Merge branch 'fsync-shadow-files-before-rename' of https://github.com/awelzel/zeek

* 'fsync-shadow-files-before-rename' of https://github.com/awelzel/zeek:
  logging/writers/ascii: shadow files: Add fsync() before rename()

src/util.cc

@@ -2162,6 +2162,36 @@ bool safe_pwrite(int fd, const unsigned char* data, size_t len, size_t offset)
 	return true;
 	}
 
+bool safe_fsync(int fd)
+	{
+	int r;
+
+	/*
+	 * Failure cases of fsync(2) are EABDF, EINTR, ENOSPC, EROFS, EINVAL, EDQUOT.
+	 *
+	 * For EINTR, one can just retry until it is not interrupted. For the others
+	 * we report an error.
+	 *
+	 * Note that we don't use the reporter here to allow use from different threads.
+	 */
+	do
+		{
+		r = fsync(fd);
+		} while ( r < 0 && errno == EINTR );
+
+	if ( r < 0 )
+		{
+		char buf[128];
+		zeek_strerror_r(errno, buf, sizeof(buf));
+		fprintf(stderr, "safe_fsync error %d: %s\n", errno, buf);
+		abort();
+
+		return false;
+		}
+
+	return true;
+	}
+
 void safe_close(int fd)
 	{
 	/*