09175a0264
Open with O_CREAT needs mode bits: https://linux.die.net/man/3/open Found by running clang FORTIFY over AOSP. Bug: 32073964 Test: Now builds with clang FORTIFY. Change-Id: Iee4c93c5482f510e0adf8104c27e394b5d87ec88
274 lines
8 KiB
C
274 lines
8 KiB
C
/*
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* Copyright (C) 2012 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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#define LOG_TAG "cutils"
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/* These defines are only needed because prebuilt headers are out of date */
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#define __USE_XOPEN2K8 1
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#define _ATFILE_SOURCE 1
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#define _GNU_SOURCE 1
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#include <dirent.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <limits.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include <cutils/fs.h>
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#include <log/log.h>
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#define ALL_PERMS (S_ISUID | S_ISGID | S_ISVTX | S_IRWXU | S_IRWXG | S_IRWXO)
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#define BUF_SIZE 64
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static int fs_prepare_path_impl(const char* path, mode_t mode, uid_t uid, gid_t gid,
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int allow_fixup, int prepare_as_dir) {
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// Check if path needs to be created
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struct stat sb;
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int create_result = -1;
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if (TEMP_FAILURE_RETRY(lstat(path, &sb)) == -1) {
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if (errno == ENOENT) {
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goto create;
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} else {
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ALOGE("Failed to lstat(%s): %s", path, strerror(errno));
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return -1;
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}
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}
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// Exists, verify status
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int type_ok = prepare_as_dir ? S_ISDIR(sb.st_mode) : S_ISREG(sb.st_mode);
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if (!type_ok) {
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ALOGE("Not a %s: %s", (prepare_as_dir ? "directory" : "regular file"), path);
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return -1;
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}
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int owner_match = ((sb.st_uid == uid) && (sb.st_gid == gid));
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int mode_match = ((sb.st_mode & ALL_PERMS) == mode);
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if (owner_match && mode_match) {
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return 0;
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} else if (allow_fixup) {
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goto fixup;
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} else {
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if (!owner_match) {
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ALOGE("Expected path %s with owner %d:%d but found %d:%d",
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path, uid, gid, sb.st_uid, sb.st_gid);
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return -1;
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} else {
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ALOGW("Expected path %s with mode %o but found %o",
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path, mode, (sb.st_mode & ALL_PERMS));
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return 0;
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}
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}
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create:
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create_result = prepare_as_dir
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? TEMP_FAILURE_RETRY(mkdir(path, mode))
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: TEMP_FAILURE_RETRY(open(path, O_CREAT | O_CLOEXEC | O_NOFOLLOW | O_RDONLY, 0644));
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if (create_result == -1) {
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if (errno != EEXIST) {
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ALOGE("Failed to %s(%s): %s",
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(prepare_as_dir ? "mkdir" : "open"), path, strerror(errno));
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return -1;
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}
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} else if (!prepare_as_dir) {
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// For regular files we need to make sure we close the descriptor
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if (close(create_result) == -1) {
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ALOGW("Failed to close file after create %s: %s", path, strerror(errno));
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}
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}
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fixup:
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if (TEMP_FAILURE_RETRY(chmod(path, mode)) == -1) {
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ALOGE("Failed to chmod(%s, %d): %s", path, mode, strerror(errno));
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return -1;
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}
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if (TEMP_FAILURE_RETRY(chown(path, uid, gid)) == -1) {
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ALOGE("Failed to chown(%s, %d, %d): %s", path, uid, gid, strerror(errno));
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return -1;
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}
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return 0;
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}
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int fs_prepare_dir(const char* path, mode_t mode, uid_t uid, gid_t gid) {
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return fs_prepare_path_impl(path, mode, uid, gid, /*allow_fixup*/ 1, /*prepare_as_dir*/ 1);
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}
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int fs_prepare_dir_strict(const char* path, mode_t mode, uid_t uid, gid_t gid) {
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return fs_prepare_path_impl(path, mode, uid, gid, /*allow_fixup*/ 0, /*prepare_as_dir*/ 1);
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}
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int fs_prepare_file_strict(const char* path, mode_t mode, uid_t uid, gid_t gid) {
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return fs_prepare_path_impl(path, mode, uid, gid, /*allow_fixup*/ 0, /*prepare_as_dir*/ 0);
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}
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int fs_read_atomic_int(const char* path, int* out_value) {
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int fd = TEMP_FAILURE_RETRY(open(path, O_RDONLY));
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if (fd == -1) {
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ALOGE("Failed to read %s: %s", path, strerror(errno));
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return -1;
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}
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char buf[BUF_SIZE];
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if (TEMP_FAILURE_RETRY(read(fd, buf, BUF_SIZE)) == -1) {
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ALOGE("Failed to read %s: %s", path, strerror(errno));
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goto fail;
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}
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if (sscanf(buf, "%d", out_value) != 1) {
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ALOGE("Failed to parse %s: %s", path, strerror(errno));
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goto fail;
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}
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close(fd);
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return 0;
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fail:
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close(fd);
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*out_value = -1;
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return -1;
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}
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int fs_write_atomic_int(const char* path, int value) {
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char temp[PATH_MAX];
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if (snprintf(temp, PATH_MAX, "%s.XXXXXX", path) >= PATH_MAX) {
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ALOGE("Path too long");
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return -1;
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}
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int fd = TEMP_FAILURE_RETRY(mkstemp(temp));
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if (fd == -1) {
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ALOGE("Failed to open %s: %s", temp, strerror(errno));
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return -1;
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}
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char buf[BUF_SIZE];
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int len = snprintf(buf, BUF_SIZE, "%d", value) + 1;
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if (len > BUF_SIZE) {
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ALOGE("Value %d too large: %s", value, strerror(errno));
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goto fail;
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}
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if (TEMP_FAILURE_RETRY(write(fd, buf, len)) < len) {
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ALOGE("Failed to write %s: %s", temp, strerror(errno));
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goto fail;
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}
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if (close(fd) == -1) {
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ALOGE("Failed to close %s: %s", temp, strerror(errno));
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goto fail_closed;
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}
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if (rename(temp, path) == -1) {
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ALOGE("Failed to rename %s to %s: %s", temp, path, strerror(errno));
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goto fail_closed;
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}
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return 0;
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fail:
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close(fd);
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fail_closed:
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unlink(temp);
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return -1;
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}
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#ifndef __APPLE__
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int fs_mkdirs(const char* path, mode_t mode) {
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int res = 0;
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int fd = 0;
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struct stat sb;
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char* buf = strdup(path);
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if (*buf != '/') {
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ALOGE("Relative paths are not allowed: %s", buf);
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res = -EINVAL;
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goto done;
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}
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if ((fd = open("/", 0)) == -1) {
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ALOGE("Failed to open(/): %s", strerror(errno));
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res = -errno;
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goto done;
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}
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char* segment = buf + 1;
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char* p = segment;
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while (*p != '\0') {
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if (*p == '/') {
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*p = '\0';
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if (!strcmp(segment, "..") || !strcmp(segment, ".") || !strcmp(segment, "")) {
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ALOGE("Invalid path: %s", buf);
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res = -EINVAL;
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goto done_close;
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}
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if (fstatat(fd, segment, &sb, AT_SYMLINK_NOFOLLOW) != 0) {
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if (errno == ENOENT) {
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/* Nothing there yet; let's create it! */
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if (mkdirat(fd, segment, mode) != 0) {
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if (errno == EEXIST) {
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/* We raced with someone; ignore */
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} else {
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ALOGE("Failed to mkdirat(%s): %s", buf, strerror(errno));
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res = -errno;
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goto done_close;
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}
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}
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} else {
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ALOGE("Failed to fstatat(%s): %s", buf, strerror(errno));
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res = -errno;
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goto done_close;
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}
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} else {
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if (S_ISLNK(sb.st_mode)) {
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ALOGE("Symbolic links are not allowed: %s", buf);
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res = -ELOOP;
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goto done_close;
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}
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if (!S_ISDIR(sb.st_mode)) {
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ALOGE("Existing segment not a directory: %s", buf);
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res = -ENOTDIR;
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goto done_close;
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}
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}
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/* Yay, segment is ready for us to step into */
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int next_fd;
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if ((next_fd = openat(fd, segment, O_NOFOLLOW | O_CLOEXEC)) == -1) {
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ALOGE("Failed to openat(%s): %s", buf, strerror(errno));
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res = -errno;
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goto done_close;
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}
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close(fd);
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fd = next_fd;
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*p = '/';
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segment = p + 1;
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}
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p++;
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}
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done_close:
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close(fd);
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done:
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free(buf);
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return res;
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}
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#endif
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