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Android su源代码

IT知识源代码android

欠伸展肢体，吟咏心自愉。这篇文章主要讲述Android su源代码相关的知识，希望能为你提供帮助。
android su源代码在AOSP中的位置是/system/extras/su

/* * Copyright (C) 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 < errno.h> #include < error.h> #include < getopt.h> #include < paths.h> #include < pwd.h> #include < stdio.h> #include < stdlib.h> #include < string.h> #include < unistd.h> #include < private/android_filesystem_config.h> void pwtoid(const char* tok, uid_t* uid, gid_t* gid) { struct passwd* pw = getpwnam(tok); if (pw) { if (uid) *uid = pw-> pw_uid; if (gid) *gid = pw-> pw_gid; } else { char* end; errno = 0; uid_t tmpid = strtoul(tok, & end, 10); if (errno != 0 || end == tok) error(1, errno, "invalid uid/gid ‘%s‘", tok); if (uid) *uid = tmpid; if (gid) *gid = tmpid; } }void extract_uidgids(const char* uidgids, uid_t* uid, gid_t* gid, gid_t* gids, int* gids_count) { char *clobberablegids; char *nexttok; char *tok; int gids_found; if (!uidgids || !*uidgids) { *gid = *uid = 0; *gids_count = 0; return; }clobberablegids = strdup(uidgids); strcpy(clobberablegids, uidgids); nexttok = clobberablegids; tok = strsep(& nexttok, ","); pwtoid(tok, uid, gid); tok = strsep(& nexttok, ","); if (!tok) { /* gid is already set above */ *gids_count = 0; free(clobberablegids); return; } pwtoid(tok, NULL, gid); gids_found = 0; while ((gids_found < *gids_count) & & (tok = strsep(& nexttok, ","))) { pwtoid(tok, NULL, gids); gids_found++; gids++; } if (nexttok & & gids_found == *gids_count) { fprintf(stderr, "too many group ids "); } *gids_count = gids_found; free(clobberablegids); }int main(int argc, char** argv) { uid_t current_uid = getuid(); if (current_uid != AID_ROOT & & current_uid != AID_SHELL) error(1, 0, "not allowed"); // Handle -h and --help. ++argv; if (*argv & & (strcmp(*argv, "--help") == 0 || strcmp(*argv, "-h") == 0)) { fprintf(stderr, "usage: su [WHO [COMMAND...]] " " " "Switch to WHO (default ‘root‘) and run the given COMMAND (default sh). " " " "WHO is a comma-separated list of user, group, and supplementary groups " "in that order. " " "); return 0; }// The default user is root. uid_t uid = 0; gid_t gid = 0; // If there are any arguments, the first argument is the uid/gid/supplementary groups. if (*argv) { gid_t gids[10]; int gids_count = sizeof(gids)/sizeof(gids[0]); extract_uidgids(*argv, & uid, & gid, gids, & gids_count); if (gids_count) { if (setgroups(gids_count, gids)) { error(1, errno, "setgroups failed"); } } ++argv; }if (setgid(gid)) error(1, errno, "setgid failed"); if (setuid(uid)) error(1, errno, "setuid failed"); // Reset parts of the environment. setenv("PATH", _PATH_DEFPATH, 1); unsetenv("IFS"); struct passwd* pw = getpwuid(uid); if (pw) { setenv("LOGNAME", pw-> pw_name, 1); setenv("USER", pw-> pw_name, 1); } else { unsetenv("LOGNAME"); unsetenv("USER"); }// Set up the arguments for exec. char* exec_args[argc + 1]; // Having too much space is fine. size_t i = 0; for (; *argv != NULL; ++i) { exec_args[i] = *argv++; } // Default to the standard shell. if (i == 0) exec_args[i++] = const_cast< char*> ("/system/bin/sh"); exec_args[i] = NULL; execvp(exec_args[0], exec_args); error(1, errno, "failed to exec %s", exec_args[0]); }

【Android su源代码】 

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