解决方法
我编写了一个实用程序类来通过硬编码来自
android_filesystem_config.h的值来获取UID / GID名称.
用法：
String uid = AndroidFilesystemConfig.getNameForId(1000);
import android.os.Build; import android.util.SparseArray; import java.util.Locale; /** * <p>System Users and Groups for the Android platform as specified in * <a href="https://android.googlesource.com/platform/system/core/+/master/include/private/android_filesystem_config.h">android_filesystem_config.h</a>.</p> * * <p>Last updated: April 20th,2016</p> * * <p><b>Note:</b> Some OEMs may have specific UIDs for other system users not in this class.</p> */ public class AndroidFilesystemConfig { /* first app user */ private static final int AID_APP = 10000; /* offset for uid ranges for each user */ private static final int AID_USER = 100000; /* start of gids for apps in each user to share */ private static final int AID_SHARED_GID_START = 50000; /* end of gids for apps in each user to share */ private static final int AID_SHARED_GID_END = 59999; private static final SparseArray<String> SYstem_IDS = new SparseArray<>(); static { putSystemId(0,"root"); /* Traditional unix root user */ putSystemId(1000,"system"); /* system server */ putSystemId(1001,"radio"); /* telephony subsystem,RIL */ putSystemId(1002,"bluetooth"); /* bluetooth subsystem */ putSystemId(1003,"graphics"); /* graphics devices */ putSystemId(1004,"input"); /* input devices */ putSystemId(1005,"audio"); /* audio devices */ putSystemId(1006,"camera"); /* camera devices */ putSystemId(1007,"log"); /* log devices */ putSystemId(1008,"compass"); /* compass device */ putSystemId(1009,"mount"); /* mountd socket */ putSystemId(1010,"wifi"); /* wifi subsystem */ putSystemId(1011,"adb"); /* android debug bridge (adbd) */ putSystemId(1012,"install"); /* group for installing packages */ putSystemId(1013,"media"); /* mediaserver process */ putSystemId(1014,"dhcp"); /* dhcp client */ putSystemId(1015,"sdcard_rw"); /* external storage write access */ putSystemId(1016,"vpn"); /* vpn system */ putSystemId(1017,"keystore"); /* keystore subsystem */ putSystemId(1018,"usb"); /* USB devices */ putSystemId(1019,"drm"); /* DRM server */ putSystemId(1020,"mdnsr"); /* MulticastDNSResponder (service discovery) */ putSystemId(1021,"gps"); /* GPS daemon */ // 1022 is deprecated and not used. putSystemId(1023,"media_rw"); /* internal media storage write access */ putSystemId(1024,"mtp"); /* MTP USB driver access */ // 1025 is deprecated and not used. putSystemId(1026,"drmrpc"); /* group for drm rpc */ putSystemId(1027,"nfc"); /* nfc subsystem */ putSystemId(1028,"sdcard_r"); /* external storage read access */ putSystemId(1029,"clat"); /* clat part of nat464 */ putSystemId(1030,"loop_radio"); /* loop radio devices */ putSystemId(1031,"mediadrm"); /* MediaDrm plugins */ putSystemId(1032,"package_info"); /* access to installed package details */ putSystemId(1033,"sdcard_pics"); /* external storage photos access */ putSystemId(1034,"sdcard_av"); /* external storage audio/video access */ putSystemId(1035,"sdcard_all"); /* access all users external storage */ putSystemId(1036,"logd"); /* log daemon */ putSystemId(1037,"shared_relro"); /* creator of shared GNU RELRO files */ putSystemId(1038,"dbus"); /* dbus-daemon IPC broker process */ putSystemId(1039,"tlsdate"); /* tlsdate unprivileged user */ putSystemId(1040,"mediaex"); /* mediaextractor process */ putSystemId(1041,"audioserver"); /* audioserver process */ putSystemId(1042,"metrics_coll"); /* metrics_collector process */ putSystemId(1043,"metricsd"); /* metricsd process */ putSystemId(1044,"webserv"); /* webservd process */ putSystemId(1045,"debuggerd"); /* debuggerd unprivileged user */ putSystemId(1046,"mediacodec"); /* mediacodec process */ putSystemId(1047,"cameraserver"); /* cameraserver process */ putSystemId(1048,"firewall"); /* firewalld process */ putSystemId(1049,"trunks"); /* trunksd process (TPM daemon) */ putSystemId(1050,"nvram"); /* Access-controlled NVRAM */ putSystemId(1051,"dns"); /* DNS resolution daemon (system: netd) */ putSystemId(1052,"dns_tether"); /* DNS resolution daemon (tether: dnsmasq) */ putSystemId(1053,"webview_zygote"); /* WebView zygote process */ putSystemId(1054,"vehicle_network"); /* Vehicle network service */ putSystemId(1055,"media_audio"); /* GID for audio files on internal media storage */ putSystemId(1056,"media_video"); /* GID for video files on internal media storage */ putSystemId(1057,"media_image"); /* GID for image files on internal media storage */ putSystemId(2000,"shell"); /* adb and debug shell user */ putSystemId(2001,"cache"); /* cache access */ putSystemId(2002,"diag"); /* access to diagnostic resources */ /* The range 2900-2999 is reserved for OEMs */ // The 3000 series are intended for use as supplemental group id's only. They indicate // special Android capabilities that the kernel is aware of. putSystemId(3001,"net_bt_admin"); /* bluetooth: get any socket */ putSystemId(3002,"net_bt"); /* bluetooth: get sco,rfcomm or l2cap sockets */ putSystemId(3003,"inet"); /* can get AF_INET and AF_INET6 sockets */ putSystemId(3004,"net_raw"); /* can get raw INET sockets */ putSystemId(3005,"net_admin"); /* can configure interfaces and routing tables. */ putSystemId(3006,"net_bw_stats"); /* read bandwidth statistics */ putSystemId(3007,"net_bw_acct"); /* change bandwidth statistics accounting */ putSystemId(3008,"net_bt_stack"); /* bluetooth: access config files */ putSystemId(3009,"readproc"); /* Allow /proc read access */ putSystemId(3010,"wakelock"); /* Allow system wakelock read/write access */ /* The range 5000-5999 is also reserved for OEMs. */ putSystemId(9997,"everybody"); /* shared between all apps in the same profile */ putSystemId(9998,"misc"); /* access to misc storage */ putSystemId(9999,"nobody"); } private static void putSystemId(int id,String name) { // Check if the uid exists before adding it so we don't add unsupported ids. if (android.os.Process.getUidForName(name) != id) { // Not valid on this system. Most likely due to a lower API. return; } SYstem_IDS.put(id,name); } /** * @return An array of system UIDs */ public static SparseArray<String> getSystemIds() { return SYstem_IDS; } /** * Returns the UID/GID name assigned to a particular id,or {@code null} if there is none. * * @param id * The UID/GID of a process or file * @return the name of the UID/GID or {@code null} if the id is unrecognized. */ public static String getNameForId(int id) { String name = SYstem_IDS.get(id); if (name == null) { if (id >= AID_SHARED_GID_START && id <= AID_SHARED_GID_END) { name = String.format(Locale.ENGLISH,"all_a%d",id - AID_SHARED_GID_START); } else { int appId = id - AID_APP; int userId = 0; // loop until we get the correct user id. // 100000 is the offset for each user. while (appId > AID_USER) { appId -= AID_USER; userId++; } if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) { // u{user_id}_a{app_id} is used on API 17+ for multiple user account support. name = String.format(Locale.ENGLISH,"u%d_a%d",userId,appId); } else { // app_{app_id} is used below API 17. name = String.format(Locale.ENGLISH,"app_%d",appId); } } } return name; } private AndroidFilesystemConfig() { throw new AssertionError("no instances"); } }
使用反射：
受odexide的回答启发,这里有一些我不建议使用的非常丑陋的反映,它将从getpwuid(uid_t)获得UID / GID名称：
public static String getNameForUid(int id) {
try {
Class<?> clazz = Class.forName("libcore.io.Libcore");
Field field = clazz.getDeclaredField("os");
if (!field.isAccessible()) {
field.setAccessible(true);
}
Object os = field.get(null);
if (os != null) {
Method getpwuid = os.getClass().getmethod("getpwuid",int.class);
if (getpwuid != null) {
if (!getpwuid.isAccessible()) {
getpwuid.setAccessible(true);
}
Object passwd = getpwuid.invoke(os,id);
if (passwd != null) {
Field pw_name = passwd.getClass().getDeclaredField("pw_name");
if (!pw_name.isAccessible()) {
pw_name.setAccessible(true);
}
return (String) pw_name.get(passwd);
}
}
}
} catch (Exception ignored) {
}
return null;
}
