init/util.cpp - platform/system/core - Gitiles

 /*
  * 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 <ctype.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <ftw.h>
 #include <pwd.h>
 #include <stdarg.h>
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
 #include <time.h>
 #include <unistd.h>

 #include <selinux/android.h>
 #include <selinux/label.h>

 #include <sys/socket.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <sys/un.h>

 #include <android-base/file.h>
 #include <android-base/logging.h>
 #include <android-base/stringprintf.h>
 #include <android-base/strings.h>
 /* for ANDROID_SOCKET_* */
 #include <cutils/sockets.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;
 }

 /*
  * create_file - opens and creates a file as dictated in init.rc.
  * This file is inherited by the daemon. We communicate the file
  * descriptor's value via the environment variable ANDROID_FILE_<basename>
  */
 int create_file(const char *path, int flags, mode_t perm, uid_t uid,
                   gid_t gid, const char *filecon)
 {
     char *secontext = NULL;
     int ret;

     if (filecon) {
         if (setsockcreatecon(filecon) == -1) {
             PLOG(ERROR) << "setsockcreatecon(\"" << filecon << "\") failed";
             return -1;
         }
     } else if (sehandle) {
         ret = selabel_lookup(sehandle, &secontext, path, perm);
         if (ret != -1) {
             ret = setfscreatecon(secontext);
             if (ret == -1) {
                 freecon(secontext);
                 PLOG(ERROR) << "setfscreatecon(\"" << secontext << "\") failed";
                 return -1;
             }
         }
     }

     int fd = TEMP_FAILURE_RETRY(open(path, flags | O_NDELAY, perm));

     if (filecon) {
         setsockcreatecon(NULL);
         lsetfilecon(path, filecon);
     } else {
         setfscreatecon(NULL);
         freecon(secontext);
     }

     if (fd == -1) {
         PLOG(ERROR) << "Failed to open/create file '" << path << "'";
         goto out_close;
     }

     if (!(flags & O_NDELAY)) fcntl(fd, F_SETFD, flags);

     ret = lchown(path, uid, gid);
     if (ret) {
         PLOG(ERROR) << "Failed to lchown file '" << path << "'";
         goto out_close;
     }
     if (perm != static_cast<mode_t>(-1)) {
         ret = fchmodat(AT_FDCWD, path, perm, AT_SYMLINK_NOFOLLOW);
         if (ret) {
             PLOG(ERROR) << "Failed to fchmodat file '" << path << "'";
             goto out_close;
         }
     }

     LOG(INFO) << "Created file '" << path << "'"
               << ", mode " << std::oct << perm << std::dec
               << ", user " << uid
               << ", group " << gid;

     return fd;

 out_close:
     if (fd >= 0) 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++ = '_';
     }
 }

 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,
                            const 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;
 }
	/*
	* 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 <ctype.h>
	#include <errno.h>
	#include <fcntl.h>
	#include <ftw.h>
	#include <pwd.h>
	#include <stdarg.h>
	#include <stdlib.h>
	#include <stdio.h>
	#include <string.h>
	#include <time.h>
	#include <unistd.h>

	#include <selinux/android.h>
	#include <selinux/label.h>

	#include <sys/socket.h>
	#include <sys/stat.h>
	#include <sys/types.h>
	#include <sys/un.h>

	#include <android-base/file.h>
	#include <android-base/logging.h>
	#include <android-base/stringprintf.h>
	#include <android-base/strings.h>
	/* for ANDROID_SOCKET_* */
	#include <cutils/sockets.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;
	}

	/*
	* create_file - opens and creates a file as dictated in init.rc.
	* This file is inherited by the daemon. We communicate the file
	* descriptor's value via the environment variable ANDROID_FILE_<basename>
	*/
	int create_file(const char *path, int flags, mode_t perm, uid_t uid,
	gid_t gid, const char *filecon)
	{
	char *secontext = NULL;
	int ret;

	if (filecon) {
	if (setsockcreatecon(filecon) == -1) {
	PLOG(ERROR) << "setsockcreatecon(\"" << filecon << "\") failed";
	return -1;
	}
	} else if (sehandle) {
	ret = selabel_lookup(sehandle, &secontext, path, perm);
	if (ret != -1) {
	ret = setfscreatecon(secontext);
	if (ret == -1) {
	freecon(secontext);
	PLOG(ERROR) << "setfscreatecon(\"" << secontext << "\") failed";
	return -1;
	}
	}
	}

	int fd = TEMP_FAILURE_RETRY(open(path, flags \| O_NDELAY, perm));

	if (filecon) {
	setsockcreatecon(NULL);
	lsetfilecon(path, filecon);
	} else {
	setfscreatecon(NULL);
	freecon(secontext);
	}

	if (fd == -1) {
	PLOG(ERROR) << "Failed to open/create file '" << path << "'";
	goto out_close;
	}

	if (!(flags & O_NDELAY)) fcntl(fd, F_SETFD, flags);

	ret = lchown(path, uid, gid);
	if (ret) {
	PLOG(ERROR) << "Failed to lchown file '" << path << "'";
	goto out_close;
	}
	if (perm != static_cast<mode_t>(-1)) {
	ret = fchmodat(AT_FDCWD, path, perm, AT_SYMLINK_NOFOLLOW);
	if (ret) {
	PLOG(ERROR) << "Failed to fchmodat file '" << path << "'";
	goto out_close;
	}
	}

	LOG(INFO) << "Created file '" << path << "'"
	<< ", mode " << std::oct << perm << std::dec
	<< ", user " << uid
	<< ", group " << gid;

	return fd;

	out_close:
	if (fd >= 0) 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++ = '_';
	}
	}

	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,
	const 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;
	}