Re: [PATCH v4] [PR/24474] Add gdb.lookup_static_symbol to the python API

["Christian Biesinger via gdb-patches" <gdb-patches at sourceware dot org>]

Hi Eli,

could you take a look at the documentation parts of the below patch
before I push? Thanks!

Christian

On Mon, Jul 29, 2019 at 8:59 PM Christian Biesinger
<cbiesinger@google.com> wrote:
>
> Thanks Simon; fixed the typo. Can I push this or should I wait for Eli
> to review the documentation?
>
> Similar to lookup_global_symbol, except that it checks the
> STATIC_SCOPE.
>
> gdb/ChangeLog:
>
> 2019-07-29  Christian Biesinger  <cbiesinger@google.com>
>
>         PR/24474: Add a function to lookup static variables.
>         * NEWS: Mention this new function.
>         * python/py-symbol.c (gdbpy_lookup_static_symbol): New function.
>         * python/python-internal.h (gdbpy_lookup_static_symbol): New function.
>         * python/python.c (python_GdbMethods): Add new function.
>
> gdb/doc/ChangeLog:
>
> 2019-07-29  Christian Biesinger  <cbiesinger@google.com>
>
>         * python.texi (Symbols In Python): Document new function
>         gdb.lookup_static_symbol.
>
> gdb/testsuite/ChangeLog:
>
> 2019-07-29  Christian Biesinger  <cbiesinger@google.com>
>
>         * gdb.python/py-symbol.c: Add a static variable and one in an anonymous
>         namespace.
>         * gdb.python/py-symbol.exp: Test gdb.lookup_static_symbol.
> ---
>  gdb/NEWS                               |  3 ++
>  gdb/doc/python.texi                    | 19 ++++++++++++
>  gdb/python/py-symbol.c                 | 40 ++++++++++++++++++++++++++
>  gdb/python/python-internal.h           |  2 ++
>  gdb/python/python.c                    |  4 +++
>  gdb/testsuite/gdb.python/py-symbol.c   |  5 ++++
>  gdb/testsuite/gdb.python/py-symbol.exp | 24 ++++++++++++++++
>  7 files changed, 97 insertions(+)
>
> diff --git a/gdb/NEWS b/gdb/NEWS
> index 4e821eab4c..ac44399304 100644
> --- a/gdb/NEWS
> +++ b/gdb/NEWS
> @@ -41,6 +41,9 @@
>       there are no filters, or when the 'backtrace' '-no-filters' option
>       is given.
>
> +  ** The new function gdb.lookup_static_symbol can be used to look up
> +     symbols with static linkage.
> +
>    ** gdb.Objfile has new methods 'lookup_global_symbol' and
>       'lookup_static_symbol' to lookup a symbol from this objfile only.
>
> diff --git a/gdb/doc/python.texi b/gdb/doc/python.texi
> index bbba519ffc..3fdccd5e43 100644
> --- a/gdb/doc/python.texi
> +++ b/gdb/doc/python.texi
> @@ -4847,6 +4847,25 @@ The result is a @code{gdb.Symbol} object or @code{None} if the symbol
>  is not found.
>  @end defun
>
> +@findex gdb.lookup_static_symbol
> +@defun gdb.lookup_static_symbol (name @r{[}, domain@r{]})
> +This function searches for a global symbol with static linkage by name.
> +The search scope can be restricted to by the domain argument.
> +
> +@var{name} is the name of the symbol.  It must be a string.
> +The optional @var{domain} argument restricts the search to the domain type.
> +The @var{domain} argument must be a domain constant defined in the @code{gdb}
> +module and described later in this chapter.
> +
> +The result is a @code{gdb.Symbol} object or @code{None} if the symbol
> +is not found.
> +
> +Note that this function will not find function-scoped static variables. To look
> +up such variables, iterate over the variables of the function's
> +@code{gdb.Block} and check that @code{block.addr_class} is
> +@code{gdb.SYMBOL_LOC_STATIC}.
> +@end defun
> +
>  A @code{gdb.Symbol} object has the following attributes:
>
>  @defvar Symbol.type
> diff --git a/gdb/python/py-symbol.c b/gdb/python/py-symbol.c
> index 8605ae71a2..2b10e21d87 100644
> --- a/gdb/python/py-symbol.c
> +++ b/gdb/python/py-symbol.c
> @@ -471,6 +471,46 @@ gdbpy_lookup_global_symbol (PyObject *self, PyObject *args, PyObject *kw)
>    return sym_obj;
>  }
>
> +/* Implementation of
> +   gdb.lookup_static_symbol (name [, domain) -> symbol or None.  */
> +
> +PyObject *
> +gdbpy_lookup_static_symbol (PyObject *self, PyObject *args, PyObject *kw)
> +{
> +  const char *name;
> +  int domain = VAR_DOMAIN;
> +  static const char *keywords[] = { "name", "domain", NULL };
> +  struct symbol *symbol = NULL;
> +  PyObject *sym_obj;
> +
> +  if (!gdb_PyArg_ParseTupleAndKeywords (args, kw, "s|i", keywords, &name,
> +                                       &domain))
> +    return NULL;
> +
> +  try
> +    {
> +      symbol = lookup_static_symbol (name, (domain_enum) domain).symbol;
> +    }
> +  catch (const gdb_exception &except)
> +    {
> +      GDB_PY_HANDLE_EXCEPTION (except);
> +    }
> +
> +  if (symbol)
> +    {
> +      sym_obj = symbol_to_symbol_object (symbol);
> +      if (!sym_obj)
> +       return NULL;
> +    }
> +  else
> +    {
> +      sym_obj = Py_None;
> +      Py_INCREF (Py_None);
> +    }
> +
> +  return sym_obj;
> +}
> +
>  /* This function is called when an objfile is about to be freed.
>     Invalidate the symbol as further actions on the symbol would result
>     in bad data.  All access to obj->symbol should be gated by
> diff --git a/gdb/python/python-internal.h b/gdb/python/python-internal.h
> index e6a3fe0ec1..c5578430cf 100644
> --- a/gdb/python/python-internal.h
> +++ b/gdb/python/python-internal.h
> @@ -424,6 +424,8 @@ PyObject *gdbpy_frame_stop_reason_string (PyObject *, PyObject *);
>  PyObject *gdbpy_lookup_symbol (PyObject *self, PyObject *args, PyObject *kw);
>  PyObject *gdbpy_lookup_global_symbol (PyObject *self, PyObject *args,
>                                       PyObject *kw);
> +PyObject *gdbpy_lookup_static_symbol (PyObject *self, PyObject *args,
> +                                     PyObject *kw);
>  PyObject *gdbpy_start_recording (PyObject *self, PyObject *args);
>  PyObject *gdbpy_current_recording (PyObject *self, PyObject *args);
>  PyObject *gdbpy_stop_recording (PyObject *self, PyObject *args);
> diff --git a/gdb/python/python.c b/gdb/python/python.c
> index 96bee7c3b0..162470dcc0 100644
> --- a/gdb/python/python.c
> +++ b/gdb/python/python.c
> @@ -1978,6 +1978,10 @@ a boolean indicating if name is a field of the current implied argument\n\
>      METH_VARARGS | METH_KEYWORDS,
>      "lookup_global_symbol (name [, domain]) -> symbol\n\
>  Return the symbol corresponding to the given name (or None)." },
> +  { "lookup_static_symbol", (PyCFunction) gdbpy_lookup_static_symbol,
> +    METH_VARARGS | METH_KEYWORDS,
> +    "lookup_static_symbol (name [, domain]) -> symbol\n\
> +Return the static-linkage symbol corresponding to the given name (or None)." },
>
>    { "lookup_objfile", (PyCFunction) gdbpy_lookup_objfile,
>      METH_VARARGS | METH_KEYWORDS,
> diff --git a/gdb/testsuite/gdb.python/py-symbol.c b/gdb/testsuite/gdb.python/py-symbol.c
> index f77c8c8585..06a931bf5d 100644
> --- a/gdb/testsuite/gdb.python/py-symbol.c
> +++ b/gdb/testsuite/gdb.python/py-symbol.c
> @@ -32,9 +32,14 @@ class SimpleClass
>      return i; /* Break in class. */
>    }
>  };
> +
> +namespace {
> +  int anon = 10;
> +};
>  #endif
>
>  int qq = 72;                   /* line of qq */
> +static int rr = 42;            /* line of rr */
>
>  int func (int arg)
>  {
> diff --git a/gdb/testsuite/gdb.python/py-symbol.exp b/gdb/testsuite/gdb.python/py-symbol.exp
> index 5b8a2be7c4..5617f127e5 100644
> --- a/gdb/testsuite/gdb.python/py-symbol.exp
> +++ b/gdb/testsuite/gdb.python/py-symbol.exp
> @@ -48,6 +48,25 @@ gdb_test "python print (gdb.lookup_global_symbol('qq').needs_frame)" \
>      "False" \
>      "print whether qq needs a frame"
>
> +set rr_line [gdb_get_line_number "line of rr"]
> +gdb_test "python print (gdb.lookup_global_symbol ('rr') is None)" "True" \
> +    "lookup_global_symbol for static var"
> +
> +gdb_test "python print (gdb.lookup_static_symbol ('rr').line)" "$rr_line" \
> +    "print line number of rr"
> +
> +gdb_test "python print (gdb.lookup_static_symbol ('rr').value ())" "42" \
> +    "print value of rr"
> +
> +gdb_test "python print (gdb.lookup_static_symbol ('rr').needs_frame)" \
> +    "False" \
> +    "print whether rr needs a frame"
> +
> +gdb_test "python print (gdb.lookup_static_symbol ('nonexistent') is None)" \
> +    "True" "lookup_static_symbol for nonexistent var"
> +
> +gdb_test "python print (gdb.lookup_static_symbol ('qq') is None)" \
> +    "True" "lookup_static_symbol for global var"
>
>  if ![runto_main] then {
>      fail "can't run to main"
> @@ -137,6 +156,11 @@ gdb_start
>  gdb_reinitialize_dir $srcdir/$subdir
>  gdb_load ${binfile}-cxx
>
> +gdb_test "python print (gdb.lookup_global_symbol ('(anonymous namespace)::anon') is None)" \
> +    "True" "anon is None"
> +gdb_test "python print (gdb.lookup_static_symbol ('(anonymous namespace)::anon').value ())" \
> +    "10" "print value of anon"
> +
>  if ![runto_main] then {
>      fail "can't run to main"
>      return 0
> --
> 2.22.0.709.g102302147b-goog
>