Being a bit more careful about memory.

This avoids some valgrind errors, and should hopefully help reduce memory corruption (Issue #150)

rt/builtin.cpp

@@ -144,13 +144,13 @@ int hscanfu64(FILE *f, uint64_t *i) {
 // This will leak memory (#149)
 char* hgets(FILE *f) {
 	char buffer[1024];
-	// this is totally insecure!
-	fscanf(f, "%s", buffer);
+	fscanf(f, "%1024s", buffer);
 
 	int len = strnlen(buffer, sizeof(buffer));
 
 	char *new_str = (char *)malloc(len + 1);
-	strncpy(new_str, buffer, sizeof(buffer));
+	memset(new_str, 0, len + 1);
+	strncpy(new_str, buffer, len);
 
 	return new_str;
 }

rt/cl++.cpp

@@ -94,7 +94,7 @@ device_list::device_list(cl_device_type type)
     // Allocate memory, gather information about all the devices.
     devices = new cl_device_id[num_ids];
 
-    status = clGetDeviceIDs(platforms[platform], type, n_dev,
+    status = clGetDeviceIDs(platforms[platform], type, min(num_ids, n_dev),
                             devices, &n_dev);
     //cerr << status << ", " << n_dev << endl;
     CL_CHECK_MSG(status, "clGetDeviceIDs");
@@ -134,7 +134,9 @@ context::context(device_list &devices)
 
 context::~context()
 {
+	//cerr << "Destroying context" << endl;
 	clReleaseContext(ctx);
+	//cerr << "Context destroyed" << endl;
 }
 
 void context::sLogError(const char *errinfo,
@@ -159,7 +161,9 @@ kernel::kernel(cl_kernel k)
 
 kernel::~kernel()
 {
+	//cerr << "Destroying kernel" << endl;
 	clReleaseKernel(k);
+	//cerr << "Kernel destroyed" << endl;
 }
 
 size_t kernel::maxWorkGroupSize(cl_device_id device)
@@ -184,7 +188,9 @@ program::program(cl_program prog)
 
 program::~program()
 {
+	//cerr << "Destroying program" << endl;
 	clReleaseProgram(prog);
+	//cerr << "Program destroyed" << endl;
 }
 
 string escape_path(const char *s) {
@@ -229,6 +235,7 @@ void program::build()
 
 kernel program::createKernel(string name)
 {
+	//cerr << "Creating kernel" << endl;
 	return kernel(clCreateKernel(prog, name.c_str(), NULL));
 }