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/*
* 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);
}
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