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platform_system_core
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platform_system_core/init/util.cpp

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/*
* 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 <stdarg.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <ctype.h>
#include <errno.h>
#include <time.h>
#include <ftw.h>
#include <pwd.h>
#include <selinux/label.h>
#include <selinux/android.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <android-base/file.h>
#include <android-base/logging.h>
#include <android-base/strings.h>
/* for ANDROID_SOCKET_* */
#include <cutils/sockets.h>
#include <android-base/stringprintf.h>
#include "init.h"
#include "log.h"
#include "property_service.h"
#include "util.h"
static unsigned int do_decode_uid(const char *s)
{
unsigned int v;
if (!s || *s == '\0')
return UINT_MAX;
if (isalpha(s[0])) {
struct passwd* pwd = getpwnam(s);
if (!pwd)
return UINT_MAX;
return pwd->pw_uid;
}
errno = 0;
v = (unsigned int) strtoul(s, 0, 0);
if (errno)
return UINT_MAX;
return v;
}
/*
* decode_uid - decodes and returns the given string, which can be either the
* numeric or name representation, into the integer uid or gid. Returns
* UINT_MAX on error.
*/
unsigned int decode_uid(const char *s) {
unsigned int v = do_decode_uid(s);
if (v == UINT_MAX) {
LOG(ERROR) << "decode_uid: Unable to find UID for '" << s << "'; returning UINT_MAX";
}
return v;
}
/*
* create_socket - creates a Unix domain socket in ANDROID_SOCKET_DIR
* ("/dev/socket") as dictated in init.rc. This socket is inherited by the
* daemon. We communicate the file descriptor's value via the environment
* variable ANDROID_SOCKET_ENV_PREFIX<name> ("ANDROID_SOCKET_foo").
*/
int create_socket(const char *name, int type, mode_t perm, uid_t uid,
gid_t gid, const char *socketcon)
{
struct sockaddr_un addr;
int fd, ret, savederrno;
char *filecon;
if (socketcon) {
if (setsockcreatecon(socketcon) == -1) {
PLOG(ERROR) << "setsockcreatecon(\"" << socketcon << "\") failed";
return -1;
}
}
fd = socket(PF_UNIX, type, 0);
if (fd < 0) {
PLOG(ERROR) << "Failed to open socket '" << name << "'";
return -1;
}
if (socketcon)
setsockcreatecon(NULL);
memset(&addr, 0 , sizeof(addr));
addr.sun_family = AF_UNIX;
snprintf(addr.sun_path, sizeof(addr.sun_path), ANDROID_SOCKET_DIR"/%s",
name);
ret = unlink(addr.sun_path);
if (ret != 0 && errno != ENOENT) {
PLOG(ERROR) << "Failed to unlink old socket '" << name << "'";
goto out_close;
}
filecon = NULL;
if (sehandle) {
ret = selabel_lookup(sehandle, &filecon, addr.sun_path, S_IFSOCK);
if (ret == 0)
setfscreatecon(filecon);
}
ret = bind(fd, (struct sockaddr *) &addr, sizeof (addr));
savederrno = errno;
setfscreatecon(NULL);
freecon(filecon);
if (ret) {
errno = savederrno;
PLOG(ERROR) << "Failed to bind socket '" << name << "'";
goto out_unlink;
}
ret = lchown(addr.sun_path, uid, gid);
if (ret) {
PLOG(ERROR) << "Failed to lchown socket '" << addr.sun_path << "'";
goto out_unlink;
}
ret = fchmodat(AT_FDCWD, addr.sun_path, perm, AT_SYMLINK_NOFOLLOW);
if (ret) {
PLOG(ERROR) << "Failed to fchmodat socket '" << addr.sun_path << "'";
goto out_unlink;
}
LOG(INFO) << "Created socket '" << addr.sun_path << "'"
<< ", mode " << std::oct << perm << std::dec
<< ", user " << uid
<< ", group " << gid;
return fd;
out_unlink:
unlink(addr.sun_path);
out_close:
close(fd);
return -1;
}
bool read_file(const char* path, std::string* content) {
content->clear();
int fd = TEMP_FAILURE_RETRY(open(path, O_RDONLY|O_NOFOLLOW|O_CLOEXEC));
if (fd == -1) {
return false;
}
// For security reasons, disallow world-writable
// or group-writable files.
struct stat sb;
if (fstat(fd, &sb) == -1) {
PLOG(ERROR) << "fstat failed for '" << path << "'";
return false;
}
if ((sb.st_mode & (S_IWGRP | S_IWOTH)) != 0) {
PLOG(ERROR) << "skipping insecure file '" << path << "'";
return false;
}
bool okay = android::base::ReadFdToString(fd, content);
close(fd);
return okay;
}
int write_file(const char* path, const char* content) {
int fd = TEMP_FAILURE_RETRY(open(path, O_WRONLY|O_CREAT|O_NOFOLLOW|O_CLOEXEC, 0600));
if (fd == -1) {
PLOG(ERROR) << "write_file: Unable to open '" << path << "'";
return -1;
}
int result = android::base::WriteStringToFd(content, fd) ? 0 : -1;
if (result == -1) {
PLOG(ERROR) << "write_file: Unable to write to '" << path << "'";
}
close(fd);
return result;
}
time_t gettime() {
timespec now;
clock_gettime(CLOCK_MONOTONIC, &now);
return now.tv_sec;
}
uint64_t gettime_ns() {
timespec now;
clock_gettime(CLOCK_MONOTONIC, &now);
return static_cast<uint64_t>(now.tv_sec) * UINT64_C(1000000000) + now.tv_nsec;
}
int mkdir_recursive(const char *pathname, mode_t mode)
{
char buf[128];
const char *slash;
const char *p = pathname;
int width;
int ret;
struct stat info;
while ((slash = strchr(p, '/')) != NULL) {
width = slash - pathname;
p = slash + 1;
if (width < 0)
break;
if (width == 0)
continue;
if ((unsigned int)width > sizeof(buf) - 1) {
LOG(ERROR) << "path too long for mkdir_recursive";
return -1;
}
memcpy(buf, pathname, width);
buf[width] = 0;
if (stat(buf, &info) != 0) {
ret = make_dir(buf, mode);
if (ret && errno != EEXIST)
return ret;
}
}
ret = make_dir(pathname, mode);
if (ret && errno != EEXIST)
return ret;
return 0;
}
/*
* replaces any unacceptable characters with '_', the
* length of the resulting string is equal to the input string
*/
void sanitize(char *s)
{
const char* accept =
"abcdefghijklmnopqrstuvwxyz"
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"0123456789"
"_-.";
if (!s)
return;
while (*s) {
s += strspn(s, accept);
if (*s) *s++ = '_';
}
}
void make_link_init(const char *oldpath, const char *newpath)
{
int ret;
char buf[256];
const char *slash;
int width;
slash = strrchr(newpath, '/');
if (!slash)
return;
width = slash - newpath;
if (width <= 0 || width > (int)sizeof(buf) - 1)
return;
memcpy(buf, newpath, width);
buf[width] = 0;
ret = mkdir_recursive(buf, 0755);
if (ret) PLOG(ERROR) << "Failed to create directory " << buf;
ret = symlink(oldpath, newpath);
if (ret && errno != EEXIST) PLOG(ERROR) << "Failed to symlink " << oldpath << " to " << newpath;
}
void remove_link(const char *oldpath, const char *newpath)
{
char path[256];
ssize_t ret;
ret = readlink(newpath, path, sizeof(path) - 1);
if (ret <= 0)
return;
path[ret] = 0;
if (!strcmp(path, oldpath))
unlink(newpath);
}
int wait_for_file(const char *filename, int timeout)
{
struct stat info;
uint64_t timeout_time_ns = gettime_ns() + timeout * UINT64_C(1000000000);
int ret = -1;
while (gettime_ns() < timeout_time_ns && ((ret = stat(filename, &info)) < 0))
usleep(10000);
return ret;
}
void import_kernel_cmdline(bool in_qemu,
std::function<void(const std::string&, const std::string&, bool)> fn) {
std::string cmdline;
android::base::ReadFileToString("/proc/cmdline", &cmdline);
for (const auto& entry : android::base::Split(android::base::Trim(cmdline), " ")) {
std::vector<std::string> pieces = android::base::Split(entry, "=");
if (pieces.size() == 2) {
fn(pieces[0], pieces[1], in_qemu);
}
}
}
int make_dir(const char *path, mode_t mode)
{
int rc;
char *secontext = NULL;
if (sehandle) {
selabel_lookup(sehandle, &secontext, path, mode);
setfscreatecon(secontext);
}
rc = mkdir(path, mode);
if (secontext) {
int save_errno = errno;
freecon(secontext);
setfscreatecon(NULL);
errno = save_errno;
}
return rc;
}
int restorecon(const char* pathname)
{
return selinux_android_restorecon(pathname, 0);
}
int restorecon_recursive(const char* pathname)
{
return selinux_android_restorecon(pathname, SELINUX_ANDROID_RESTORECON_RECURSE);
}
/*
* Writes hex_len hex characters (1/2 byte) to hex from bytes.
*/
std::string bytes_to_hex(const uint8_t* bytes, size_t bytes_len) {
std::string hex("0x");
for (size_t i = 0; i < bytes_len; i++)
android::base::StringAppendF(&hex, "%02x", bytes[i]);
return hex;
}
/*
* Returns true is pathname is a directory
*/
bool is_dir(const char* pathname) {
struct stat info;
if (stat(pathname, &info) == -1) {
return false;
}
return S_ISDIR(info.st_mode);
}
bool expand_props(const std::string& src, std::string* dst) {
const char* src_ptr = src.c_str();
if (!dst) {
return false;
}
/* - variables can either be $x.y or ${x.y}, in case they are only part
* of the string.
* - will accept $$ as a literal $.
* - no nested property expansion, i.e. ${foo.${bar}} is not supported,
* bad things will happen
* - ${x.y:-default} will return default value if property empty.
*/
while (*src_ptr) {
const char* c;
c = strchr(src_ptr, '$');
if (!c) {
dst->append(src_ptr);
return true;
}
dst->append(src_ptr, c);
c++;
if (*c == '$') {
dst->push_back(*(c++));
src_ptr = c;
continue;
} else if (*c == '\0') {
return true;
}
std::string prop_name;
std::string def_val;
if (*c == '{') {
c++;
const char* end = strchr(c, '}');
if (!end) {
// failed to find closing brace, abort.
LOG(ERROR) << "unexpected end of string in '" << src << "', looking for }";
return false;
}
prop_name = std::string(c, end);
c = end + 1;
size_t def = prop_name.find(":-");
if (def < prop_name.size()) {
def_val = prop_name.substr(def + 2);
prop_name = prop_name.substr(0, def);
}
} else {
prop_name = c;
LOG(ERROR) << "using deprecated syntax for specifying property '" << c << "', use ${name} instead";
c += prop_name.size();
}
if (prop_name.empty()) {
LOG(ERROR) << "invalid zero-length property name in '" << src << "'";
return false;
}
std::string prop_val = property_get(prop_name.c_str());
if (prop_val.empty()) {
if (def_val.empty()) {
LOG(ERROR) << "property '" << prop_name << "' doesn't exist while expanding '" << src << "'";
return false;
}
prop_val = def_val;
}
dst->append(prop_val);
src_ptr = c;
}
return true;
}
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