Make writemoves (and solver) safer by checking buffer size

2 files changed, 38 insertions, 7 deletions

diff --git a/src/solvers/h48/solve.h b/src/solvers/h48/solve.h
index f2babdf..bcc8b33 100644
--- a/src/solvers/h48/solve.h
+++ b/src/solvers/h48/solve.h
@@ -10,6 +10,7 @@ typedef struct {
         uint8_t k;
         const uint32_t *cocsepdata;
         const uint8_t *h48data;
+        uint64_t solutions_size;
         char **nextsol;
         uint8_t nissbranch;
         int8_t npremoves;
@@ -55,26 +56,40 @@ allowednextmove_h48(uint8_t *moves, uint8_t n, uint32_t h48branch)
 STATIC void
 solve_h48_appendsolution(dfsarg_solveh48_t *arg)
 {
-        int strl;
+        int64_t strl;
         uint8_t invertedpremoves[MAXLEN];
         char *solution = *arg->nextsol; 
 
-        strl = writemoves(arg->moves, arg->nmoves, *arg->nextsol);
+        strl = writemoves(
+            arg->moves, arg->nmoves, arg->solutions_size, *arg->nextsol);
+
+        if (strl < 0)
+                goto solve_h48_appendsolution_error;
         *arg->nextsol += strl; 
+        arg->solutions_size -= strl;
 
         if (arg->npremoves) {
                 **arg->nextsol = ' ';
                 (*arg->nextsol)++;
 
                 invertmoves(arg->premoves, arg->npremoves, invertedpremoves);
-                strl = writemoves(invertedpremoves, arg->npremoves, *arg->nextsol);
+                strl = writemoves(invertedpremoves,
+                    arg->npremoves, arg->solutions_size, *arg->nextsol);
+
+                if (strl < 0)
+                        goto solve_h48_appendsolution_error;
                 *arg->nextsol += strl;
+                arg->solutions_size -= strl;
         }
         LOG("Solution found: %s\n", solution);
 
         **arg->nextsol = '\n';
         (*arg->nextsol)++;
         (*arg->nsols)++;
+
+solve_h48_appendsolution_error:
+        /* We could add some logging, but writemoves() already does */
+        return;
 }
 
 STATIC_INLINE bool
@@ -188,6 +203,7 @@ solve_h48(
                 .k = info.bits,
                 .cocsepdata = get_cocsepdata_constptr(data),
                 .h48data = get_h48data_constptr(data),
+                .solutions_size = solutions_size,
                 .nextsol = &solutions
         };
 
diff --git a/src/solvers/h48/solve_multithread.h b/src/solvers/h48/solve_multithread.h
index 3ba914a..8e00404 100644
--- a/src/solvers/h48/solve_multithread.h
+++ b/src/solvers/h48/solve_multithread.h
@@ -27,12 +27,17 @@ STATIC void
 solve_h48_appendsolution_thread(dfsarg_solveh48_t *arg, task_queue_t *tq)
 {
         pthread_mutex_lock(&tq->mutex);
-        int strl = 0;
+        int64_t strl = 0;
         uint8_t invertedpremoves[MAXLEN];
         char *solution = *arg->nextsol;
 
-        strl = writemoves(arg->moves, arg->nmoves, *arg->nextsol);
+        strl = writemoves(
+            arg->moves, arg->nmoves, arg->solutions_size, *arg->nextsol);
+
+        if (strl < 0)
+                goto solve_h48_appendsolution_thread_error;
         *arg->nextsol += strl;
+        arg->solutions_size -= strl;
 
         if (arg->npremoves)
         {
@@ -40,14 +45,22 @@ solve_h48_appendsolution_thread(dfsarg_solveh48_t *arg, task_queue_t *tq)
                 (*arg->nextsol)++;
 
                 invertmoves(arg->premoves, arg->npremoves, invertedpremoves);
-                strl = writemoves(invertedpremoves, arg->npremoves, *arg->nextsol);
+                strl = writemoves(invertedpremoves,
+                    arg->npremoves, arg->solutions_size, *arg->nextsol);
+
+                if (strl < 0)
+                        goto solve_h48_appendsolution_thread_error;
                 *arg->nextsol += strl;
+                arg->solutions_size -= strl;
         }
         LOG("Solution found: %s\n", solution);
 
         **arg->nextsol = '\n';
         (*arg->nextsol)++;
         (*arg->nsols)++;
+
+solve_h48_appendsolution_thread_error:
+        /* We could add some logging, but writemoves() already does */
         pthread_mutex_unlock(&tq->mutex);
 }
 
@@ -264,7 +277,9 @@ solve_h48_multithread(
                 .k = info.bits,
                 .cocsepdata = get_cocsepdata_constptr(data),
                 .h48data = get_h48data_constptr(data),
-                .nextsol = &solutions};
+                .solutions_size = solutions_size,
+                .nextsol = &solutions
+        };
 
         task_queue_t q;
         init_queue(&q);