gdb/python/py-utils.c

   1 /* General utility routines for GDB/Python.
   2
   3    Copyright (C) 2008-2020 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include "defs.h"
  21 #include "charset.h"
  22 #include "value.h"
  23 #include "python-internal.h"
  24
  25 /* Converts a Python 8-bit string to a unicode string object.  Assumes the
  26    8-bit string is in the host charset.  If an error occurs during conversion,
  27    returns NULL with a python exception set.
  28
  29    As an added bonus, the functions accepts a unicode string and returns it
  30    right away, so callers don't need to check which kind of string they've
  31    got.  In Python 3, all strings are Unicode so this case is always the
  32    one that applies.
  33
  34    If the given object is not one of the mentioned string types, NULL is
  35    returned, with the TypeError python exception set.  */
  36 gdbpy_ref<>
  37 python_string_to_unicode (PyObject *obj)
  38 {
  39   PyObject *unicode_str;
  40
  41   /* If obj is already a unicode string, just return it.
  42      I wish life was always that simple...  */
  43   if (PyUnicode_Check (obj))
  44     {
  45       unicode_str = obj;
  46       Py_INCREF (obj);
  47     }
  48 #ifndef IS_PY3K
  49   else if (PyString_Check (obj))
  50     unicode_str = PyUnicode_FromEncodedObject (obj, host_charset (), NULL);
  51 #endif
  52   else
  53     {
  54       PyErr_SetString (PyExc_TypeError,
  55                        _("Expected a string or unicode object."));
  56       unicode_str = NULL;
  57     }
  58
  59   return gdbpy_ref<> (unicode_str);
  60 }
  61
  62 /* Returns a newly allocated string with the contents of the given unicode
  63    string object converted to CHARSET.  If an error occurs during the
  64    conversion, NULL will be returned and a python exception will be
  65    set.  */
  66 static gdb::unique_xmalloc_ptr<char>
  67 unicode_to_encoded_string (PyObject *unicode_str, const char *charset)
  68 {
  69   /* Translate string to named charset.  */
  70   gdbpy_ref<> string (PyUnicode_AsEncodedString (unicode_str, charset, NULL));
  71   if (string == NULL)
  72     return NULL;
  73
  74   return gdb::unique_xmalloc_ptr<char>
  75     (xstrdup (PyBytes_AsString (string.get ())));
  76 }
  77
  78 /* Returns a PyObject with the contents of the given unicode string
  79    object converted to a named charset.  If an error occurs during
  80    the conversion, NULL will be returned and a python exception will
  81    be set.  */
  82 static gdbpy_ref<>
  83 unicode_to_encoded_python_string (PyObject *unicode_str, const char *charset)
  84 {
  85   /* Translate string to named charset.  */
  86   return gdbpy_ref<> (PyUnicode_AsEncodedString (unicode_str, charset, NULL));
  87 }
  88
  89 /* Returns a newly allocated string with the contents of the given
  90    unicode string object converted to the target's charset.  If an
  91    error occurs during the conversion, NULL will be returned and a
  92    python exception will be set.  */
  93 gdb::unique_xmalloc_ptr<char>
  94 unicode_to_target_string (PyObject *unicode_str)
  95 {
  96   return unicode_to_encoded_string (unicode_str,
  97                                     target_charset (python_gdbarch));
  98 }
  99
 100 /* Returns a PyObject with the contents of the given unicode string
 101    object converted to the target's charset.  If an error occurs
 102    during the conversion, NULL will be returned and a python exception
 103    will be set.  */
 104 static gdbpy_ref<>
 105 unicode_to_target_python_string (PyObject *unicode_str)
 106 {
 107   return unicode_to_encoded_python_string (unicode_str,
 108                                            target_charset (python_gdbarch));
 109 }
 110
 111 /* Converts a python string (8-bit or unicode) to a target string in
 112    the target's charset.  Returns NULL on error, with a python
 113    exception set.  */
 114 gdb::unique_xmalloc_ptr<char>
 115 python_string_to_target_string (PyObject *obj)
 116 {
 117   gdbpy_ref<> str = python_string_to_unicode (obj);
 118   if (str == NULL)
 119     return NULL;
 120
 121   return unicode_to_target_string (str.get ());
 122 }
 123
 124 /* Converts a python string (8-bit or unicode) to a target string in the
 125    target's charset.  Returns NULL on error, with a python exception
 126    set.
 127
 128    In Python 3, the returned object is a "bytes" object (not a string).  */
 129 gdbpy_ref<>
 130 python_string_to_target_python_string (PyObject *obj)
 131 {
 132   gdbpy_ref<> str = python_string_to_unicode (obj);
 133   if (str == NULL)
 134     return str;
 135
 136   return unicode_to_target_python_string (str.get ());
 137 }
 138
 139 /* Converts a python string (8-bit or unicode) to a target string in
 140    the host's charset.  Returns NULL on error, with a python exception
 141    set.  */
 142 gdb::unique_xmalloc_ptr<char>
 143 python_string_to_host_string (PyObject *obj)
 144 {
 145   gdbpy_ref<> str = python_string_to_unicode (obj);
 146   if (str == NULL)
 147     return NULL;
 148
 149   return unicode_to_encoded_string (str.get (), host_charset ());
 150 }
 151
 152 /* Convert a host string to a python string.  */
 153
 154 gdbpy_ref<>
 155 host_string_to_python_string (const char *str)
 156 {
 157   return gdbpy_ref<> (PyString_Decode (str, strlen (str), host_charset (),
 158                                        NULL));
 159 }
 160
 161 /* Return true if OBJ is a Python string or unicode object, false
 162    otherwise.  */
 163
 164 int
 165 gdbpy_is_string (PyObject *obj)
 166 {
 167 #ifdef IS_PY3K
 168   return PyUnicode_Check (obj);
 169 #else
 170   return PyString_Check (obj) || PyUnicode_Check (obj);
 171 #endif
 172 }
 173
 174 /* Return the string representation of OBJ, i.e., str (obj).
 175    If the result is NULL a python error occurred, the caller must clear it.  */
 176
 177 gdb::unique_xmalloc_ptr<char>
 178 gdbpy_obj_to_string (PyObject *obj)
 179 {
 180   gdbpy_ref<> str_obj (PyObject_Str (obj));
 181
 182   if (str_obj != NULL)
 183     {
 184       gdb::unique_xmalloc_ptr<char> msg;
 185
 186 #ifdef IS_PY3K
 187       msg = python_string_to_host_string (str_obj.get ());
 188 #else
 189       msg.reset (xstrdup (PyString_AsString (str_obj.get ())));
 190 #endif
 191
 192       return msg;
 193     }
 194
 195   return NULL;
 196 }
 197
 198 /* See python-internal.h.  */
 199
 200 gdb::unique_xmalloc_ptr<char>
 201 gdbpy_err_fetch::to_string () const
 202 {
 203   /* There are a few cases to consider.
 204      For example:
 205      value is a string when PyErr_SetString is used.
 206      value is not a string when raise "foo" is used, instead it is None
 207      and type is "foo".
 208      So the algorithm we use is to print `str (value)' if it's not
 209      None, otherwise we print `str (type)'.
 210      Using str (aka PyObject_Str) will fetch the error message from
 211      gdb.GdbError ("message").  */
 212
 213   if (m_error_value && m_error_value != Py_None)
 214     return gdbpy_obj_to_string (m_error_value);
 215   else
 216     return gdbpy_obj_to_string (m_error_type);
 217 }
 218
 219 /* See python-internal.h.  */
 220
 221 gdb::unique_xmalloc_ptr<char>
 222 gdbpy_err_fetch::type_to_string () const
 223 {
 224   return gdbpy_obj_to_string (m_error_type);
 225 }
 226
 227 /* Convert a GDB exception to the appropriate Python exception.
 228
 229    This sets the Python error indicator.  */
 230
 231 void
 232 gdbpy_convert_exception (const struct gdb_exception &exception)
 233 {
 234   PyObject *exc_class;
 235
 236   if (exception.reason == RETURN_QUIT)
 237     exc_class = PyExc_KeyboardInterrupt;
 238   else if (exception.error == MEMORY_ERROR)
 239     exc_class = gdbpy_gdb_memory_error;
 240   else
 241     exc_class = gdbpy_gdb_error;
 242
 243   PyErr_Format (exc_class, "%s", exception.what ());
 244 }
 245
 246 /* Converts OBJ to a CORE_ADDR value.
 247
 248    Returns 0 on success or -1 on failure, with a Python exception set.
 249 */
 250
 251 int
 252 get_addr_from_python (PyObject *obj, CORE_ADDR *addr)
 253 {
 254   if (gdbpy_is_value_object (obj))
 255     {
 256
 257       try
 258         {
 259           *addr = value_as_address (value_object_to_value (obj));
 260         }
 261       catch (const gdb_exception &except)
 262         {
 263           GDB_PY_SET_HANDLE_EXCEPTION (except);
 264         }
 265     }
 266   else
 267     {
 268       gdbpy_ref<> num (PyNumber_Long (obj));
 269       gdb_py_ulongest val;
 270
 271       if (num == NULL)
 272         return -1;
 273
 274       val = gdb_py_long_as_ulongest (num.get ());
 275       if (PyErr_Occurred ())
 276         return -1;
 277
 278       if (sizeof (val) > sizeof (CORE_ADDR) && ((CORE_ADDR) val) != val)
 279         {
 280           PyErr_SetString (PyExc_ValueError,
 281                            _("Overflow converting to address."));
 282           return -1;
 283         }
 284
 285       *addr = val;
 286     }
 287
 288   return 0;
 289 }
 290
 291 /* Convert a LONGEST to the appropriate Python object -- either an
 292    integer object or a long object, depending on its value.  */
 293
 294 gdbpy_ref<>
 295 gdb_py_object_from_longest (LONGEST l)
 296 {
 297 #ifdef IS_PY3K
 298   if (sizeof (l) > sizeof (long))
 299     return gdbpy_ref<> (PyLong_FromLongLong (l));
 300   return gdbpy_ref<> (PyLong_FromLong (l));
 301 #else
 302 #ifdef HAVE_LONG_LONG           /* Defined by Python.  */
 303   /* If we have 'long long', and the value overflows a 'long', use a
 304      Python Long; otherwise use a Python Int.  */
 305   if (sizeof (l) > sizeof (long)
 306       && (l > PyInt_GetMax () || l < (- (LONGEST) PyInt_GetMax ()) - 1))
 307     return gdbpy_ref<> (PyLong_FromLongLong (l));
 308 #endif
 309   return gdbpy_ref<> (PyInt_FromLong (l));
 310 #endif
 311 }
 312
 313 /* Convert a ULONGEST to the appropriate Python object -- either an
 314    integer object or a long object, depending on its value.  */
 315
 316 gdbpy_ref<>
 317 gdb_py_object_from_ulongest (ULONGEST l)
 318 {
 319 #ifdef IS_PY3K
 320   if (sizeof (l) > sizeof (unsigned long))
 321     return gdbpy_ref<> (PyLong_FromUnsignedLongLong (l));
 322   return gdbpy_ref<> (PyLong_FromUnsignedLong (l));
 323 #else
 324 #ifdef HAVE_LONG_LONG           /* Defined by Python.  */
 325   /* If we have 'long long', and the value overflows a 'long', use a
 326      Python Long; otherwise use a Python Int.  */
 327   if (sizeof (l) > sizeof (unsigned long) && l > PyInt_GetMax ())
 328     return gdbpy_ref<> (PyLong_FromUnsignedLongLong (l));
 329 #endif
 330
 331   if (l > PyInt_GetMax ())
 332     return gdbpy_ref<> (PyLong_FromUnsignedLong (l));
 333
 334   return gdbpy_ref<> (PyInt_FromLong (l));
 335 #endif
 336 }
 337
 338 /* Like PyInt_AsLong, but returns 0 on failure, 1 on success, and puts
 339    the value into an out parameter.  */
 340
 341 int
 342 gdb_py_int_as_long (PyObject *obj, long *result)
 343 {
 344   *result = PyInt_AsLong (obj);
 345   return ! (*result == -1 && PyErr_Occurred ());
 346 }
 347
 348 \f
 349
 350 /* Generic implementation of the __dict__ attribute for objects that
 351    have a dictionary.  The CLOSURE argument should be the type object.
 352    This only handles positive values for tp_dictoffset.  */
 353
 354 PyObject *
 355 gdb_py_generic_dict (PyObject *self, void *closure)
 356 {
 357   PyObject *result;
 358   PyTypeObject *type_obj = (PyTypeObject *) closure;
 359   char *raw_ptr;
 360
 361   raw_ptr = (char *) self + type_obj->tp_dictoffset;
 362   result = * (PyObject **) raw_ptr;
 363
 364   Py_INCREF (result);
 365   return result;
 366 }
 367
 368 /* Like PyModule_AddObject, but does not steal a reference to
 369    OBJECT.  */
 370
 371 int
 372 gdb_pymodule_addobject (PyObject *module, const char *name, PyObject *object)
 373 {
 374   int result;
 375
 376   Py_INCREF (object);
 377   result = PyModule_AddObject (module, name, object);
 378   if (result < 0)
 379     Py_DECREF (object);
 380   return result;
 381 }
 382
 383 /* Handle a Python exception when the special gdb.GdbError treatment
 384    is desired.  This should only be called when an exception is set.
 385    If the exception is a gdb.GdbError, throw a gdb exception with the
 386    exception text.  For other exceptions, print the Python stack and
 387    then throw a gdb exception.  */
 388
 389 void
 390 gdbpy_handle_exception ()
 391 {
 392   gdbpy_err_fetch fetched_error;
 393   gdb::unique_xmalloc_ptr<char> msg = fetched_error.to_string ();
 394
 395   if (msg == NULL)
 396     {
 397       /* An error occurred computing the string representation of the
 398          error message.  This is rare, but we should inform the user.  */
 399       printf_filtered (_("An error occurred in Python "
 400                          "and then another occurred computing the "
 401                          "error message.\n"));
 402       gdbpy_print_stack ();
 403     }
 404
 405   /* Don't print the stack for gdb.GdbError exceptions.
 406      It is generally used to flag user errors.
 407
 408      We also don't want to print "Error occurred in Python command"
 409      for user errors.  However, a missing message for gdb.GdbError
 410      exceptions is arguably a bug, so we flag it as such.  */
 411
 412   if (fetched_error.type_matches (PyExc_KeyboardInterrupt))
 413     throw_quit ("Quit");
 414   else if (! fetched_error.type_matches (gdbpy_gdberror_exc)
 415            || msg == NULL || *msg == '\0')
 416     {
 417       fetched_error.restore ();
 418       gdbpy_print_stack ();
 419       if (msg != NULL && *msg != '\0')
 420         error (_("Error occurred in Python: %s"), msg.get ());
 421       else
 422         error (_("Error occurred in Python."));
 423     }
 424   else
 425     error ("%s", msg.get ());
 426 }