Linux platform refactoring (#264)

* Clean up model syscall invocation
* Move read_string to Cpu
* move push/pop helpers to Cpu
* Reorg Linux initialization
* Update linux test
* fstat64 test harness
* assert read_string only considers concrete bytes
* Ensure that correct aliases exist during ctor
* Improve alias check

tests/test_linux.py

@@ -1,6 +1,7 @@
+import os
 import unittest
 
-from manticore.platforms import linux
+from manticore.platforms import linux, linux_syscalls
 
 
 class LinuxTest(unittest.TestCase):
@@ -37,10 +38,10 @@ class LinuxTest(unittest.TestCase):
         envp_ptr = argv_ptr + len(real_argv)*8 + 8
 
         for i, arg in enumerate(real_argv):
-            self.assertEqual(self.linux._read_string(cpu.read_int(argv_ptr + i*8)), arg)
+            self.assertEqual(cpu.read_string(cpu.read_int(argv_ptr + i*8)), arg)
 
         for i, env in enumerate(envp):
-            self.assertEqual(self.linux._read_string(cpu.read_int(envp_ptr + i*8)), env)
+            self.assertEqual(cpu.read_string(cpu.read_int(envp_ptr + i*8)), env)
 
     def test_load_maps(self):
         mappings = self.linux.current.memory.mappings()
@@ -57,3 +58,25 @@ class LinuxTest(unittest.TestCase):
         self.assertEqual(first_map_name, '/bin/ls')
         self.assertEqual(second_map_name, '/bin/ls')
 
+    def test_syscall_fstat(self):
+        nr_fstat64 = 197
+
+        # Create a minimal state
+        model = linux.SLinux.empty_platform('armv7')
+        model.current.memory.mmap(0x1000, 0x1000, 'rw ')
+        model.current.SP = 0x2000-4
+
+        # open a file
+        filename = model.current.push_bytes('/bin/true\x00')
+        fd = model.sys_open(filename, os.O_RDONLY, 0600)
+
+        stat = model.current.SP - 0x100
+        model.current.R0 = fd
+        model.current.R1 = stat
+        model.current.R7 = nr_fstat64
+        self.assertEquals(linux_syscalls.armv7[nr_fstat64], 'sys_fstat64')
+
+        model.syscall()
+
+        print ''.join(model.current.read_bytes(stat, 100)).encode('hex')
+