2 files changed, 20 insertions(+), 12 deletions(-)

M main.c
M pack_bits.c

@@ 150,8 150,8 @@ struct Result read_data(char * filename) {
     fseek(fptr, strip_offsets[i], 0);
     unsigned char * other = malloc(strip_bytes[i]);
     fread(other, sizeof(char), strip_bytes[i], fptr);
-    int expected = expected_length(other, strip_bytes[i]);
-    unsigned char * unpacked = unpack(other, strip_bytes[0], expected);
+    size_t expected = expected_length(other, strip_bytes[i]);
+    unsigned char * unpacked = unpack(other, strip_bytes[i], expected);
     for (int j = 0; j < expected; j++) {
       pixels[total_pointer] = unpacked[j];
       total_pointer += 1;

@@ 1,37 1,45 @@
 #include <stdio.h>
 #include <stdlib.h>
 
-int expected_length(unsigned char hexArray[], int current_length) {    
+size_t expected_length(unsigned char hexArray[], int current_length) {
+  /*
+   Compute the expected length of a resulting array after performing PackBits
+   decompression. This is necessary in order to allocate a suffciently large
+   buffer. PackBits is not efficient in all cases, and in some unlucky cases
+   the compressed array can be larger than the decompressed array.
+   */
   int i = 0;
-  int expected_size = 0;
+  size_t expected_length = 0;
   while (i < current_length) {
     int hex = hexArray[i];
     if (hex > 128) {
       hex = 256 - hex;
       // Repeat the byte immediately after this one
       // 256 - hex times
-      for (int j = 0; j <= hex; j++) {
-	expected_size += 1;
+      for (int j = 0; j <= hex; ++j) {
+	expected_length += 1;
       }
       i++;
     }
     else if (hex < 128) {
       // Treat the next hex bytes as literal
-      for (int j = 0; j <= hex; j++) {
-	expected_size += 1;
+      for (int j = 0; j <= hex; ++j) {
+	expected_length += 1;
       }
       i += hex + 1;
     }
     i++;
   }
-  return expected_size;
+  return expected_length;
 }
 
-unsigned char * unpack(unsigned char hexArray[], int current_length, int expected_legnth) {
+unsigned char * unpack(unsigned char hexArray[], int current_length, size_t expected_length) {
+  /*
+   Decompress a PackBits array
+   */
   int i = 0;
-  unsigned char * output = malloc(expected_length);
+  unsigned char * output = (unsigned char*) malloc(expected_length * sizeof(char));
   int output_ptr = 0;
-  int expected_size = 0;
   while (i < current_length) {
     int hex = hexArray[i];
     if (hex > 128) {