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-rw-r--r--libutils/file.cpp115
1 files changed, 115 insertions, 0 deletions
diff --git a/libutils/file.cpp b/libutils/file.cpp
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+++ b/libutils/file.cpp
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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.
+ */
+
+#define LOG_TAG "utils.file"
+#include <cutils/log.h>
+
+#include "utils/file.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#include <utils/Compat.h> // For TEMP_FAILURE_RETRY on Darwin.
+
+bool android::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 android::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 android::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 android::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 android::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);
+}