Support asm/disasm on Windows (#2437)

* Support asm/disasm on Windows

Find binutils toolchains like https://gnutoolchains.com/ if they exist in the PATH.

* Update CHANGELOG

* Update binutils install docs

* cpp reads from stdin when no infile is given

No need for a tempfile here.

CHANGELOG.md

@@ -90,6 +90,7 @@ The table below shows which release corresponds to each branch, and what date th
 - [#2427][2427] Document behaviour of remote()'s sni argument as string.
 - [#2382][2382] added optional port, gdb_args and gdbserver_args parameters to gdb.debug()
 - [#2435][2435] Speed up gdbserver handshake in gdb.debug()
+- [#2437][2437] Support asm/disasm on Windows
 
 [2371]: https://github.com/Gallopsled/pwntools/pull/2371
 [2360]: https://github.com/Gallopsled/pwntools/pull/2360
@@ -109,6 +110,7 @@ The table below shows which release corresponds to each branch, and what date th
 [2427]: https://github.com/Gallopsled/pwntools/pull/2405
 [2382]: https://github.com/Gallopsled/pwntools/pull/2382
 [2435]: https://github.com/Gallopsled/pwntools/pull/2435
+[2437]: https://github.com/Gallopsled/pwntools/pull/2437
 
 ## 4.13.0 (`beta`)
 

docs/source/install/binutils.rst

@@ -42,6 +42,12 @@ repo <https://github.com/Gallopsled/pwntools-binutils/>`__.
     $ wget https://raw.githubusercontent.com/Gallopsled/pwntools-binutils/master/macos/binutils-$ARCH.rb
     $ brew install ./binutils-$ARCH.rb
 
+Windows
+^^^^^^^^^^^^^^^^
+
+Windows support is experimental. You can try installing a prebuilt version of binutils
+for your desired architecture from the `GNU Toolchains <https://gnutoolchains.com/>`__ project.
+
 Alternate OSes
 ^^^^^^^^^^^^^^^^
 

pwnlib/asm.py

@@ -206,6 +206,9 @@ def which_binutils(util, check_version=False):
     if platform.system() == 'Darwin':
         utils = ['g'+util, util]
 
+    if platform.system() == 'Windows':
+        utils = [util + '.exe']
+
     for arch in arches:
         for gutil in utils:
             # e.g. objdump
@@ -220,7 +223,7 @@ def which_binutils(util, check_version=False):
                             '%s-%s' % (arch, gutil)]
 
             for pattern in patterns:
-                for dir in environ['PATH'].split(':'):
+                for dir in environ['PATH'].split(os.pathsep):
                     for res in sorted(glob(path.join(dir, pattern))):
                         if check_version:
                             ver = check_binutils_version(res)
@@ -457,15 +460,19 @@ def cpp(shellcode):
         >>> cpp("SYS_setresuid", os = "freebsd")
         '311\n'
     """
+    if platform.system() == 'Windows':
+        cpp = which_binutils('cpp')
+    else:
+        cpp = 'cpp'
+
     code = _include_header() + shellcode
     cmd  = [
-        'cpp',
+        cpp,
         '-C',
         '-nostdinc',
         '-undef',
         '-P',
         '-I' + _incdir,
-        '/dev/stdin'
     ]
     return _run(cmd, code).strip('\n').rstrip() + '\n'