) l->connect_to);
+            l->connect_to = cto;
+            if (l->transport != transport) {
+                remove_transport_disconnect(l->transport, &l->disconnect);
+                l->transport = transport;
+                add_transport_disconnect(l->transport, &l->disconnect);
+            }
+            return 0;
+        }
+    }
+
+    if((l = calloc(1, sizeof(alistener))) == 0) goto nomem;
+    if((l->local_name = strdup(local_name)) == 0) goto nomem;
+    if((l->connect_to = strdup(connect_to)) == 0) goto nomem;
+
+
+    l->fd = local_name_to_fd(local_name);
+    if(l->fd < 0) {
+        free((void*) l->local_name);
+        free((void*) l->connect_to);
+        free(l);
+        printf("cannot bind '%s'\n", local_name);
+        return -2;
+    }
+
+    close_on_exec(l->fd);
+    if(!strcmp(l->connect_to, "*smartsocket*")) {
+        fdevent_install(&l->fde, l->fd, ss_listener_event_func, l);
+    } else {
+        fdevent_install(&l->fde, l->fd, listener_event_func, l);
+    }
+    fdevent_set(&l->fde, FDE_READ);
+
+    l->next = &listener_list;
+    l->prev = listener_list.prev;
+    l->next->prev = l;
+    l->prev->next = l;
+    l->transport = transport;
+
+    if (transport) {
+        l->disconnect.opaque = l;
+        l->disconnect.func   = listener_disconnect;
+        add_transport_disconnect(transport, &l->disconnect);
+    }
+    return 0;
+
+nomem:
+    fatal("cannot allocate listener");
+    return 0;
+}
+
+#ifdef HAVE_WIN32_PROC
+static BOOL WINAPI ctrlc_handler(DWORD type)
+{
+    exit(STATUS_CONTROL_C_EXIT);
+    return TRUE;
+}
+#endif
+
+static void adb_cleanup(void)
+{
+    usb_cleanup();
+}
+
+void start_logging(void)
+{
+#ifdef HAVE_WIN32_PROC
+    char    temp[ MAX_PATH ];
+    FILE*   fnul;
+    FILE*   flog;
+
+    GetTempPath( sizeof(temp) - 8, temp );
+    strcat( temp, "adb.log" );
+
+    /* Win32 specific redirections */
+    fnul = fopen( "NUL", "rt" );
+    if (fnul != NULL)
+        stdin[0] = fnul[0];
+
+    flog = fopen( temp, "at" );
+    if (flog == NULL)
+        flog = fnul;
+
+    setvbuf( flog, NULL, _IONBF, 0 );
+
+    stdout[0] = flog[0];
+    stderr[0] = flog[0];
+    fprintf(stderr,"--- adb starting (pid %d) ---\n", getpid());
+#else
+    int fd;
+
+    fd = unix_open("/dev/null", O_RDONLY);
+    dup2(fd, 0);
+    adb_close(fd);
+
+    fd = unix_open("/tmp/adb.log", O_WRONLY | O_CREAT | O_APPEND, 0640);
+    if(fd < 0) {
+        fd = unix_open("/dev/null", O_WRONLY);
+    }
+    dup2(fd, 1);
+    dup2(fd, 2);
+    adb_close(fd);
+    fprintf(stderr,"--- adb starting (pid %d) ---\n", getpid());
+#endif
+}
+
+#if !ADB_HOST
+void start_device_log(void)
+{
+    int fd;
+    char    path[PATH_MAX];
+    struct tm now;
+    time_t t;
+    char value[PROPERTY_VALUE_MAX];
+
+    // read the trace mask from persistent property persist.adb.trace_mask
+    // give up if the property is not set or cannot be parsed
+    property_get("persist.adb.trace_mask", value, "");
+    if (sscanf(value, "%x", &adb_trace_mask) != 1)
+        return;
+
+    adb_mkdir("/data/adb", 0775);
+    tzset();
+    time(&t);
+    localtime_r(&t, &now);
+    strftime(path, sizeof(path),
+                "/data/adb/adb-%Y-%m-%d-%H-%M-%S.txt",
+                &now);
+    fd = unix_open(path, O_WRONLY | O_CREAT | O_TRUNC, 0640);
+    if (fd < 0)
+        return;
+
+    // redirect stdout and stderr to the log file
+    dup2(fd, 1);
+    dup2(fd, 2);
+    fprintf(stderr,"--- adb starting (pid %d) ---\n", getpid());
+    adb_close(fd);
+
+    fd = unix_open("/dev/null", O_RDONLY);
+    dup2(fd, 0);
+    adb_close(fd);
+}
+#endif
+
+#if ADB_HOST
+int launch_server(int server_port)
+{
+#ifdef HAVE_WIN32_PROC
+    /* we need to start the server in the background                    */
+    /* we create a PIPE that will be used to wait for the server's "OK" */
+    /* message since the pipe handles must be inheritable, we use a     */
+    /* security attribute                                               */
+    HANDLE                pipe_read, pipe_write;
+    SECURITY_ATTRIBUTES   sa;
+    STARTUPINFO           startup;
+    PROCESS_INFORMATION   pinfo;
+    char                  program_path[ MAX_PATH ];
+    int                   ret;
+
+    sa.nLength = sizeof(sa);
+    sa.lpSecurityDescriptor = NULL;
+    sa.bInheritHandle = TRUE;
+
+    /* create pipe, and ensure its read handle isn't inheritable */
+    ret = CreatePipe( &pipe_read, &pipe_write, &sa, 0 );
+    if (!ret) {
+        fprintf(stderr, "CreatePipe() failure, error %ld\n", GetLastError() );
+        return -1;
+    }
+
+    SetHandleInformation( pipe_read, HANDLE_FLAG_INHERIT, 0 );
+
+    ZeroMemory( &startup, sizeof(startup) );
+    startup.cb = sizeof(startup);
+    startup.hStdInput  = GetStdHandle( STD_INPUT_HANDLE );
+    startup.hStdOutput = pipe_write;
+    startup.hStdError  = GetStdHandle( STD_ERROR_HANDLE );
+    startup.dwFlags    = STARTF_USESTDHANDLES;
+
+    ZeroMemory( &pinfo, sizeof(pinfo) );
+
+    /* get path of current program */
+    GetModuleFileName( NULL, program_path, sizeof(program_path) );
+
+    ret = CreateProcess(
+            program_path,                              /* program path  */
+            "adb fork-server server",
+                                    /* the fork-server argument will set the
+                                       debug = 2 in the child           */
+            NULL,                   /* process handle is not inheritable */
+            NULL,                    /* thread handle is not inheritable */
+            TRUE,                          /* yes, inherit some handles */
+            DETACHED_PROCESS, /* the new process doesn't have a console */
+            NULL,                     /* use parent's environment block */
+            NULL,                    /* use parent's starting directory */
+            &startup,                 /* startup info, i.e. std handles */
+            &pinfo );
+
+    CloseHandle( pipe_write );
+
+    if (!ret) {
+        fprintf(stderr, "CreateProcess failure, error %ld\n", GetLastError() );
+        CloseHandle( pipe_read );
+        return -1;
+    }
+
+    CloseHandle( pinfo.hProcess );
+    CloseHandle( pinfo.hThread );
+
+    /* wait for the "OK\n" message */
+    {
+        char  temp[3];
+        DWORD  count;
+
+        ret = ReadFile( pipe_read, temp, 3, &count, NULL );
+        CloseHandle( pipe_read );
+        if ( !ret ) {
+            fprintf(stderr, "could not read ok from ADB Server, error = %ld\n", GetLastError() );
+            return -1;
+        }
+        if (count != 3 || temp[0] != 'O' || temp[1] != 'K' || temp[2] != '\n') {
+            fprintf(stderr, "ADB server didn't ACK\n" );
+            return -1;
+        }
+    }
+#elif defined(HAVE_FORKEXEC)
+    char    path[PATH_MAX];
+    int     fd[2];
+
+    // set up a pipe so the child can tell us when it is ready.
+    // fd[0] will be parent's end, and fd[1] will get mapped to stderr in the child.
+    if (pipe(fd)) {
+        fprintf(stderr, "pipe failed in launch_server, errno: %d\n", errno);
+        return -1;
+    }
+    get_my_path(path, PATH_MAX);
+    pid_t pid = fork();
+    if(pid < 0) return -1;
+
+    if (pid == 0) {
+        // child side of the fork
+
+        // redirect stderr to the pipe
+        // we use stderr instead of stdout due to stdout's buffering behavior.
+        adb_close(fd[0]);
+        dup2(fd[1], STDERR_FILENO);
+        adb_close(fd[1]);
+
+        // child process
+        int result = execl(path, "adb", "fork-server", "server", NULL);
+        // this should not return
+        fprintf(stderr, "OOPS! execl returned %d, errno: %d\n", result, errno);
+    } else  {
+        // parent side of the fork
+
+        char  temp[3];
+
+        temp[0] = 'A'; temp[1] = 'B'; temp[2] = 'C';
+        // wait for the "OK\n" message
+        adb_close(fd[1]);
+        int ret = adb_read(fd[0], temp, 3);
+        int saved_errno = errno;
+        adb_close(fd[0]);
+        if (ret < 0) {
+            fprintf(stderr, "could not read ok from ADB Server, errno = %d\n", saved_errno);
+            return -1;
+        }
+        if (ret != 3 || temp[0] != 'O' || temp[1] != 'K' || temp[2] != '\n') {
+            fprintf(stderr, "ADB server didn't ACK\n" );
+            return -1;
+        }
+
+        setsid();
+    }
+#else
+#error "cannot implement background server start on this platform"
+#endif
+    return 0;
+}
+#endif
+
+/* Constructs a local name of form tcp:port.
+ * target_str points to the target string, it's content will be overwritten.
+ * target_size is the capacity of the target string.
+ * server_port is the port number to use for the local name.
+ */
+void build_local_name(char* target_str, size_t target_size, int server_port)
+{
+  snprintf(target_str, target_size, "tcp:%d", server_port);
+}
+
+int adb_main()
+{
+    atexit(adb_cleanup);
+#if defined(HAVE_FORKEXEC)
+    // No SIGCHLD. Let the service subproc handle its children.
+    signal(SIGPIPE, SIG_IGN);
+#endif
+
+    init_transport_registration();
+
+    // The minimal version of adbd only uses USB.
+    if (access("/dev/android_adb", F_OK) == 0) {
+        // listen on USB
+        usb_init();
+    }
+
+    D("Event loop starting\n");
+
+    fdevent_loop();
+
+    usb_cleanup();
+
+    return 0;
+}
+
+#if ADB_HOST
+void connect_device(char* host, char* buffer, int buffer_size)
+{
+    int port, fd;
+    char* portstr = strchr(host, ':');
+    char hostbuf[100];
+    char serial[100];
+
+    strncpy(hostbuf, host, sizeof(hostbuf) - 1);
+    if (portstr) {
+        if (portstr - host >= sizeof(hostbuf)) {
+            snprintf(buffer, buffer_size, "bad host name %s", host);
+            return;
+        }
+        // zero terminate the host at the point we found the colon
+        hostbuf[portstr - host] = 0;
+        if (sscanf(portstr + 1, "%d", &port) == 0) {
+            snprintf(buffer, buffer_size, "bad port number %s", portstr);
+            return;
+        }
+    } else {
+        port = DEFAULT_ADB_LOCAL_TRANSPORT_PORT;
+    }
+
+    snprintf(serial, sizeof(serial), "%s:%d", hostbuf, port);
+    if (find_transport(serial)) {
+        snprintf(buffer, buffer_size, "already connected to %s", serial);
+        return;
+    }
+
+    fd = socket_network_client(hostbuf, port, SOCK_STREAM);
+    if (fd < 0) {
+        snprintf(buffer, buffer_size, "unable to connect to %s:%d", host, port);
+        return;
+    }
+
+    D("client: connected on remote on fd %d\n", fd);
+    close_on_exec(fd);
+    disable_tcp_nagle(fd);
+    register_socket_transport(fd, serial, port, 0);
+    snprintf(buffer, buffer_size, "connected to %s", serial);
+}
+
+void connect_emulator(char* port_spec, char* buffer, int buffer_size)
+{
+    char* port_separator = strchr(port_spec, ',');
+    if (!port_separator) {
+        snprintf(buffer, buffer_size,
+                "unable to parse '%s' as <console port>,<adb port>",
+                port_spec);
+        return;
+    }
+
+    // Zero-terminate console port and make port_separator point to 2nd port.
+    *port_separator++ = 0;
+    int console_port = strtol(port_spec, NULL, 0);
+    int adb_port = strtol(port_separator, NULL, 0);
+    if (!(console_port > 0 && adb_port > 0)) {
+        *(port_separator - 1) = ',';
+        snprintf(buffer, buffer_size,
+                "Invalid port numbers: Expected positive numbers, got '%s'",
+                port_spec);
+        return;
+    }
+
+    /* Check if the emulator is already known.
+     * Note: There's a small but harmless race condition here: An emulator not
+     * present just yet could be registered by another invocation right
+     * after doing this check here. However, local_connect protects
+     * against double-registration too. From here, a better error message
+     * can be produced. In the case of the race condition, the very specific
+     * error message won't be shown, but the data doesn't get corrupted. */
+    atransport* known_emulator = find_emulator_transport_by_adb_port(adb_port);
+    if (known_emulator != NULL) {
+        snprintf(buffer, buffer_size,
+                "Emulator on port %d already registered.", adb_port);
+        return;
+    }
+
+    /* Check if more emulators can be registered. Similar unproblematic
+     * race condition as above. */
+    int candidate_slot = get_available_local_transport_index();
+    if (candidate_slot < 0) {
+        snprintf(buffer, buffer_size, "Cannot accept more emulators.");
+        return;
+    }
+
+    /* Preconditions met, try to connect to the emulator. */
+    if (!local_connect_arbitrary_ports(console_port, adb_port)) {
+        snprintf(buffer, buffer_size,
+                "Connected to emulator on ports %d,%d", console_port, adb_port);
+    } else {
+        snprintf(buffer, buffer_size,
+                "Could not connect to emulator on ports %d,%d",
+                console_port, adb_port);
+    }
+}
+#endif
+
+int handle_host_request(char *service, transport_type ttype, char* serial, int reply_fd, asocket *s)
+{
+    atransport *transport = NULL;
+    char buf[4096];
+
+    if(!strcmp(service, "kill")) {
+        fprintf(stderr,"adb server killed by remote request\n");
+        fflush(stdout);
+        adb_write(reply_fd, "OKAY", 4);
+        usb_cleanup();
+        exit(0);
+    }
+
+#if ADB_HOST
+    // "transport:" is used for switching transport with a specified serial number
+    // "transport-usb:" is used for switching transport to the only USB transport
+    // "transport-local:" is used for switching transport to the only local transport
+    // "transport-any:" is used for switching transport to the only transport
+    if (!strncmp(service, "transport", strlen("transport"))) {
+        char* error_string = "unknown failure";
+        transport_type type = kTransportAny;
+
+        if (!strncmp(service, "transport-usb", strlen("transport-usb"))) {
+            type = kTransportUsb;
+        } else if (!strncmp(service, "transport-local", strlen("transport-local"))) {
+            type = kTransportLocal;
+        } else if (!strncmp(service, "transport-any", strlen("transport-any"))) {
+            type = kTransportAny;
+        } else if (!strncmp(service, "transport:", strlen("transport:"))) {
+            service += strlen("transport:");
+            serial = service;
+        }
+
+        transport = acquire_one_transport(CS_ANY, type, serial, &error_string);
+
+        if (transport) {
+            s->transport = transport;
+            adb_write(reply_fd, "OKAY", 4);
+        } else {
+            sendfailmsg(reply_fd, error_string);
+        }
+        return 1;
+    }
+
+    // return a list of all connected devices
+    if (!strcmp(service, "devices")) {
+        char buffer[4096];
+        memset(buf, 0, sizeof(buf));
+        memset(buffer, 0, sizeof(buffer));
+        D("Getting device list \n");
+        list_transports(buffer, sizeof(buffer));
+        snprintf(buf, sizeof(buf), "OKAY%04x%s",(unsigned)strlen(buffer),buffer);
+        D("Wrote device list \n");
+        writex(reply_fd, buf, strlen(buf));
+        return 0;
+    }
+
+    // add a new TCP transport, device or emulator
+    if (!strncmp(service, "connect:", 8)) {
+        char buffer[4096];
+        char* host = service + 8;
+        if (!strncmp(host, "emu:", 4)) {
+            connect_emulator(host + 4, buffer, sizeof(buffer));
+        } else {
+            connect_device(host, buffer, sizeof(buffer));
+        }
+        // Send response for emulator and device
+        snprintf(buf, sizeof(buf), "OKAY%04x%s",(unsigned)strlen(buffer), buffer);
+        writex(reply_fd, buf, strlen(buf));
+        return 0;
+    }
+
+    // remove TCP transport
+    if (!strncmp(service, "disconnect:", 11)) {
+        char buffer[4096];
+        memset(buffer, 0, sizeof(buffer));
+        char* serial = service + 11;
+        if (serial[0] == 0) {
+            // disconnect from all TCP devices
+            unregister_all_tcp_transports();
+        } else {
+            char hostbuf[100];
+            // assume port 5555 if no port is specified
+            if (!strchr(serial, ':')) {
+                snprintf(hostbuf, sizeof(hostbuf) - 1, "%s:5555", serial);
+                serial = hostbuf;
+            }
+            atransport *t = find_transport(serial);
+
+            if (t) {
+                unregister_transport(t);
+            } else {
+                snprintf(buffer, sizeof(buffer), "No such device %s", serial);
+            }
+        }
+
+        snprintf(buf, sizeof(buf), "OKAY%04x%s",(unsigned)strlen(buffer), buffer);
+        writex(reply_fd, buf, strlen(buf));
+        return 0;
+    }
+
+    // returns our value for ADB_SERVER_VERSION
+    if (!strcmp(service, "version")) {
+        char version[12];
+        snprintf(version, sizeof version, "%04x", ADB_SERVER_VERSION);
+        snprintf(buf, sizeof buf, "OKAY%04x%s", (unsigned)strlen(version), version);
+        writex(reply_fd, buf, strlen(buf));
+        return 0;
+    }
+
+    if(!strncmp(service,"get-serialno",strlen("get-serialno"))) {
+        char *out = "unknown";
+         transport = acquire_one_transport(CS_ANY, ttype, serial, NULL);
+       if (transport && transport->serial) {
+            out = transport->serial;
+        }
+        snprintf(buf, sizeof buf, "OKAY%04x%s",(unsigned)strlen(out),out);
+        writex(reply_fd, buf, strlen(buf));
+        return 0;
+    }
+    // indicates a new emulator instance has started
+    if (!strncmp(service,"emulator:",9)) {
+        int  port = atoi(service+9);
+        local_connect(port);
+        /* we don't even need to send a reply */
+        return 0;
+    }
+#endif // ADB_HOST
+
+    if(!strncmp(service,"forward:",8) || !strncmp(service,"killforward:",12)) {
+        char *local, *remote, *err;
+        int r;
+        atransport *transport;
+
+        int createForward = strncmp(service,"kill",4);
+
+        local = service + (createForward ? 8 : 12);
+        remote = strchr(local,';');
+        if(remote == 0) {
+            sendfailmsg(reply_fd, "malformed forward spec");
+            return 0;
+        }
+
+        *remote++ = 0;
+        if((local[0] == 0) || (remote[0] == 0) || (remote[0] == '*')){
+            sendfailmsg(reply_fd, "malformed forward spec");
+            return 0;
+        }
+
+        transport = acquire_one_transport(CS_ANY, ttype, serial, &err);
+        if (!transport) {
+            sendfailmsg(reply_fd, err);
+            return 0;
+        }
+
+        if (createForward) {
+            r = install_listener(local, remote, transport);
+        } else {
+            r = remove_listener(local, remote, transport);
+        }
+        if(r == 0) {
+                /* 1st OKAY is connect, 2nd OKAY is status */
+            writex(reply_fd, "OKAYOKAY", 8);
+            return 0;
+        }
+
+        if (createForward) {
+            sendfailmsg(reply_fd, (r == -1) ? "cannot rebind smartsocket" : "cannot bind socket");
+        } else {
+            sendfailmsg(reply_fd, "cannot remove listener");
+        }
+        return 0;
+    }
+
+    if(!strncmp(service,"get-state",strlen("get-state"))) {
+        transport = acquire_one_transport(CS_ANY, ttype, serial, NULL);
+        char *state = connection_state_name(transport);
+        snprintf(buf, sizeof buf, "OKAY%04x%s",(unsigned)strlen(state),state);
+        writex(reply_fd, buf, strlen(buf));
+        return 0;
+    }
+    return -1;
+}