cngf-pf

commit 8ee190a791f59c6d83108b5f7018217a652f47c8
parent a836eef18c61a0535fe1fbfe1123f3f8530a59de
Author: Anders Damsgaard <anders@adamsgaard.dk>
Date:   Fri,  3 Jul 2026 11:37:32 +0200

fix(simulation): restore mu_wall on coupled_shear_solver error returns

Diffstat:
M
simulation.c
 | 
10
++++++++--
M
test/test_error_path.c
 | 
10
++++++++++

2 files changed, 18 insertions(+), 2 deletions(-)
diff --git a/simulation.c b/simulation.c
@@ -835,8 +835,10 @@ int coupled_shear_solver(struct simulation *sim, const int max_iter,
 
 			/* step 5, Eq. 13 */
 			if (sim->fluid && (sim->t > 0))
-				if (darcy_solver_1d(sim))
+				if (darcy_solver_1d(sim)) {
+					sim->mu_wall = mu_wall_orig;
 					return 11;
+				}
 
 			/* step 6 */
 			compute_effective_stress(sim); /* Eq. 9 */
@@ -846,8 +848,10 @@ int coupled_shear_solver(struct simulation *sim, const int max_iter,
 			compute_cooperativity_length(sim); /* Eq. 12 */
 
 			/* step 8, Eq. 11 */
-			if (implicit_1d_sor_poisson_solver(sim))
+			if (implicit_1d_sor_poisson_solver(sim)) {
+				sim->mu_wall = mu_wall_orig;
 				return 12;
+			}
 
 			/* step 9 */
 			compute_shear_strain_rate_plastic(sim); /* Eq. 8 */
@@ -883,6 +887,7 @@ int coupled_shear_solver(struct simulation *sim, const int max_iter,
 					        "after %d iterations\n",
 					        coupled_iter);
 					fprintf(stderr, ".. Residual normalized error: %g\n", r_norm_max);
+					sim->mu_wall = mu_wall_orig;
 					return 1;
 				}
 			}
@@ -909,6 +914,7 @@ int coupled_shear_solver(struct simulation *sim, const int max_iter,
 			        "vel_res_norm=%g, mu_wall=%g\n",
 			        sim->v_x[sim->nz - 1], sim->v_x_fix, sim->v_x_limit, vel_res_norm,
 			        sim->mu_wall);
+			sim->mu_wall = mu_wall_orig;
 			return 10;
 		}
 	} while ((!isnan(sim->v_x_fix) || !isnan(sim->v_x_limit)) &&
diff --git a/test/test_error_path.c b/test/test_error_path.c
@@ -14,6 +14,7 @@ int
 main(void)
 {
 	int i, ret;
+	double mu_wall_orig;
 	struct simulation sim;
 
 	init_sim(&sim);
@@ -35,6 +36,7 @@ main(void)
 
 	/* max_iter = 0 forces the stress solver to exceed its iteration budget
 	 * and return a non-zero code rather than aborting the process */
+	mu_wall_orig = sim.mu_wall;
 	ret = coupled_shear_solver(&sim, 0, 1e-5);
 
 	free_arrays(&sim);
@@ -44,6 +46,14 @@ main(void)
 		return 1;
 	}
 
+	/* a failed solve must not leak the perturbed wall friction back to the
+	 * caller; an embedder reuses the struct for the next column */
+	if (sim.mu_wall != mu_wall_orig) {
+		fprintf(stderr, "error: mu_wall not restored on failure: %g != %g\n",
+		        sim.mu_wall, mu_wall_orig);
+		return 1;
+	}
+
 	printf("ok: coupled_shear_solver returned %d without terminating\n", ret);
 	return 0;
 }