cmds/installd/installd.c - platform/frameworks/native - Git at Google

 /*
 ** Copyright 2008, 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.
 */

 #include <sys/capability.h>
 #include <linux/prctl.h>

 #include "installd.h"


 #define BUFFER_MAX    1024  /* input buffer for commands */
 #define TOKEN_MAX     8     /* max number of arguments in buffer */
 #define REPLY_MAX     256   /* largest reply allowed */

 static int do_ping(char **arg, char reply[REPLY_MAX])
 {
     return 0;
 }

 static int do_install(char **arg, char reply[REPLY_MAX])
 {
     return install(arg[0], atoi(arg[1]), atoi(arg[2]), arg[3]); /* pkgname, uid, gid, seinfo */
 }

 static int do_dexopt(char **arg, char reply[REPLY_MAX])
 {
         /* apk_path, uid, is_public */
     return dexopt(arg[0], atoi(arg[1]), atoi(arg[2]));
 }

 static int do_move_dex(char **arg, char reply[REPLY_MAX])
 {
     return move_dex(arg[0], arg[1]); /* src, dst */
 }

 static int do_rm_dex(char **arg, char reply[REPLY_MAX])
 {
     return rm_dex(arg[0]); /* pkgname */
 }

 static int do_remove(char **arg, char reply[REPLY_MAX])
 {
     return uninstall(arg[0], atoi(arg[1])); /* pkgname, userid */
 }

 static int do_rename(char **arg, char reply[REPLY_MAX])
 {
     return renamepkg(arg[0], arg[1]); /* oldpkgname, newpkgname */
 }

 static int do_fixuid(char **arg, char reply[REPLY_MAX])
 {
     return fix_uid(arg[0], atoi(arg[1]), atoi(arg[2])); /* pkgname, uid, gid */
 }

 static int do_free_cache(char **arg, char reply[REPLY_MAX]) /* TODO int:free_size */
 {
     return free_cache((int64_t)atoll(arg[0])); /* free_size */
 }

 static int do_rm_cache(char **arg, char reply[REPLY_MAX])
 {
     return delete_cache(arg[0], atoi(arg[1])); /* pkgname, userid */
 }

 static int do_get_size(char **arg, char reply[REPLY_MAX])
 {
     int64_t codesize = 0;
     int64_t datasize = 0;
     int64_t cachesize = 0;
     int64_t asecsize = 0;
     int res = 0;

         /* pkgdir, persona, apkpath */
     res = get_size(arg[0], atoi(arg[1]), arg[2], arg[3], arg[4], arg[5],
             &codesize, &datasize, &cachesize, &asecsize);

     /*
      * Each int64_t can take up 22 characters printed out. Make sure it
      * doesn't go over REPLY_MAX in the future.
      */
     snprintf(reply, REPLY_MAX, "%" PRId64 " %" PRId64 " %" PRId64 " %" PRId64,
             codesize, datasize, cachesize, asecsize);
     return res;
 }

 static int do_rm_user_data(char **arg, char reply[REPLY_MAX])
 {
     return delete_user_data(arg[0], atoi(arg[1])); /* pkgname, userid */
 }

 static int do_mk_user_data(char **arg, char reply[REPLY_MAX])
 {
     return make_user_data(arg[0], atoi(arg[1]), atoi(arg[2])); /* pkgname, uid, userid */
 }

 static int do_rm_user(char **arg, char reply[REPLY_MAX])
 {
     return delete_persona(atoi(arg[0])); /* userid */
 }

 static int do_movefiles(char **arg, char reply[REPLY_MAX])
 {
     return movefiles();
 }

 static int do_linklib(char **arg, char reply[REPLY_MAX])
 {
     return linklib(arg[0], arg[1], atoi(arg[2]));
 }

 struct cmdinfo {
     const char *name;
     unsigned numargs;
     int (*func)(char **arg, char reply[REPLY_MAX]);
 };

 struct cmdinfo cmds[] = {
     { "ping",                 0, do_ping },
     { "install",              4, do_install },
     { "dexopt",               3, do_dexopt },
     { "movedex",              2, do_move_dex },
     { "rmdex",                1, do_rm_dex },
     { "remove",               2, do_remove },
     { "rename",               2, do_rename },
     { "fixuid",               3, do_fixuid },
     { "freecache",            1, do_free_cache },
     { "rmcache",              2, do_rm_cache },
     { "getsize",              6, do_get_size },
     { "rmuserdata",           2, do_rm_user_data },
     { "movefiles",            0, do_movefiles },
     { "linklib",              3, do_linklib },
     { "mkuserdata",           3, do_mk_user_data },
     { "rmuser",               1, do_rm_user },
 };

 static int readx(int s, void *_buf, int count)
 {
     char *buf = _buf;
     int n = 0, r;
     if (count < 0) return -1;
     while (n < count) {
         r = read(s, buf + n, count - n);
         if (r < 0) {
             if (errno == EINTR) continue;
             ALOGE("read error: %s\n", strerror(errno));
             return -1;
         }
         if (r == 0) {
             ALOGE("eof\n");
             return -1; /* EOF */
         }
         n += r;
     }
     return 0;
 }

 static int writex(int s, const void *_buf, int count)
 {
     const char *buf = _buf;
     int n = 0, r;
     if (count < 0) return -1;
     while (n < count) {
         r = write(s, buf + n, count - n);
         if (r < 0) {
             if (errno == EINTR) continue;
             ALOGE("write error: %s\n", strerror(errno));
             return -1;
         }
         n += r;
     }
     return 0;
 }


 /* Tokenize the command buffer, locate a matching command,
  * ensure that the required number of arguments are provided,
  * call the function(), return the result.
  */
 static int execute(int s, char cmd[BUFFER_MAX])
 {
     char reply[REPLY_MAX];
     char *arg[TOKEN_MAX+1];
     unsigned i;
     unsigned n = 0;
     unsigned short count;
     int ret = -1;

 //    ALOGI("execute('%s')\n", cmd);

         /* default reply is "" */
     reply[0] = 0;

         /* n is number of args (not counting arg[0]) */
     arg[0] = cmd;
     while (*cmd) {
         if (isspace(*cmd)) {
             *cmd++ = 0;
             n++;
             arg[n] = cmd;
             if (n == TOKEN_MAX) {
                 ALOGE("too many arguments\n");
                 goto done;
             }
         }
         cmd++;
     }

     for (i = 0; i < sizeof(cmds) / sizeof(cmds[0]); i++) {
         if (!strcmp(cmds[i].name,arg[0])) {
             if (n != cmds[i].numargs) {
                 ALOGE("%s requires %d arguments (%d given)\n",
                      cmds[i].name, cmds[i].numargs, n);
             } else {
                 ret = cmds[i].func(arg + 1, reply);
             }
             goto done;
         }
     }
     ALOGE("unsupported command '%s'\n", arg[0]);

 done:
     if (reply[0]) {
         n = snprintf(cmd, BUFFER_MAX, "%d %s", ret, reply);
     } else {
         n = snprintf(cmd, BUFFER_MAX, "%d", ret);
     }
     if (n > BUFFER_MAX) n = BUFFER_MAX;
     count = n;

 //    ALOGI("reply: '%s'\n", cmd);
     if (writex(s, &count, sizeof(count))) return -1;
     if (writex(s, cmd, count)) return -1;
     return 0;
 }

 /**
  * Initialize all the global variables that are used elsewhere. Returns 0 upon
  * success and -1 on error.
  */
 void free_globals() {
     size_t i;

     for (i = 0; i < android_system_dirs.count; i++) {
         if (android_system_dirs.dirs[i].path != NULL) {
             free(android_system_dirs.dirs[i].path);
         }
     }

     free(android_system_dirs.dirs);
 }

 int initialize_globals() {
     // Get the android data directory.
     if (get_path_from_env(&android_data_dir, "ANDROID_DATA") < 0) {
         return -1;
     }

     // Get the android app directory.
     if (copy_and_append(&android_app_dir, &android_data_dir, APP_SUBDIR) < 0) {
         return -1;
     }

     // Get the android protected app directory.
     if (copy_and_append(&android_app_private_dir, &android_data_dir, PRIVATE_APP_SUBDIR) < 0) {
         return -1;
     }

     // Get the android app native library directory.
     if (copy_and_append(&android_app_lib_dir, &android_data_dir, APP_LIB_SUBDIR) < 0) {
         return -1;
     }

     // Get the sd-card ASEC mount point.
     if (get_path_from_env(&android_asec_dir, "ASEC_MOUNTPOINT") < 0) {
         return -1;
     }

     // Get the android media directory.
     if (copy_and_append(&android_media_dir, &android_data_dir, MEDIA_SUBDIR) < 0) {
         return -1;
     }

     // Take note of the system and vendor directories.
     android_system_dirs.count = 2;

     android_system_dirs.dirs = calloc(android_system_dirs.count, sizeof(dir_rec_t));
     if (android_system_dirs.dirs == NULL) {
         ALOGE("Couldn't allocate array for dirs; aborting\n");
         return -1;
     }

     // system
     if (get_path_from_env(&android_system_dirs.dirs[0], "ANDROID_ROOT") < 0) {
         free_globals();
         return -1;
     }

     // append "app/" to dirs[0]
     char *system_app_path = build_string2(android_system_dirs.dirs[0].path, APP_SUBDIR);
     android_system_dirs.dirs[0].path = system_app_path;
     android_system_dirs.dirs[0].len = strlen(system_app_path);

     // vendor
     // TODO replace this with an environment variable (doesn't exist yet)
     android_system_dirs.dirs[1].path = "/vendor/app/";
     android_system_dirs.dirs[1].len = strlen(android_system_dirs.dirs[1].path);

     return 0;
 }

 int initialize_directories() {
     int res = -1;

     // Read current filesystem layout version to handle upgrade paths
     char version_path[PATH_MAX];
     snprintf(version_path, PATH_MAX, "%s.layout_version", android_data_dir.path);

     int oldVersion;
     if (fs_read_atomic_int(version_path, &oldVersion) == -1) {
         oldVersion = 0;
     }
     int version = oldVersion;

     // /data/user
     char *user_data_dir = build_string2(android_data_dir.path, SECONDARY_USER_PREFIX);
     // /data/data
     char *legacy_data_dir = build_string2(android_data_dir.path, PRIMARY_USER_PREFIX);
     // /data/user/0
     char *primary_data_dir = build_string3(android_data_dir.path, SECONDARY_USER_PREFIX, "0");
     if (!user_data_dir || !legacy_data_dir || !primary_data_dir) {
         goto fail;
     }

     // Make the /data/user directory if necessary
     if (access(user_data_dir, R_OK) < 0) {
         if (mkdir(user_data_dir, 0711) < 0) {
             goto fail;
         }
         if (chown(user_data_dir, AID_SYSTEM, AID_SYSTEM) < 0) {
             goto fail;
         }
         if (chmod(user_data_dir, 0711) < 0) {
             goto fail;
         }
     }
     // Make the /data/user/0 symlink to /data/data if necessary
     if (access(primary_data_dir, R_OK) < 0) {
         if (symlink(legacy_data_dir, primary_data_dir)) {
             goto fail;
         }
     }

     if (version == 0) {
         // Introducing multi-user, so migrate /data/media contents into /data/media/0
         ALOGD("Upgrading /data/media for multi-user");

         // Ensure /data/media
         if (fs_prepare_dir(android_media_dir.path, 0770, AID_MEDIA_RW, AID_MEDIA_RW) == -1) {
             goto fail;
         }

         // /data/media.tmp
         char media_tmp_dir[PATH_MAX];
         snprintf(media_tmp_dir, PATH_MAX, "%smedia.tmp", android_data_dir.path);

         // Only copy when upgrade not already in progress
         if (access(media_tmp_dir, F_OK) == -1) {
             if (rename(android_media_dir.path, media_tmp_dir) == -1) {
                 ALOGE("Failed to move legacy media path: %s", strerror(errno));
                 goto fail;
             }
         }

         // Create /data/media again
         if (fs_prepare_dir(android_media_dir.path, 0770, AID_MEDIA_RW, AID_MEDIA_RW) == -1) {
             goto fail;
         }

         // /data/media/0
         char owner_media_dir[PATH_MAX];
         snprintf(owner_media_dir, PATH_MAX, "%s0", android_media_dir.path);

         // Move any owner data into place
         if (access(media_tmp_dir, F_OK) == 0) {
             if (rename(media_tmp_dir, owner_media_dir) == -1) {
                 ALOGE("Failed to move owner media path: %s", strerror(errno));
                 goto fail;
             }
         }

         // Ensure media directories for any existing users
         DIR *dir;
         struct dirent *dirent;
         char user_media_dir[PATH_MAX];

         dir = opendir(user_data_dir);
         if (dir != NULL) {
             while ((dirent = readdir(dir))) {
                 if (dirent->d_type == DT_DIR) {
                     const char *name = dirent->d_name;

                     // skip "." and ".."
                     if (name[0] == '.') {
                         if (name[1] == 0) continue;
                         if ((name[1] == '.') && (name[2] == 0)) continue;
                     }

                     // /data/media/<user_id>
                     snprintf(user_media_dir, PATH_MAX, "%s%s", android_media_dir.path, name);
                     if (fs_prepare_dir(user_media_dir, 0770, AID_MEDIA_RW, AID_MEDIA_RW) == -1) {
                         goto fail;
                     }
                 }
             }
             closedir(dir);
         }

         version = 1;
     }

     // /data/media/obb
     char media_obb_dir[PATH_MAX];
     snprintf(media_obb_dir, PATH_MAX, "%sobb", android_media_dir.path);

     if (version == 1) {
         // Introducing /data/media/obb for sharing OBB across users; migrate
         // any existing OBB files from owner.
         ALOGD("Upgrading to shared /data/media/obb");

         // /data/media/0/Android/obb
         char owner_obb_path[PATH_MAX];
         snprintf(owner_obb_path, PATH_MAX, "%s0/Android/obb", android_media_dir.path);

         // Only move if target doesn't already exist
         if (access(media_obb_dir, F_OK) != 0 && access(owner_obb_path, F_OK) == 0) {
             if (rename(owner_obb_path, media_obb_dir) == -1) {
                 ALOGE("Failed to move OBB from owner: %s", strerror(errno));
                 goto fail;
             }
         }

         version = 2;
     }

     if (ensure_media_user_dirs(0) == -1) {
         ALOGE("Failed to setup media for user 0");
         goto fail;
     }
     if (fs_prepare_dir(media_obb_dir, 0770, AID_MEDIA_RW, AID_MEDIA_RW) == -1) {
         goto fail;
     }

     // Persist layout version if changed
     if (version != oldVersion) {
         if (fs_write_atomic_int(version_path, version) == -1) {
             ALOGE("Failed to save version to %s: %s", version_path, strerror(errno));
             goto fail;
         }
     }

     // Success!
     res = 0;

 fail:
     free(user_data_dir);
     free(legacy_data_dir);
     free(primary_data_dir);
     return res;
 }

 static void drop_privileges() {
     if (prctl(PR_SET_KEEPCAPS, 1) < 0) {
         ALOGE("prctl(PR_SET_KEEPCAPS) failed: %s\n", strerror(errno));
         exit(1);
     }

     if (setgid(AID_INSTALL) < 0) {
         ALOGE("setgid() can't drop privileges; exiting.\n");
         exit(1);
     }

     if (setuid(AID_INSTALL) < 0) {
         ALOGE("setuid() can't drop privileges; exiting.\n");
         exit(1);
     }

     struct __user_cap_header_struct capheader;
     struct __user_cap_data_struct capdata[2];
     memset(&capheader, 0, sizeof(capheader));
     memset(&capdata, 0, sizeof(capdata));
     capheader.version = _LINUX_CAPABILITY_VERSION_3;
     capheader.pid = 0;

     capdata[CAP_TO_INDEX(CAP_DAC_OVERRIDE)].permitted |= CAP_TO_MASK(CAP_DAC_OVERRIDE);
     capdata[CAP_TO_INDEX(CAP_CHOWN)].permitted        |= CAP_TO_MASK(CAP_CHOWN);
     capdata[CAP_TO_INDEX(CAP_SETUID)].permitted       |= CAP_TO_MASK(CAP_SETUID);
     capdata[CAP_TO_INDEX(CAP_SETGID)].permitted       |= CAP_TO_MASK(CAP_SETGID);

     capdata[0].effective = capdata[0].permitted;
     capdata[1].effective = capdata[1].permitted;
     capdata[0].inheritable = 0;
     capdata[1].inheritable = 0;

     if (capset(&capheader, &capdata[0]) < 0) {
         ALOGE("capset failed: %s\n", strerror(errno));
         exit(1);
     }
 }

 int main(const int argc, const char *argv[]) {
     char buf[BUFFER_MAX];
     struct sockaddr addr;
     socklen_t alen;
     int lsocket, s, count;

     ALOGI("installd firing up\n");

     if (initialize_globals() < 0) {
         ALOGE("Could not initialize globals; exiting.\n");
         exit(1);
     }

     if (initialize_directories() < 0) {
         ALOGE("Could not create directories; exiting.\n");
         exit(1);
     }

     drop_privileges();

     lsocket = android_get_control_socket(SOCKET_PATH);
     if (lsocket < 0) {
         ALOGE("Failed to get socket from environment: %s\n", strerror(errno));
         exit(1);
     }
     if (listen(lsocket, 5)) {
         ALOGE("Listen on socket failed: %s\n", strerror(errno));
         exit(1);
     }
     fcntl(lsocket, F_SETFD, FD_CLOEXEC);

     for (;;) {
         alen = sizeof(addr);
         s = accept(lsocket, &addr, &alen);
         if (s < 0) {
             ALOGE("Accept failed: %s\n", strerror(errno));
             continue;
         }
         fcntl(s, F_SETFD, FD_CLOEXEC);

         ALOGI("new connection\n");
         for (;;) {
             unsigned short count;
             if (readx(s, &count, sizeof(count))) {
                 ALOGE("failed to read size\n");
                 break;
             }
             if ((count < 1) || (count >= BUFFER_MAX)) {
                 ALOGE("invalid size %d\n", count);
                 break;
             }
             if (readx(s, buf, count)) {
                 ALOGE("failed to read command\n");
                 break;
             }
             buf[count] = 0;
             if (execute(s, buf)) break;
         }
         ALOGI("closing connection\n");
         close(s);
     }

     return 0;
 }
	/*
	** Copyright 2008, 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.
	*/

	#include <sys/capability.h>
	#include <linux/prctl.h>

	#include "installd.h"


	#define BUFFER_MAX 1024 /* input buffer for commands */
	#define TOKEN_MAX 8 /* max number of arguments in buffer */
	#define REPLY_MAX 256 /* largest reply allowed */

	static int do_ping(char **arg, char reply[REPLY_MAX])
	{
	return 0;
	}

	static int do_install(char **arg, char reply[REPLY_MAX])
	{
	return install(arg[0], atoi(arg[1]), atoi(arg[2]), arg[3]); /* pkgname, uid, gid, seinfo */
	}

	static int do_dexopt(char **arg, char reply[REPLY_MAX])
	{
	/* apk_path, uid, is_public */
	return dexopt(arg[0], atoi(arg[1]), atoi(arg[2]));
	}

	static int do_move_dex(char **arg, char reply[REPLY_MAX])
	{
	return move_dex(arg[0], arg[1]); /* src, dst */
	}

	static int do_rm_dex(char **arg, char reply[REPLY_MAX])
	{
	return rm_dex(arg[0]); /* pkgname */
	}

	static int do_remove(char **arg, char reply[REPLY_MAX])
	{
	return uninstall(arg[0], atoi(arg[1])); /* pkgname, userid */
	}

	static int do_rename(char **arg, char reply[REPLY_MAX])
	{
	return renamepkg(arg[0], arg[1]); /* oldpkgname, newpkgname */
	}

	static int do_fixuid(char **arg, char reply[REPLY_MAX])
	{
	return fix_uid(arg[0], atoi(arg[1]), atoi(arg[2])); /* pkgname, uid, gid */
	}

	static int do_free_cache(char *arg, char reply[REPLY_MAX]) / TODO int:free_size */
	{
	return free_cache((int64_t)atoll(arg[0])); /* free_size */
	}

	static int do_rm_cache(char **arg, char reply[REPLY_MAX])
	{
	return delete_cache(arg[0], atoi(arg[1])); /* pkgname, userid */
	}

	static int do_get_size(char **arg, char reply[REPLY_MAX])
	{
	int64_t codesize = 0;
	int64_t datasize = 0;
	int64_t cachesize = 0;
	int64_t asecsize = 0;
	int res = 0;

	/* pkgdir, persona, apkpath */
	res = get_size(arg[0], atoi(arg[1]), arg[2], arg[3], arg[4], arg[5],
	&codesize, &datasize, &cachesize, &asecsize);

	/*
	* Each int64_t can take up 22 characters printed out. Make sure it
	* doesn't go over REPLY_MAX in the future.
	*/
	snprintf(reply, REPLY_MAX, "%" PRId64 " %" PRId64 " %" PRId64 " %" PRId64,
	codesize, datasize, cachesize, asecsize);
	return res;
	}

	static int do_rm_user_data(char **arg, char reply[REPLY_MAX])
	{
	return delete_user_data(arg[0], atoi(arg[1])); /* pkgname, userid */
	}

	static int do_mk_user_data(char **arg, char reply[REPLY_MAX])
	{
	return make_user_data(arg[0], atoi(arg[1]), atoi(arg[2])); /* pkgname, uid, userid */
	}

	static int do_rm_user(char **arg, char reply[REPLY_MAX])
	{
	return delete_persona(atoi(arg[0])); /* userid */
	}

	static int do_movefiles(char **arg, char reply[REPLY_MAX])
	{
	return movefiles();
	}

	static int do_linklib(char **arg, char reply[REPLY_MAX])
	{
	return linklib(arg[0], arg[1], atoi(arg[2]));
	}

	struct cmdinfo {
	const char *name;
	unsigned numargs;
	int (func)(char *arg, char reply[REPLY_MAX]);
	};

	struct cmdinfo cmds[] = {
	{ "ping", 0, do_ping },
	{ "install", 4, do_install },
	{ "dexopt", 3, do_dexopt },
	{ "movedex", 2, do_move_dex },
	{ "rmdex", 1, do_rm_dex },
	{ "remove", 2, do_remove },
	{ "rename", 2, do_rename },
	{ "fixuid", 3, do_fixuid },
	{ "freecache", 1, do_free_cache },
	{ "rmcache", 2, do_rm_cache },
	{ "getsize", 6, do_get_size },
	{ "rmuserdata", 2, do_rm_user_data },
	{ "movefiles", 0, do_movefiles },
	{ "linklib", 3, do_linklib },
	{ "mkuserdata", 3, do_mk_user_data },
	{ "rmuser", 1, do_rm_user },
	};

	static int readx(int s, void *_buf, int count)
	{
	char *buf = _buf;
	int n = 0, r;
	if (count < 0) return -1;
	while (n < count) {
	r = read(s, buf + n, count - n);
	if (r < 0) {
	if (errno == EINTR) continue;
	ALOGE("read error: %s\n", strerror(errno));
	return -1;
	}
	if (r == 0) {
	ALOGE("eof\n");
	return -1; /* EOF */
	}
	n += r;
	}
	return 0;
	}

	static int writex(int s, const void *_buf, int count)
	{
	const char *buf = _buf;
	int n = 0, r;
	if (count < 0) return -1;
	while (n < count) {
	r = write(s, buf + n, count - n);
	if (r < 0) {
	if (errno == EINTR) continue;
	ALOGE("write error: %s\n", strerror(errno));
	return -1;
	}
	n += r;
	}
	return 0;
	}


	/* Tokenize the command buffer, locate a matching command,
	* ensure that the required number of arguments are provided,
	* call the function(), return the result.
	*/
	static int execute(int s, char cmd[BUFFER_MAX])
	{
	char reply[REPLY_MAX];
	char *arg[TOKEN_MAX+1];
	unsigned i;
	unsigned n = 0;
	unsigned short count;
	int ret = -1;

	// ALOGI("execute('%s')\n", cmd);

	/* default reply is "" */
	reply[0] = 0;

	/* n is number of args (not counting arg[0]) */
	arg[0] = cmd;
	while (*cmd) {
	if (isspace(*cmd)) {
	*cmd++ = 0;
	n++;
	arg[n] = cmd;
	if (n == TOKEN_MAX) {
	ALOGE("too many arguments\n");
	goto done;
	}
	}
	cmd++;
	}

	for (i = 0; i < sizeof(cmds) / sizeof(cmds[0]); i++) {
	if (!strcmp(cmds[i].name,arg[0])) {
	if (n != cmds[i].numargs) {
	ALOGE("%s requires %d arguments (%d given)\n",
	cmds[i].name, cmds[i].numargs, n);
	} else {
	ret = cmds[i].func(arg + 1, reply);
	}
	goto done;
	}
	}
	ALOGE("unsupported command '%s'\n", arg[0]);

	done:
	if (reply[0]) {
	n = snprintf(cmd, BUFFER_MAX, "%d %s", ret, reply);
	} else {
	n = snprintf(cmd, BUFFER_MAX, "%d", ret);
	}
	if (n > BUFFER_MAX) n = BUFFER_MAX;
	count = n;

	// ALOGI("reply: '%s'\n", cmd);
	if (writex(s, &count, sizeof(count))) return -1;
	if (writex(s, cmd, count)) return -1;
	return 0;
	}

	/**
	* Initialize all the global variables that are used elsewhere. Returns 0 upon
	* success and -1 on error.
	*/
	void free_globals() {
	size_t i;

	for (i = 0; i < android_system_dirs.count; i++) {
	if (android_system_dirs.dirs[i].path != NULL) {
	free(android_system_dirs.dirs[i].path);
	}
	}

	free(android_system_dirs.dirs);
	}

	int initialize_globals() {
	// Get the android data directory.
	if (get_path_from_env(&android_data_dir, "ANDROID_DATA") < 0) {
	return -1;
	}

	// Get the android app directory.
	if (copy_and_append(&android_app_dir, &android_data_dir, APP_SUBDIR) < 0) {
	return -1;
	}

	// Get the android protected app directory.
	if (copy_and_append(&android_app_private_dir, &android_data_dir, PRIVATE_APP_SUBDIR) < 0) {
	return -1;
	}

	// Get the android app native library directory.
	if (copy_and_append(&android_app_lib_dir, &android_data_dir, APP_LIB_SUBDIR) < 0) {
	return -1;
	}

	// Get the sd-card ASEC mount point.
	if (get_path_from_env(&android_asec_dir, "ASEC_MOUNTPOINT") < 0) {
	return -1;
	}

	// Get the android media directory.
	if (copy_and_append(&android_media_dir, &android_data_dir, MEDIA_SUBDIR) < 0) {
	return -1;
	}

	// Take note of the system and vendor directories.
	android_system_dirs.count = 2;

	android_system_dirs.dirs = calloc(android_system_dirs.count, sizeof(dir_rec_t));
	if (android_system_dirs.dirs == NULL) {
	ALOGE("Couldn't allocate array for dirs; aborting\n");
	return -1;
	}

	// system
	if (get_path_from_env(&android_system_dirs.dirs[0], "ANDROID_ROOT") < 0) {
	free_globals();
	return -1;
	}

	// append "app/" to dirs[0]
	char *system_app_path = build_string2(android_system_dirs.dirs[0].path, APP_SUBDIR);
	android_system_dirs.dirs[0].path = system_app_path;
	android_system_dirs.dirs[0].len = strlen(system_app_path);

	// vendor
	// TODO replace this with an environment variable (doesn't exist yet)
	android_system_dirs.dirs[1].path = "/vendor/app/";
	android_system_dirs.dirs[1].len = strlen(android_system_dirs.dirs[1].path);

	return 0;
	}

	int initialize_directories() {
	int res = -1;

	// Read current filesystem layout version to handle upgrade paths
	char version_path[PATH_MAX];
	snprintf(version_path, PATH_MAX, "%s.layout_version", android_data_dir.path);

	int oldVersion;
	if (fs_read_atomic_int(version_path, &oldVersion) == -1) {
	oldVersion = 0;
	}
	int version = oldVersion;

	// /data/user
	char *user_data_dir = build_string2(android_data_dir.path, SECONDARY_USER_PREFIX);
	// /data/data
	char *legacy_data_dir = build_string2(android_data_dir.path, PRIMARY_USER_PREFIX);
	// /data/user/0
	char *primary_data_dir = build_string3(android_data_dir.path, SECONDARY_USER_PREFIX, "0");
	if (!user_data_dir \|\| !legacy_data_dir \|\| !primary_data_dir) {
	goto fail;
	}

	// Make the /data/user directory if necessary
	if (access(user_data_dir, R_OK) < 0) {
	if (mkdir(user_data_dir, 0711) < 0) {
	goto fail;
	}
	if (chown(user_data_dir, AID_SYSTEM, AID_SYSTEM) < 0) {
	goto fail;
	}
	if (chmod(user_data_dir, 0711) < 0) {
	goto fail;
	}
	}
	// Make the /data/user/0 symlink to /data/data if necessary
	if (access(primary_data_dir, R_OK) < 0) {
	if (symlink(legacy_data_dir, primary_data_dir)) {
	goto fail;
	}
	}

	if (version == 0) {
	// Introducing multi-user, so migrate /data/media contents into /data/media/0
	ALOGD("Upgrading /data/media for multi-user");

	// Ensure /data/media
	if (fs_prepare_dir(android_media_dir.path, 0770, AID_MEDIA_RW, AID_MEDIA_RW) == -1) {
	goto fail;
	}

	// /data/media.tmp
	char media_tmp_dir[PATH_MAX];
	snprintf(media_tmp_dir, PATH_MAX, "%smedia.tmp", android_data_dir.path);

	// Only copy when upgrade not already in progress
	if (access(media_tmp_dir, F_OK) == -1) {
	if (rename(android_media_dir.path, media_tmp_dir) == -1) {
	ALOGE("Failed to move legacy media path: %s", strerror(errno));
	goto fail;
	}
	}

	// Create /data/media again
	if (fs_prepare_dir(android_media_dir.path, 0770, AID_MEDIA_RW, AID_MEDIA_RW) == -1) {
	goto fail;
	}

	// /data/media/0
	char owner_media_dir[PATH_MAX];
	snprintf(owner_media_dir, PATH_MAX, "%s0", android_media_dir.path);

	// Move any owner data into place
	if (access(media_tmp_dir, F_OK) == 0) {
	if (rename(media_tmp_dir, owner_media_dir) == -1) {
	ALOGE("Failed to move owner media path: %s", strerror(errno));
	goto fail;
	}
	}

	// Ensure media directories for any existing users
	DIR *dir;
	struct dirent *dirent;
	char user_media_dir[PATH_MAX];

	dir = opendir(user_data_dir);
	if (dir != NULL) {
	while ((dirent = readdir(dir))) {
	if (dirent->d_type == DT_DIR) {
	const char *name = dirent->d_name;

	// skip "." and ".."
	if (name[0] == '.') {
	if (name[1] == 0) continue;
	if ((name[1] == '.') && (name[2] == 0)) continue;
	}

	// /data/media/<user_id>
	snprintf(user_media_dir, PATH_MAX, "%s%s", android_media_dir.path, name);
	if (fs_prepare_dir(user_media_dir, 0770, AID_MEDIA_RW, AID_MEDIA_RW) == -1) {
	goto fail;
	}
	}
	}
	closedir(dir);
	}

	version = 1;
	}

	// /data/media/obb
	char media_obb_dir[PATH_MAX];
	snprintf(media_obb_dir, PATH_MAX, "%sobb", android_media_dir.path);

	if (version == 1) {
	// Introducing /data/media/obb for sharing OBB across users; migrate
	// any existing OBB files from owner.
	ALOGD("Upgrading to shared /data/media/obb");

	// /data/media/0/Android/obb
	char owner_obb_path[PATH_MAX];
	snprintf(owner_obb_path, PATH_MAX, "%s0/Android/obb", android_media_dir.path);

	// Only move if target doesn't already exist
	if (access(media_obb_dir, F_OK) != 0 && access(owner_obb_path, F_OK) == 0) {
	if (rename(owner_obb_path, media_obb_dir) == -1) {
	ALOGE("Failed to move OBB from owner: %s", strerror(errno));
	goto fail;
	}
	}

	version = 2;
	}

	if (ensure_media_user_dirs(0) == -1) {
	ALOGE("Failed to setup media for user 0");
	goto fail;
	}
	if (fs_prepare_dir(media_obb_dir, 0770, AID_MEDIA_RW, AID_MEDIA_RW) == -1) {
	goto fail;
	}

	// Persist layout version if changed
	if (version != oldVersion) {
	if (fs_write_atomic_int(version_path, version) == -1) {
	ALOGE("Failed to save version to %s: %s", version_path, strerror(errno));
	goto fail;
	}
	}

	// Success!
	res = 0;

	fail:
	free(user_data_dir);
	free(legacy_data_dir);
	free(primary_data_dir);
	return res;
	}

	static void drop_privileges() {
	if (prctl(PR_SET_KEEPCAPS, 1) < 0) {
	ALOGE("prctl(PR_SET_KEEPCAPS) failed: %s\n", strerror(errno));
	exit(1);
	}

	if (setgid(AID_INSTALL) < 0) {
	ALOGE("setgid() can't drop privileges; exiting.\n");
	exit(1);
	}

	if (setuid(AID_INSTALL) < 0) {
	ALOGE("setuid() can't drop privileges; exiting.\n");
	exit(1);
	}

	struct __user_cap_header_struct capheader;
	struct __user_cap_data_struct capdata[2];
	memset(&capheader, 0, sizeof(capheader));
	memset(&capdata, 0, sizeof(capdata));
	capheader.version = _LINUX_CAPABILITY_VERSION_3;
	capheader.pid = 0;

	capdata[CAP_TO_INDEX(CAP_DAC_OVERRIDE)].permitted \|= CAP_TO_MASK(CAP_DAC_OVERRIDE);
	capdata[CAP_TO_INDEX(CAP_CHOWN)].permitted \|= CAP_TO_MASK(CAP_CHOWN);
	capdata[CAP_TO_INDEX(CAP_SETUID)].permitted \|= CAP_TO_MASK(CAP_SETUID);
	capdata[CAP_TO_INDEX(CAP_SETGID)].permitted \|= CAP_TO_MASK(CAP_SETGID);

	capdata[0].effective = capdata[0].permitted;
	capdata[1].effective = capdata[1].permitted;
	capdata[0].inheritable = 0;
	capdata[1].inheritable = 0;

	if (capset(&capheader, &capdata[0]) < 0) {
	ALOGE("capset failed: %s\n", strerror(errno));
	exit(1);
	}
	}

	int main(const int argc, const char *argv[]) {
	char buf[BUFFER_MAX];
	struct sockaddr addr;
	socklen_t alen;
	int lsocket, s, count;

	ALOGI("installd firing up\n");

	if (initialize_globals() < 0) {
	ALOGE("Could not initialize globals; exiting.\n");
	exit(1);
	}

	if (initialize_directories() < 0) {
	ALOGE("Could not create directories; exiting.\n");
	exit(1);
	}

	drop_privileges();

	lsocket = android_get_control_socket(SOCKET_PATH);
	if (lsocket < 0) {
	ALOGE("Failed to get socket from environment: %s\n", strerror(errno));
	exit(1);
	}
	if (listen(lsocket, 5)) {
	ALOGE("Listen on socket failed: %s\n", strerror(errno));
	exit(1);
	}
	fcntl(lsocket, F_SETFD, FD_CLOEXEC);

	for (;;) {
	alen = sizeof(addr);
	s = accept(lsocket, &addr, &alen);
	if (s < 0) {
	ALOGE("Accept failed: %s\n", strerror(errno));
	continue;
	}
	fcntl(s, F_SETFD, FD_CLOEXEC);

	ALOGI("new connection\n");
	for (;;) {
	unsigned short count;
	if (readx(s, &count, sizeof(count))) {
	ALOGE("failed to read size\n");
	break;
	}
	if ((count < 1) \|\| (count >= BUFFER_MAX)) {
	ALOGE("invalid size %d\n", count);
	break;
	}
	if (readx(s, buf, count)) {
	ALOGE("failed to read command\n");
	break;
	}
	buf[count] = 0;
	if (execute(s, buf)) break;
	}
	ALOGI("closing connection\n");
	close(s);
	}

	return 0;
	}