Function OpenTransientFile

src/backend/storage/file/fd.c:2553–2557

* Open a file with OpenTransientFilePerm() and pass default file mode for * the fileMode parameter. */

 * the fileMode parameter.
 */
int
OpenTransientFile(const char *fileName, int fileFlags)
{
	return OpenTransientFilePerm(fileName, fileFlags, pg_file_create_mode);
}

/*
 * Like AllocateFile, but returns an unbuffered fd like open(2)