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