Bug #165: Deletion of unnecessary null pointer checks

The function "free" performs input parameter validation.
http://pubs.opengroup.org/onlinepubs/9699919799/functions/free.html

It is therefore not needed to check a passed pointer before this function call.
A corresponding update suggestion was generated by the software "Coccinelle"
from the following semantic patch approach.
http://coccinelle.lip6.fr/

@Remove_unnecessary_pointer_checks1@
expression x;
@@
-if (x != \(0 \| NULL\))
    free(x);

@Remove_unnecessary_pointer_checks2@
expression x;
@@
-if (x != \(0 \| NULL\)) {
    free(x);
    x = \(0 \| NULL\);
-}

@Remove_unnecessary_pointer_checks3@
expression a, b;
@@
-if (a != \(0 \| NULL\) && b != \(0 \| NULL\))
+if (a)
    free(b);

@Remove_unnecessary_pointer_checks4@
expression a, b;
@@
-if (a != \(0 \| NULL\) && b != \(0 \| NULL\)) {
+if (a) {
    free(b);
    b = \(0 \| NULL\);
 }

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>

util.c

@@ -198,18 +198,13 @@ char* absolute_path(const char *filename)
 	goto end;
 
 error:
-	if (path != NULL) {
-		free(path);
-		path = NULL;
-	}
+	free(path);
+	path = NULL;
 
 end:
-	if (dirname != NULL)
-		free(dirname);
-	if (cwd != NULL)
-		free(cwd);
-	if (twd != NULL)
-		free(twd);
+	free(dirname);
+	free(cwd);
+	free(twd);
 
 	return path;
 }
@@ -254,7 +249,7 @@ int r_closedir(r_dir_t *rdir)
 			rdir->dir = NULL;
 	}
 
-	if (rdir->d != 0 && rdir->name != NULL) {
+	if (rdir->d != 0) {
 		free(rdir->name);
 		rdir->name = NULL;
 	}