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cpython/Python/traceback.c

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/* Traceback implementation */
#include "Python.h"
#include "code.h"
#include "frameobject.h"
#include "structmember.h"
#include "osdefs.h"
#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#endif
#define OFF(x) offsetof(PyTracebackObject, x)
#define PUTS(fd, str) write(fd, str, (int)strlen(str))
#define MAX_STRING_LENGTH 500
#define MAX_FRAME_DEPTH 100
#define MAX_NTHREADS 100
/* Function from Parser/tokenizer.c */
extern char * PyTokenizer_FindEncodingFilename(int, PyObject *);
_Py_IDENTIFIER(TextIOWrapper);
_Py_IDENTIFIER(close);
_Py_IDENTIFIER(open);
_Py_IDENTIFIER(path);
static PyObject *
tb_dir(PyTracebackObject *self)
{
return Py_BuildValue("[ssss]", "tb_frame", "tb_next",
"tb_lasti", "tb_lineno");
}
static PyMethodDef tb_methods[] = {
{"__dir__", (PyCFunction)tb_dir, METH_NOARGS},
{NULL, NULL, 0, NULL},
};
static PyMemberDef tb_memberlist[] = {
{"tb_next", T_OBJECT, OFF(tb_next), READONLY},
{"tb_frame", T_OBJECT, OFF(tb_frame), READONLY},
{"tb_lasti", T_INT, OFF(tb_lasti), READONLY},
{"tb_lineno", T_INT, OFF(tb_lineno), READONLY},
{NULL} /* Sentinel */
};
static void
tb_dealloc(PyTracebackObject *tb)
{
PyObject_GC_UnTrack(tb);
Py_TRASHCAN_SAFE_BEGIN(tb)
Py_XDECREF(tb->tb_next);
Py_XDECREF(tb->tb_frame);
PyObject_GC_Del(tb);
Py_TRASHCAN_SAFE_END(tb)
}
static int
tb_traverse(PyTracebackObject *tb, visitproc visit, void *arg)
{
Py_VISIT(tb->tb_next);
Py_VISIT(tb->tb_frame);
return 0;
}
static void
tb_clear(PyTracebackObject *tb)
{
Py_CLEAR(tb->tb_next);
Py_CLEAR(tb->tb_frame);
}
PyTypeObject PyTraceBack_Type = {
PyVarObject_HEAD_INIT(&PyType_Type, 0)
"traceback",
sizeof(PyTracebackObject),
0,
(destructor)tb_dealloc, /*tp_dealloc*/
0, /*tp_print*/
0, /*tp_getattr*/
0, /*tp_setattr*/
0, /*tp_reserved*/
0, /*tp_repr*/
0, /*tp_as_number*/
0, /*tp_as_sequence*/
0, /*tp_as_mapping*/
0, /* tp_hash */
0, /* tp_call */
0, /* tp_str */
PyObject_GenericGetAttr, /* tp_getattro */
0, /* tp_setattro */
0, /* tp_as_buffer */
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,/* tp_flags */
0, /* tp_doc */
(traverseproc)tb_traverse, /* tp_traverse */
(inquiry)tb_clear, /* tp_clear */
0, /* tp_richcompare */
0, /* tp_weaklistoffset */
0, /* tp_iter */
0, /* tp_iternext */
tb_methods, /* tp_methods */
tb_memberlist, /* tp_members */
0, /* tp_getset */
0, /* tp_base */
0, /* tp_dict */
};
static PyTracebackObject *
newtracebackobject(PyTracebackObject *next, PyFrameObject *frame)
{
PyTracebackObject *tb;
if ((next != NULL && !PyTraceBack_Check(next)) ||
frame == NULL || !PyFrame_Check(frame)) {
PyErr_BadInternalCall();
return NULL;
}
tb = PyObject_GC_New(PyTracebackObject, &PyTraceBack_Type);
if (tb != NULL) {
Py_XINCREF(next);
tb->tb_next = next;
Py_XINCREF(frame);
tb->tb_frame = frame;
tb->tb_lasti = frame->f_lasti;
tb->tb_lineno = PyFrame_GetLineNumber(frame);
PyObject_GC_Track(tb);
}
return tb;
}
int
PyTraceBack_Here(PyFrameObject *frame)
{
PyThreadState *tstate = PyThreadState_GET();
PyTracebackObject *oldtb = (PyTracebackObject *) tstate->curexc_traceback;
PyTracebackObject *tb = newtracebackobject(oldtb, frame);
if (tb == NULL)
return -1;
tstate->curexc_traceback = (PyObject *)tb;
Py_XDECREF(oldtb);
return 0;
}
static PyObject *
_Py_FindSourceFile(PyObject *filename, char* namebuf, size_t namelen, PyObject *io)
{
Py_ssize_t i;
PyObject *binary;
PyObject *v;
Py_ssize_t npath;
size_t taillen;
PyObject *syspath;
PyObject *path;
const char* tail;
PyObject *filebytes;
const char* filepath;
Py_ssize_t len;
PyObject* result;
filebytes = PyUnicode_EncodeFSDefault(filename);
if (filebytes == NULL) {
PyErr_Clear();
return NULL;
}
filepath = PyBytes_AS_STRING(filebytes);
/* Search tail of filename in sys.path before giving up */
tail = strrchr(filepath, SEP);
if (tail == NULL)
tail = filepath;
else
tail++;
taillen = strlen(tail);
syspath = _PySys_GetObjectId(&PyId_path);
if (syspath == NULL || !PyList_Check(syspath))
goto error;
npath = PyList_Size(syspath);
for (i = 0; i < npath; i++) {
v = PyList_GetItem(syspath, i);
if (v == NULL) {
PyErr_Clear();
break;
}
if (!PyUnicode_Check(v))
continue;
path = PyUnicode_EncodeFSDefault(v);
if (path == NULL) {
PyErr_Clear();
continue;
}
len = PyBytes_GET_SIZE(path);
if (len + 1 + (Py_ssize_t)taillen >= (Py_ssize_t)namelen - 1) {
Py_DECREF(path);
continue; /* Too long */
}
strcpy(namebuf, PyBytes_AS_STRING(path));
Py_DECREF(path);
if (strlen(namebuf) != (size_t)len)
continue; /* v contains '\0' */
if (len > 0 && namebuf[len-1] != SEP)
namebuf[len++] = SEP;
strcpy(namebuf+len, tail);
binary = _PyObject_CallMethodId(io, &PyId_open, "ss", namebuf, "rb");
if (binary != NULL) {
result = binary;
goto finally;
}
PyErr_Clear();
}
goto error;
error:
result = NULL;
finally:
Py_DECREF(filebytes);
return result;
}
int
_Py_DisplaySourceLine(PyObject *f, PyObject *filename, int lineno, int indent)
{
int err = 0;
int fd;
int i;
char *found_encoding;
char *encoding;
PyObject *io;
PyObject *binary;
PyObject *fob = NULL;
PyObject *lineobj = NULL;
PyObject *res;
char buf[MAXPATHLEN+1];
int kind;
void *data;
/* open the file */
if (filename == NULL)
return 0;
io = PyImport_ImportModuleNoBlock("io");
if (io == NULL)
return -1;
binary = _PyObject_CallMethodId(io, &PyId_open, "Os", filename, "rb");
if (binary == NULL) {
PyErr_Clear();
binary = _Py_FindSourceFile(filename, buf, sizeof(buf), io);
if (binary == NULL) {
Py_DECREF(io);
return -1;
}
}
/* use the right encoding to decode the file as unicode */
fd = PyObject_AsFileDescriptor(binary);
if (fd < 0) {
Py_DECREF(io);
Py_DECREF(binary);
return 0;
}
found_encoding = PyTokenizer_FindEncodingFilename(fd, filename);
if (found_encoding == NULL)
PyErr_Clear();
encoding = (found_encoding != NULL) ? found_encoding : "utf-8";
/* Reset position */
if (lseek(fd, 0, SEEK_SET) == (off_t)-1) {
Py_DECREF(io);
Py_DECREF(binary);
PyMem_FREE(found_encoding);
return 0;
}
fob = _PyObject_CallMethodId(io, &PyId_TextIOWrapper, "Os", binary, encoding);
Py_DECREF(io);
Py_DECREF(binary);
PyMem_FREE(found_encoding);
if (fob == NULL) {
PyErr_Clear();
return 0;
}
/* get the line number lineno */
for (i = 0; i < lineno; i++) {
Py_XDECREF(lineobj);
lineobj = PyFile_GetLine(fob, -1);
if (!lineobj) {
err = -1;
break;
}
}
res = _PyObject_CallMethodId(fob, &PyId_close, "");
if (res)
Py_DECREF(res);
else
PyErr_Clear();
Py_DECREF(fob);
if (!lineobj || !PyUnicode_Check(lineobj)) {
Py_XDECREF(lineobj);
return err;
}
/* remove the indentation of the line */
kind = PyUnicode_KIND(lineobj);
data = PyUnicode_DATA(lineobj);
for (i=0; i < PyUnicode_GET_LENGTH(lineobj); i++) {
Py_UCS4 ch = PyUnicode_READ(kind, data, i);
if (ch != ' ' && ch != '\t' && ch != '\014')
break;
}
if (i) {
PyObject *truncated;
truncated = PyUnicode_Substring(lineobj, i, PyUnicode_GET_LENGTH(lineobj));
if (truncated) {
Py_DECREF(lineobj);
lineobj = truncated;
} else {
PyErr_Clear();
}
}
/* Write some spaces before the line */
strcpy(buf, " ");
assert (strlen(buf) == 10);
while (indent > 0) {
if (indent < 10)
buf[indent] = '\0';
err = PyFile_WriteString(buf, f);
if (err != 0)
break;
indent -= 10;
}
/* finally display the line */
if (err == 0)
err = PyFile_WriteObject(lineobj, f, Py_PRINT_RAW);
Py_DECREF(lineobj);
if (err == 0)
err = PyFile_WriteString("\n", f);
return err;
}
static int
tb_displayline(PyObject *f, PyObject *filename, int lineno, PyObject *name)
{
int err;
PyObject *line;
if (filename == NULL || name == NULL)
return -1;
line = PyUnicode_FromFormat(" File \"%U\", line %d, in %U\n",
filename, lineno, name);
if (line == NULL)
return -1;
err = PyFile_WriteObject(line, f, Py_PRINT_RAW);
Py_DECREF(line);
if (err != 0)
return err;
/* ignore errors since we can't report them, can we? */
if (_Py_DisplaySourceLine(f, filename, lineno, 4))
PyErr_Clear();
return err;
}
static int
tb_printinternal(PyTracebackObject *tb, PyObject *f, long limit)
{
int err = 0;
long depth = 0;
PyTracebackObject *tb1 = tb;
while (tb1 != NULL) {
depth++;
tb1 = tb1->tb_next;
}
while (tb != NULL && err == 0) {
if (depth <= limit) {
err = tb_displayline(f,
tb->tb_frame->f_code->co_filename,
tb->tb_lineno,
tb->tb_frame->f_code->co_name);
}
depth--;
tb = tb->tb_next;
if (err == 0)
err = PyErr_CheckSignals();
}
return err;
}
#define PyTraceBack_LIMIT 1000
int
PyTraceBack_Print(PyObject *v, PyObject *f)
{
int err;
PyObject *limitv;
long limit = PyTraceBack_LIMIT;
if (v == NULL)
return 0;
if (!PyTraceBack_Check(v)) {
PyErr_BadInternalCall();
return -1;
}
limitv = PySys_GetObject("tracebacklimit");
if (limitv) {
PyObject *exc_type, *exc_value, *exc_tb;
PyErr_Fetch(&exc_type, &exc_value, &exc_tb);
limit = PyLong_AsLong(limitv);
if (limit == -1 && PyErr_Occurred()) {
if (PyErr_ExceptionMatches(PyExc_OverflowError)) {
limit = PyTraceBack_LIMIT;
}
else {
Py_XDECREF(exc_type);
Py_XDECREF(exc_value);
Py_XDECREF(exc_tb);
return 0;
}
}
else if (limit <= 0) {
limit = PyTraceBack_LIMIT;
}
PyErr_Restore(exc_type, exc_value, exc_tb);
}
err = PyFile_WriteString("Traceback (most recent call last):\n", f);
if (!err)
err = tb_printinternal((PyTracebackObject *)v, f, limit);
return err;
}
/* Reverse a string. For example, "abcd" becomes "dcba".
This function is signal safe. */
static void
reverse_string(char *text, const size_t len)
{
char tmp;
size_t i, j;
if (len == 0)
return;
for (i=0, j=len-1; i < j; i++, j--) {
tmp = text[i];
text[i] = text[j];
text[j] = tmp;
}
}
/* Format an integer in range [0; 999999] to decimal,
and write it into the file fd.
This function is signal safe. */
static void
dump_decimal(int fd, int value)
{
char buffer[7];
int len;
if (value < 0 || 999999 < value)
return;
len = 0;
do {
buffer[len] = '0' + (value % 10);
value /= 10;
len++;
} while (value);
reverse_string(buffer, len);
write(fd, buffer, len);
}
/* Format an integer in range [0; 0xffffffff] to hexadecimal of 'width' digits,
and write it into the file fd.
This function is signal safe. */
static void
dump_hexadecimal(int fd, unsigned long value, int width)
{
int len;
char buffer[sizeof(unsigned long) * 2 + 1];
len = 0;
do {
buffer[len] = Py_hexdigits[value & 15];
value >>= 4;
len++;
} while (len < width || value);
reverse_string(buffer, len);
write(fd, buffer, len);
}
/* Write an unicode object into the file fd using ascii+backslashreplace.
This function is signal safe. */
static void
dump_ascii(int fd, PyObject *text)
{
PyASCIIObject *ascii = (PyASCIIObject *)text;
Py_ssize_t i, size;
int truncated;
int kind;
void *data = NULL;
wchar_t *wstr = NULL;
Py_UCS4 ch;
size = ascii->length;
kind = ascii->state.kind;
if (ascii->state.compact) {
if (ascii->state.ascii)
data = ((PyASCIIObject*)text) + 1;
else
data = ((PyCompactUnicodeObject*)text) + 1;
}
else if (kind != PyUnicode_WCHAR_KIND) {
data = ((PyUnicodeObject *)text)->data.any;
if (data == NULL)
return;
}
else {
wstr = ((PyASCIIObject *)text)->wstr;
if (wstr == NULL)
return;
size = ((PyCompactUnicodeObject *)text)->wstr_length;
}
if (MAX_STRING_LENGTH < size) {
size = MAX_STRING_LENGTH;
truncated = 1;
}
else
truncated = 0;
for (i=0; i < size; i++) {
if (kind != PyUnicode_WCHAR_KIND)
ch = PyUnicode_READ(kind, data, i);
else
ch = wstr[i];
if (' ' <= ch && ch <= 126) {
/* printable ASCII character */
char c = (char)ch;
write(fd, &c, 1);
}
else if (ch <= 0xff) {
PUTS(fd, "\\x");
dump_hexadecimal(fd, ch, 2);
}
else if (ch <= 0xffff) {
PUTS(fd, "\\u");
dump_hexadecimal(fd, ch, 4);
}
else {
PUTS(fd, "\\U");
dump_hexadecimal(fd, ch, 8);
}
}
if (truncated)
PUTS(fd, "...");
}
/* Write a frame into the file fd: "File "xxx", line xxx in xxx".
This function is signal safe. */
static void
dump_frame(int fd, PyFrameObject *frame)
{
PyCodeObject *code;
int lineno;
code = frame->f_code;
PUTS(fd, " File ");
if (code != NULL && code->co_filename != NULL
&& PyUnicode_Check(code->co_filename))
{
write(fd, "\"", 1);
dump_ascii(fd, code->co_filename);
write(fd, "\"", 1);
} else {
PUTS(fd, "???");
}
/* PyFrame_GetLineNumber() was introduced in Python 2.7.0 and 3.2.0 */
lineno = PyCode_Addr2Line(code, frame->f_lasti);
PUTS(fd, ", line ");
dump_decimal(fd, lineno);
PUTS(fd, " in ");
if (code != NULL && code->co_name != NULL
&& PyUnicode_Check(code->co_name))
dump_ascii(fd, code->co_name);
else
PUTS(fd, "???");
write(fd, "\n", 1);
}
static void
dump_traceback(int fd, PyThreadState *tstate, int write_header)
{
PyFrameObject *frame;
unsigned int depth;
if (write_header)
PUTS(fd, "Stack (most recent call first):\n");
frame = _PyThreadState_GetFrame(tstate);
if (frame == NULL)
return;
depth = 0;
while (frame != NULL) {
if (MAX_FRAME_DEPTH <= depth) {
PUTS(fd, " ...\n");
break;
}
if (!PyFrame_Check(frame))
break;
dump_frame(fd, frame);
frame = frame->f_back;
depth++;
}
}
void
_Py_DumpTraceback(int fd, PyThreadState *tstate)
{
dump_traceback(fd, tstate, 1);
}
/* Write the thread identifier into the file 'fd': "Current thread 0xHHHH:\" if
is_current is true, "Thread 0xHHHH:\n" otherwise.
This function is signal safe. */
static void
write_thread_id(int fd, PyThreadState *tstate, int is_current)
{
if (is_current)
PUTS(fd, "Current thread 0x");
else
PUTS(fd, "Thread 0x");
dump_hexadecimal(fd, (unsigned long)tstate->thread_id, sizeof(unsigned long)*2);
PUTS(fd, " (most recent call first):\n");
}
const char*
_Py_DumpTracebackThreads(int fd, PyInterpreterState *interp,
PyThreadState *current_thread)
{
PyThreadState *tstate;
unsigned int nthreads;
/* Get the current interpreter from the current thread */
tstate = PyInterpreterState_ThreadHead(interp);
if (tstate == NULL)
return "unable to get the thread head state";
/* Dump the traceback of each thread */
tstate = PyInterpreterState_ThreadHead(interp);
nthreads = 0;
do
{
if (nthreads != 0)
write(fd, "\n", 1);
if (nthreads >= MAX_NTHREADS) {
PUTS(fd, "...\n");
break;
}
write_thread_id(fd, tstate, tstate == current_thread);
dump_traceback(fd, tstate, 0);
tstate = PyThreadState_Next(tstate);
nthreads++;
} while (tstate != NULL);
return NULL;
}
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