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/*
* 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 "android-base/file.h"
#include <errno.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <string>
#include "android-base/macros.h" // For TEMP_FAILURE_RETRY on Darwin.
#include "android-base/utf8.h"
#define LOG_TAG "base.file"
#include "cutils/log.h"
#include "utils/Compat.h"
namespace android {
namespace base {
// Versions of standard library APIs that support UTF-8 strings.
using namespace android::base::utf8;
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 | O_BINARY));
if (fd == -1) {
return false;
}
bool result = ReadFdToString(fd, content);
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 flags = O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC | O_NOFOLLOW | O_BINARY;
int fd = TEMP_FAILURE_RETRY(open(path.c_str(), flags, 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);
}
close(fd);
return true;
}
#endif
bool WriteStringToFile(const std::string& content, const std::string& path) {
int flags = O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC | O_NOFOLLOW | O_BINARY;
int fd = TEMP_FAILURE_RETRY(open(path.c_str(), flags, DEFFILEMODE));
if (fd == -1) {
return false;
}
bool result = WriteStringToFd(content, fd);
close(fd);
return result || CleanUpAfterFailedWrite(path);
}
bool ReadFully(int fd, void* data, size_t byte_count) {
uint8_t* p = reinterpret_cast<uint8_t*>(data);
size_t remaining = byte_count;
while (remaining > 0) {
ssize_t n = TEMP_FAILURE_RETRY(read(fd, p, remaining));
if (n <= 0) return false;
p += n;
remaining -= n;
}
return true;
}
bool WriteFully(int fd, const void* data, size_t byte_count) {
const uint8_t* p = reinterpret_cast<const uint8_t*>(data);
size_t remaining = byte_count;
while (remaining > 0) {
ssize_t n = TEMP_FAILURE_RETRY(write(fd, p, remaining));
if (n == -1) return false;
p += n;
remaining -= n;
}
return true;
}
bool RemoveFileIfExists(const std::string& path, std::string* err) {
struct stat st;
#if defined(_WIN32)
//TODO: Windows version can't handle symbol link correctly.
int result = stat(path.c_str(), &st);
bool file_type_removable = (result == 0 && S_ISREG(st.st_mode));
#else
int result = lstat(path.c_str(), &st);
bool file_type_removable = (result == 0 && (S_ISREG(st.st_mode) || S_ISLNK(st.st_mode)));
#endif
if (result == 0) {
if (!file_type_removable) {
if (err != nullptr) {
*err = "is not a regular or symbol link file";
}
return false;
}
if (unlink(path.c_str()) == -1) {
if (err != nullptr) {
*err = strerror(errno);
}
return false;
}
}
return true;
}
} // namespace base
} // namespace android
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