479 lines
12 KiB
C++
479 lines
12 KiB
C++
/*
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* Copyright (C) 2008 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <stdarg.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <fcntl.h>
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#include <ctype.h>
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#include <errno.h>
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#include <time.h>
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#include <ftw.h>
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#include <selinux/label.h>
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#include <selinux/android.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <sys/un.h>
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#include <base/file.h>
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#include <base/strings.h>
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/* for ANDROID_SOCKET_* */
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#include <cutils/sockets.h>
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#include <base/stringprintf.h>
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#include <private/android_filesystem_config.h>
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#include "init.h"
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#include "log.h"
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#include "util.h"
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/*
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* android_name_to_id - returns the integer uid/gid associated with the given
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* name, or UINT_MAX on error.
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*/
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static unsigned int android_name_to_id(const char *name)
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{
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const struct android_id_info *info = android_ids;
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unsigned int n;
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for (n = 0; n < android_id_count; n++) {
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if (!strcmp(info[n].name, name))
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return info[n].aid;
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}
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return UINT_MAX;
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}
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static unsigned int do_decode_uid(const char *s)
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{
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unsigned int v;
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if (!s || *s == '\0')
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return UINT_MAX;
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if (isalpha(s[0]))
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return android_name_to_id(s);
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errno = 0;
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v = (unsigned int) strtoul(s, 0, 0);
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if (errno)
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return UINT_MAX;
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return v;
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}
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/*
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* decode_uid - decodes and returns the given string, which can be either the
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* numeric or name representation, into the integer uid or gid. Returns
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* UINT_MAX on error.
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*/
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unsigned int decode_uid(const char *s) {
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unsigned int v = do_decode_uid(s);
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if (v == UINT_MAX) {
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ERROR("decode_uid: Unable to find UID for '%s'. Returning UINT_MAX\n", s);
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}
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return v;
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}
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/*
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* create_socket - creates a Unix domain socket in ANDROID_SOCKET_DIR
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* ("/dev/socket") as dictated in init.rc. This socket is inherited by the
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* daemon. We communicate the file descriptor's value via the environment
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* variable ANDROID_SOCKET_ENV_PREFIX<name> ("ANDROID_SOCKET_foo").
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*/
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int create_socket(const char *name, int type, mode_t perm, uid_t uid,
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gid_t gid, const char *socketcon)
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{
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struct sockaddr_un addr;
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int fd, ret;
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char *filecon;
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if (socketcon)
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setsockcreatecon(socketcon);
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fd = socket(PF_UNIX, type, 0);
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if (fd < 0) {
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ERROR("Failed to open socket '%s': %s\n", name, strerror(errno));
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return -1;
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}
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if (socketcon)
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setsockcreatecon(NULL);
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memset(&addr, 0 , sizeof(addr));
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addr.sun_family = AF_UNIX;
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snprintf(addr.sun_path, sizeof(addr.sun_path), ANDROID_SOCKET_DIR"/%s",
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name);
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ret = unlink(addr.sun_path);
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if (ret != 0 && errno != ENOENT) {
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ERROR("Failed to unlink old socket '%s': %s\n", name, strerror(errno));
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goto out_close;
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}
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filecon = NULL;
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if (sehandle) {
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ret = selabel_lookup(sehandle, &filecon, addr.sun_path, S_IFSOCK);
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if (ret == 0)
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setfscreatecon(filecon);
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}
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ret = bind(fd, (struct sockaddr *) &addr, sizeof (addr));
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if (ret) {
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ERROR("Failed to bind socket '%s': %s\n", name, strerror(errno));
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goto out_unlink;
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}
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setfscreatecon(NULL);
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freecon(filecon);
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chown(addr.sun_path, uid, gid);
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chmod(addr.sun_path, perm);
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INFO("Created socket '%s' with mode '%o', user '%d', group '%d'\n",
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addr.sun_path, perm, uid, gid);
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return fd;
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out_unlink:
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unlink(addr.sun_path);
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out_close:
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close(fd);
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return -1;
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}
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bool read_file(const char* path, std::string* content) {
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content->clear();
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int fd = TEMP_FAILURE_RETRY(open(path, O_RDONLY|O_NOFOLLOW|O_CLOEXEC));
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if (fd == -1) {
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return false;
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}
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// For security reasons, disallow world-writable
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// or group-writable files.
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struct stat sb;
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if (fstat(fd, &sb) == -1) {
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ERROR("fstat failed for '%s': %s\n", path, strerror(errno));
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return false;
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}
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if ((sb.st_mode & (S_IWGRP | S_IWOTH)) != 0) {
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ERROR("skipping insecure file '%s'\n", path);
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return false;
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}
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bool okay = android::base::ReadFdToString(fd, content);
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close(fd);
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return okay;
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}
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int write_file(const char* path, const char* content) {
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int fd = TEMP_FAILURE_RETRY(open(path, O_WRONLY|O_CREAT|O_NOFOLLOW|O_CLOEXEC, 0600));
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if (fd == -1) {
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NOTICE("write_file: Unable to open '%s': %s\n", path, strerror(errno));
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return -1;
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}
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int result = android::base::WriteStringToFd(content, fd) ? 0 : -1;
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if (result == -1) {
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NOTICE("write_file: Unable to write to '%s': %s\n", path, strerror(errno));
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}
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close(fd);
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return result;
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}
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#define MAX_MTD_PARTITIONS 16
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static struct {
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char name[16];
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int number;
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} mtd_part_map[MAX_MTD_PARTITIONS];
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static int mtd_part_count = -1;
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static void find_mtd_partitions(void)
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{
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int fd;
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char buf[1024];
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char *pmtdbufp;
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ssize_t pmtdsize;
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int r;
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fd = open("/proc/mtd", O_RDONLY|O_CLOEXEC);
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if (fd < 0)
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return;
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buf[sizeof(buf) - 1] = '\0';
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pmtdsize = read(fd, buf, sizeof(buf) - 1);
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pmtdbufp = buf;
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while (pmtdsize > 0) {
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int mtdnum, mtdsize, mtderasesize;
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char mtdname[16];
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mtdname[0] = '\0';
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mtdnum = -1;
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r = sscanf(pmtdbufp, "mtd%d: %x %x %15s",
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&mtdnum, &mtdsize, &mtderasesize, mtdname);
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if ((r == 4) && (mtdname[0] == '"')) {
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char *x = strchr(mtdname + 1, '"');
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if (x) {
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*x = 0;
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}
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INFO("mtd partition %d, %s\n", mtdnum, mtdname + 1);
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if (mtd_part_count < MAX_MTD_PARTITIONS) {
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strcpy(mtd_part_map[mtd_part_count].name, mtdname + 1);
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mtd_part_map[mtd_part_count].number = mtdnum;
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mtd_part_count++;
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} else {
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ERROR("too many mtd partitions\n");
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}
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}
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while (pmtdsize > 0 && *pmtdbufp != '\n') {
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pmtdbufp++;
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pmtdsize--;
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}
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if (pmtdsize > 0) {
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pmtdbufp++;
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pmtdsize--;
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}
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}
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close(fd);
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}
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int mtd_name_to_number(const char *name)
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{
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int n;
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if (mtd_part_count < 0) {
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mtd_part_count = 0;
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find_mtd_partitions();
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}
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for (n = 0; n < mtd_part_count; n++) {
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if (!strcmp(name, mtd_part_map[n].name)) {
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return mtd_part_map[n].number;
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}
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}
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return -1;
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}
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time_t gettime() {
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timespec now;
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clock_gettime(CLOCK_MONOTONIC, &now);
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return now.tv_sec;
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}
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uint64_t gettime_ns() {
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timespec now;
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clock_gettime(CLOCK_MONOTONIC, &now);
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return static_cast<uint64_t>(now.tv_sec) * UINT64_C(1000000000) + now.tv_nsec;
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}
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int mkdir_recursive(const char *pathname, mode_t mode)
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{
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char buf[128];
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const char *slash;
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const char *p = pathname;
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int width;
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int ret;
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struct stat info;
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while ((slash = strchr(p, '/')) != NULL) {
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width = slash - pathname;
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p = slash + 1;
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if (width < 0)
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break;
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if (width == 0)
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continue;
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if ((unsigned int)width > sizeof(buf) - 1) {
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ERROR("path too long for mkdir_recursive\n");
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return -1;
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}
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memcpy(buf, pathname, width);
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buf[width] = 0;
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if (stat(buf, &info) != 0) {
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ret = make_dir(buf, mode);
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if (ret && errno != EEXIST)
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return ret;
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}
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}
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ret = make_dir(pathname, mode);
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if (ret && errno != EEXIST)
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return ret;
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return 0;
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}
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/*
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* replaces any unacceptable characters with '_', the
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* length of the resulting string is equal to the input string
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*/
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void sanitize(char *s)
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{
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const char* accept =
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"abcdefghijklmnopqrstuvwxyz"
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"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
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"0123456789"
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"_-.";
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if (!s)
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return;
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while (*s) {
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s += strspn(s, accept);
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if (*s) *s++ = '_';
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}
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}
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void make_link(const char *oldpath, const char *newpath)
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{
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int ret;
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char buf[256];
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char *slash;
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int width;
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slash = strrchr(newpath, '/');
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if (!slash)
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return;
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width = slash - newpath;
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if (width <= 0 || width > (int)sizeof(buf) - 1)
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return;
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memcpy(buf, newpath, width);
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buf[width] = 0;
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ret = mkdir_recursive(buf, 0755);
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if (ret)
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ERROR("Failed to create directory %s: %s (%d)\n", buf, strerror(errno), errno);
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ret = symlink(oldpath, newpath);
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if (ret && errno != EEXIST)
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ERROR("Failed to symlink %s to %s: %s (%d)\n", oldpath, newpath, strerror(errno), errno);
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}
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void remove_link(const char *oldpath, const char *newpath)
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{
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char path[256];
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ssize_t ret;
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ret = readlink(newpath, path, sizeof(path) - 1);
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if (ret <= 0)
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return;
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path[ret] = 0;
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if (!strcmp(path, oldpath))
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unlink(newpath);
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}
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int wait_for_file(const char *filename, int timeout)
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{
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struct stat info;
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time_t timeout_time = gettime() + timeout;
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int ret = -1;
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while (gettime() < timeout_time && ((ret = stat(filename, &info)) < 0))
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usleep(10000);
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return ret;
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}
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void open_devnull_stdio(void)
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{
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// Try to avoid the mknod() call if we can. Since SELinux makes
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// a /dev/null replacement available for free, let's use it.
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int fd = open("/sys/fs/selinux/null", O_RDWR);
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if (fd == -1) {
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// OOPS, /sys/fs/selinux/null isn't available, likely because
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// /sys/fs/selinux isn't mounted. Fall back to mknod.
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static const char *name = "/dev/__null__";
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if (mknod(name, S_IFCHR | 0600, (1 << 8) | 3) == 0) {
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fd = open(name, O_RDWR);
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unlink(name);
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}
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if (fd == -1) {
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exit(1);
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}
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}
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dup2(fd, 0);
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dup2(fd, 1);
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dup2(fd, 2);
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if (fd > 2) {
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close(fd);
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}
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}
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void import_kernel_cmdline(bool in_qemu,
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std::function<void(const std::string&, const std::string&, bool)> fn) {
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std::string cmdline;
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android::base::ReadFileToString("/proc/cmdline", &cmdline);
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for (const auto& entry : android::base::Split(android::base::Trim(cmdline), " ")) {
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std::vector<std::string> pieces = android::base::Split(entry, "=");
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if (pieces.size() == 2) {
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fn(pieces[0], pieces[1], in_qemu);
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}
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}
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}
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int make_dir(const char *path, mode_t mode)
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{
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int rc;
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char *secontext = NULL;
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if (sehandle) {
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selabel_lookup(sehandle, &secontext, path, mode);
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setfscreatecon(secontext);
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}
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rc = mkdir(path, mode);
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if (secontext) {
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int save_errno = errno;
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freecon(secontext);
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setfscreatecon(NULL);
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errno = save_errno;
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}
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return rc;
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}
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int restorecon(const char* pathname)
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{
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return selinux_android_restorecon(pathname, 0);
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}
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int restorecon_recursive(const char* pathname)
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{
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return selinux_android_restorecon(pathname, SELINUX_ANDROID_RESTORECON_RECURSE);
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}
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/*
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* Writes hex_len hex characters (1/2 byte) to hex from bytes.
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*/
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std::string bytes_to_hex(const uint8_t* bytes, size_t bytes_len) {
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std::string hex("0x");
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for (size_t i = 0; i < bytes_len; i++)
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android::base::StringAppendF(&hex, "%02x", bytes[i]);
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return hex;
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}
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/*
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* Returns true is pathname is a directory
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*/
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bool is_dir(const char* pathname) {
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struct stat info;
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if (stat(pathname, &info) == -1) {
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return false;
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}
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return S_ISDIR(info.st_mode);
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}
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