diff options
Diffstat (limited to 'base/file.cpp')
-rw-r--r-- | base/file.cpp | 123 |
1 files changed, 123 insertions, 0 deletions
diff --git a/base/file.cpp b/base/file.cpp new file mode 100644 index 000000000..773f33bd6 --- /dev/null +++ b/base/file.cpp @@ -0,0 +1,123 @@ +/* + * Copyright (C) 2015 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 "base/file.h" + +#include <errno.h> +#include <fcntl.h> +#include <sys/stat.h> +#include <sys/types.h> + +#include <string> + +#define LOG_TAG "base.file" +#include "cutils/log.h" +#include "utils/Compat.h" // For TEMP_FAILURE_RETRY on Darwin. + +namespace android { +namespace base { + +bool ReadFdToString(int fd, std::string* content) { + content->clear(); + + char buf[BUFSIZ]; + ssize_t n; + while ((n = TEMP_FAILURE_RETRY(read(fd, &buf[0], sizeof(buf)))) > 0) { + content->append(buf, n); + } + return (n == 0) ? true : false; +} + +bool ReadFileToString(const std::string& path, std::string* content) { + content->clear(); + + int fd = + TEMP_FAILURE_RETRY(open(path.c_str(), O_RDONLY | O_CLOEXEC | O_NOFOLLOW)); + if (fd == -1) { + return false; + } + bool result = ReadFdToString(fd, content); + TEMP_FAILURE_RETRY(close(fd)); + return result; +} + +bool WriteStringToFd(const std::string& content, int fd) { + const char* p = content.data(); + size_t left = content.size(); + while (left > 0) { + ssize_t n = TEMP_FAILURE_RETRY(write(fd, p, left)); + if (n == -1) { + return false; + } + p += n; + left -= n; + } + return true; +} + +static bool CleanUpAfterFailedWrite(const std::string& path) { + // Something went wrong. Let's not leave a corrupt file lying around. + int saved_errno = errno; + unlink(path.c_str()); + errno = saved_errno; + return false; +} + +#if !defined(_WIN32) +bool WriteStringToFile(const std::string& content, const std::string& path, + mode_t mode, uid_t owner, gid_t group) { + int fd = TEMP_FAILURE_RETRY( + open(path.c_str(), O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC | O_NOFOLLOW, + mode)); + if (fd == -1) { + ALOGE("android::WriteStringToFile open failed: %s", strerror(errno)); + return false; + } + + // We do an explicit fchmod here because we assume that the caller really + // meant what they said and doesn't want the umask-influenced mode. + if (fchmod(fd, mode) == -1) { + ALOGE("android::WriteStringToFile fchmod failed: %s", strerror(errno)); + return CleanUpAfterFailedWrite(path); + } + if (fchown(fd, owner, group) == -1) { + ALOGE("android::WriteStringToFile fchown failed: %s", strerror(errno)); + return CleanUpAfterFailedWrite(path); + } + if (!WriteStringToFd(content, fd)) { + ALOGE("android::WriteStringToFile write failed: %s", strerror(errno)); + return CleanUpAfterFailedWrite(path); + } + TEMP_FAILURE_RETRY(close(fd)); + return true; +} +#endif + +bool WriteStringToFile(const std::string& content, const std::string& path) { + int fd = TEMP_FAILURE_RETRY( + open(path.c_str(), O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC | O_NOFOLLOW, + DEFFILEMODE)); + if (fd == -1) { + return false; + } + + bool result = WriteStringToFd(content, fd); + TEMP_FAILURE_RETRY(close(fd)); + return result || CleanUpAfterFailedWrite(path); +} + +} // namespace base +} // namespace android |