spdlog: rotating_file_sink: Set log files ownership

Add option to pass user id (uid)  and group id (gid) when
creating rotating log files.
When creating and rotating files set the ownership to the given
uid and gid.
Default values are -1 which will not change the ownership.

Signed-off-by: Oded <odedr@sentinelone.com>

include/spdlog/sinks/rotating_file_sink-inl.h

@@ -25,13 +25,19 @@ namespace sinks {
 
 template<typename Mutex>
 SPDLOG_INLINE rotating_file_sink<Mutex>::rotating_file_sink(
-    filename_t base_filename, std::size_t max_size, std::size_t max_files, bool rotate_on_open)
+    filename_t base_filename, std::size_t max_size, std::size_t max_files, bool rotate_on_open, uid_t uid, gid_t gid)
     : base_filename_(std::move(base_filename))
     , max_size_(max_size)
     , max_files_(max_files)
+	, uid_ (uid)
+	, gid_ (gid)
 {
     file_helper_.open(calc_filename(base_filename_, 0));
+
     current_size_ = file_helper_.size(); // expensive. called only once
+
+	set_file_ownership(calc_filename(base_filename_, 0));
+
 	if (rotate_on_open && current_size_ > 0)
     {
         rotate_();
@@ -110,11 +116,16 @@ SPDLOG_INLINE void rotating_file_sink<Mutex>::rotate_()
             {
                 file_helper_.reopen(true); // truncate the log file anyway to prevent it to grow beyond its limit!
                 current_size_ = 0;
-                throw_spdlog_ex("rotating_file_sink: failed renaming " + filename_to_str(src) + " to " + filename_to_str(target), errno);
+                auto last_error = errno;
+                set_file_ownership(calc_filename(base_filename_, 0));
+                throw_spdlog_ex("rotating_file_sink: failed renaming " + filename_to_str(src) + " to " + filename_to_str(target), last_error);
             }
         }
+
+		set_file_ownership(target);
     }
     file_helper_.reopen(true);
+    set_file_ownership(calc_filename(base_filename_, 0));
 }
 
 // delete the target if exists, and rename the src file  to target
@@ -126,6 +137,14 @@ SPDLOG_INLINE bool rotating_file_sink<Mutex>::rename_file_(const filename_t &src
     (void)details::os::remove(target_filename);
     return details::os::rename(src_filename, target_filename) == 0;
 }
+template<typename Mutex>
+SPDLOG_INLINE void rotating_file_sink<Mutex>::set_file_ownership(filename_t filename)
+{
+	if (chown(filename.data(), uid_, gid_) < 0) {
+		throw spdlog_ex(
+			"set_file_ownership: failed changing file ownership " + details::os::filename_to_str(filename), errno);
+	}
+}
 
 } // namespace sinks
 } // namespace spdlog

include/spdlog/sinks/rotating_file_sink.h

@@ -3,6 +3,7 @@
 
 #pragma once
 
+#include <unistd.h>
 #include <spdlog/sinks/base_sink.h>
 #include <spdlog/details/file_helper.h>
 #include <spdlog/details/null_mutex.h>
@@ -22,7 +23,7 @@ template<typename Mutex>
 class rotating_file_sink final : public base_sink<Mutex>
 {
 public:
-    rotating_file_sink(filename_t base_filename, std::size_t max_size, std::size_t max_files, bool rotate_on_open = false);
+    rotating_file_sink(filename_t base_filename, std::size_t max_size, std::size_t max_files, bool rotate_on_open = false, uid_t uid = -1, gid_t gid = -1);
     static filename_t calc_filename(const filename_t &filename, std::size_t index);
     filename_t filename();
 
@@ -42,11 +43,15 @@ private:
     // return true on success, false otherwise.
     bool rename_file_(const filename_t &src_filename, const filename_t &target_filename);
 
+    void set_file_ownership(filename_t filename);
+
     filename_t base_filename_;
     std::size_t max_size_;
     std::size_t max_files_;
     std::size_t current_size_;
     details::file_helper file_helper_;
+    uid_t uid_;
+    gid_t gid_;
 };
 
 using rotating_file_sink_mt = rotating_file_sink<std::mutex>;
@@ -60,9 +65,9 @@ using rotating_file_sink_st = rotating_file_sink<details::null_mutex>;
 
 template<typename Factory = spdlog::synchronous_factory>
 inline std::shared_ptr<logger> rotating_logger_mt(
-    const std::string &logger_name, const filename_t &filename, size_t max_file_size, size_t max_files, bool rotate_on_open = false)
+    const std::string &logger_name, const filename_t &filename, size_t max_file_size, size_t max_files, bool rotate_on_open = false, uid_t uid = -1, gid_t gid = -1)
 {
-    return Factory::template create<sinks::rotating_file_sink_mt>(logger_name, filename, max_file_size, max_files, rotate_on_open);
+    return Factory::template create<sinks::rotating_file_sink_mt>(logger_name, filename, max_file_size, max_files, rotate_on_open, uid, gid);
 }
 
 template<typename Factory = spdlog::synchronous_factory>