/*

* This file exposes PyAST_Validate interface to check the integrity

* of the given abstract syntax tree (potentially constructed manually).

*/

#include "Python.h"

#include "Python-ast.h"

#include "ast.h"

#include <assert.h>

static int validate_stmts(asdl_stmt_seq *);

static int validate_exprs(asdl_expr_seq*, expr_context_ty, int);

static int _validate_nonempty_seq(asdl_seq *, const char *, const char *);

static int validate_stmt(stmt_ty);

static int validate_expr(expr_ty, expr_context_ty);

static int

validate_name(PyObject *name)

{

assert(PyUnicode_Check(name));

static const char * const forbidden[] = {

"None",

"True",

"False",

NULL

};

for (int i = 0; forbidden[i] != NULL; i++) {

if (_PyUnicode_EqualToASCIIString(name, forbidden[i])) {

PyErr_Format(PyExc_ValueError, "Name node can't be used with '%s' constant", forbidden[i]);

return 0;

}

}

return 1;

}

static int

validate_comprehension(asdl_comprehension_seq *gens)

{

Py_ssize_t i;

if (!asdl_seq_LEN(gens)) {

PyErr_SetString(PyExc_ValueError, "comprehension with no generators");

return 0;

}

for (i = 0; i < asdl_seq_LEN(gens); i++) {

comprehension_ty comp = asdl_seq_GET(gens, i);

if (!validate_expr(comp->target, Store) ||

!validate_expr(comp->iter, Load) ||

!validate_exprs(comp->ifs, Load, 0))

return 0;

}

return 1;

}

static int

validate_keywords(asdl_keyword_seq *keywords)

{

Py_ssize_t i;

for (i = 0; i < asdl_seq_LEN(keywords); i++)

if (!validate_expr((asdl_seq_GET(keywords, i))->value, Load))

return 0;

return 1;

}

static int

validate_args(asdl_arg_seq *args)

{

Py_ssize_t i;

for (i = 0; i < asdl_seq_LEN(args); i++) {

arg_ty arg = asdl_seq_GET(args, i);

if (arg->annotation && !validate_expr(arg->annotation, Load))

return 0;

}

return 1;

}

static const char *

expr_context_name(expr_context_ty ctx)

{

switch (ctx) {

case Load:

return "Load";

case Store:

return "Store";

case Del:

return "Del";

default:

Py_UNREACHABLE();

}

}

static int

validate_arguments(arguments_ty args)

{

if (!validate_args(args->posonlyargs) || !validate_args(args->args)) {

return 0;

}

if (args->vararg && args->vararg->annotation

&& !validate_expr(args->vararg->annotation, Load)) {

return 0;

}

if (!validate_args(args->kwonlyargs))

return 0;

if (args->kwarg && args->kwarg->annotation

&& !validate_expr(args->kwarg->annotation, Load)) {

return 0;

}

if (asdl_seq_LEN(args->defaults) > asdl_seq_LEN(args->posonlyargs) + asdl_seq_LEN(args->args)) {

PyErr_SetString(PyExc_ValueError, "more positional defaults than args on arguments");

return 0;

}

if (asdl_seq_LEN(args->kw_defaults) != asdl_seq_LEN(args->kwonlyargs)) {

PyErr_SetString(PyExc_ValueError, "length of kwonlyargs is not the same as "

"kw_defaults on arguments");

return 0;

}

return validate_exprs(args->defaults, Load, 0) && validate_exprs(args->kw_defaults, Load, 1);

}

static int

validate_constant(PyObject *value)

{

if (value == Py_None || value == Py_Ellipsis)

return 1;

if (PyLong_CheckExact(value)

|| PyFloat_CheckExact(value)

|| PyComplex_CheckExact(value)

|| PyBool_Check(value)

|| PyUnicode_CheckExact(value)

|| PyBytes_CheckExact(value))

return 1;

if (PyTuple_CheckExact(value) || PyFrozenSet_CheckExact(value)) {

PyObject *it;

it = PyObject_GetIter(value);

if (it == NULL)

return 0;

while (1) {

PyObject *item = PyIter_Next(it);

if (item == NULL) {

if (PyErr_Occurred()) {

Py_DECREF(it);

return 0;

}

break;

}

if (!validate_constant(item)) {

Py_DECREF(it);

Py_DECREF(item);

return 0;

}

Py_DECREF(item);

}

Py_DECREF(it);

return 1;

}

if (!PyErr_Occurred()) {

PyErr_Format(PyExc_TypeError,

"got an invalid type in Constant: %s",

_PyType_Name(Py_TYPE(value)));

}

return 0;

}

static int

validate_expr(expr_ty exp, expr_context_ty ctx)

{

int check_ctx = 1;

expr_context_ty actual_ctx;

/* First check expression context. */

switch (exp->kind) {

case Attribute_kind:

actual_ctx = exp->v.Attribute.ctx;

break;

case Subscript_kind:

actual_ctx = exp->v.Subscript.ctx;

break;

case Starred_kind:

actual_ctx = exp->v.Starred.ctx;

break;

case Name_kind:

if (!validate_name(exp->v.Name.id)) {

return 0;

}

actual_ctx = exp->v.Name.ctx;

break;

case List_kind:

actual_ctx = exp->v.List.ctx;

break;

case Tuple_kind:

actual_ctx = exp->v.Tuple.ctx;

break;

default:

if (ctx != Load) {

PyErr_Format(PyExc_ValueError, "expression which can't be "

"assigned to in %s context", expr_context_name(ctx));

return 0;

}

check_ctx = 0;

/* set actual_ctx to prevent gcc warning */

actual_ctx = 0;

}

if (check_ctx && actual_ctx != ctx) {

PyErr_Format(PyExc_ValueError, "expression must have %s context but has %s instead",

expr_context_name(ctx), expr_context_name(actual_ctx));

return 0;

}

/* Now validate expression. */

switch (exp->kind) {

case BoolOp_kind:

if (asdl_seq_LEN(exp->v.BoolOp.values) < 2) {

PyErr_SetString(PyExc_ValueError, "BoolOp with less than 2 values");

return 0;

}

return validate_exprs(exp->v.BoolOp.values, Load, 0);

case BinOp_kind:

return validate_expr(exp->v.BinOp.left, Load) &&

validate_expr(exp->v.BinOp.right, Load);

case UnaryOp_kind:

return validate_expr(exp->v.UnaryOp.operand, Load);

case Lambda_kind:

return validate_arguments(exp->v.Lambda.args) &&

validate_expr(exp->v.Lambda.body, Load);

case IfExp_kind:

return validate_expr(exp->v.IfExp.test, Load) &&

validate_expr(exp->v.IfExp.body, Load) &&

validate_expr(exp->v.IfExp.orelse, Load);

case Dict_kind:

if (asdl_seq_LEN(exp->v.Dict.keys) != asdl_seq_LEN(exp->v.Dict.values)) {

PyErr_SetString(PyExc_ValueError,

"Dict doesn't have the same number of keys as values");

return 0;

}

/* null_ok=1 for keys expressions to allow dict unpacking to work in

dict literals, i.e. ``{**{a:b}}`` */

return validate_exprs(exp->v.Dict.keys, Load, /*null_ok=*/ 1) &&

validate_exprs(exp->v.Dict.values, Load, /*null_ok=*/ 0);

case Set_kind:

return validate_exprs(exp->v.Set.elts, Load, 0);

#define COMP(NAME) \

case NAME ## _kind: \

return validate_comprehension(exp->v.NAME.generators) && \

validate_expr(exp->v.NAME.elt, Load);

COMP(ListComp)

COMP(SetComp)

COMP(GeneratorExp)

#undef COMP

case DictComp_kind:

return validate_comprehension(exp->v.DictComp.generators) &&

validate_expr(exp->v.DictComp.key, Load) &&

validate_expr(exp->v.DictComp.value, Load);

case Yield_kind:

return !exp->v.Yield.value || validate_expr(exp->v.Yield.value, Load);

case YieldFrom_kind:

return validate_expr(exp->v.YieldFrom.value, Load);

case Await_kind:

return validate_expr(exp->v.Await.value, Load);

case Compare_kind:

if (!asdl_seq_LEN(exp->v.Compare.comparators)) {

PyErr_SetString(PyExc_ValueError, "Compare with no comparators");

return 0;

}

if (asdl_seq_LEN(exp->v.Compare.comparators) !=

asdl_seq_LEN(exp->v.Compare.ops)) {

PyErr_SetString(PyExc_ValueError, "Compare has a different number "

"of comparators and operands");

return 0;

}

return validate_exprs(exp->v.Compare.comparators, Load, 0) &&

validate_expr(exp->v.Compare.left, Load);

case Call_kind:

return validate_expr(exp->v.Call.func, Load) &&

validate_exprs(exp->v.Call.args, Load, 0) &&

validate_keywords(exp->v.Call.keywords);

case Constant_kind:

if (!validate_constant(exp->v.Constant.value)) {

return 0;

}

return 1;

case JoinedStr_kind:

return validate_exprs(exp->v.JoinedStr.values, Load, 0);

case FormattedValue_kind:

if (validate_expr(exp->v.FormattedValue.value, Load) == 0)

return 0;

if (exp->v.FormattedValue.format_spec)

return validate_expr(exp->v.FormattedValue.format_spec, Load);

return 1;

case Attribute_kind:

return validate_expr(exp->v.Attribute.value, Load);

case Subscript_kind:

return validate_expr(exp->v.Subscript.slice, Load) &&

validate_expr(exp->v.Subscript.value, Load);

case Starred_kind:

return validate_expr(exp->v.Starred.value, ctx);

case Slice_kind:

return (!exp->v.Slice.lower || validate_expr(exp->v.Slice.lower, Load)) &&

(!exp->v.Slice.upper || validate_expr(exp->v.Slice.upper, Load)) &&

(!exp->v.Slice.step || validate_expr(exp->v.Slice.step, Load));

case List_kind:

return validate_exprs(exp->v.List.elts, ctx, 0);

case Tuple_kind:

return validate_exprs(exp->v.Tuple.elts, ctx, 0);

case NamedExpr_kind:

return validate_expr(exp->v.NamedExpr.value, Load);

/* This last case doesn't have any checking. */

case Name_kind:

return 1;

}

PyErr_SetString(PyExc_SystemError, "unexpected expression");

return 0;

}

static int

_validate_nonempty_seq(asdl_seq *seq, const char *what, const char *owner)

{

if (asdl_seq_LEN(seq))

return 1;

PyErr_Format(PyExc_ValueError, "empty %s on %s", what, owner);

return 0;

}

#define validate_nonempty_seq(seq, what, owner) _validate_nonempty_seq((asdl_seq*)seq, what, owner)

static int

validate_assignlist(asdl_expr_seq *targets, expr_context_ty ctx)

{

return validate_nonempty_seq(targets, "targets", ctx == Del ? "Delete" : "Assign") &&

validate_exprs(targets, ctx, 0);

}

static int

validate_body(asdl_stmt_seq *body, const char *owner)

{

return validate_nonempty_seq(body, "body", owner) && validate_stmts(body);

}

static int

validate_stmt(stmt_ty stmt)

{

Py_ssize_t i;

switch (stmt->kind) {

case FunctionDef_kind:

return validate_body(stmt->v.FunctionDef.body, "FunctionDef") &&

validate_arguments(stmt->v.FunctionDef.args) &&

validate_exprs(stmt->v.FunctionDef.decorator_list, Load, 0) &&

(!stmt->v.FunctionDef.returns ||

validate_expr(stmt->v.FunctionDef.returns, Load));

case ClassDef_kind:

return validate_body(stmt->v.ClassDef.body, "ClassDef") &&

validate_exprs(stmt->v.ClassDef.bases, Load, 0) &&

validate_keywords(stmt->v.ClassDef.keywords) &&

validate_exprs(stmt->v.ClassDef.decorator_list, Load, 0);

case Return_kind:

return !stmt->v.Return.value || validate_expr(stmt->v.Return.value, Load);

case Delete_kind:

return validate_assignlist(stmt->v.Delete.targets, Del);

case Assign_kind:

return validate_assignlist(stmt->v.Assign.targets, Store) &&

validate_expr(stmt->v.Assign.value, Load);

case AugAssign_kind:

return validate_expr(stmt->v.AugAssign.target, Store) &&

validate_expr(stmt->v.AugAssign.value, Load);

case AnnAssign_kind:

if (stmt->v.AnnAssign.target->kind != Name_kind &&

stmt->v.AnnAssign.simple) {

PyErr_SetString(PyExc_TypeError,

"AnnAssign with simple non-Name target");

return 0;

}

return validate_expr(stmt->v.AnnAssign.target, Store) &&

(!stmt->v.AnnAssign.value ||

validate_expr(stmt->v.AnnAssign.value, Load)) &&

validate_expr(stmt->v.AnnAssign.annotation, Load);

case For_kind:

return validate_expr(stmt->v.For.target, Store) &&

validate_expr(stmt->v.For.iter, Load) &&

validate_body(stmt->v.For.body, "For") &&

validate_stmts(stmt->v.For.orelse);

case AsyncFor_kind:

return validate_expr(stmt->v.AsyncFor.target, Store) &&

validate_expr(stmt->v.AsyncFor.iter, Load) &&

validate_body(stmt->v.AsyncFor.body, "AsyncFor") &&

validate_stmts(stmt->v.AsyncFor.orelse);

case While_kind:

return validate_expr(stmt->v.While.test, Load) &&

validate_body(stmt->v.While.body, "While") &&

validate_stmts(stmt->v.While.orelse);

case If_kind:

return validate_expr(stmt->v.If.test, Load) &&

validate_body(stmt->v.If.body, "If") &&

validate_stmts(stmt->v.If.orelse);

case With_kind:

if (!validate_nonempty_seq(stmt->v.With.items, "items", "With"))

return 0;

for (i = 0; i < asdl_seq_LEN(stmt->v.With.items); i++) {

withitem_ty item = asdl_seq_GET(stmt->v.With.items, i);

if (!validate_expr(item->context_expr, Load) ||

(item->optional_vars && !validate_expr(item->optional_vars, Store)))

return 0;

}

return validate_body(stmt->v.With.body, "With");

case AsyncWith_kind:

if (!validate_nonempty_seq(stmt->v.AsyncWith.items, "items", "AsyncWith"))

return 0;

for (i = 0; i < asdl_seq_LEN(stmt->v.AsyncWith.items); i++) {

withitem_ty item = asdl_seq_GET(stmt->v.AsyncWith.items, i);

if (!validate_expr(item->context_expr, Load) ||

(item->optional_vars && !validate_expr(item->optional_vars, Store)))

return 0;

}

return validate_body(stmt->v.AsyncWith.body, "AsyncWith");

case Raise_kind:

if (stmt->v.Raise.exc) {

return validate_expr(stmt->v.Raise.exc, Load) &&

(!stmt->v.Raise.cause || validate_expr(stmt->v.Raise.cause, Load));

}

if (stmt->v.Raise.cause) {

PyErr_SetString(PyExc_ValueError, "Raise with cause but no exception");

return 0;

}

return 1;

case Try_kind:

if (!validate_body(stmt->v.Try.body, "Try"))

return 0;

if (!asdl_seq_LEN(stmt->v.Try.handlers) &&

!asdl_seq_LEN(stmt->v.Try.finalbody)) {

PyErr_SetString(PyExc_ValueError, "Try has neither except handlers nor finalbody");

return 0;

}

if (!asdl_seq_LEN(stmt->v.Try.handlers) &&

asdl_seq_LEN(stmt->v.Try.orelse)) {

PyErr_SetString(PyExc_ValueError, "Try has orelse but no except handlers");

return 0;

}

for (i = 0; i < asdl_seq_LEN(stmt->v.Try.handlers); i++) {

excepthandler_ty handler = asdl_seq_GET(stmt->v.Try.handlers, i);

if ((handler->v.ExceptHandler.type &&

!validate_expr(handler->v.ExceptHandler.type, Load)) ||

!validate_body(handler->v.ExceptHandler.body, "ExceptHandler"))

return 0;

}

return (!asdl_seq_LEN(stmt->v.Try.finalbody) ||

validate_stmts(stmt->v.Try.finalbody)) &&

(!asdl_seq_LEN(stmt->v.Try.orelse) ||

validate_stmts(stmt->v.Try.orelse));

case Assert_kind:

return validate_expr(stmt->v.Assert.test, Load) &&

(!stmt->v.Assert.msg || validate_expr(stmt->v.Assert.msg, Load));

case Import_kind:

return validate_nonempty_seq(stmt->v.Import.names, "names", "Import");

case ImportFrom_kind:

if (stmt->v.ImportFrom.level < 0) {

PyErr_SetString(PyExc_ValueError, "Negative ImportFrom level");

return 0;

}

return validate_nonempty_seq(stmt->v.ImportFrom.names, "names", "ImportFrom");

case Global_kind:

return validate_nonempty_seq(stmt->v.Global.names, "names", "Global");

case Nonlocal_kind:

return validate_nonempty_seq(stmt->v.Nonlocal.names, "names", "Nonlocal");

case Expr_kind:

return validate_expr(stmt->v.Expr.value, Load);

case AsyncFunctionDef_kind:

return validate_body(stmt->v.AsyncFunctionDef.body, "AsyncFunctionDef") &&

validate_arguments(stmt->v.AsyncFunctionDef.args) &&

validate_exprs(stmt->v.AsyncFunctionDef.decorator_list, Load, 0) &&

(!stmt->v.AsyncFunctionDef.returns ||

validate_expr(stmt->v.AsyncFunctionDef.returns, Load));

case Pass_kind:

case Break_kind:

case Continue_kind:

return 1;

default:

PyErr_SetString(PyExc_SystemError, "unexpected statement");

return 0;

}

}

static int

validate_stmts(asdl_stmt_seq *seq)

{

Py_ssize_t i;

for (i = 0; i < asdl_seq_LEN(seq); i++) {

stmt_ty stmt = asdl_seq_GET(seq, i);

if (stmt) {

if (!validate_stmt(stmt))

return 0;

}

else {

PyErr_SetString(PyExc_ValueError,

"None disallowed in statement list");

return 0;

}

}

return 1;

}

static int

validate_exprs(asdl_expr_seq *exprs, expr_context_ty ctx, int null_ok)

{

Py_ssize_t i;

for (i = 0; i < asdl_seq_LEN(exprs); i++) {

expr_ty expr = asdl_seq_GET(exprs, i);

if (expr) {

if (!validate_expr(expr, ctx))

return 0;

}

else if (!null_ok) {

PyErr_SetString(PyExc_ValueError,

"None disallowed in expression list");

return 0;

}

}

return 1;

}

int

PyAST_Validate(mod_ty mod)

{

int res = 0;

switch (mod->kind) {

case Module_kind:

res = validate_stmts(mod->v.Module.body);

break;

case Interactive_kind:

res = validate_stmts(mod->v.Interactive.body);

break;

case Expression_kind:

res = validate_expr(mod->v.Expression.body, Load);

break;

default:

PyErr_SetString(PyExc_SystemError, "impossible module node");

res = 0;

break;

}

return res;

}

PyObject *

_PyAST_GetDocString(asdl_stmt_seq *body)

{

if (!asdl_seq_LEN(body)) {

return NULL;

}

stmt_ty st = asdl_seq_GET(body, 0);

if (st->kind != Expr_kind) {

return NULL;

}

expr_ty e = st->v.Expr.value;

if (e->kind == Constant_kind && PyUnicode_CheckExact(e->v.Constant.value)) {

return e->v.Constant.value;

}

return NULL;

}