1 files changed, 176 insertions, 0 deletions
diff --git a/Examples/python/libffi/example.i b/Examples/python/libffi/example.i
new file mode 100644
index 0000000..9a29ec0
--- /dev/null
+++ b/Examples/python/libffi/example.i
@@ -0,0 +1,176 @@
+/* File : example.i */
+%module example
+
+%{
+#include <unistd.h>
+#include <ffi.h>
+%}
+
+/* A wrapper for execlp() using libffi to handle an arbitrary
+   number of arguments */
+
+%typemap(in) (...) {
+   char **argv;
+   int    argc;
+   int    i;
+
+   argc = PyTuple_Size(varargs);
+   argv = (char **) malloc(sizeof(char *)*(argc+1));
+   for (i = 0; i < argc; i++) {
+      PyObject *o = PyTuple_GetItem(varargs,i);
+      if (!PyString_Check(o)) {
+          PyErr_SetString(PyExc_ValueError,"Expected a string");
+          return NULL;
+      }
+      argv[i] = PyString_AsString(o);
+   }
+   argv[i] = NULL;
+   $1 = (void *) argv;
+}
+
+/* Rewrite the function call, using libffi */    
+%feature("action") execlp {
+  int       i, vc;
+  ffi_cif   cif;
+  ffi_type  **types;
+  void      **values;
+  char      **args;
+
+  vc = PyTuple_Size(varargs);
+  types  = (ffi_type **) malloc((vc+3)*sizeof(ffi_type *));
+  values = (void **) malloc((vc+3)*sizeof(void *));
+  args   = (char **) arg3;
+
+  /* Set up path parameter */
+  types[0] = &ffi_type_pointer;
+  values[0] = &arg1;
+  
+  /* Set up first argument */
+  types[1] = &ffi_type_pointer;
+  values[1] = &arg2;
+
+  /* Set up rest of parameters */
+  for (i = 0; i <= vc; i++) {
+    types[2+i] = &ffi_type_pointer;
+    values[2+i] = &args[i];
+  }
+  if (ffi_prep_cif(&cif, FFI_DEFAULT_ABI, vc+3,
+                   &ffi_type_uint, types) == FFI_OK) {
+    ffi_call(&cif, (void (*)()) execlp, &result, values);
+  } else {
+    PyErr_SetString(PyExc_RuntimeError, "Whoa!!!!!");
+    free(types);
+    free(values);
+    free(arg3);
+    return NULL;
+  }
+  free(types);
+  free(values);
+  free(arg3);
+}
+
+int execlp(const char *path, const char *arg1, ...);
+
+
+/* A wrapper for printf() using libffi */
+
+%{
+  typedef struct {
+    int type;
+    union {
+      int    ivalue;
+      double dvalue;
+      void   *pvalue;
+    } val;
+  } vtype;
+  enum { VT_INT, VT_DOUBLE, VT_POINTER };
+  %}
+
+%typemap(in) (const char *fmt, ...) {
+  vtype *argv;
+  int    argc;
+  int    i;
+
+  $1 = PyString_AsString($input);
+
+  argc = PyTuple_Size(varargs);
+  argv = (vtype *) malloc(argc*sizeof(vtype));
+  for (i = 0; i < argc; i++) {
+    PyObject *o = PyTuple_GetItem(varargs,i);
+    if (PyInt_Check(o)) {
+      argv[i].type = VT_INT;
+      argv[i].val.ivalue = PyInt_AsLong(o);
+    } else if (PyFloat_Check(o)) {
+      argv[i].type = VT_DOUBLE;
+      argv[i].val.dvalue = PyFloat_AsDouble(o);
+    } else if (PyString_Check(o)) {
+      argv[i].type = VT_POINTER;
+      argv[i].val.pvalue = (void *) PyString_AsString(o);
+    } else {
+      PyErr_SetString(PyExc_ValueError,"Unsupported argument type");
+      free(argv);
+      return NULL;
+    }
+  }
+
+  $2 = (void *) argv;
+}
+
+/* Rewrite the function call, using libffi */    
+%feature("action") printf {
+  int       i, vc;
+  ffi_cif   cif;
+  ffi_type  **types;
+  void      **values;
+  vtype     *args;
+
+  vc = PyTuple_Size(varargs);
+  types  = (ffi_type **) malloc((vc+1)*sizeof(ffi_type *));
+  values = (void **) malloc((vc+1)*sizeof(void *));
+  args   = (vtype *) arg2;
+
+  /* Set up fmt parameter */
+  types[0] = &ffi_type_pointer;
+  values[0] = &arg1;
+
+  /* Set up rest of parameters */
+  for (i = 0; i < vc; i++) {
+    switch(args[i].type) {
+    case VT_INT:
+      types[1+i] = &ffi_type_uint;
+      values[1+i] = &args[i].val.ivalue;
+      break;
+    case VT_DOUBLE:
+      types[1+i] = &ffi_type_double;
+      values[1+i] = &args[i].val.dvalue;
+      break;
+    case VT_POINTER:
+      types[1+i] = &ffi_type_pointer;
+      values[1+i] = &args[i].val.pvalue;
+      break;
+    default:
+      abort();    /* Whoa! We're seriously hosed */
+      break;   
+    }
+  }
+  if (ffi_prep_cif(&cif, FFI_DEFAULT_ABI, vc+1,
+                   &ffi_type_uint, types) == FFI_OK) {
+    ffi_call(&cif, (void (*)()) printf, &result, values);
+  } else {
+    PyErr_SetString(PyExc_RuntimeError, "Whoa!!!!!");
+    free(types);
+    free(values);
+    free(args);
+    return NULL;
+  }
+  free(types);
+  free(values);
+  free(args);
+}
+
+int printf(const char *fmt, ...);
+
+
+  
+
+