diff --git a/rootdir/init.rc b/rootdir/init.rc
index a359713..b96ff4c 100644
--- a/rootdir/init.rc
+++ b/rootdir/init.rc
@@ -112,7 +112,6 @@
     write /proc/sys/kernel/sched_tunable_scaling 0
     write /proc/sys/kernel/sched_latency_ns 10000000
     write /proc/sys/kernel/sched_wakeup_granularity_ns 2000000
-    write /proc/sys/kernel/sched_compat_yield 1
     write /proc/sys/kernel/sched_child_runs_first 0
 
     write /proc/sys/kernel/randomize_va_space 2
diff --git a/run-as/Android.mk b/run-as/Android.mk
index 3774acc..2e305d7 100644
--- a/run-as/Android.mk
+++ b/run-as/Android.mk
@@ -1,12 +1,8 @@
 LOCAL_PATH:= $(call my-dir)
+
 include $(CLEAR_VARS)
-
-LOCAL_SRC_FILES := run-as.c package.c
-
-LOCAL_SHARED_LIBRARIES := libselinux
-
-LOCAL_MODULE := run-as
-
 LOCAL_CFLAGS := -Werror
-
+LOCAL_MODULE := run-as
+LOCAL_SHARED_LIBRARIES := libselinux libpackagelistparser
+LOCAL_SRC_FILES := run-as.cpp
 include $(BUILD_EXECUTABLE)
diff --git a/run-as/package.c b/run-as/package.c
deleted file mode 100644
index aea89e5..0000000
--- a/run-as/package.c
+++ /dev/null
@@ -1,556 +0,0 @@
-/*
-**
-** Copyright 2010, 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 <errno.h>
-#include <fcntl.h>
-#include <stdio.h>
-#include <string.h>
-#include <sys/mman.h>
-#include <sys/stat.h>
-#include <unistd.h>
-
-#include <private/android_filesystem_config.h>
-#include "package.h"
-
-/*
- *  WARNING WARNING WARNING WARNING
- *
- *  The following code runs as root on production devices, before
- *  the run-as command has dropped the uid/gid. Hence be very
- *  conservative and keep in mind the following:
- *
- *  - Performance does not matter here, clarity and safety of the code
- *    does however. Documentation is a must.
- *
- *  - Avoid calling C library functions with complex implementations
- *    like malloc() and printf(). You want to depend on simple system
- *    calls instead, which behaviour is not going to be altered in
- *    unpredictible ways by environment variables or system properties.
- *
- *  - Do not trust user input and/or the filesystem whenever possible.
- *
- */
-
-/* The file containing the list of installed packages on the system */
-#define PACKAGES_LIST_FILE  "/data/system/packages.list"
-
-/* Copy 'srclen' string bytes from 'src' into buffer 'dst' of size 'dstlen'
- * This function always zero-terminate the destination buffer unless
- * 'dstlen' is 0, even in case of overflow.
- * Returns a pointer into the src string, leaving off where the copy
- * has stopped. The copy will stop when dstlen, srclen or a null
- * character on src has been reached.
- */
-static const char*
-string_copy(char* dst, size_t dstlen, const char* src, size_t srclen)
-{
-    const char* srcend = src + srclen;
-    const char* dstend = dst + dstlen;
-
-    if (dstlen == 0)
-        return src;
-
-    dstend--; /* make room for terminating zero */
-
-    while (dst < dstend && src < srcend && *src != '\0')
-        *dst++ = *src++;
-
-    *dst = '\0'; /* zero-terminate result */
-    return src;
-}
-
-/* Open 'filename' and map it into our address-space.
- * Returns buffer address, or NULL on error
- * On exit, *filesize will be set to the file's size, or 0 on error
- */
-static void*
-map_file(const char* filename, size_t* filesize)
-{
-    int  fd, ret, old_errno;
-    struct stat  st;
-    size_t  length = 0;
-    void*   address = NULL;
-    gid_t   oldegid;
-
-    *filesize = 0;
-
-    /*
-     * Temporarily switch effective GID to allow us to read
-     * the packages file
-     */
-
-    oldegid = getegid();
-    if (setegid(AID_PACKAGE_INFO) < 0) {
-        return NULL;
-    }
-
-    /* open the file for reading */
-    fd = TEMP_FAILURE_RETRY(open(filename, O_RDONLY));
-    if (fd < 0) {
-        return NULL;
-    }
-
-    /* restore back to our old egid */
-    if (setegid(oldegid) < 0) {
-        goto EXIT;
-    }
-
-    /* get its size */
-    ret = TEMP_FAILURE_RETRY(fstat(fd, &st));
-    if (ret < 0)
-        goto EXIT;
-
-    /* Ensure that the file is owned by the system user */
-    if ((st.st_uid != AID_SYSTEM) || (st.st_gid != AID_PACKAGE_INFO)) {
-        goto EXIT;
-    }
-
-    /* Ensure that the file has sane permissions */
-    if ((st.st_mode & S_IWOTH) != 0) {
-        goto EXIT;
-    }
-
-    /* Ensure that the size is not ridiculously large */
-    length = (size_t)st.st_size;
-    if ((off_t)length != st.st_size) {
-        errno = ENOMEM;
-        goto EXIT;
-    }
-
-    /* Memory-map the file now */
-    do {
-        address = mmap(NULL, length, PROT_READ, MAP_PRIVATE, fd, 0);
-    } while (address == MAP_FAILED && errno == EINTR);
-    if (address == MAP_FAILED) {
-        address = NULL;
-        goto EXIT;
-    }
-
-    /* We're good, return size */
-    *filesize = length;
-
-EXIT:
-    /* close the file, preserve old errno for better diagnostics */
-    old_errno = errno;
-    close(fd);
-    errno = old_errno;
-
-    return address;
-}
-
-/* unmap the file, but preserve errno */
-static void
-unmap_file(void*  address, size_t  size)
-{
-    int old_errno = errno;
-    TEMP_FAILURE_RETRY(munmap(address, size));
-    errno = old_errno;
-}
-
-/* Check that a given directory:
- * - exists
- * - is owned by a given uid/gid
- * - is a real directory, not a symlink
- * - isn't readable or writable by others
- *
- * Return 0 on success, or -1 on error.
- * errno is set to EINVAL in case of failed check.
- */
-static int
-check_directory_ownership(const char* path, uid_t uid)
-{
-    int ret;
-    struct stat st;
-
-    do {
-        ret = lstat(path, &st);
-    } while (ret < 0 && errno == EINTR);
-
-    if (ret < 0)
-        return -1;
-
-    /* must be a real directory, not a symlink */
-    if (!S_ISDIR(st.st_mode))
-        goto BAD;
-
-    /* must be owned by specific uid/gid */
-    if (st.st_uid != uid || st.st_gid != uid)
-        goto BAD;
-
-    /* must not be readable or writable by others */
-    if ((st.st_mode & (S_IROTH|S_IWOTH)) != 0)
-        goto BAD;
-
-    /* everything ok */
-    return 0;
-
-BAD:
-    errno = EINVAL;
-    return -1;
-}
-
-/* This function is used to check the data directory path for safety.
- * We check that every sub-directory is owned by the 'system' user
- * and exists and is not a symlink. We also check that the full directory
- * path is properly owned by the user ID.
- *
- * Return 0 on success, -1 on error.
- */
-int
-check_data_path(const char* dataPath, uid_t  uid)
-{
-    int  nn;
-
-    /* the path should be absolute */
-    if (dataPath[0] != '/') {
-        errno = EINVAL;
-        return -1;
-    }
-
-    /* look for all sub-paths, we do that by finding
-     * directory separators in the input path and
-     * checking each sub-path independently
-     */
-    for (nn = 1; dataPath[nn] != '\0'; nn++)
-    {
-        char subpath[PATH_MAX];
-
-        /* skip non-separator characters */
-        if (dataPath[nn] != '/')
-            continue;
-
-        /* handle trailing separator case */
-        if (dataPath[nn+1] == '\0') {
-            break;
-        }
-
-        /* found a separator, check that dataPath is not too long. */
-        if (nn >= (int)(sizeof subpath)) {
-            errno = EINVAL;
-            return -1;
-        }
-
-        /* reject any '..' subpath */
-        if (nn >= 3               &&
-            dataPath[nn-3] == '/' &&
-            dataPath[nn-2] == '.' &&
-            dataPath[nn-1] == '.') {
-            errno = EINVAL;
-            return -1;
-        }
-
-        /* copy to 'subpath', then check ownership */
-        memcpy(subpath, dataPath, nn);
-        subpath[nn] = '\0';
-
-        if (check_directory_ownership(subpath, AID_SYSTEM) < 0)
-            return -1;
-    }
-
-    /* All sub-paths were checked, now verify that the full data
-     * directory is owned by the application uid
-     */
-    if (check_directory_ownership(dataPath, uid) < 0)
-        return -1;
-
-    /* all clear */
-    return 0;
-}
-
-/* Return TRUE iff a character is a space or tab */
-static inline int
-is_space(char c)
-{
-    return (c == ' ' || c == '\t');
-}
-
-/* Skip any space or tab character from 'p' until 'end' is reached.
- * Return new position.
- */
-static const char*
-skip_spaces(const char*  p, const char*  end)
-{
-    while (p < end && is_space(*p))
-        p++;
-
-    return p;
-}
-
-/* Skip any non-space and non-tab character from 'p' until 'end'.
- * Return new position.
- */
-static const char*
-skip_non_spaces(const char* p, const char* end)
-{
-    while (p < end && !is_space(*p))
-        p++;
-
-    return p;
-}
-
-/* Find the first occurence of 'ch' between 'p' and 'end'
- * Return its position, or 'end' if none is found.
- */
-static const char*
-find_first(const char* p, const char* end, char ch)
-{
-    while (p < end && *p != ch)
-        p++;
-
-    return p;
-}
-
-/* Check that the non-space string starting at 'p' and eventually
- * ending at 'end' equals 'name'. Return new position (after name)
- * on success, or NULL on failure.
- *
- * This function fails is 'name' is NULL, empty or contains any space.
- */
-static const char*
-compare_name(const char* p, const char* end, const char* name)
-{
-    /* 'name' must not be NULL or empty */
-    if (name == NULL || name[0] == '\0' || p == end)
-        return NULL;
-
-    /* compare characters to those in 'name', excluding spaces */
-    while (*name) {
-        /* note, we don't check for *p == '\0' since
-         * it will be caught in the next conditional.
-         */
-        if (p >= end || is_space(*p))
-            goto BAD;
-
-        if (*p != *name)
-            goto BAD;
-
-        p++;
-        name++;
-    }
-
-    /* must be followed by end of line or space */
-    if (p < end && !is_space(*p))
-        goto BAD;
-
-    return p;
-
-BAD:
-    return NULL;
-}
-
-/* Parse one or more whitespace characters starting from '*pp'
- * until 'end' is reached. Updates '*pp' on exit.
- *
- * Return 0 on success, -1 on failure.
- */
-static int
-parse_spaces(const char** pp, const char* end)
-{
-    const char* p = *pp;
-
-    if (p >= end || !is_space(*p)) {
-        errno = EINVAL;
-        return -1;
-    }
-    p   = skip_spaces(p, end);
-    *pp = p;
-    return 0;
-}
-
-/* Parse a positive decimal number starting from '*pp' until 'end'
- * is reached. Adjust '*pp' on exit. Return decimal value or -1
- * in case of error.
- *
- * If the value is larger than INT_MAX, -1 will be returned,
- * and errno set to EOVERFLOW.
- *
- * If '*pp' does not start with a decimal digit, -1 is returned
- * and errno set to EINVAL.
- */
-static int
-parse_positive_decimal(const char** pp, const char* end)
-{
-    const char* p = *pp;
-    int value = 0;
-    int overflow = 0;
-
-    if (p >= end || *p < '0' || *p > '9') {
-        errno = EINVAL;
-        return -1;
-    }
-
-    while (p < end) {
-        int      ch = *p;
-        unsigned d  = (unsigned)(ch - '0');
-        int      val2;
-
-        if (d >= 10U) /* d is unsigned, no lower bound check */
-            break;
-
-        val2 = value*10 + (int)d;
-        if (val2 < value)
-            overflow = 1;
-        value = val2;
-        p++;
-    }
-    *pp = p;
-
-    if (overflow) {
-        errno = EOVERFLOW;
-        value = -1;
-    }
-    return value;
-}
-
-/* Read the system's package database and extract information about
- * 'pkgname'. Return 0 in case of success, or -1 in case of error.
- *
- * If the package is unknown, return -1 and set errno to ENOENT
- * If the package database is corrupted, return -1 and set errno to EINVAL
- */
-int
-get_package_info(const char* pkgName, uid_t userId, PackageInfo *info)
-{
-    char*        buffer;
-    size_t       buffer_len;
-    const char*  p;
-    const char*  buffer_end;
-    int          result = -1;
-
-    info->uid          = 0;
-    info->isDebuggable = 0;
-    info->dataDir[0]   = '\0';
-    info->seinfo[0]    = '\0';
-
-    buffer = map_file(PACKAGES_LIST_FILE, &buffer_len);
-    if (buffer == NULL)
-        return -1;
-
-    p          = buffer;
-    buffer_end = buffer + buffer_len;
-
-    /* expect the following format on each line of the control file:
-     *
-     *  <pkgName> <uid> <debugFlag> <dataDir> <seinfo>
-     *
-     * where:
-     *  <pkgName>    is the package's name
-     *  <uid>        is the application-specific user Id (decimal)
-     *  <debugFlag>  is 1 if the package is debuggable, or 0 otherwise
-     *  <dataDir>    is the path to the package's data directory (e.g. /data/data/com.example.foo)
-     *  <seinfo>     is the seinfo label associated with the package
-     *
-     * The file is generated in com.android.server.PackageManagerService.Settings.writeLP()
-     */
-
-    while (p < buffer_end) {
-        /* find end of current line and start of next one */
-        const char*  end  = find_first(p, buffer_end, '\n');
-        const char*  next = (end < buffer_end) ? end + 1 : buffer_end;
-        const char*  q;
-        int          uid, debugFlag;
-
-        /* first field is the package name */
-        p = compare_name(p, end, pkgName);
-        if (p == NULL)
-            goto NEXT_LINE;
-
-        /* skip spaces */
-        if (parse_spaces(&p, end) < 0)
-            goto BAD_FORMAT;
-
-        /* second field is the pid */
-        uid = parse_positive_decimal(&p, end);
-        if (uid < 0)
-            return -1;
-
-        info->uid = (uid_t) uid;
-
-        /* skip spaces */
-        if (parse_spaces(&p, end) < 0)
-            goto BAD_FORMAT;
-
-        /* third field is debug flag (0 or 1) */
-        debugFlag = parse_positive_decimal(&p, end);
-        switch (debugFlag) {
-        case 0:
-            info->isDebuggable = 0;
-            break;
-        case 1:
-            info->isDebuggable = 1;
-            break;
-        default:
-            goto BAD_FORMAT;
-        }
-
-        /* skip spaces */
-        if (parse_spaces(&p, end) < 0)
-            goto BAD_FORMAT;
-
-        /* fourth field is data directory path and must not contain
-         * spaces.
-         */
-        q = skip_non_spaces(p, end);
-        if (q == p)
-            goto BAD_FORMAT;
-
-        /* If userId == 0 (i.e. user is device owner) we can use dataDir value
-         * from packages.list, otherwise compose data directory as
-         * /data/user/$uid/$packageId
-         */
-        if (userId == 0) {
-            p = string_copy(info->dataDir, sizeof info->dataDir, p, q - p);
-        } else {
-            snprintf(info->dataDir,
-                     sizeof info->dataDir,
-                     "/data/user/%d/%s",
-                     userId,
-                     pkgName);
-            p = q;
-        }
-
-        /* skip spaces */
-        if (parse_spaces(&p, end) < 0)
-            goto BAD_FORMAT;
-
-        /* fifth field is the seinfo string */
-        q = skip_non_spaces(p, end);
-        if (q == p)
-            goto BAD_FORMAT;
-
-        string_copy(info->seinfo, sizeof info->seinfo, p, q - p);
-
-        /* Ignore the rest */
-        result = 0;
-        goto EXIT;
-
-    NEXT_LINE:
-        p = next;
-    }
-
-    /* the package is unknown */
-    errno = ENOENT;
-    result = -1;
-    goto EXIT;
-
-BAD_FORMAT:
-    errno = EINVAL;
-    result = -1;
-
-EXIT:
-    unmap_file(buffer, buffer_len);
-    return result;
-}
diff --git a/run-as/package.h b/run-as/package.h
deleted file mode 100644
index eeb5913..0000000
--- a/run-as/package.h
+++ /dev/null
@@ -1,44 +0,0 @@
-/*
-**
-** Copyright 2010, 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.
-*/
-#ifndef RUN_AS_PACKAGE_H
-#define RUN_AS_PACKAGE_H
-
-#include <limits.h>
-#include <sys/types.h>
-
-typedef enum {
-    PACKAGE_IS_DEBUGGABLE = 0,
-    PACKAGE_IS_NOT_DEBUGGABLE,
-    PACKAGE_IS_UNKNOWN,
-} PackageStatus;
-
-typedef struct {
-    uid_t  uid;
-    char   isDebuggable;
-    char   dataDir[PATH_MAX];
-    char   seinfo[PATH_MAX];
-} PackageInfo;
-
-/* see documentation in package.c for these functions */
-
-extern int  get_package_info(const char* packageName,
-                             uid_t userId,
-                             PackageInfo*  info);
-
-extern int  check_data_path(const char* dataDir, uid_t uid);
-
-#endif /* RUN_AS_PACKAGE_H */
diff --git a/run-as/run-as.c b/run-as/run-as.c
deleted file mode 100644
index f0fd2fe..0000000
--- a/run-as/run-as.c
+++ /dev/null
@@ -1,224 +0,0 @@
-/*
-**
-** Copyright 2010, 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 PROGNAME "run-as"
-#define LOG_TAG  PROGNAME
-
-#include <dirent.h>
-#include <errno.h>
-#include <paths.h>
-#include <pwd.h>
-#include <stdarg.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <sys/capability.h>
-#include <sys/cdefs.h>
-#include <sys/stat.h>
-#include <sys/types.h>
-#include <time.h>
-#include <unistd.h>
-
-#include <private/android_filesystem_config.h>
-#include <selinux/android.h>
-
-#include "package.h"
-
-/*
- *  WARNING WARNING WARNING WARNING
- *
- *  This program runs with CAP_SETUID and CAP_SETGID capabilities on Android
- *  production devices. Be very conservative when modifying it to avoid any
- *  serious security issue. Keep in mind the following:
- *
- *  - This program should only run for the 'root' or 'shell' users
- *
- *  - Avoid anything that is more complex than simple system calls
- *    until the uid/gid has been dropped to that of a normal user
- *    or you are sure to exit.
- *
- *    This avoids depending on environment variables, system properties
- *    and other external factors that may affect the C library in
- *    unpredictable ways.
- *
- *  - Do not trust user input and/or the filesystem whenever possible.
- *
- *  Read README.TXT for more details.
- *
- *
- *
- * The purpose of this program is to run a command as a specific
- * application user-id. Typical usage is:
- *
- *   run-as <package-name> <command> <args>
- *
- *  The 'run-as' binary is installed with CAP_SETUID and CAP_SETGID file
- *  capabilities, but will check the following:
- *
- *  - that it is invoked from the 'shell' or 'root' user (abort otherwise)
- *  - that '<package-name>' is the name of an installed and debuggable package
- *  - that the package's data directory is well-formed (see package.c)
- *
- *  If so, it will drop to the application's user id / group id, cd to the
- *  package's data directory, then run the command there.
- *
- *  NOTE: In the future it might not be possible to cd to the package's data
- *  directory under that package's user id / group id, in which case this
- *  utility will need to be changed accordingly.
- *
- *  This can be useful for a number of different things on production devices:
- *
- *  - Allow application developers to look at their own applicative data
- *    during development.
- *
- *  - Run the 'gdbserver' binary executable to allow native debugging
- */
-
-__noreturn static void
-panic(const char* format, ...)
-{
-    va_list args;
-    int e = errno;
-
-    fprintf(stderr, "%s: ", PROGNAME);
-    va_start(args, format);
-    vfprintf(stderr, format, args);
-    va_end(args);
-    exit(e ? -e : 1);
-}
-
-static void
-usage(void)
-{
-    panic("Usage:\n    " PROGNAME " <package-name> [--user <uid>] <command> [<args>]\n");
-}
-
-int main(int argc, char **argv)
-{
-    const char* pkgname;
-    uid_t myuid, uid, gid, userAppId = 0;
-    int commandArgvOfs = 2, userId = 0;
-    PackageInfo info;
-    struct __user_cap_header_struct capheader;
-    struct __user_cap_data_struct capdata[2];
-
-    /* check arguments */
-    if (argc < 2) {
-        usage();
-    }
-
-    /* check userid of caller - must be 'shell' or 'root' */
-    myuid = getuid();
-    if (myuid != AID_SHELL && myuid != AID_ROOT) {
-        panic("only 'shell' or 'root' users can run this program\n");
-    }
-
-    memset(&capheader, 0, sizeof(capheader));
-    memset(&capdata, 0, sizeof(capdata));
-    capheader.version = _LINUX_CAPABILITY_VERSION_3;
-    capdata[CAP_TO_INDEX(CAP_SETUID)].effective |= CAP_TO_MASK(CAP_SETUID);
-    capdata[CAP_TO_INDEX(CAP_SETGID)].effective |= CAP_TO_MASK(CAP_SETGID);
-    capdata[CAP_TO_INDEX(CAP_SETUID)].permitted |= CAP_TO_MASK(CAP_SETUID);
-    capdata[CAP_TO_INDEX(CAP_SETGID)].permitted |= CAP_TO_MASK(CAP_SETGID);
-
-    if (capset(&capheader, &capdata[0]) < 0) {
-        panic("Could not set capabilities: %s\n", strerror(errno));
-    }
-
-    pkgname = argv[1];
-
-    /* get user_id from command line if provided */
-    if ((argc >= 4) && !strcmp(argv[2], "--user")) {
-        userId = atoi(argv[3]);
-        if (userId < 0)
-            panic("Negative user id %d is provided\n", userId);
-        commandArgvOfs += 2;
-    }
-
-    /* retrieve package information from system (does setegid) */
-    if (get_package_info(pkgname, userId, &info) < 0) {
-        panic("Package '%s' is unknown\n", pkgname);
-    }
-
-    /* verify that user id is not too big. */
-    if ((UID_MAX - info.uid) / AID_USER < (uid_t)userId) {
-        panic("User id %d is too big\n", userId);
-    }
-
-    /* calculate user app ID. */
-    userAppId = (AID_USER * userId) + info.uid;
-
-    /* reject system packages */
-    if (userAppId < AID_APP) {
-        panic("Package '%s' is not an application\n", pkgname);
-    }
-
-    /* reject any non-debuggable package */
-    if (!info.isDebuggable) {
-        panic("Package '%s' is not debuggable\n", pkgname);
-    }
-
-    /* check that the data directory path is valid */
-    if (check_data_path(info.dataDir, userAppId) < 0) {
-        panic("Package '%s' has corrupt installation\n", pkgname);
-    }
-
-    /* Ensure that we change all real/effective/saved IDs at the
-     * same time to avoid nasty surprises.
-     */
-    uid = gid = userAppId;
-    if(setresgid(gid,gid,gid) || setresuid(uid,uid,uid)) {
-        panic("Permission denied\n");
-    }
-
-    /* Required if caller has uid and gid all non-zero */
-    memset(&capdata, 0, sizeof(capdata));
-    if (capset(&capheader, &capdata[0]) < 0) {
-        panic("Could not clear all capabilities: %s\n", strerror(errno));
-    }
-
-    if (selinux_android_setcontext(uid, 0, info.seinfo, pkgname) < 0) {
-        panic("Could not set SELinux security context: %s\n", strerror(errno));
-    }
-
-    // cd into the data directory, and set $HOME correspondingly.
-    if (TEMP_FAILURE_RETRY(chdir(info.dataDir)) < 0) {
-        panic("Could not cd to package's data directory: %s\n", strerror(errno));
-    }
-    setenv("HOME", info.dataDir, 1);
-
-    // Reset parts of the environment, like su would.
-    setenv("PATH", _PATH_DEFPATH, 1);
-    unsetenv("IFS");
-
-    // Set the user-specific parts for this user.
-    struct passwd* pw = getpwuid(uid);
-    setenv("LOGNAME", pw->pw_name, 1);
-    setenv("SHELL", pw->pw_shell, 1);
-    setenv("USER", pw->pw_name, 1);
-
-    /* User specified command for exec. */
-    if ((argc >= commandArgvOfs + 1) &&
-        (execvp(argv[commandArgvOfs], argv+commandArgvOfs) < 0)) {
-        panic("exec failed for %s: %s\n", argv[commandArgvOfs], strerror(errno));
-    }
-
-    /* Default exec shell. */
-    execlp("/system/bin/sh", "sh", NULL);
-
-    panic("exec failed: %s\n", strerror(errno));
-}
diff --git a/run-as/run-as.cpp b/run-as/run-as.cpp
new file mode 100644
index 0000000..50b47b9
--- /dev/null
+++ b/run-as/run-as.cpp
@@ -0,0 +1,246 @@
+/*
+ * Copyright (C) 2010 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 <errno.h>
+#include <error.h>
+#include <paths.h>
+#include <pwd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/capability.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <packagelistparser/packagelistparser.h>
+#include <private/android_filesystem_config.h>
+#include <selinux/android.h>
+
+// The purpose of this program is to run a command as a specific
+// application user-id. Typical usage is:
+//
+//   run-as <package-name> <command> <args>
+//
+//  The 'run-as' binary is installed with CAP_SETUID and CAP_SETGID file
+//  capabilities, but will check the following:
+//
+//  - that it is invoked from the 'shell' or 'root' user (abort otherwise)
+//  - that '<package-name>' is the name of an installed and debuggable package
+//  - that the package's data directory is well-formed
+//
+//  If so, it will drop to the application's user id / group id, cd to the
+//  package's data directory, then run the command there.
+//
+//  This can be useful for a number of different things on production devices:
+//
+//  - Allow application developers to look at their own application data
+//    during development.
+//
+//  - Run the 'gdbserver' binary executable to allow native debugging
+//
+
+static bool packagelist_parse_callback(pkg_info* this_package, void* userdata) {
+  pkg_info* p = reinterpret_cast<pkg_info*>(userdata);
+  if (strcmp(p->name, this_package->name) == 0) {
+    *p = *this_package;
+    return false; // Stop searching.
+  }
+  packagelist_free(this_package);
+  return true; // Keep searching.
+}
+
+static bool check_directory(const char* path, uid_t uid) {
+  struct stat st;
+  if (TEMP_FAILURE_RETRY(lstat(path, &st)) == -1) return false;
+
+  // /data/user/0 is a known safe symlink.
+  if (strcmp("/data/user/0", path) == 0) return true;
+
+  // Must be a real directory, not a symlink.
+  if (!S_ISDIR(st.st_mode)) return false;
+
+  // Must be owned by specific uid/gid.
+  if (st.st_uid != uid || st.st_gid != uid) return false;
+
+  // Must not be readable or writable by others.
+  if ((st.st_mode & (S_IROTH|S_IWOTH)) != 0) return false;
+
+  return true;
+}
+
+// This function is used to check the data directory path for safety.
+// We check that every sub-directory is owned by the 'system' user
+// and exists and is not a symlink. We also check that the full directory
+// path is properly owned by the user ID.
+static bool check_data_path(const char* data_path, uid_t uid) {
+  // The path should be absolute.
+  if (data_path[0] != '/') return false;
+
+  // Look for all sub-paths, we do that by finding
+  // directory separators in the input path and
+  // checking each sub-path independently.
+  for (int nn = 1; data_path[nn] != '\0'; nn++) {
+    char subpath[PATH_MAX];
+
+    /* skip non-separator characters */
+    if (data_path[nn] != '/') continue;
+
+    /* handle trailing separator case */
+    if (data_path[nn+1] == '\0') break;
+
+    /* found a separator, check that data_path is not too long. */
+    if (nn >= (int)(sizeof subpath)) return false;
+
+    /* reject any '..' subpath */
+    if (nn >= 3               &&
+        data_path[nn-3] == '/' &&
+        data_path[nn-2] == '.' &&
+        data_path[nn-1] == '.') {
+      return false;
+    }
+
+    /* copy to 'subpath', then check ownership */
+    memcpy(subpath, data_path, nn);
+    subpath[nn] = '\0';
+
+    if (!check_directory(subpath, AID_SYSTEM)) return false;
+  }
+
+  // All sub-paths were checked, now verify that the full data
+  // directory is owned by the application uid.
+  return check_directory(data_path, uid);
+}
+
+int main(int argc, char* argv[]) {
+  // Check arguments.
+  if (argc < 2) {
+    error(1, 0, "usage: run-as <package-name> [--user <uid>] <command> [<args>]\n");
+  }
+
+  // This program runs with CAP_SETUID and CAP_SETGID capabilities on Android
+  // production devices. Check user id of caller --- must be 'shell' or 'root'.
+  if (getuid() != AID_SHELL && getuid() != AID_ROOT) {
+    error(1, 0, "only 'shell' or 'root' users can run this program");
+  }
+
+  __user_cap_header_struct capheader;
+  __user_cap_data_struct capdata[2];
+  memset(&capheader, 0, sizeof(capheader));
+  memset(&capdata, 0, sizeof(capdata));
+  capheader.version = _LINUX_CAPABILITY_VERSION_3;
+  capdata[CAP_TO_INDEX(CAP_SETUID)].effective |= CAP_TO_MASK(CAP_SETUID);
+  capdata[CAP_TO_INDEX(CAP_SETGID)].effective |= CAP_TO_MASK(CAP_SETGID);
+  capdata[CAP_TO_INDEX(CAP_SETUID)].permitted |= CAP_TO_MASK(CAP_SETUID);
+  capdata[CAP_TO_INDEX(CAP_SETGID)].permitted |= CAP_TO_MASK(CAP_SETGID);
+  if (capset(&capheader, &capdata[0]) == -1) {
+    error(1, errno, "couldn't set capabilities");
+  }
+
+  char* pkgname = argv[1];
+  int cmd_argv_offset = 2;
+
+  // Get user_id from command line if provided.
+  int userId = 0;
+  if ((argc >= 4) && !strcmp(argv[2], "--user")) {
+    userId = atoi(argv[3]);
+    if (userId < 0) error(1, 0, "negative user id: %d", userId);
+    cmd_argv_offset += 2;
+  }
+
+  // Retrieve package information from system, switching egid so we can read the file.
+  gid_t old_egid = getegid();
+  if (setegid(AID_PACKAGE_INFO) == -1) error(1, errno, "setegid(AID_PACKAGE_INFO) failed");
+  pkg_info info;
+  memset(&info, 0, sizeof(info));
+  info.name = pkgname;
+  if (!packagelist_parse(packagelist_parse_callback, &info)) {
+    error(1, errno, "packagelist_parse failed");
+  }
+  if (info.uid == 0) {
+    error(1, 0, "unknown package: %s", pkgname);
+  }
+  if (setegid(old_egid) == -1) error(1, errno, "couldn't restore egid");
+
+  // Verify that user id is not too big.
+  if ((UID_MAX - info.uid) / AID_USER < (uid_t)userId) {
+    error(1, 0, "user id too big: %d", userId);
+  }
+
+  // Calculate user app ID.
+  uid_t userAppId = (AID_USER * userId) + info.uid;
+
+  // Reject system packages.
+  if (userAppId < AID_APP) {
+    error(1, 0, "package not an application: %s", pkgname);
+  }
+
+  // Reject any non-debuggable package.
+  if (!info.debuggable) {
+    error(1, 0, "package not debuggable: %s", pkgname);
+  }
+
+  // Check that the data directory path is valid.
+  if (!check_data_path(info.data_dir, userAppId)) {
+    error(1, 0, "package has corrupt installation: %s", pkgname);
+  }
+
+  // Ensure that we change all real/effective/saved IDs at the
+  // same time to avoid nasty surprises.
+  uid_t uid = userAppId;
+  uid_t gid = userAppId;
+  if (setresgid(gid, gid, gid) == -1) {
+    error(1, errno, "setresgid failed");
+  }
+  if (setresuid(uid, uid, uid) == -1) {
+    error(1, errno, "setresuid failed");
+  }
+
+  // Required if caller has uid and gid all non-zero.
+  memset(&capdata, 0, sizeof(capdata));
+  if (capset(&capheader, &capdata[0]) == -1) {
+    error(1, errno, "couldn't clear all capabilities");
+  }
+
+  if (selinux_android_setcontext(uid, 0, info.seinfo, pkgname) < 0) {
+    error(1, errno, "couldn't set SELinux security context");
+  }
+
+  // cd into the data directory, and set $HOME correspondingly.
+  if (TEMP_FAILURE_RETRY(chdir(info.data_dir)) == -1) {
+    error(1, errno, "couldn't chdir to package's data directory");
+  }
+  setenv("HOME", info.data_dir, 1);
+
+  // Reset parts of the environment, like su would.
+  setenv("PATH", _PATH_DEFPATH, 1);
+  unsetenv("IFS");
+
+  // Set the user-specific parts for this user.
+  passwd* pw = getpwuid(uid);
+  setenv("LOGNAME", pw->pw_name, 1);
+  setenv("SHELL", pw->pw_shell, 1);
+  setenv("USER", pw->pw_name, 1);
+
+  // User specified command for exec.
+  if ((argc >= cmd_argv_offset + 1) &&
+      (execvp(argv[cmd_argv_offset], argv+cmd_argv_offset) == -1)) {
+    error(1, errno, "exec failed for %s", argv[cmd_argv_offset]);
+  }
+
+  // Default exec shell.
+  execlp(_PATH_BSHELL, "sh", NULL);
+  error(1, errno, "exec failed");
+}