safer data types multiplication

src/bmp.c

@@ -4,25 +4,24 @@
 
 #define HEADER_SIZE 54
 
-void write_str(unsigned char *buffer, unsigned short offset,
-               unsigned short size, unsigned char *value) {
-  int i;
+void write_str(unsigned char *buffer, unsigned int offset, unsigned int size,
+               unsigned char *value) {
+  unsigned int i;
   for (i = 0; i < size; i++) {
     buffer[offset + i] = (unsigned char)value[i];
   }
 }
 
-void write_num(unsigned char *buffer, unsigned short offset,
-               unsigned short size, unsigned short value) {
-  int i;
+void write_num(unsigned char *buffer, unsigned int offset, unsigned int size,
+               unsigned int value) {
+  unsigned int i;
   for (i = 0; i < size; i++) {
     buffer[offset + i] = (unsigned char)((value >> (8 * i)) & 0xFFu);
   }
 }
 
-void write_nul(unsigned char *buffer, unsigned short offset,
-               unsigned short size) {
-  int i;
+void write_nul(unsigned char *buffer, unsigned int offset, unsigned int size) {
+  unsigned int i;
   for (i = 0; i < size; i++) {
     buffer[offset + i] = 0;
   }
@@ -31,10 +30,11 @@ void write_nul(unsigned char *buffer, unsigned short offset,
 unsigned char *bmp_header(unsigned short width, unsigned short height,
                           unsigned char color_depth) {
   unsigned char *output = (unsigned char *)malloc(HEADER_SIZE);
-
+  unsigned int data_length = ((unsigned int)width) * ((unsigned int)height) *
+                             ((unsigned int)color_depth);
   write_str(output, 0x00, 0x02, (unsigned char *)"BM"); // 0x00(2) BM
   write_num(output, 0x02, 0x04,
-            HEADER_SIZE + width * height * color_depth); // 0x02(4) file size
+            HEADER_SIZE + data_length);       // 0x02(4) file size
   write_nul(output, 0x06, 0x04);              // 0x06(4) application reserved
   write_num(output, 0x0A, 0x04, HEADER_SIZE); // 0x0A(4) data offset
   write_num(output, 0x0E, 0x04, 40);          // 0x0E(4) DIB header size
@@ -44,7 +44,7 @@ unsigned char *bmp_header(unsigned short width, unsigned short height,
   write_num(output, 0x1C, 0x02, color_depth * 8); // 0x1C(2) bits per pixel
   write_nul(output, 0x1E, 0x04); // 0x1E(4) BI_RGB, no compression
   write_num(output, 0x22, 0x04,
-            width * height * color_depth); // 0x22(4) size of raw bitmap data
+            data_length);              // 0x22(4) size of raw bitmap data
   write_num(output, 0x26, 0x04, 2835); // 0x26(4) horizontal print resolution
   write_num(output, 0x2A, 0x04, 2835); // 0x2A(4) vertical print resolution
   write_nul(output, 0x2E, 0x04);       // 0x2E(4) color in palette
@@ -53,18 +53,22 @@ unsigned char *bmp_header(unsigned short width, unsigned short height,
   return output;
 }
 
-unsigned short bmp_data_line_length(unsigned short width,
-                                    unsigned char color_depth) {
-  unsigned short line_offset = (width * color_depth) % 4;
+unsigned int bmp_data_line_length(unsigned short width,
+                                  unsigned char color_depth) {
+  unsigned int data_length =
+      ((unsigned int)width) * ((unsigned int)color_depth);
+  unsigned int line_offset = data_length % 4;
   unsigned short line_padding = line_offset > 0 ? 4 - line_offset : 0;
-  return width * color_depth + line_padding;
+  return data_length + line_padding;
 }
 
 void bmp_data_line(unsigned char *buffer, unsigned short width,
                    unsigned char color_depth, unsigned char *data) {
-  unsigned short line_offset = (width * color_depth) % 4;
+  unsigned int data_length =
+      ((unsigned int)width) * ((unsigned int)color_depth);
+  unsigned int line_offset = data_length % 4;
   unsigned short line_padding = line_offset > 0 ? 4 - line_offset : 0;
-  write_str(buffer, 0, width * color_depth, data);
+  write_str(buffer, 0, data_length, data);
   if (line_padding > 0) {
     write_nul(buffer, width * color_depth, line_padding);
   }
@@ -78,11 +82,13 @@ void bmp_generate(unsigned short width, unsigned short height,
   unsigned char *header = bmp_header(width, height, color_depth);
   fwrite(header, HEADER_SIZE, 1, fptr);
   free(header);
+  unsigned int data_length =
+      ((unsigned int)width) * ((unsigned int)color_depth);
   unsigned short y;
-  unsigned char *data_buffer = malloc(width * color_depth);
+  unsigned char *data_buffer = malloc(data_length);
   unsigned char *line_buffer = malloc(bmp_data_line_length(width, color_depth));
   for (y = 0; y < height; y++) {
-    generate_line(height - y - 1, data_buffer);
+    generate_line(height - y - 1, data_buffer, data_length);
     bmp_data_line(line_buffer, width, color_depth, data_buffer);
     fwrite(line_buffer, bmp_data_line_length(width, color_depth), 1, fptr);
   }

src/generator.c

@@ -1,14 +1,17 @@
 #include "args.h"
 #include "bmp.h"
 #include <stdio.h>
-#include <string.h>
 
 #define COLOR_DEPTH 3
 
 parameters global_params;
 
-void generate_line(unsigned short y, unsigned char *data_buffer) {
-  memset(data_buffer, y, global_params.width * COLOR_DEPTH);
+void generate_line(unsigned short y, unsigned char *data_buffer,
+                   unsigned int len) {
+  unsigned int i;
+  for (i = 0; i < len; i++) {
+    data_buffer[i] = global_params.start[i % 3];
+  }
 }
 
 void debug_parameters(parameters params) {

src/rand.h

@@ -1,7 +1,7 @@
 #ifndef RAND_H
 #define RAND_H
 
-void set_seed(float new_seed);
+void set_seed(unsigned long new_seed);
 unsigned char rand_uchar(unsigned int max);
 unsigned short rand_ushort(unsigned int max);
 

src/types.h

@@ -17,6 +17,7 @@ struct Parameters {
 
 typedef struct Parameters parameters;
 
-typedef void line_fn(unsigned short y, unsigned char *data_buffer);
+typedef void line_fn(unsigned short y, unsigned char *data_buffer,
+                     unsigned int len);
 
 #endif