libcutils: add android_get_control_file() am: 0b034d9d7b am: c020d3fa6e (67c52fa2) · Commits · e / os / android_system_core

include/cutils/files.h

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		/*
		* Copyright (C) 2016 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.
		*/

		#ifndef __CUTILS_FILES_H
		#define __CUTILS_FILES_H

		#define ANDROID_FILE_ENV_PREFIX "ANDROID_FILE_"

		#ifdef __cplusplus
		extern "C" {
		#endif

		/*
		* android_get_control_file - simple helper function to get the file
		* descriptor of our init-managed file. `path' is the filename path as
		* given in init.rc. Returns -1 on error.
		*/
		int android_get_control_file(const char* path);

		#ifdef __cplusplus
		}
		#endif

		#endif /* __CUTILS_FILES_H */

libcutils/Android.bp

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		@@ -34,6 +34,7 @@ cc_library {
		host_supported: true,
		srcs: [
		"config_utils.c",
		"files.cpp",
		"fs_config.c",
		"canned_fs_config.c",
		"hashmap.c",

libcutils/files.cpp

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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);
		}

libcutils/tests/Android.bp

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		@@ -14,7 +14,7 @@

		cc_defaults {
		name: "libcutils_test_default",
		srcs: ["sockets_test.cpp"],
		srcs: ["sockets_test.cpp", "files_test.cpp"],

		target: {
		android: {

libcutils/tests/files_test.cpp

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		/*
		* Copyright (C) 2016 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 <fcntl.h>
		#include <stdio.h>
		#include <stdlib.h>
		#include <sys/types.h>
		#include <time.h>

		#include <cutils/files.h>
		#include <gtest/gtest.h>

		TEST(FilesTest, android_get_control_file) {
		static const char key[] = ANDROID_FILE_ENV_PREFIX "_dev_kmsg";
		static const char name[] = "/dev/kmsg";

		EXPECT_EQ(unsetenv(key), 0);
		EXPECT_EQ(android_get_control_file(name), -1);

		int fd;
		ASSERT_GE(fd = open(name, O_RDONLY \| O_CLOEXEC), 0);
		EXPECT_EQ(android_get_control_file(name), -1);

		char val[32];
		snprintf(val, sizeof(val), "%d", fd);
		EXPECT_EQ(setenv(key, val, true), 0);

		EXPECT_EQ(android_get_control_file(name), fd);
		close(fd);
		EXPECT_EQ(android_get_control_file(name), -1);
		EXPECT_EQ(unsetenv(key), 0);
		EXPECT_EQ(android_get_control_file(name), -1);
		}