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/******************************************************************************
* Remote Debugging Module - Object Reading Functions
*
* This file contains functions for reading Python objects from remote
* process memory, including strings, bytes, and integers.
******************************************************************************/
#include "_remote_debugging.h"
/* ============================================================================
* MEMORY READING FUNCTIONS
* ============================================================================ */
#define DEFINE_MEMORY_READER(type_name, c_type, error_msg) \
int \
read_##type_name(RemoteUnwinderObject *unwinder, uintptr_t address, c_type *result) \
{ \
int res = _Py_RemoteDebug_PagedReadRemoteMemory(&unwinder->handle, address, sizeof(c_type), result); \
if (res < 0) { \
set_exception_cause(unwinder, PyExc_RuntimeError, error_msg); \
return -1; \
} \
return 0; \
}
DEFINE_MEMORY_READER(ptr, uintptr_t, "Failed to read pointer from remote memory")
DEFINE_MEMORY_READER(Py_ssize_t, Py_ssize_t, "Failed to read Py_ssize_t from remote memory")
DEFINE_MEMORY_READER(char, char, "Failed to read char from remote memory")
int
read_py_ptr(RemoteUnwinderObject *unwinder, uintptr_t address, uintptr_t *ptr_addr)
{
if (read_ptr(unwinder, address, ptr_addr)) {
set_exception_cause(unwinder, PyExc_RuntimeError, "Failed to read Python pointer");
return -1;
}
*ptr_addr &= ~Py_TAG_BITS;
return 0;
}
/* ============================================================================
* PYTHON OBJECT READING FUNCTIONS
* ============================================================================ */
PyObject *
read_py_str(
RemoteUnwinderObject *unwinder,
uintptr_t address,
Py_ssize_t max_len
) {
PyObject *result = NULL;
char *buf = NULL;
// Read the entire PyUnicodeObject at once
char unicode_obj[SIZEOF_UNICODE_OBJ];
int res = _Py_RemoteDebug_PagedReadRemoteMemory(
&unwinder->handle,
address,
SIZEOF_UNICODE_OBJ,
unicode_obj
);
if (res < 0) {
set_exception_cause(unwinder, PyExc_RuntimeError, "Failed to read PyUnicodeObject");
goto err;
}
Py_ssize_t len = GET_MEMBER(Py_ssize_t, unicode_obj, unwinder->debug_offsets.unicode_object.length);
if (len < 0 || len > max_len) {
PyErr_Format(PyExc_RuntimeError,
"Invalid string length (%zd) at 0x%lx", len, address);
set_exception_cause(unwinder, PyExc_RuntimeError, "Invalid string length in remote Unicode object");
return NULL;
}
buf = (char *)PyMem_RawMalloc(len+1);
if (buf == NULL) {
PyErr_NoMemory();
set_exception_cause(unwinder, PyExc_MemoryError, "Failed to allocate buffer for string reading");
return NULL;
}
size_t offset = (size_t)unwinder->debug_offsets.unicode_object.asciiobject_size;
res = _Py_RemoteDebug_PagedReadRemoteMemory(&unwinder->handle, address + offset, len, buf);
if (res < 0) {
set_exception_cause(unwinder, PyExc_RuntimeError, "Failed to read string data from remote memory");
goto err;
}
buf[len] = '\0';
result = PyUnicode_FromStringAndSize(buf, len);
if (result == NULL) {
set_exception_cause(unwinder, PyExc_RuntimeError, "Failed to create PyUnicode from remote string data");
goto err;
}
PyMem_RawFree(buf);
assert(result != NULL);
return result;
err:
if (buf != NULL) {
PyMem_RawFree(buf);
}
return NULL;
}
PyObject *
read_py_bytes(
RemoteUnwinderObject *unwinder,
uintptr_t address,
Py_ssize_t max_len
) {
PyObject *result = NULL;
char *buf = NULL;
// Read the entire PyBytesObject at once
char bytes_obj[SIZEOF_BYTES_OBJ];
int res = _Py_RemoteDebug_PagedReadRemoteMemory(
&unwinder->handle,
address,
SIZEOF_BYTES_OBJ,
bytes_obj
);
if (res < 0) {
set_exception_cause(unwinder, PyExc_RuntimeError, "Failed to read PyBytesObject");
goto err;
}
Py_ssize_t len = GET_MEMBER(Py_ssize_t, bytes_obj, unwinder->debug_offsets.bytes_object.ob_size);
if (len < 0 || len > max_len) {
PyErr_Format(PyExc_RuntimeError,
"Invalid bytes length (%zd) at 0x%lx", len, address);
set_exception_cause(unwinder, PyExc_RuntimeError, "Invalid bytes length in remote bytes object");
return NULL;
}
buf = (char *)PyMem_RawMalloc(len+1);
if (buf == NULL) {
PyErr_NoMemory();
set_exception_cause(unwinder, PyExc_MemoryError, "Failed to allocate buffer for bytes reading");
return NULL;
}
size_t offset = (size_t)unwinder->debug_offsets.bytes_object.ob_sval;
res = _Py_RemoteDebug_PagedReadRemoteMemory(&unwinder->handle, address + offset, len, buf);
if (res < 0) {
set_exception_cause(unwinder, PyExc_RuntimeError, "Failed to read bytes data from remote memory");
goto err;
}
buf[len] = '\0';
result = PyBytes_FromStringAndSize(buf, len);
if (result == NULL) {
set_exception_cause(unwinder, PyExc_RuntimeError, "Failed to create PyBytes from remote bytes data");
goto err;
}
PyMem_RawFree(buf);
assert(result != NULL);
return result;
err:
if (buf != NULL) {
PyMem_RawFree(buf);
}
return NULL;
}
long
read_py_long(
RemoteUnwinderObject *unwinder,
uintptr_t address
)
{
unsigned int shift = PYLONG_BITS_IN_DIGIT;
// Read the entire PyLongObject at once
char long_obj[SIZEOF_LONG_OBJ];
int bytes_read = _Py_RemoteDebug_PagedReadRemoteMemory(
&unwinder->handle,
address,
(size_t)unwinder->debug_offsets.long_object.size,
long_obj);
if (bytes_read < 0) {
set_exception_cause(unwinder, PyExc_RuntimeError, "Failed to read PyLongObject");
return -1;
}
uintptr_t lv_tag = GET_MEMBER(uintptr_t, long_obj, unwinder->debug_offsets.long_object.lv_tag);
int negative = (lv_tag & 3) == 2;
Py_ssize_t size = lv_tag >> 3;
if (size == 0) {
return 0;
}
// If the long object has inline digits, use them directly
digit *digits;
if (size <= _PY_NSMALLNEGINTS + _PY_NSMALLPOSINTS) {
// For small integers, digits are inline in the long_value.ob_digit array
digits = (digit *)PyMem_RawMalloc(size * sizeof(digit));
if (!digits) {
PyErr_NoMemory();
set_exception_cause(unwinder, PyExc_MemoryError, "Failed to allocate digits for small PyLong");
return -1;
}
memcpy(digits, long_obj + unwinder->debug_offsets.long_object.ob_digit, size * sizeof(digit));
} else {
// For larger integers, we need to read the digits separately
digits = (digit *)PyMem_RawMalloc(size * sizeof(digit));
if (!digits) {
PyErr_NoMemory();
set_exception_cause(unwinder, PyExc_MemoryError, "Failed to allocate digits for large PyLong");
return -1;
}
bytes_read = _Py_RemoteDebug_PagedReadRemoteMemory(
&unwinder->handle,
address + (uintptr_t)unwinder->debug_offsets.long_object.ob_digit,
sizeof(digit) * size,
digits
);
if (bytes_read < 0) {
set_exception_cause(unwinder, PyExc_RuntimeError, "Failed to read PyLong digits from remote memory");
goto error;
}
}
long long value = 0;
// In theory this can overflow, but because of llvm/llvm-project#16778
// we can't use __builtin_mul_overflow because it fails to link with
// __muloti4 on aarch64. In practice this is fine because all we're
// testing here are task numbers that would fit in a single byte.
for (Py_ssize_t i = 0; i < size; ++i) {
long long factor = digits[i] * (1UL << (Py_ssize_t)(shift * i));
value += factor;
}
PyMem_RawFree(digits);
if (negative) {
value *= -1;
}
return (long)value;
error:
PyMem_RawFree(digits);
return -1;
}
|
