[gdb/python] Fix abort on Py_Initialize
I tried out making python initialization fail by passing an incorrect
PYTHONHOME with python 3.6, and got:
...
$ PYTHONHOME=foo gdb -q
Fatal Python error: Py_Initialize: Unable to get the locale encoding
ModuleNotFoundError: No module named 'encodings'
Current thread 0x0000ffff89269c80 (most recent call first):
Fatal signal: Aborted
...
Aborted (core dumped)
$
...
This is as per spec: when Py_Initialize () fails, a fatal error is raised
using Py_FatalError.
This can be worked around using:
...
$ PYTHONHOME=foo gdb -q -eiex "set python ignore-environment on"
(gdb)
...
but it would be better if gdb didn't abort.
I found an article [1] describing two solutions:
- try out Py_Initialize in a separate process, and
- catch the abort using a signal handler.
This patch implements the latter solution.
Obviously we cannot call into python anymore after the abort, so we avoid
calling Py_IsInitialized (), and instead use a new variable py_isinitialized.
This gets us instead:
...
$ PYTHONHOME=foo gdb -q
Fatal Python error: Py_Initialize: Unable to get the locale encoding
ModuleNotFoundError: No module named 'encodings'
Current thread 0x0000fffecfd49c80 (most recent call first):
Python not initialized
$
...
Tested on aarch64-linux.
Approved-By: Tom Tromey <tom@tromey.com>
PR python/32379
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=32379
[1] https://stackoverflow.com/questions/7688374/how-to-i-catch-and-handle-a-fatal-error-when-py-initialize-fails
diff --git a/gdb/python/python.c b/gdb/python/python.c
index 820fb58..f9d8e87 100644
--- a/gdb/python/python.c
+++ b/gdb/python/python.c
@@ -2297,6 +2297,42 @@ gdbpy_gdb_exiting (int exit_code)
gdbpy_print_stack ();
}
+/* Signal handler to convert a SIGABRT into an exception. */
+
+static void
+catch_python_fatal (int signum)
+{
+ signal (SIGABRT, catch_python_fatal);
+
+ throw_exception_sjlj (gdb_exception {RETURN_ERROR, GENERIC_ERROR});
+}
+
+/* Stand-in for Py_IsInitialized (). To be used because after a python fatal
+ error, no calls into Python are allowed. */
+
+static bool py_isinitialized = false;
+
+/* Call Py_Initialize (), and return true if successful. */
+
+static bool ATTRIBUTE_UNUSED
+py_initialize ()
+{
+ auto prev_handler = signal (SIGABRT, catch_python_fatal);
+ SCOPE_EXIT { signal (SIGABRT, prev_handler); };
+
+ TRY_SJLJ
+ {
+ Py_Initialize ();
+ py_isinitialized = true;
+ }
+ CATCH_SJLJ (e, RETURN_MASK_ERROR)
+ {
+ }
+ END_CATCH_SJLJ;
+
+ return py_isinitialized;
+}
+
static bool
do_start_initialization ()
{
@@ -2353,7 +2389,8 @@ do_start_initialization ()
remain alive for the duration of the program's execution, so
it is not freed after this call. */
Py_SetProgramName (progname_copy);
- Py_Initialize ();
+ if (!py_initialize ())
+ return false;
#else
PyConfig config;
@@ -2383,9 +2420,11 @@ do_start_initialization ()
status.exitcode);
return false;
}
+ py_isinitialized = true;
#endif
#else
- Py_Initialize ();
+ if (!py_initialize ())
+ return false;
#endif
#if PY_VERSION_HEX < 0x03090000
@@ -2727,7 +2766,7 @@ do_initialize (const struct extension_language_defn *extlang)
static void
gdbpy_initialize (const struct extension_language_defn *extlang)
{
- if (!do_start_initialization () && Py_IsInitialized () && PyErr_Occurred ())
+ if (!do_start_initialization () && py_isinitialized && PyErr_Occurred ())
gdbpy_print_stack ();
gdbpy_enter enter_py;
