Refactor python shared snippets

.gitignore

@@ -32,3 +32,4 @@
 *.app
 
 dwarf-assembly
+__pycache__

compare_sizes.py

@@ -9,7 +9,7 @@ import os
 import subprocess
 from collections import namedtuple
 
-from generate_eh_elf import elf_so_deps
+from shared_python import elf_so_deps
 
 
 ''' An ELF object, including the path to the ELF itself, and the path to its
@@ -41,11 +41,11 @@ def section_size(elf_loc, section_name):
     except subprocess.CalledProcessError as exn:
         raise Exception(("Cannot obtain section {} size for {}: objdump "
                          "terminated with exit code {}.").format(
-                             section_name, elf_loc))
+                             section_name, elf_loc, exn.returncode))
 
     for line in objdump_out.split('\n'):
         line = line.strip()
-        if not line or not ('0' <= line[0] <= '9'):  # not a section line
+        if not line or not '0' <= line[0] <= '9':  # not a section line
             continue
 
         spl = line.split()

generate_eh_elf.py

@@ -9,10 +9,10 @@ all the shared objects it depends upon.
 import os
 import sys
 import subprocess
-import re
 import tempfile
 import argparse
-from collections import namedtuple
+
+from shared_python import elf_so_deps, do_remote, is_newer
 
 
 DWARF_ASSEMBLY_BIN = os.path.join(
@@ -23,33 +23,6 @@ C_BIN = (
     else os.environ['C'])
 
 
-def elf_so_deps(path):
-    ''' Get the list of shared objects dependencies of the given ELF object.
-    This is obtained by running `ldd`. '''
-
-    deps_list = []
-
-    try:
-        ldd_output = subprocess.check_output(['/usr/bin/ldd', path]) \
-            .decode('utf-8')
-        ldd_re = re.compile(r'^.* => (.*) \(0x[0-9a-fA-F]*\)$')
-
-        ldd_lines = ldd_output.strip().split('\n')
-        for line in ldd_lines:
-            line = line.strip()
-            match = ldd_re.match(line)
-            if match is None:
-                continue  # Just ignore that line — it might be eg. linux-vdso
-            deps_list.append(match.group(1))
-
-        return deps_list
-
-    except subprocess.CalledProcessError as e:
-        raise Exception(
-            ("Cannot get dependencies for {}: ldd terminated with exit code "
-             "{}.").format(path, e.returncode))
-
-
 def gen_dw_asm_c(obj_path, out_path, dwarf_assembly_args):
     ''' Generate the C code produced by dwarf-assembly from `obj_path`, saving
     it as `out_path` '''
@@ -61,66 +34,13 @@ def gen_dw_asm_c(obj_path, out_path, dwarf_assembly_args):
                 [DWARF_ASSEMBLY_BIN, obj_path] + dwarf_assembly_args) \
                 .decode('utf-8')
             out_handle.write(dw_asm_output)
-    except subprocess.CalledProcessError as e:
+    except subprocess.CalledProcessError as exn:
         raise Exception(
             ("Cannot generate C code from object file {} using {}: process "
              "terminated with exit code {}.").format(
                  obj_path,
                  DWARF_ASSEMBLY_BIN,
-                 e.returncode))
+                 exn.returncode))
-
-
-def do_remote(remote, command, send_files=None, retr_files=None):
-    def ssh_do(cmd_args, working_directory=None):
-        try:
-            cmd = ['ssh', remote]
-            if working_directory:
-                cmd += ['cd', working_directory, '&&']
-            cmd += cmd_args
-
-            return subprocess.check_output(cmd).decode('utf-8').strip()
-        except subprocess.CalledProcessError as e:
-            return None
-
-    def ssh_copy(what, where, is_upload):
-        if is_upload:
-            where = '{}:{}'.format(remote, where)
-        else:
-            what = '{}:{}'.format(remote, what)
-
-        subprocess.check_output(['scp', what, where])
-
-    TransferredFile = namedtuple('TransferredFile', 'local remote')
-
-    def interpret_transferred_file(descr):
-        if type(descr) == type(''):
-            return TransferredFile(descr, descr)
-        if os.path.isdir(descr[1]):
-            to = os.path.join(descr[1], descr[0])
-        else:
-            to = descr[1]
-        return TransferredFile(descr[0], to)
-
-    # Create temp dir
-    tmp_dir = ssh_do(['mktemp', '-d'])
-
-    # Upload `send_files`
-    for f in send_files:
-        dest = tmp_dir+'/'
-        ssh_copy(f, dest, is_upload=True)
-
-    # Do whatever must be done
-    output = ssh_do(command, working_directory=tmp_dir)
-
-    # Download `retr_files`
-    for f in map(interpret_transferred_file, retr_files):
-        src = os.path.join(tmp_dir, f.local)
-        ssh_copy(src, f.remote, is_upload=False)
-
-    # Remove temp dir
-    ssh_do(['rm', '-rf', tmp_dir])
-
-    return output
 
 
 def gen_eh_elf(obj_path, args, dwarf_assembly_args=None):
@@ -141,15 +61,8 @@ def gen_eh_elf(obj_path, args, dwarf_assembly_args=None):
     out_base_name = os.path.basename(obj_path) + '.eh_elf'
     out_so_path = os.path.join(out_dir, (out_base_name + '.so'))
 
-    try:
+    if is_newer(out_so_path, obj_path):
-        so_mtime = os.path.getmtime(out_so_path)
+        return  # The object is recent enough, no need to recreate it
-        obj_mtime = os.path.getmtime(obj_path)
-
-        if obj_mtime < so_mtime:
-            return  # The object is recent enough, no need to recreate it
-    except OSError:
-        pass
-
 
     with tempfile.TemporaryDirectory() as compile_dir:
         # Generate the C source file

shared_python.py

@@ -0,0 +1,116 @@
+""" Shared snippets between the various python scripts of this project """
+
+import subprocess
+import re
+import os
+from collections import namedtuple
+
+
+def is_newer(file1, file2):
+    ''' Returns True iff file1 is newer than file2 '''
+    try:
+        f1_mtime = os.path.getmtime(file1)
+        f2_mtime = os.path.getmtime(file2)
+
+        if f1_mtime > f2_mtime:
+            return True
+    except OSError:
+        pass
+
+    return False
+
+
+def elf_so_deps(path):
+    ''' Get the list of shared objects dependencies of the given ELF object.
+    This is obtained by running `ldd`. '''
+
+    deps_list = []
+
+    try:
+        ldd_output = subprocess.check_output(['/usr/bin/ldd', path]) \
+            .decode('utf-8')
+        ldd_re = re.compile(r'^.* => (.*) \(0x[0-9a-fA-F]*\)$')
+
+        ldd_lines = ldd_output.strip().split('\n')
+        for line in ldd_lines:
+            line = line.strip()
+            match = ldd_re.match(line)
+            if match is None:
+                continue  # Just ignore that line — it might be eg. linux-vdso
+            deps_list.append(match.group(1))
+
+        return deps_list
+
+    except subprocess.CalledProcessError as exn:
+        raise Exception(
+            ("Cannot get dependencies for {}: ldd terminated with exit code "
+             "{}.").format(path, exn.returncode))
+
+
+def do_remote(remote, command, send_files=None, retr_files=None):
+    ''' Execute remotely (via ssh) a given command
+
+    The command is executed on the machine described by `remote` (see ssh(1)).
+
+    send_files is a list of file paths that must be first copied at the root of
+    a temporary directory on `remote` before running the command. Consider
+    yourself jailed in that directory.
+
+    retr_files is a list of files that will be copied to the local machine
+    after the command is executed. Each list item can either be a string, which
+    is both the path on the remote and the local machine; or a pair
+    `(file_name, local_path)`. In the latter case, `file_name` is copied as
+    `local_path/file_name` if `local_path` is a directory, or as `local_path`
+    otherwise, on the local machine.
+    '''
+
+    def ssh_do(cmd_args, working_directory=None):
+        try:
+            cmd = ['ssh', remote]
+            if working_directory:
+                cmd += ['cd', working_directory, '&&']
+            cmd += cmd_args
+
+            return subprocess.check_output(cmd).decode('utf-8').strip()
+        except subprocess.CalledProcessError as e:
+            return None
+
+    def ssh_copy(what, where, is_upload):
+        if is_upload:
+            where = '{}:{}'.format(remote, where)
+        else:
+            what = '{}:{}'.format(remote, what)
+
+        subprocess.check_output(['scp', what, where])
+
+    TransferredFile = namedtuple('TransferredFile', 'local remote')
+
+    def interpret_transferred_file(descr):
+        if isinstance(descr, type('')):
+            return TransferredFile(descr, descr)
+        if os.path.isdir(descr[1]):
+            to = os.path.join(descr[1], descr[0])
+        else:
+            to = descr[1]
+        return TransferredFile(descr[0], to)
+
+    # Create temp dir
+    tmp_dir = ssh_do(['mktemp', '-d'])
+
+    # Upload `send_files`
+    for f in send_files:
+        dest = tmp_dir+'/'
+        ssh_copy(f, dest, is_upload=True)
+
+    # Do whatever must be done
+    output = ssh_do(command, working_directory=tmp_dir)
+
+    # Download `retr_files`
+    for f in map(interpret_transferred_file, retr_files):
+        src = os.path.join(tmp_dir, f.local)
+        ssh_copy(src, f.remote, is_upload=False)
+
+    # Remove temp dir
+    ssh_do(['rm', '-rf', tmp_dir])
+
+    return output