/* * Copyright (C) 2016 The Android Open Source Project * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #include <cutils/android_get_control_file.h> #include <ctype.h> #include <errno.h> #include <fcntl.h> #include <limits.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/stat.h> #include <sys/types.h> #include <unistd.h> #include <string> #include <android-base/file.h> #include <android-base/stringprintf.h> #include "android_get_control_env.h" int __android_get_control_from_env(const char* prefix, const char* name) { if (!prefix || !name) return -1; char *key = NULL; if (asprintf(&key, "%s%s", prefix, name) < 0) return -1; if (!key) return -1; char *cp = key; while (*cp) { if (!isalnum(*cp)) *cp = '_'; ++cp; } const char* val = getenv(key); free(key); if (!val) return -1; errno = 0; long fd = strtol(val, NULL, 10); if (errno) return -1; // Since we are inheriting an fd, it could legitimately exceed _SC_OPEN_MAX if ((fd < 0) || (fd > INT_MAX)) return -1; // Still open? if (TEMP_FAILURE_RETRY(fcntl(fd, F_GETFD)) < 0) return -1; return static_cast<int>(fd); } int android_get_control_file(const char* path) { std::string given_path; if (!android::base::Realpath(path, &given_path)) return -1; // Try path, then realpath(path), as keys to get the fd from env. auto fd = __android_get_control_from_env(ANDROID_FILE_ENV_PREFIX, path); if (fd < 0) { fd = __android_get_control_from_env(ANDROID_FILE_ENV_PREFIX, given_path.c_str()); if (fd < 0) return fd; } // Find file path from /proc and make sure it is correct auto proc = android::base::StringPrintf("/proc/self/fd/%d", fd); std::string fd_path; if (!android::base::Realpath(proc, &fd_path)) return -1; if (given_path != fd_path) return -1; // It is what we think it is return fd; }