gh-138122: Split Modules/_remote_debugging_module.c into multiple files (#141934)

gh-1381228: Split Modules/_remote_debugging_module.c into multiple files

Modules/_remote_debugging/object_reading.c

@@ -0,0 +1,247 @@
+/******************************************************************************
+ * 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;
+}