Function SetDataDir

src/backend/utils/init/miscinit.c:412–425

* Set data directory, but make sure it's an absolute path. Use this, * never set DataDir directly. */

 * never set DataDir directly.
 */
void
SetDataDir(const char *dir)
{
	char	   *new;

	AssertArg(dir);

	/* If presented path is relative, convert to absolute */
	new = make_absolute_path(dir);

	if (DataDir)
		free(DataDir);
	DataDir = new;
}

/*
 * Change working directory to DataDir.  Most of the postmaster and backend