[PATCH] Add support for gdb.PYTHONDIR as $gdb_datadir/python.

[Joel Brobecker <brobecker@adacore.com>]

Here is a new stab at implementing a "pythondir":

Python scripts to be used by GDB can be stored in that directory,
and will be automatically found by the interpreter when importing them.
This patch also sets up <gdb_pythondir>/gdb as the directory where gdb
submodules can be stored.  For now, there is nothing there, but it can
now be added easily without further code changes.

The difference with the previous patch is that this pythondir is no
longer changeable during configure - it's now hardcoded.

Another tiny differnce is that I named the associated "variable"
in the gdb module as "PYTHONDIR", rather than "pythondir".  This is
because Python does not have constants and the usual convention to
name variables that are supposed to be constant is to use all-upper-case.


gdb/ChangeLog:
2010-06-24  Joel Brobecker  <brobecker@adacore.com>

        * python/python.c (_initialize_python): Add new "constant"
        PYTHONDIR in gdb module.  Insert this path at the head of
        sys.path. Set gdb.__path__ to gdb.PYTHONDIR + '/gdb' and
        exec its __init__.py script if it exists in that directory.

Tested on x86_64-linux, no regression.  I also verified by hand that
sys.path has the expected path at the start of the list, and that an
import of a script in that directory works as expected.

I guess documentation and NEWS will have to be written if this patch
goes in...

---
 gdb/python/python.c |   14 ++++++++++++++
 1 files changed, 14 insertions(+), 0 deletions(-)

diff --git a/gdb/python/python.c b/gdb/python/python.c
index 31880c1..0018816 100644
--- a/gdb/python/python.c
+++ b/gdb/python/python.c
@@ -668,6 +668,13 @@ Enables or disables printing of Python stack traces."),
   PyModule_AddStringConstant (gdb_module, "VERSION", (char*) version);
   PyModule_AddStringConstant (gdb_module, "HOST_CONFIG", (char*) host_name);
   PyModule_AddStringConstant (gdb_module, "TARGET_CONFIG", (char*) target_name);
+  {
+    char *gdb_pythondir;
+
+    gdb_pythondir = concat (gdb_datadir, SLASH_STRING, "python", NULL);
+    PyModule_AddStringConstant (gdb_module, "PYTHONDIR", gdb_pythondir);
+    xfree (gdb_pythondir);
+  }
 
   gdbpy_gdberror_exc = PyErr_NewException ("gdb.GdbError", NULL, NULL);
   PyModule_AddObject (gdb_module, "GdbError", gdbpy_gdberror_exc);
@@ -720,6 +727,13 @@ class GdbOutputFile:\n\
 \n\
 sys.stderr = GdbOutputFile()\n\
 sys.stdout = GdbOutputFile()\n\
+\n\
+sys.path.insert(0, gdb.PYTHONDIR)\n\
+gdb.__path__ = [gdb.PYTHONDIR + '/gdb']\n\
+from os.path import exists\n\
+ipy = gdb.PYTHONDIR + '/gdb/__init__.py'\n\
+if exists (ipy):\n\
+  execfile (ipy)\n\
 ");
 
   /* Release the GIL while gdb runs.  */
-- 
1.7.1