Python/traceback.c

   1
   2 /* Traceback implementation */
   3
   4 #include "Python.h"
   5
   6 #include "code.h"
   7 #include "frameobject.h"
   8 #include "structmember.h"
   9 #include "osdefs.h"
  10 #include "traceback.h"
  11
  12 #define OFF(x) offsetof(PyTracebackObject, x)
  13
  14 static struct memberlist tb_memberlist[] = {
  15         {"tb_next",     T_OBJECT,       OFF(tb_next)},
  16         {"tb_frame",    T_OBJECT,       OFF(tb_frame)},
  17         {"tb_lasti",    T_INT,          OFF(tb_lasti)},
  18         {"tb_lineno",   T_INT,          OFF(tb_lineno)},
  19         {NULL}  /* Sentinel */
  20 };
  21
  22 static PyObject *
  23 tb_getattr(PyTracebackObject *tb, char *name)
  24 {
  25         return PyMember_Get((char *)tb, tb_memberlist, name);
  26 }
  27
  28 static void
  29 tb_dealloc(PyTracebackObject *tb)
  30 {
  31         PyObject_GC_UnTrack(tb);
  32         Py_TRASHCAN_SAFE_BEGIN(tb)
  33         Py_XDECREF(tb->tb_next);
  34         Py_XDECREF(tb->tb_frame);
  35         PyObject_GC_Del(tb);
  36         Py_TRASHCAN_SAFE_END(tb)
  37 }
  38
  39 static int
  40 tb_traverse(PyTracebackObject *tb, visitproc visit, void *arg)
  41 {
  42         Py_VISIT(tb->tb_next);
  43         Py_VISIT(tb->tb_frame);
  44         return 0;
  45 }
  46
  47 static void
  48 tb_clear(PyTracebackObject *tb)
  49 {
  50         Py_CLEAR(tb->tb_next);
  51         Py_CLEAR(tb->tb_frame);
  52 }
  53
  54 PyTypeObject PyTraceBack_Type = {
  55         PyVarObject_HEAD_INIT(&PyType_Type, 0)
  56         "traceback",
  57         sizeof(PyTracebackObject),
  58         0,
  59         (destructor)tb_dealloc, /*tp_dealloc*/
  60         0,              /*tp_print*/
  61         (getattrfunc)tb_getattr, /*tp_getattr*/
  62         0,              /*tp_setattr*/
  63         0,              /*tp_compare*/
  64         0,              /*tp_repr*/
  65         0,              /*tp_as_number*/
  66         0,              /*tp_as_sequence*/
  67         0,              /*tp_as_mapping*/
  68         0,              /* tp_hash */
  69         0,              /* tp_call */
  70         0,              /* tp_str */
  71         0,              /* tp_getattro */
  72         0,              /* tp_setattro */
  73         0,                                      /* tp_as_buffer */
  74         Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,/* tp_flags */
  75         0,                                      /* tp_doc */
  76         (traverseproc)tb_traverse,              /* tp_traverse */
  77         (inquiry)tb_clear,                      /* tp_clear */
  78         0,                                      /* tp_richcompare */
  79         0,                                      /* tp_weaklistoffset */
  80         0,                                      /* tp_iter */
  81         0,                                      /* tp_iternext */
  82         0,                                      /* tp_methods */
  83         0,                      /* tp_members */
  84         0,                      /* tp_getset */
  85         0,                                      /* tp_base */
  86         0,                                      /* tp_dict */
  87 };
  88
  89 static PyTracebackObject *
  90 newtracebackobject(PyTracebackObject *next, PyFrameObject *frame)
  91 {
  92         PyTracebackObject *tb;
  93         if ((next != NULL && !PyTraceBack_Check(next)) ||
  94                         frame == NULL || !PyFrame_Check(frame)) {
  95                 PyErr_BadInternalCall();
  96                 return NULL;
  97         }
  98         tb = PyObject_GC_New(PyTracebackObject, &PyTraceBack_Type);
  99         if (tb != NULL) {
 100                 Py_XINCREF(next);
 101                 tb->tb_next = next;
 102                 Py_XINCREF(frame);
 103                 tb->tb_frame = frame;
 104                 tb->tb_lasti = frame->f_lasti;
 105                 tb->tb_lineno = PyCode_Addr2Line(frame->f_code,
 106                                                  frame->f_lasti);
 107                 PyObject_GC_Track(tb);
 108         }
 109         return tb;
 110 }
 111
 112 int
 113 PyTraceBack_Here(PyFrameObject *frame)
 114 {
 115         PyThreadState *tstate = PyThreadState_GET();
 116         PyTracebackObject *oldtb = (PyTracebackObject *) tstate->curexc_traceback;
 117         PyTracebackObject *tb = newtracebackobject(oldtb, frame);
 118         if (tb == NULL)
 119                 return -1;
 120         tstate->curexc_traceback = (PyObject *)tb;
 121         Py_XDECREF(oldtb);
 122         return 0;
 123 }
 124
 125 int
 126 _Py_DisplaySourceLine(PyObject *f, const char *filename, int lineno, int indent)
 127 {
 128         int err = 0;
 129         FILE *xfp = NULL;
 130         char linebuf[2000];
 131         int i;
 132         char namebuf[MAXPATHLEN+1];
 133
 134         if (filename == NULL)
 135                 return -1;
 136         /* This is needed by Emacs' compile command */
 137 #define FMT "  File \"%.500s\", line %d, in %.500s\n"
 138         xfp = fopen(filename, "r" PY_STDIOTEXTMODE);
 139         if (xfp == NULL) {
 140                 /* Search tail of filename in sys.path before giving up */
 141                 PyObject *path;
 142                 const char *tail = strrchr(filename, SEP);
 143                 if (tail == NULL)
 144                         tail = filename;
 145                 else
 146                         tail++;
 147                 path = PySys_GetObject("path");
 148                 if (path != NULL && PyList_Check(path)) {
 149                         Py_ssize_t _npath = PyList_Size(path);
 150                         int npath = Py_SAFE_DOWNCAST(_npath, Py_ssize_t, int);
 151                         size_t taillen = strlen(tail);
 152                         for (i = 0; i < npath; i++) {
 153                                 PyObject *v = PyList_GetItem(path, i);
 154                                 if (v == NULL) {
 155                                         PyErr_Clear();
 156                                         break;
 157                                 }
 158                                 if (PyString_Check(v)) {
 159                                         size_t len;
 160                                         len = PyString_GET_SIZE(v);
 161                                         if (len + 1 + taillen >= MAXPATHLEN)
 162                                                 continue; /* Too long */
 163                                         strcpy(namebuf, PyString_AsString(v));
 164                                         if (strlen(namebuf) != len)
 165                                                 continue; /* v contains '\0' */
 166                                         if (len > 0 && namebuf[len-1] != SEP)
 167                                                 namebuf[len++] = SEP;
 168                                         strcpy(namebuf+len, tail);
 169                                         xfp = fopen(namebuf, "r" PY_STDIOTEXTMODE);
 170                                         if (xfp != NULL) {
 171                                                 filename = namebuf;
 172                                                 break;
 173                                         }
 174                                 }
 175                         }
 176                 }
 177         }
 178
 179         if (xfp == NULL)
 180             return err;
 181         if (err != 0) {
 182             fclose(xfp);
 183             return err;
 184         }
 185
 186         for (i = 0; i < lineno; i++) {
 187                 char* pLastChar = &linebuf[sizeof(linebuf)-2];
 188                 do {
 189                         *pLastChar = '\0';
 190                         if (Py_UniversalNewlineFgets(linebuf, sizeof linebuf, xfp, NULL) == NULL)
 191                                 break;
 192                         /* fgets read *something*; if it didn't get as
 193                            far as pLastChar, it must have found a newline
 194                            or hit the end of the file;  if pLastChar is \n,
 195                            it obviously found a newline; else we haven't
 196                            yet seen a newline, so must continue */
 197                 } while (*pLastChar != '\0' && *pLastChar != '\n');
 198         }
 199         if (i == lineno) {
 200                 char buf[11];
 201                 char *p = linebuf;
 202                 while (*p == ' ' || *p == '\t' || *p == '\014')
 203                         p++;
 204
 205                 /* Write some spaces before the line */
 206                 strcpy(buf, "          ");
 207                 assert (strlen(buf) == 10);
 208                 while (indent > 0) {
 209                         if(indent < 10)
 210                                 buf[indent] = '\0';
 211                         err = PyFile_WriteString(buf, f);
 212                         if (err != 0)
 213                                 break;
 214                         indent -= 10;
 215                 }
 216
 217                 if (err == 0)
 218                         err = PyFile_WriteString(p, f);
 219                 if (err == 0 && strchr(p, '\n') == NULL)
 220                         err = PyFile_WriteString("\n", f);
 221         }
 222         fclose(xfp);
 223         return err;
 224 }
 225
 226 static int
 227 tb_displayline(PyObject *f, const char *filename, int lineno, const char *name)
 228 {
 229         int err = 0;
 230         char linebuf[2000];
 231
 232         if (filename == NULL || name == NULL)
 233                 return -1;
 234         /* This is needed by Emacs' compile command */
 235 #define FMT "  File \"%.500s\", line %d, in %.500s\n"
 236         PyOS_snprintf(linebuf, sizeof(linebuf), FMT, filename, lineno, name);
 237         err = PyFile_WriteString(linebuf, f);
 238         if (err != 0)
 239                 return err;
 240         return _Py_DisplaySourceLine(f, filename, lineno, 4);
 241 }
 242
 243 static int
 244 tb_printinternal(PyTracebackObject *tb, PyObject *f, long limit)
 245 {
 246         int err = 0;
 247         long depth = 0;
 248         PyTracebackObject *tb1 = tb;
 249         while (tb1 != NULL) {
 250                 depth++;
 251                 tb1 = tb1->tb_next;
 252         }
 253         while (tb != NULL && err == 0) {
 254                 if (depth <= limit) {
 255                         err = tb_displayline(f,
 256                             PyString_AsString(
 257                                     tb->tb_frame->f_code->co_filename),
 258                             tb->tb_lineno,
 259                             PyString_AsString(tb->tb_frame->f_code->co_name));
 260                 }
 261                 depth--;
 262                 tb = tb->tb_next;
 263                 if (err == 0)
 264                         err = PyErr_CheckSignals();
 265         }
 266         return err;
 267 }
 268
 269 int
 270 PyTraceBack_Print(PyObject *v, PyObject *f)
 271 {
 272         int err;
 273         PyObject *limitv;
 274         long limit = 1000;
 275         if (v == NULL)
 276                 return 0;
 277         if (!PyTraceBack_Check(v)) {
 278                 PyErr_BadInternalCall();
 279                 return -1;
 280         }
 281         limitv = PySys_GetObject("tracebacklimit");
 282         if (limitv && PyInt_Check(limitv)) {
 283                 limit = PyInt_AsLong(limitv);
 284                 if (limit <= 0)
 285                         return 0;
 286         }
 287         err = PyFile_WriteString("Traceback (most recent call last):\n", f);
 288         if (!err)
 289                 err = tb_printinternal((PyTracebackObject *)v, f, limit);
 290         return err;
 291 }