py/objexcept.c

/*
 * This file is part of the Micro Python project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2013, 2014 Damien P. George
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include <string.h>
#include <stdarg.h>
#include <assert.h>
#include <stdio.h>

#include "py/mpstate.h"
#include "py/objlist.h"
#include "py/objstr.h"
#include "py/objtuple.h"
#include "py/objtype.h"
#include "py/runtime.h"
#include "py/gc.h"
#include "py/mperrno.h"

// Instance of MemoryError exception - needed by mp_malloc_fail
const mp_obj_exception_t mp_const_MemoryError_obj = {{&mp_type_MemoryError}, 0, 0, NULL, (mp_obj_tuple_t*)&mp_const_empty_tuple_obj};

// Optionally allocated buffer for storing the first argument of an exception
// allocated when the heap is locked.
#if MICROPY_ENABLE_EMERGENCY_EXCEPTION_BUF
#   if MICROPY_EMERGENCY_EXCEPTION_BUF_SIZE > 0
#define mp_emergency_exception_buf_size MICROPY_EMERGENCY_EXCEPTION_BUF_SIZE

void mp_init_emergency_exception_buf(void) {
    // Nothing to do since the buffer was declared statically. We put this
    // definition here so that the calling code can call this function
    // regardless of how its configured (makes the calling code a bit cleaner).
}

#else
#define mp_emergency_exception_buf_size MP_STATE_VM(mp_emergency_exception_buf_size)

void mp_init_emergency_exception_buf(void) {
    mp_emergency_exception_buf_size = 0;
    MP_STATE_VM(mp_emergency_exception_buf) = NULL;
}

mp_obj_t mp_alloc_emergency_exception_buf(mp_obj_t size_in) {
    mp_int_t size = mp_obj_get_int(size_in);
    void *buf = NULL;
    if (size > 0) {
        buf = m_new(byte, size);
    }

    int old_size = mp_emergency_exception_buf_size;
    void *old_buf = MP_STATE_VM(mp_emergency_exception_buf);

    // Update the 2 variables atomically so that an interrupt can't occur
    // between the assignments.
    mp_uint_t atomic_state = MICROPY_BEGIN_ATOMIC_SECTION();
    mp_emergency_exception_buf_size = size;
    MP_STATE_VM(mp_emergency_exception_buf) = buf;
    MICROPY_END_ATOMIC_SECTION(atomic_state);

    if (old_buf != NULL) {
        m_del(byte, old_buf, old_size);
    }
    return mp_const_none;
}
#endif
#endif  // MICROPY_ENABLE_EMERGENCY_EXCEPTION_BUF

// Instance of GeneratorExit exception - needed by generator.close()
// This would belong to objgenerator.c, but to keep mp_obj_exception_t
// definition module-private so far, have it here.
const mp_obj_exception_t mp_const_GeneratorExit_obj = {{&mp_type_GeneratorExit}, 0, 0, NULL, (mp_obj_tuple_t*)&mp_const_empty_tuple_obj};

STATIC void mp_obj_exception_print(const mp_print_t *print, mp_obj_t o_in, mp_print_kind_t kind) {
    mp_obj_exception_t *o = MP_OBJ_TO_PTR(o_in);
    mp_print_kind_t k = kind & ~PRINT_EXC_SUBCLASS;
    bool is_subclass = kind & PRINT_EXC_SUBCLASS;
    if (!is_subclass && (k == PRINT_REPR || k == PRINT_EXC)) {
        mp_print_str(print, qstr_str(o->base.type->name));
    }

    if (k == PRINT_EXC) {
        mp_print_str(print, ": ");
    }

    if (k == PRINT_STR || k == PRINT_EXC) {
        if (o->args == NULL || o->args->len == 0) {
            mp_print_str(print, "");
            return;
        } else if (o->args->len == 1) {
            #if MICROPY_PY_UERRNO
            // try to provide a nice OSError error message
            if (o->base.type == &mp_type_OSError && MP_OBJ_IS_SMALL_INT(o->args->items[0])) {
                qstr qst = mp_errno_to_str(o->args->items[0]);
                if (qst != MP_QSTR_NULL) {
                    mp_printf(print, "[Errno %d] %q", MP_OBJ_SMALL_INT_VALUE(o->args->items[0]), qst);
                    return;
                }
            }
            #endif
            mp_obj_print_helper(print, o->args->items[0], PRINT_STR);
            return;
        }
    }
    mp_obj_tuple_print(print, MP_OBJ_FROM_PTR(o->args), kind);
}

mp_obj_t mp_obj_exception_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
    mp_arg_check_num(n_args, n_kw, 0, MP_OBJ_FUN_ARGS_MAX, false);
    mp_obj_exception_t *o = m_new_obj_var_maybe(mp_obj_exception_t, mp_obj_t, 0);
    if (o == NULL) {
        // Couldn't allocate heap memory; use local data instead.
        o = &MP_STATE_VM(mp_emergency_exception_obj);
        // We can't store any args.
        o->args = (mp_obj_tuple_t*)&mp_const_empty_tuple_obj;
    } else {
        o->args = MP_OBJ_TO_PTR(mp_obj_new_tuple(n_args, args));
    }
    o->base.type = type;
    o->traceback_data = NULL;
    return MP_OBJ_FROM_PTR(o);
}

// Get exception "value" - that is, first argument, or None
mp_obj_t mp_obj_exception_get_value(mp_obj_t self_in) {
    mp_obj_exception_t *self = MP_OBJ_TO_PTR(self_in);
    if (self->args->len == 0) {
        return mp_const_none;
    } else {
        return self->args->items[0];
    }
}

STATIC void exception_attr(mp_obj_t self_in, qstr attr, mp_obj_t *dest) {
    mp_obj_exception_t *self = MP_OBJ_TO_PTR(self_in);
    if (dest[0] != MP_OBJ_NULL) {
        // store/delete attribute
        if (attr == MP_QSTR___traceback__ && dest[1] == mp_const_none) {
            // We allow 'exc.__traceback__ = None' assignment as low-level
            // optimization of pre-allocating exception instance and raising
            // it repeatedly - this avoids memory allocation during raise.
            // However, uPy will keep adding traceback entries to such
            // exception instance, so before throwing it, traceback should
            // be cleared like above.
            self->traceback_len = 0;
            dest[0] = MP_OBJ_NULL; // indicate success
        }
        return;
    }
    if (attr == MP_QSTR_args) {
        dest[0] = MP_OBJ_FROM_PTR(self->args);
    } else if (self->base.type == &mp_type_StopIteration && attr == MP_QSTR_value) {
        dest[0] = mp_obj_exception_get_value(self_in);
    }
}

STATIC mp_obj_t exc___init__(size_t n_args, const mp_obj_t *args) {
    mp_obj_exception_t *self = MP_OBJ_TO_PTR(args[0]);
    mp_obj_t argst = mp_obj_new_tuple(n_args - 1, args + 1);
    self->args = MP_OBJ_TO_PTR(argst);
    return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(exc___init___obj, 1, MP_OBJ_FUN_ARGS_MAX, exc___init__);

STATIC const mp_rom_map_elem_t exc_locals_dict_table[] = {
    { MP_ROM_QSTR(MP_QSTR___init__), MP_ROM_PTR(&exc___init___obj) },
};

STATIC MP_DEFINE_CONST_DICT(exc_locals_dict, exc_locals_dict_table);

const mp_obj_type_t mp_type_BaseException = {
    { &mp_type_type },
    .name = MP_QSTR_BaseException,
    .print = mp_obj_exception_print,
    .make_new = mp_obj_exception_make_new,
    .attr = exception_attr,
    .locals_dict = (mp_obj_dict_t*)&exc_locals_dict,
};

#define MP_DEFINE_EXCEPTION(exc_name, base_name) \
const mp_obj_type_t mp_type_ ## exc_name = { \
    { &mp_type_type }, \
    .name = MP_QSTR_ ## exc_name, \
    .print = mp_obj_exception_print, \
    .make_new = mp_obj_exception_make_new, \
    .attr = exception_attr, \
    .parent = &mp_type_ ## base_name, \
};

// List of all exceptions, arranged as in the table at:
// http://docs.python.org/3/library/exceptions.html
MP_DEFINE_EXCEPTION(SystemExit, BaseException)
MP_DEFINE_EXCEPTION(KeyboardInterrupt, BaseException)
MP_DEFINE_EXCEPTION(GeneratorExit, BaseException)
MP_DEFINE_EXCEPTION(Exception, BaseException)
  #if MICROPY_PY_ASYNC_AWAIT
  MP_DEFINE_EXCEPTION(StopAsyncIteration, Exception)
  #endif
  MP_DEFINE_EXCEPTION(StopIteration, Exception)
  MP_DEFINE_EXCEPTION(ArithmeticError, Exception)
    //MP_DEFINE_EXCEPTION(FloatingPointError, ArithmeticError)
    MP_DEFINE_EXCEPTION(OverflowError, ArithmeticError)
    MP_DEFINE_EXCEPTION(ZeroDivisionError, ArithmeticError)
  MP_DEFINE_EXCEPTION(AssertionError, Exception)
  MP_DEFINE_EXCEPTION(AttributeError, Exception)
  //MP_DEFINE_EXCEPTION(BufferError, Exception)
  //MP_DEFINE_EXCEPTION(EnvironmentError, Exception) use OSError instead
  MP_DEFINE_EXCEPTION(EOFError, Exception)
  MP_DEFINE_EXCEPTION(ImportError, Exception)
  //MP_DEFINE_EXCEPTION(IOError, Exception) use OSError instead
  MP_DEFINE_EXCEPTION(LookupError, Exception)
    MP_DEFINE_EXCEPTION(IndexError, LookupError)
    MP_DEFINE_EXCEPTION(KeyError, LookupError)
  MP_DEFINE_EXCEPTION(MemoryError, Exception)
  MP_DEFINE_EXCEPTION(NameError, Exception)
    /*
    MP_DEFINE_EXCEPTION(UnboundLocalError, NameError)
    */
  MP_DEFINE_EXCEPTION(OSError, Exception)
#if MICROPY_PY_BUILTINS_TIMEOUTERROR
    MP_DEFINE_EXCEPTION(TimeoutError, OSError)
#endif
    /*
    MP_DEFINE_EXCEPTION(BlockingIOError, OSError)
    MP_DEFINE_EXCEPTION(ChildProcessError, OSError)
    MP_DEFINE_EXCEPTION(ConnectionError, OSError)
      MP_DEFINE_EXCEPTION(BrokenPipeError, ConnectionError)
      MP_DEFINE_EXCEPTION(ConnectionAbortedError, ConnectionError)
      MP_DEFINE_EXCEPTION(ConnectionRefusedError, ConnectionError)
      MP_DEFINE_EXCEPTION(ConnectionResetError, ConnectionError)
    MP_DEFINE_EXCEPTION(InterruptedError, OSError)
    MP_DEFINE_EXCEPTION(IsADirectoryError, OSError)
    MP_DEFINE_EXCEPTION(NotADirectoryError, OSError)
    MP_DEFINE_EXCEPTION(PermissionError, OSError)
    MP_DEFINE_EXCEPTION(ProcessLookupError, OSError)
    MP_DEFINE_EXCEPTION(FileExistsError, OSError)
    MP_DEFINE_EXCEPTION(FileNotFoundError, OSError)
    MP_DEFINE_EXCEPTION(ReferenceError, Exception)
    */
  MP_DEFINE_EXCEPTION(RuntimeError, Exception)
    MP_DEFINE_EXCEPTION(NotImplementedError, RuntimeError)
  MP_DEFINE_EXCEPTION(SyntaxError, Exception)
    MP_DEFINE_EXCEPTION(IndentationError, SyntaxError)
    /*
      MP_DEFINE_EXCEPTION(TabError, IndentationError)
      */
  //MP_DEFINE_EXCEPTION(SystemError, Exception)
  MP_DEFINE_EXCEPTION(TypeError, Exception)
#if MICROPY_EMIT_NATIVE
    MP_DEFINE_EXCEPTION(ViperTypeError, TypeError)
#endif
  MP_DEFINE_EXCEPTION(ValueError, Exception)
#if MICROPY_PY_BUILTINS_STR_UNICODE
    MP_DEFINE_EXCEPTION(UnicodeError, ValueError)
    //TODO: Implement more UnicodeError subclasses which take arguments
#endif
  /*
  MP_DEFINE_EXCEPTION(Warning, Exception)
    MP_DEFINE_EXCEPTION(DeprecationWarning, Warning)
    MP_DEFINE_EXCEPTION(PendingDeprecationWarning, Warning)
    MP_DEFINE_EXCEPTION(RuntimeWarning, Warning)
    MP_DEFINE_EXCEPTION(SyntaxWarning, Warning)
    MP_DEFINE_EXCEPTION(UserWarning, Warning)
    MP_DEFINE_EXCEPTION(FutureWarning, Warning)
    MP_DEFINE_EXCEPTION(ImportWarning, Warning)
    MP_DEFINE_EXCEPTION(UnicodeWarning, Warning)
    MP_DEFINE_EXCEPTION(BytesWarning, Warning)
    MP_DEFINE_EXCEPTION(ResourceWarning, Warning)
    */

mp_obj_t mp_obj_new_exception(const mp_obj_type_t *exc_type) {
    return mp_obj_new_exception_args(exc_type, 0, NULL);
}

// "Optimized" version for common(?) case of having 1 exception arg
mp_obj_t mp_obj_new_exception_arg1(const mp_obj_type_t *exc_type, mp_obj_t arg) {
    return mp_obj_new_exception_args(exc_type, 1, &arg);
}

mp_obj_t mp_obj_new_exception_args(const mp_obj_type_t *exc_type, size_t n_args, const mp_obj_t *args) {
    assert(exc_type->make_new == mp_obj_exception_make_new);
    return exc_type->make_new(exc_type, n_args, 0, args);
}

mp_obj_t mp_obj_new_exception_msg(const mp_obj_type_t *exc_type, const char *msg) {
    return mp_obj_new_exception_msg_varg(exc_type, msg);
}

mp_obj_t mp_obj_new_exception_msg_varg(const mp_obj_type_t *exc_type, const char *fmt, ...) {
    // check that the given type is an exception type
    assert(exc_type->make_new == mp_obj_exception_make_new);

    // make exception object
    mp_obj_exception_t *o = m_new_obj_var_maybe(mp_obj_exception_t, mp_obj_t, 0);
    if (o == NULL) {
        // Couldn't allocate heap memory; use local data instead.
        // Unfortunately, we won't be able to format the string...
        o = &MP_STATE_VM(mp_emergency_exception_obj);
        o->base.type = exc_type;
        o->traceback_data = NULL;
        o->args = (mp_obj_tuple_t*)&mp_const_empty_tuple_obj;

#if MICROPY_ENABLE_EMERGENCY_EXCEPTION_BUF
        // If the user has provided a buffer, then we try to create a tuple
        // of length 1, which has a string object and the string data.

        if (mp_emergency_exception_buf_size > (sizeof(mp_obj_tuple_t) + sizeof(mp_obj_str_t) + sizeof(mp_obj_t))) {
            mp_obj_tuple_t *tuple = (mp_obj_tuple_t *)MP_STATE_VM(mp_emergency_exception_buf);
            mp_obj_str_t *str = (mp_obj_str_t *)&tuple->items[1];

            tuple->base.type = &mp_type_tuple;
            tuple->len = 1;
            tuple->items[0] = MP_OBJ_FROM_PTR(str);

            byte *str_data = (byte *)&str[1];
            size_t max_len = (byte*)MP_STATE_VM(mp_emergency_exception_buf) + mp_emergency_exception_buf_size
                         - str_data;

            vstr_t vstr;
            vstr_init_fixed_buf(&vstr, max_len, (char *)str_data);

            va_list ap;
            va_start(ap, fmt);
            vstr_vprintf(&vstr, fmt, ap);
            va_end(ap);

            str->base.type = &mp_type_str;
            str->hash = qstr_compute_hash(str_data, str->len);
            str->len = vstr.len;
            str->data = str_data;

            o->args = tuple;

            size_t offset = &str_data[str->len] - (byte*)MP_STATE_VM(mp_emergency_exception_buf);
            offset += sizeof(void *) - 1;
            offset &= ~(sizeof(void *) - 1);

            if ((mp_emergency_exception_buf_size - offset) > (sizeof(o->traceback_data[0]) * 3)) {
                // We have room to store some traceback.
                o->traceback_data = (size_t*)((byte *)MP_STATE_VM(mp_emergency_exception_buf) + offset);
                o->traceback_alloc = ((byte*)MP_STATE_VM(mp_emergency_exception_buf) + mp_emergency_exception_buf_size - (byte *)o->traceback_data) / sizeof(o->traceback_data[0]);
                o->traceback_len = 0;
            }
        }
#endif // MICROPY_ENABLE_EMERGENCY_EXCEPTION_BUF
    } else {
        o->base.type = exc_type;
        o->traceback_data = NULL;
        o->args = MP_OBJ_TO_PTR(mp_obj_new_tuple(1, NULL));

        assert(fmt != NULL);
        {
            if (strchr(fmt, '%') == NULL) {
                // no formatting substitutions, avoid allocating vstr.
                o->args->items[0] = mp_obj_new_str(fmt, strlen(fmt), false);
            } else {
                // render exception message and store as .args[0]
                va_list ap;
                vstr_t vstr;
                vstr_init(&vstr, 16);
                va_start(ap, fmt);
                vstr_vprintf(&vstr, fmt, ap);
                va_end(ap);
                o->args->items[0] = mp_obj_new_str_from_vstr(&mp_type_str, &vstr);
            }
        }
    }

    return MP_OBJ_FROM_PTR(o);
}

// return true if the given object is an exception type
bool mp_obj_is_exception_type(mp_obj_t self_in) {
    if (MP_OBJ_IS_TYPE(self_in, &mp_type_type)) {
        // optimisation when self_in is a builtin exception
        mp_obj_type_t *self = MP_OBJ_TO_PTR(self_in);
        if (self->make_new == mp_obj_exception_make_new) {
            return true;
        }
    }
    return mp_obj_is_subclass_fast(self_in, MP_OBJ_FROM_PTR(&mp_type_BaseException));
}

// return true if the given object is an instance of an exception type
bool mp_obj_is_exception_instance(mp_obj_t self_in) {
    return mp_obj_is_exception_type(MP_OBJ_FROM_PTR(mp_obj_get_type(self_in)));
}

// Return true if exception (type or instance) is a subclass of given
// exception type.  Assumes exc_type is a subclass of BaseException, as
// defined by mp_obj_is_exception_type(exc_type).
bool mp_obj_exception_match(mp_obj_t exc, mp_const_obj_t exc_type) {
    // if exc is an instance of an exception, then extract and use its type
    if (mp_obj_is_exception_instance(exc)) {
        exc = MP_OBJ_FROM_PTR(mp_obj_get_type(exc));
    }
    return mp_obj_is_subclass_fast(exc, exc_type);
}

// traceback handling functions

#define GET_NATIVE_EXCEPTION(self, self_in) \
    /* make sure self_in is an exception instance */ \
    assert(mp_obj_is_exception_instance(self_in)); \
    mp_obj_exception_t *self; \
    if (mp_obj_is_native_exception_instance(self_in)) { \
        self = MP_OBJ_TO_PTR(self_in); \
    } else { \
        self = MP_OBJ_TO_PTR(((mp_obj_instance_t*)MP_OBJ_TO_PTR(self_in))->subobj[0]); \
    }

void mp_obj_exception_clear_traceback(mp_obj_t self_in) {
    GET_NATIVE_EXCEPTION(self, self_in);
    // just set the traceback to the null object
    // we don't want to call any memory management functions here
    self->traceback_data = NULL;
}

void mp_obj_exception_add_traceback(mp_obj_t self_in, qstr file, size_t line, qstr block) {
    GET_NATIVE_EXCEPTION(self, self_in);

    // append this traceback info to traceback data
    // if memory allocation fails (eg because gc is locked), just return

    if (self->traceback_data == NULL) {
        self->traceback_data = m_new_maybe(size_t, 3);
        if (self->traceback_data == NULL) {
            return;
        }
        self->traceback_alloc = 3;
        self->traceback_len = 0;
    } else if (self->traceback_len + 3 > self->traceback_alloc) {
        // be conservative with growing traceback data
        size_t *tb_data = m_renew_maybe(size_t, self->traceback_data, self->traceback_alloc, self->traceback_alloc + 3, true);
        if (tb_data == NULL) {
            return;
        }
        self->traceback_data = tb_data;
        self->traceback_alloc += 3;
    }

    size_t *tb_data = &self->traceback_data[self->traceback_len];
    self->traceback_len += 3;
    tb_data[0] = file;
    tb_data[1] = line;
    tb_data[2] = block;
}

void mp_obj_exception_get_traceback(mp_obj_t self_in, size_t *n, size_t **values) {
    GET_NATIVE_EXCEPTION(self, self_in);

    if (self->traceback_data == NULL) {
        *n = 0;
        *values = NULL;
    } else {
        *n = self->traceback_len;
        *values = self->traceback_data;
    }
}