fishdescriptor: Work if child is not running as root, but we are

[chiark-utils.git] / fishdescriptor / py / fishdescriptor / fish.py

diff --git a/fishdescriptor/py/fishdescriptor/fish.py b/fishdescriptor/py/fishdescriptor/fish.py
index 15ad7660faa3e19861a8d08cb2dde2106348cdf2..b47ac3dbb6aeb493b56f86a33aed9ff1cbf72669 100644 (file)
--- a/fishdescriptor/py/fishdescriptor/fish.py
+++ b/fishdescriptor/py/fishdescriptor/fish.py
@@ -1,3 +1,24 @@
+# fish.py
+
+# This file is part of chiark-utils, a collection of useful programs
+# used on chiark.greenend.org.uk.
+#
+# This file is:
+#  Copyright 2018 Citrix Systems Ltd
+#
+# This is free software; you can redistribute it and/or modify it under the
+# terms of the GNU General Public License as published by the Free Software
+# Foundation; either version 3, or (at your option) any later version.
+#
+# This is distributed in the hope that it will be useful, but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+# FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
+# details.
+#
+# You should have received a copy of the GNU General Public License along
+# with this program; if not, consult the Free Software Foundation's
+# website at www.fsf.org, or the GNU Project website at www.gnu.org.
+
 # python 3 only
 
 import socket
@@ -5,18 +26,28 @@ import subprocess
 import os
 import pwd
 import struct
+import tempfile
+import shutil
+import sys
 
 def _shuffle_fd3():
     os.dup2(1,3)
     os.dup2(2,1)
 
+class Error(Exception): pass
+
 class Donor():
-    def __init__(d, pid):
+    def __init__(d, pid, debug=None):
         d.pid = pid
+        if debug is None:
+            d._stderr = tempfile.TemporaryFile(mode='w+')
+        else:
+            d._stderr = None
         d._sp = subprocess.Popen(
             preexec_fn = _shuffle_fd3,
             stdin = subprocess.PIPE,
             stdout = subprocess.PIPE,
+            stderr = d._stderr,
             close_fds = False,
             args = ['gdb', '-p', str(pid), '-batch', '-ex',
                     'python import fishdescriptor.indonor as id;'+
@@ -25,12 +56,21 @@ class Donor():
         )            
 
     def _eval_integer(d, expr):
-        l = d._sp.stdout.readline()
-        if l != b'!\n': raise RuntimeError("indonor said %s" % repr(l))
-        d._sp.stdin.write(expr.encode('utf-8') + b'\n')
-        d._sp.stdin.flush()
-        l = d._sp.stdout.readline().rstrip(b'\n')
-        return int(l)
+        try:
+            l = d._sp.stdout.readline()
+            if not len(l): raise Error('gdb process donor python repl quit')
+            if l != b'!\n': raise RuntimeError("indonor said %s" % repr(l))
+            d._sp.stdin.write(expr.encode('utf-8') + b'\n')
+            d._sp.stdin.flush()
+            l = d._sp.stdout.readline().rstrip(b'\n')
+            return int(l)
+        except Exception as e:
+            if d._stderr is not None:
+                d._stderr.seek(0)
+                shutil.copyfileobj(d._stderr, sys.stderr)
+                d._stderr.seek(0)
+                d._stderr.truncate()
+            raise e
 
     def _eval_success(d, expr):
         r = d._eval_integer(expr)
@@ -114,6 +154,7 @@ class Donor():
 
             s = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
             s.bind(our_sockname)
+            os.chmod(our_sockname, 666)
             s.listen(1)
 
             ancil_len = d.donate(our_sockname, fds)