| /* |
| * 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. |
| */ |
| |
| // This file contains files implementation that can be shared between |
| // platforms as long as the correct headers are included. |
| #define _GNU_SOURCE 1 // for asprintf |
| |
| #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 <cutils/files.h> |
| |
| #ifndef TEMP_FAILURE_RETRY // _WIN32 does not define |
| #define TEMP_FAILURE_RETRY(exp) (exp) |
| #endif |
| |
| int android_get_control_file(const char* path) { |
| if (!path) return -1; |
| |
| char *key = NULL; |
| if (asprintf(&key, ANDROID_FILE_ENV_PREFIX "%s", path) < 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; |
| |
| // validity checking |
| if ((fd < 0) || (fd > INT_MAX)) return -1; |
| #if defined(_SC_OPEN_MAX) |
| if (fd >= sysconf(_SC_OPEN_MAX)) return -1; |
| #elif defined(OPEN_MAX) |
| if (fd >= OPEN_MAX) return -1; |
| #elif defined(_POSIX_OPEN_MAX) |
| if (fd >= _POSIX_OPEN_MAX) return -1; |
| #endif |
| |
| #if defined(F_GETFD) |
| if (TEMP_FAILURE_RETRY(fcntl(fd, F_GETFD)) < 0) return -1; |
| #elif defined(F_GETFL) |
| if (TEMP_FAILURE_RETRY(fcntl(fd, F_GETFL)) < 0) return -1; |
| #else |
| struct stat s; |
| if (TEMP_FAILURE_RETRY(fstat(fd, &s)) < 0) return -1; |
| #endif |
| |
| #if defined(__linux__) |
| char *proc = NULL; |
| if (asprintf(&proc, "/proc/self/fd/%ld", fd) < 0) return -1; |
| if (!proc) return -1; |
| |
| size_t len = strlen(path); |
| char *buf = static_cast<char *>(calloc(1, len + 2)); |
| if (!buf) { |
| free(proc); |
| return -1; |
| } |
| ssize_t ret = TEMP_FAILURE_RETRY(readlink(proc, buf, len + 1)); |
| free(proc); |
| int cmp = (len != static_cast<size_t>(ret)) || strcmp(buf, path); |
| free(buf); |
| if (ret < 0) return -1; |
| if (cmp != 0) return -1; |
| #endif |
| |
| // It is what we think it is |
| return static_cast<int>(fd); |
| } |