From a4365445d4d32001362f6e8bfae93a3b8f152fde Mon Sep 17 00:00:00 2001
From: jakob <jakob@memeware.net>
Date: Mon, 28 Aug 2017 14:32:57 -0400
Subject: Initial implementation of the ptrace wrapper

---
 .gitignore           |  1 +
 hypodermic/ptrace.py | 75 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 setup.py             |  2 +-
 wrapper/Makefile     | 12 +++++++++
 wrapper/ptrace.c     | 51 +++++++++++++++++++++++++++++++++++
 5 files changed, 140 insertions(+), 1 deletion(-)
 create mode 100644 hypodermic/ptrace.py
 create mode 100644 wrapper/Makefile
 create mode 100644 wrapper/ptrace.c

diff --git a/.gitignore b/.gitignore
index d77a563..e7ffb10 100644
--- a/.gitignore
+++ b/.gitignore
@@ -10,3 +10,4 @@ dist/
 *.egg-info
 *.pyc
 *.egg
+libptracew.so
diff --git a/hypodermic/ptrace.py b/hypodermic/ptrace.py
new file mode 100644
index 0000000..fdfe5b8
--- /dev/null
+++ b/hypodermic/ptrace.py
@@ -0,0 +1,75 @@
+# Copyright (C) 2017 Jakob Kreuze, All Rights Reserved.
+#
+# This file is part of Hypodermic.
+#
+# Hypodermic 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 of the License, or (at your
+# option) any later version.
+#
+# Hypodermic 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 Hypodermic. If not, see <http://www.gnu.org/licenses/>.
+
+"""Wrapper for the ptrace system call, since python-ptrace sucks."""
+
+import ctypes
+
+
+# TODO: Instantiate from binary path, as well.
+class Process(object):
+    """Process attached via ptrace.
+
+    Note:
+        The process is implicitly detached from upon destruction of this
+        object.
+
+    Args:
+        pid (int): The pid of the process to attach to.
+
+    Raises:
+        TypeError: If the pid argument is not an int.
+        OSError: If the pid cannot be attached to.
+    """
+
+    def __init__(self, pid: int):
+        if not isinstance(pid, int):
+            raise TypeError("pid argument must be an int")
+        self._load_ffi_methods()
+
+        if self._attach(ctypes.c_int(pid)):
+            raise OSError("Could not attach to pid {}".format(pid))
+        self.pid = pid
+
+    def __del__(self):
+        if hasattr(self, "pid"):
+            self.detach()
+
+    def _load_ffi_methods(self):
+        # FIXME: How are we going to deal with the path?
+        self._so = ctypes.cdll.LoadLibrary("/tmp/libptracew.so")
+        self._attach = self._so.attach
+        self._detach = self._so.detach
+        self._cont = self._so.cont
+
+    def detach(self):
+        """Explicitly detaches from the process.
+
+        Raises:
+            OSError: If the process cannot be detached from.
+        """
+        if self._detach(ctypes.c_int(self.pid)):
+            raise OSError("Could not detach from pid {}".format(self.pid))
+
+    def cont(self):
+        """Continues until the program is haulted.
+
+        Raises:
+            OSError: If the process cannot be continued.
+        """
+        if self._cont(ctypes.c_int(self.pid)):
+            raise OSError("Could not continue")
diff --git a/setup.py b/setup.py
index 82a2754..118ca85 100644
--- a/setup.py
+++ b/setup.py
@@ -26,7 +26,7 @@ setup(
     download_url="https://github.com/TsarFox/hypodermic",
     packages=["hypodermic"],
     include_package_data=True,
-    install_requires=["python-ptrace"],
+    install_requires=[],
     extras_require={},
     tests_require=[],
     entry_points={"console_scripts": ["hypodermic = hypodermic.main:main"]},
diff --git a/wrapper/Makefile b/wrapper/Makefile
new file mode 100644
index 0000000..1019833
--- /dev/null
+++ b/wrapper/Makefile
@@ -0,0 +1,12 @@
+CC := gcc
+
+CFLAGS = -Wall -Wextra -Os -std=c99 -pedantic -fstack-protector-all
+CFLAGS += $(USER_CFLAGS)
+
+LDFLAGS = -shared
+LDFLAGS += $(USER_LDFLAGS)
+
+all: libptracew.so
+
+libtestw.so: ptrace.c
+	$(CC) $(CFLAGS) $^ -o $@ $(LDFLAGS)
diff --git a/wrapper/ptrace.c b/wrapper/ptrace.c
new file mode 100644
index 0000000..3ce42a1
--- /dev/null
+++ b/wrapper/ptrace.c
@@ -0,0 +1,51 @@
+/* Copyright (C) 2017 Jakob Kreuze, All Rights Reserved.
+
+   This file is part of Hypodermic.
+
+   Hypodermic 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 of the License, or (at
+   your option) any later version.
+
+   Hypodermic 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 Hypodermic. If not, see <http://www.gnu.org/licenses/>. */
+
+#include <sys/ptrace.h>
+#include <sys/wait.h>
+
+#include <stddef.h>
+
+
+int attach(int pid) {
+    if ((ptrace(PTRACE_ATTACH, pid, NULL, NULL)) < 0) {
+        return -1;
+    }
+
+    waitpid(pid, NULL, WUNTRACED);
+    return 0;
+}
+
+
+int detach(int pid) {
+    return ptrace(PTRACE_DETACH, pid, NULL, NULL) < 0;
+}
+
+
+int cont(int pid) {
+    int s;
+
+    if ((ptrace(PTRACE_CONT, pid, NULL, NULL)) < 0) {
+        return -1;
+    }
+
+    while (!WIFSTOPPED(s)) {
+        waitpid(pid, &s, WNOHANG);
+    }
+
+    return 0;
+}
-- 
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