Function coredump

freebsd/kern/kern_sig.c:3730–3866

 */

static int
coredump(struct thread *td)
{
	struct proc *p = td->td_proc;
	struct ucred *cred = td->td_ucred;
	struct vnode *vp;
	struct flock lf;
	struct vattr vattr;
	size_t fullpathsize;
	int error, error1, locked;
	char *name;			/* name of corefile */
	void *rl_cookie;
	off_t limit;
	char *fullpath, *freepath = NULL;
	struct sbuf *sb;

	PROC_LOCK_ASSERT(p, MA_OWNED);
	MPASS((p->p_flag & P_HADTHREADS) == 0 || p->p_singlethread == td);

	if (!do_coredump || (!sugid_coredump && (p->p_flag & P_SUGID) != 0) ||
	    (p->p_flag2 & P2_NOTRACE) != 0) {
		PROC_UNLOCK(p);
		return (EFAULT);
	}

	/*
	 * Note that the bulk of limit checking is done after
	 * the corefile is created.  The exception is if the limit
	 * for corefiles is 0, in which case we don't bother
	 * creating the corefile at all.  This layout means that
	 * a corefile is truncated instead of not being created,
	 * if it is larger than the limit.
	 */
	limit = (off_t)lim_cur(td, RLIMIT_CORE);
	if (limit == 0 || racct_get_available(p, RACCT_CORE) == 0) {
		PROC_UNLOCK(p);
		return (EFBIG);
	}
	PROC_UNLOCK(p);

	error = corefile_open(p->p_comm, cred->cr_uid, p->p_pid, td,
	    compress_user_cores, p->p_sig, &vp, &name);
	if (error != 0)
		return (error);

	/*
	 * Don't dump to non-regular files or files with links.
	 * Do not dump into system files. Effective user must own the corefile.
	 */
	if (vp->v_type != VREG || VOP_GETATTR(vp, &vattr, cred) != 0 ||
	    vattr.va_nlink != 1 || (vp->v_vflag & VV_SYSTEM) != 0 ||
	    vattr.va_uid != cred->cr_uid) {
		VOP_UNLOCK(vp);
		error = EFAULT;
		goto out;
	}

	VOP_UNLOCK(vp);