Merge "Add a WriteStringToFile overload that cares about permissions." (27d28d3b) · Commits · e / os / android_system_core

include/utils/file.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -18,11 +18,14 @@
		#define UTILS_FILE_H

		#include <string>
		#include <sys/stat.h>

		namespace android {

		bool ReadFileToString(const std::string& path, std::string* content);
		bool WriteStringToFile(const std::string& content, const std::string& path);
		bool WriteStringToFile(const std::string& content, const std::string& path,
		mode_t mode, uid_t owner, gid_t group);

		} // namespace android

libutils/file.cpp

+35 −8

Original line number	Diff line number	Diff line
		@@ -46,14 +46,7 @@ bool android::ReadFileToString(const std::string& path, std::string* content) {
		}
		}

		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;
		}

		static bool WriteStringToFd(const std::string& content, int fd) {
		const char* p = content.data();
		size_t left = content.size();
		while (left > 0) {
		@@ -68,3 +61,37 @@ bool android::WriteStringToFile(const std::string& content, const std::string& p
		TEMP_FAILURE_RETRY(close(fd));
		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;
		}

		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) {
		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 && fchown(fd, owner, group) == -1 && WriteStringToFd(content, fd)) {
		return true;
		}
		return CleanUpAfterFailedWrite(path);
		}

		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;
		}
		return WriteStringToFd(content, fd) \|\| CleanUpAfterFailedWrite(path);
		}