altos/draw: Add validation for line drawing

[fw/altos] / src / draw / ao_line.c

diff --git a/src/draw/ao_line.c b/src/draw/ao_line.c
index 318f101e05b4edaadb93891bfdb9f69174d1248f..832a916c76aed9dbe1042f7a024febe071ae93c6 100644 (file)
--- a/src/draw/ao_line.c
+++ b/src/draw/ao_line.c
@@ -54,8 +54,9 @@
  *     adjust_x = e / e1;
  */
 
-
-
+#ifdef VALIDATE
+#include <stdio.h>
+#endif
 
 static void
 ao_bres(const struct ao_bitmap *dst_bitmap,
@@ -88,9 +89,22 @@ ao_bres(const struct ao_bitmap       *dst_bitmap,
        while (len--) {
                /* clip each point */
 
+#ifdef VALIDATE
+               if (x1 < 0 || dst_bitmap->width <= x1) {
+                       printf("bad line x %d\n", x1);
+                       return;
+               }
+               if (y1 < 0 || dst_bitmap->height <= y1) {
+                       printf("bad line y %d\n", y1);
+                       return;
+               }
+#endif
                *dst = ao_do_mask_rrop(*dst, and, xor, mask);
 
                if (axis == X_AXIS) {
+#ifdef VALIDATE
+                       x1 += signdx;
+#endif
                        if (signdx < 0)
                                mask = ao_left(mask, 1);
                        else
@@ -101,13 +115,22 @@ ao_bres(const struct ao_bitmap    *dst_bitmap,
                        }
                        e += e1;
                        if (e >= 0) {
+#ifdef VALIDATE
+                               y1 += signdy;
+#endif
                                dst += stride;
                                e += e3;
                        }
                } else {
+#ifdef VALIDATE
+                       y1 += signdy;
+#endif
                        dst += stride;
                        e += e1;
                        if (e >= 0) {
+#ifdef VALIDATE
+                               x1 += signdx;
+#endif
                                if (signdx < 0)
                                        mask = ao_left(mask, 1);
                                else
@@ -142,12 +165,12 @@ struct ao_cbox {
 /* -b <= a, so we need to make a bigger */
 static int16_t
 div_ceil(int32_t a, int16_t b) {
-       return (a + b + b - 1) / b - 1;
+       return (int16_t) ((a + b + b - 1) / b - 1);
 }
 
 static int16_t
 div_floor_plus_one(int32_t a, int16_t b) {
-       return (a + b) / b;
+       return (int16_t) ((a + b) / b);
 }
 
 static int8_t
@@ -202,10 +225,10 @@ ao_clip_line(struct ao_cc *c, struct ao_cbox *b)
                adjust_minor = adj_min;
        }
 
-       c->e += adjust_major * c->e1 + adjust_minor * c->e3;
+       c->e = (int16_t) (c->e + adjust_major * c->e1 + adjust_minor * c->e3);
 
-       c->major += c->sign_major * adjust_major;
-       c->minor += c->sign_minor * adjust_minor;
+       c->major = (int16_t) (c->major + c->sign_major * adjust_major);
+       c->minor = (int16_t) (c->minor + c->sign_minor * adjust_minor);
 
        return true;
 }
@@ -239,7 +262,7 @@ ao_line(const struct ao_bitmap      *dst,
        if (adx > ady) {
                axis = X_AXIS;
                e1 = ady << 1;
-               e2 = e1 - (adx << 1);
+               e2 = e1 - (int16_t) (adx << 1);
                e = e1 - adx;
 
                clip_1.major = x1;
@@ -256,7 +279,7 @@ ao_line(const struct ao_bitmap      *dst,
        } else {
                axis = Y_AXIS;
                e1 = adx << 1;
-               e2 = e1 - (ady << 1);
+               e2 = e1 - (int16_t) (ady << 1);
                e = e1 - ady;
 
                clip_1.major = y1;
@@ -289,7 +312,7 @@ ao_line(const struct ao_bitmap      *dst,
        if (!ao_clip_line(&clip_2, &cbox))
                return;
 
-       len = clip_1.sign_major * (clip_2.major - clip_1.major) + clip_2.first;
+       len = (int16_t) (clip_1.sign_major * (clip_2.major - clip_1.major) + clip_2.first);
 
        if (len <= 0)
                return;