read_blif bug fix

When using Odin_II in -b mode, large post-ABC BLIFs cause segfault
Unguarded strtok was passing null pointer to strcmp
Simply guarded the failed strtok, unclear whether this resolves
underlying issue.
Similar issue still happens if large BLIFs used in simulator.
Also fixed typo.

Author: mflawn

ODIN_II/SRC/read_blif.cpp

@@ -1380,7 +1380,7 @@ hard_block_model *read_hard_block_model(char *name_subckt, hard_block_ports *por
 		while (vtr::fgets(buffer, READ_BLIF_BUFFER, file))
 		{
 			char *token = vtr::strtok(buffer,TOKENS, file, buffer);
-			// match .model followed buy the subcircuit name.
+			// match .model followed by the subcircuit name.
 			if (token && !strcmp(token,".model") && !strcmp(vtr::strtok(NULL,TOKENS, file, buffer), name_subckt))
 			{
 				model = (hard_block_model *)vtr::calloc(1, sizeof(hard_block_model));
@@ -1397,28 +1397,31 @@ hard_block_model *read_hard_block_model(char *name_subckt, hard_block_ports *por
 				while (vtr::fgets(buffer, READ_BLIF_BUFFER, file))
 				{
 					char *first_word = vtr::strtok(buffer, TOKENS, file, buffer);
-					if(!strcmp(first_word, ".inputs"))
+					if(first_word)
 					{
-						char *name;
-						while ((name = vtr::strtok(NULL, TOKENS, file, buffer)))
+						if(!strcmp(first_word, ".inputs"))
 						{
-							model->inputs->names = (char **)vtr::realloc(model->inputs->names, sizeof(char *) * (model->inputs->count + 1));
-							model->inputs->names[model->inputs->count++] = vtr::strdup(name);
+							char *name;
+							while ((name = vtr::strtok(NULL, TOKENS, file, buffer)))
+							{
+								model->inputs->names = (char **)vtr::realloc(model->inputs->names, sizeof(char *) * (model->inputs->count + 1));
+								model->inputs->names[model->inputs->count++] = vtr::strdup(name);
+							}
 						}
-					}
-					else if(!strcmp(first_word, ".outputs"))
-					{
-						char *name;
-						while ((name = vtr::strtok(NULL, TOKENS, file, buffer)))
+						else if(!strcmp(first_word, ".outputs"))
+						{
+							char *name;
+							while ((name = vtr::strtok(NULL, TOKENS, file, buffer)))
+							{
+								model->outputs->names = (char **)vtr::realloc(model->outputs->names, sizeof(char *) * (model->outputs->count + 1));
+								model->outputs->names[model->outputs->count++] = vtr::strdup(name);
+							}
+						}
+						else if(!strcmp(first_word, ".end"))
 						{
-							model->outputs->names = (char **)vtr::realloc(model->outputs->names, sizeof(char *) * (model->outputs->count + 1));
-							model->outputs->names[model->outputs->count++] = vtr::strdup(name);
+							break;
 						}
 					}
-					else if(!strcmp(first_word, ".end"))
-					{
-						break;
-					}
 				}
 				break;
 			}