[v3] Make GDB compile with Python 3 on MinGW

Message ID 20190815174200.242339-1-cbiesinger@google.com
State Superseded
Headers show
Series
  • [v3] Make GDB compile with Python 3 on MinGW
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Commit Message

H.J. Lu via Gdb-patches Aug. 15, 2019, 5:42 p.m.
[Fixes two minor typos]

PyFile_FromString and PyFile_AsFile have been removed in Python 3.
There is no obvious replacement that works here, and we can't just
pass our FILE* to a DLL in Windows because it may use a different
C runtime.

So we just call a Python function which reads and executes file
contents. Care must be taken to execute it in the context of
__main__.

Tested by inverting the ifdef and running the testsuite on Debian
Linux (even without the patch, I failed at running the testsuite
on Windows). I did test with both Python 2 and 3.

gdb/ChangeLog:

2019-08-13  Christian Biesinger  <cbiesinger@google.com>

	* python/lib/gdb/__init__.py: Add an execute_file function.
	* python/python.c (python_run_simple_file): Call gdb.execute_file
	on Windows.
---
 gdb/python/lib/gdb/__init__.py | 26 ++++++++++++++++++++++++++
 gdb/python/python.c            | 26 +++++++++++++++++---------
 2 files changed, 43 insertions(+), 9 deletions(-)

-- 
2.23.0.rc1.153.gdeed80330f-goog

Comments

Pedro Alves Aug. 15, 2019, 6:02 p.m. | #1
On 8/15/19 6:42 PM, Christian Biesinger via gdb-patches wrote:
> +      error (_("Installation error: gdb._execute_file function is missing"));

> +      return;


That "return" statement is dead code, error throws an exception.

Thanks,
Pedro Alves
H.J. Lu via Gdb-patches Aug. 15, 2019, 6:49 p.m. | #2
Thanks, will send a patch in a second with that fixed (and which
undoes the WIN32 ifdef change I accidentally had in the last version)

Christian

On Thu, Aug 15, 2019 at 1:02 PM Pedro Alves <palves@redhat.com> wrote:
>

> On 8/15/19 6:42 PM, Christian Biesinger via gdb-patches wrote:

> > +      error (_("Installation error: gdb._execute_file function is missing"));

> > +      return;

>

> That "return" statement is dead code, error throws an exception.

>

> Thanks,

> Pedro Alves

Patch

diff --git a/gdb/python/lib/gdb/__init__.py b/gdb/python/lib/gdb/__init__.py
index af74df80c8..afe5b08f3a 100644
--- a/gdb/python/lib/gdb/__init__.py
+++ b/gdb/python/lib/gdb/__init__.py
@@ -106,6 +106,32 @@  def execute_unwinders(pending_frame):
 
     return None
 
+def _execute_file(filepath):
+    """This function is used to replace Python 2's PyRun_SimpleFile.
+
+    Loads and executes the given file.
+
+    We could use the runpy module, but its documentation says:
+    "Furthermore, any functions and classes defined by the executed code are
+    not guaranteed to work correctly after a runpy function has returned."
+    """
+    globals = sys.modules['__main__'].__dict__
+    set_file = False
+    # Set file (if not set) so that the imported file can use it (e.g. to
+    # access file-relative paths). This matches what PyRun_SimpleFile does.
+    if not hasattr(globals, '__file__'):
+        globals['__file__'] = filepath
+        set_file = True
+    try:
+        with open(filepath, 'rb') as file:
+            # We pass globals also as locals to match what Python does
+            # in PyRun_SimpleFile.
+            compiled = compile(file.read(), filepath, 'exec')
+            exec(compiled, globals, globals)
+    finally:
+        if set_file:
+            del globals['__file__']
+
 
 # Convenience variable to GDB's python directory
 PYTHONDIR = os.path.dirname(os.path.dirname(__file__))
diff --git a/gdb/python/python.c b/gdb/python/python.c
index 162470dcc0..46aedba0ed 100644
--- a/gdb/python/python.c
+++ b/gdb/python/python.c
@@ -323,14 +323,13 @@  python_interactive_command (const char *arg, int from_tty)
    A FILE * from one runtime does not necessarily operate correctly in
    the other runtime.
 
-   To work around this potential issue, we create on Windows hosts the
-   FILE object using Python routines, thus making sure that it is
-   compatible with the Python library.  */
+   To work around this potential issue, we run code in Python to load
+   the script.  */
 
 static void
 python_run_simple_file (FILE *file, const char *filename)
 {
-#ifndef _WIN32
+#ifdef _WIN32
 
   PyRun_SimpleFile (file, filename);
 
@@ -339,14 +338,23 @@  python_run_simple_file (FILE *file, const char *filename)
   /* Because we have a string for a filename, and are using Python to
      open the file, we need to expand any tilde in the path first.  */
   gdb::unique_xmalloc_ptr<char> full_path (tilde_expand (filename));
-  gdbpy_ref<> python_file (PyFile_FromString (full_path.get (), (char *) "r"));
-  if (python_file == NULL)
+
+  if (gdb_python_module == nullptr
+      || ! PyObject_HasAttrString (gdb_python_module, "_execute_file"))
     {
-      gdbpy_print_stack ();
-      error (_("Error while opening file: %s"), full_path.get ());
+      error (_("Installation error: gdb._execute_file function is missing"));
+      return;
     }
 
-  PyRun_SimpleFile (PyFile_AsFile (python_file.get ()), filename);
+  gdbpy_ref<> return_value
+    (PyObject_CallMethod (gdb_python_module, "_execute_file", "s",
+			  full_path.get ()));
+  if (return_value == nullptr)
+    {
+      /* Use PyErr_PrintEx instead of gdbpy_print_stack to better match the
+         behavior of the non-Windows codepath.  */
+      PyErr_PrintEx(0);
+    }
 
 #endif /* _WIN32 */
 }