Merge pull request #235 from pfalcon/modffi

unix: Initial FFI module implementation

examples/unix/ffi_example.py

+import ffi
+
+libc = ffi.open("libc.so.6")
+print("libc:", libc)
+print()
+
+# Declare few functions
+perror = libc.func("v", "perror", ["s"])
+time = libc.func("i", "time", "p")
+open = libc.func("i", "open", ["s", "i"])
+qsort = libc.func("v", "qsort", "piip")
+# And one variable
+errno = libc.var("i", "errno")
+
+print("time:", time)
+print("UNIX time is:", time(None))
+print()
+
+perror("ffi before error")
+open("somethingnonexistent__", 0)
+print(errno)
+perror("ffi after error")
+print()
+
+def cmp(pa, pb):
+    a = ffi.as_bytearray(pa, 1)
+    b = ffi.as_bytearray(pb, 1)
+    print("cmp:", a, b)
+    return a[0] - b[0]
+
+cmp_c = ffi.callback("i", cmp, "pp")
+print("callback:", cmp_c)
+
+# TODO: violates Py semantics, pass bytearray
+s = "foobar"
+print("org string:", s)
+qsort(s, len(s), 1, cmp_c)
+print("qsort'ed:", s)

unix/Makefile

@@ -11,7 +11,7 @@ include ../py/py.mk
 
 # compiler settings
 CFLAGS = -I. -I$(PY_SRC) -Wall -Werror -ansi -std=gnu99 -DUNIX
-LDFLAGS = -lm
+LDFLAGS = -lm -ldl -lffi
 
 # Debugging/Optimization
 ifdef DEBUG
@@ -25,6 +25,7 @@ SRC_C = \
 	main.c \
 	file.c \
 	socket.c \
+	ffi.c \
 
 OBJ = $(PY_O) $(addprefix $(BUILD)/, $(SRC_C:.c=.o))
 LIB = -lreadline

unix/ffi.c

+#include <assert.h>
+#include <string.h>
+#include <errno.h>
+#include <dlfcn.h>
+#include <ffi.h>
+
+#include "nlr.h"
+#include "misc.h"
+#include "mpconfig.h"
+#include "qstr.h"
+#include "obj.h"
+#include "runtime.h"
+
+typedef struct _mp_obj_opaque_t {
+    mp_obj_base_t base;
+    void *val;
+} mp_obj_opaque_t;
+
+typedef struct _mp_obj_ffimod_t {
+    mp_obj_base_t base;
+    void *handle;
+} mp_obj_ffimod_t;
+
+typedef struct _mp_obj_ffivar_t {
+    mp_obj_base_t base;
+    void *var;
+    char type;
+//    ffi_type *type;
+} mp_obj_ffivar_t;
+
+typedef struct _mp_obj_ffifunc_t {
+    mp_obj_base_t base;
+    void *func;
+    char rettype;
+    ffi_cif cif;
+    ffi_type *params[];
+} mp_obj_ffifunc_t;
+
+typedef struct _mp_obj_fficallback_t {
+    mp_obj_base_t base;
+    void *func;
+    ffi_closure *clo;
+    char rettype;
+    ffi_cif cif;
+    ffi_type *params[];
+} mp_obj_fficallback_t;
+
+static const mp_obj_type_t opaque_type;
+static const mp_obj_type_t ffimod_type;
+static const mp_obj_type_t ffifunc_type;
+static const mp_obj_type_t fficallback_type;
+static const mp_obj_type_t ffivar_type;
+
+static ffi_type *char2ffi_type(char c)
+{
+    switch (c) {
+        case 'b': return &ffi_type_schar;
+        case 'B': return &ffi_type_uchar;
+        case 'i': return &ffi_type_sint;
+        case 'I': return &ffi_type_uint;
+        case 'l': return &ffi_type_slong;
+        case 'L': return &ffi_type_ulong;
+        case 'p':
+        case 's': return &ffi_type_pointer;
+        case 'v': return &ffi_type_void;
+        default: return NULL;
+    }
+}
+
+static ffi_type *get_ffi_type(mp_obj_t o_in)
+{
+    if (MP_OBJ_IS_STR(o_in)) {
+        uint len;
+        const byte *s = mp_obj_str_get_data(o_in, &len);
+        ffi_type *t = char2ffi_type(*s);
+        if (t != NULL) {
+            return t;
+        }
+    }
+    // TODO: Support actual libffi type objects
+
+    nlr_jump(mp_obj_new_exception_msg_varg(MP_QSTR_OSError, "Unknown type"));
+}
+
+static mp_obj_t return_ffi_value(int val, char type)
+{
+    switch (type) {
+        case 's': {
+            const char *s = (const char *)val;
+            return mp_obj_new_str((const byte *)s, strlen(s), false);
+        }
+        case 'v':
+            return mp_const_none;
+        default:
+            return mp_obj_new_int(val);
+    }
+}
+
+// FFI module
+
+static void ffimod_print(void (*print)(void *env, const char *fmt, ...), void *env, mp_obj_t self_in, mp_print_kind_t kind) {
+    mp_obj_ffimod_t *self = self_in;
+    print(env, "<ffimod %p>", self->handle);
+}
+
+static mp_obj_t ffimod_close(mp_obj_t self_in) {
+    mp_obj_ffimod_t *self = self_in;
+    dlclose(self->handle);
+    return mp_const_none;
+}
+static MP_DEFINE_CONST_FUN_OBJ_1(ffimod_close_obj, ffimod_close);
+
+static mp_obj_t ffimod_func(uint n_args, const mp_obj_t *args) {
+    mp_obj_ffimod_t *self = args[0];
+    const char *rettype = mp_obj_str_get_str(args[1]);
+    const char *symname = mp_obj_str_get_str(args[2]);
+
+    void *sym = dlsym(self->handle, symname);
+    if (sym == NULL) {
+        nlr_jump(mp_obj_new_exception_msg_varg(MP_QSTR_OSError, "[Errno %d]", errno));
+    }
+    int nparams = MP_OBJ_SMALL_INT_VALUE(mp_obj_len_maybe(args[3]));
+    mp_obj_ffifunc_t *o = m_new_obj_var(mp_obj_ffifunc_t, ffi_type*, nparams);
+    o->base.type = &ffifunc_type;
+
+    o->func = sym;
+    o->rettype = *rettype;
+
+    mp_obj_t iterable = rt_getiter(args[3]);
+    mp_obj_t item;
+    int i = 0;
+    while ((item = rt_iternext(iterable)) != mp_const_stop_iteration) {
+        o->params[i++] = get_ffi_type(item);
+    }
+
+    int res = ffi_prep_cif(&o->cif, FFI_DEFAULT_ABI, nparams, char2ffi_type(*rettype), o->params);
+    if (res != FFI_OK) {
+        nlr_jump(mp_obj_new_exception_msg_varg(MP_QSTR_OSError, "Error in ffi_prep_cif"));
+    }
+
+    return o;
+}
+MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(ffimod_func_obj, 4, 4, ffimod_func);
+
+static void call_py_func(ffi_cif *cif, void *ret, void** args, mp_obj_t func) {
+    mp_obj_t pyargs[cif->nargs];
+    for (int i = 0; i < cif->nargs; i++) {
+        pyargs[i] = mp_obj_new_int(*(int*)args[i]);
+    }
+    mp_obj_t res = rt_call_function_n_kw(func, cif->nargs, 0, pyargs);
+
+    *(ffi_arg*)ret = mp_obj_int_get(res);
+}
+
+static mp_obj_t mod_ffi_callback(mp_obj_t rettype_in, mp_obj_t func_in, mp_obj_t paramtypes_in) {
+    const char *rettype = mp_obj_str_get_str(rettype_in);
+
+    int nparams = MP_OBJ_SMALL_INT_VALUE(mp_obj_len_maybe(paramtypes_in));
+    mp_obj_fficallback_t *o = m_new_obj_var(mp_obj_fficallback_t, ffi_type*, nparams);
+    o->base.type = &fficallback_type;
+
+    o->clo = ffi_closure_alloc(sizeof(ffi_closure), &o->func);
+
+    o->rettype = *rettype;
+
+    mp_obj_t iterable = rt_getiter(paramtypes_in);
+    mp_obj_t item;
+    int i = 0;
+    while ((item = rt_iternext(iterable)) != mp_const_stop_iteration) {
+        o->params[i++] = get_ffi_type(item);
+    }
+
+    int res = ffi_prep_cif(&o->cif, FFI_DEFAULT_ABI, nparams, char2ffi_type(*rettype), o->params);
+    if (res != FFI_OK) {
+        nlr_jump(mp_obj_new_exception_msg_varg(MP_QSTR_OSError, "Error in ffi_prep_cif"));
+    }
+
+    res = ffi_prep_closure_loc(o->clo, &o->cif, call_py_func, func_in, o->func);
+    if (res != FFI_OK) {
+        nlr_jump(mp_obj_new_exception_msg_varg(MP_QSTR_OSError, "ffi_prep_closure_loc"));
+    }
+
+    return o;
+}
+MP_DEFINE_CONST_FUN_OBJ_3(mod_ffi_callback_obj, mod_ffi_callback);
+
+static mp_obj_t ffimod_var(mp_obj_t self_in, mp_obj_t vartype_in, mp_obj_t symname_in) {
+    mp_obj_ffimod_t *self = self_in;
+    const char *rettype = mp_obj_str_get_str(vartype_in);
+    const char *symname = mp_obj_str_get_str(symname_in);
+
+    void *sym = dlsym(self->handle, symname);
+    if (sym == NULL) {
+        nlr_jump(mp_obj_new_exception_msg_varg(MP_QSTR_OSError, "[Errno %d]", errno));
+    }
+    mp_obj_ffivar_t *o = m_new_obj(mp_obj_ffivar_t);
+    o->base.type = &ffivar_type;
+
+    o->var = sym;
+    o->type = *rettype;
+    return o;
+}
+MP_DEFINE_CONST_FUN_OBJ_3(ffimod_var_obj, ffimod_var);
+
+static mp_obj_t ffimod_make_new(mp_obj_t type_in, uint n_args, uint n_kw, const mp_obj_t *args) {
+    const char *fname = mp_obj_str_get_str(args[0]);
+    void *mod = dlopen(fname, RTLD_NOW | RTLD_LOCAL);
+
+    if (mod == NULL) {
+        nlr_jump(mp_obj_new_exception_msg_varg(MP_QSTR_OSError, "[Errno %d]", errno));
+    }
+    mp_obj_ffimod_t *o = m_new_obj(mp_obj_ffimod_t);
+    o->base.type = type_in;
+    o->handle = mod;
+    return o;
+}
+
+static const mp_method_t ffimod_type_methods[] = {
+        { "func", &ffimod_func_obj },
+        { "var", &ffimod_var_obj },
+        { "close", &ffimod_close_obj },
+        { NULL, NULL },
+};
+
+static const mp_obj_type_t ffimod_type = {
+    { &mp_const_type },
+    "ffimod",
+    .print = ffimod_print,
+    .make_new = ffimod_make_new,
+    .methods = ffimod_type_methods,
+};
+
+// FFI function
+
+static void ffifunc_print(void (*print)(void *env, const char *fmt, ...), void *env, mp_obj_t self_in, mp_print_kind_t kind) {
+    mp_obj_ffifunc_t *self = self_in;
+    print(env, "<ffifunc %p>", self->func);
+}
+
+mp_obj_t ffifunc_call(mp_obj_t self_in, uint n_args, uint n_kw, const mp_obj_t *args) {
+    mp_obj_ffifunc_t *self = self_in;
+    assert(n_kw == 0);
+    assert(n_args == self->cif.nargs);
+
+    int values[n_args];
+    void *valueptrs[n_args];
+    int i;
+    for (i = 0; i < n_args; i++) {
+        mp_obj_t a = args[i];
+        if (a == mp_const_none) {
+            values[i] = 0;
+        } else if (MP_OBJ_IS_INT(a)) {
+            values[i] = mp_obj_int_get(a);
+        } else if (MP_OBJ_IS_STR(a) || MP_OBJ_IS_TYPE(a, &bytes_type)) {
+            const char *s = mp_obj_str_get_str(a);
+            values[i] = (int)s;
+        } else if (MP_OBJ_IS_TYPE(a, &fficallback_type)) {
+            mp_obj_fficallback_t *p = a;
+            values[i] = (int)p->func;
+        } else {
+            assert(0);
+        }
+        valueptrs[i] = &values[i];
+    }
+
+    int retval;
+    ffi_call(&self->cif, self->func, &retval, valueptrs);
+    return return_ffi_value(retval, self->rettype);
+}
+
+static const mp_obj_type_t ffifunc_type = {
+    { &mp_const_type },
+    "ffifunc",
+    .print = ffifunc_print,
+    .call = ffifunc_call,
+};
+
+// FFI callback for Python function
+
+static void fficallback_print(void (*print)(void *env, const char *fmt, ...), void *env, mp_obj_t self_in, mp_print_kind_t kind) {
+    mp_obj_fficallback_t *self = self_in;
+    print(env, "<fficallback %p>", self->func);
+}
+
+static const mp_obj_type_t fficallback_type = {
+    { &mp_const_type },
+    "fficallback",
+    .print = fficallback_print,
+};
+
+// FFI variable
+
+static void ffivar_print(void (*print)(void *env, const char *fmt, ...), void *env, mp_obj_t self_in, mp_print_kind_t kind) {
+    mp_obj_ffivar_t *self = self_in;
+    print(env, "<ffivar @%p: 0x%x>", self->var, *(int*)self->var);
+}
+
+static const mp_obj_type_t ffivar_type = {
+    { &mp_const_type },
+    "ffivar",
+    .print = ffivar_print,
+};
+
+// Generic opaque storage object
+
+static const mp_obj_type_t opaque_type = {
+    { &mp_const_type },
+    "opaqueval",
+//    .print = opaque_print,
+};
+
+
+mp_obj_t mod_ffi_open(uint n_args, const mp_obj_t *args) {
+    return ffimod_make_new((mp_obj_t)&ffimod_type, n_args, 0, args);
+}
+MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mod_ffi_open_obj, 1, 2, mod_ffi_open);
+
+mp_obj_t mod_ffi_as_bytearray(mp_obj_t ptr, mp_obj_t size) {
+    return mp_obj_new_bytearray_by_ref(mp_obj_int_get(size), (void*)mp_obj_int_get(ptr));
+}
+MP_DEFINE_CONST_FUN_OBJ_2(mod_ffi_as_bytearray_obj, mod_ffi_as_bytearray);
+
+
+void ffi_init() {
+    mp_obj_t m = mp_obj_new_module(QSTR_FROM_STR_STATIC("ffi"));
+    rt_store_attr(m, MP_QSTR_open, (mp_obj_t)&mod_ffi_open_obj);
+    rt_store_attr(m, QSTR_FROM_STR_STATIC("callback"), (mp_obj_t)&mod_ffi_callback_obj);
+    // there would be as_bytes, but bytes currently is value, not reference type!
+    rt_store_attr(m, QSTR_FROM_STR_STATIC("as_bytearray"), (mp_obj_t)&mod_ffi_as_bytearray_obj);
+}

unix/main.c

@@ -24,6 +24,7 @@
 extern const mp_obj_fun_native_t mp_builtin_open_obj;
 void file_init();
 void rawsocket_init();
+void ffi_init();
 
 static void execute_from_lexer(mp_lexer_t *lex, mp_parse_input_kind_t input_kind, bool is_repl) {
     if (lex == NULL) {
@@ -227,6 +228,7 @@ int main(int argc, char **argv) {
 
     file_init();
     rawsocket_init();
+    ffi_init();
 
     // Here is some example code to create a class and instance of that class.
     // First is the Python, then the C code.