lint_hunks: show style violations in the index

Shows the subset of style violations that intersect with lines modified
in the current index.

Change-Id: I0b51674fd43df118e8bbf55b684a1ca0bd0e1d40

tools/lint-hunks.py

+#!/usr/bin/python
+##  Copyright (c) 2012 The WebM project authors. All Rights Reserved.
+##
+##  Use of this source code is governed by a BSD-style license
+##  that can be found in the LICENSE file in the root of the source
+##  tree. An additional intellectual property rights grant can be found
+##  in the file PATENTS.  All contributing project authors may
+##  be found in the AUTHORS file in the root of the source tree.
+##
+"""Performs style checking on each diff hunk."""
+import getopt
+import os
+import StringIO
+import subprocess
+import sys
+
+import diff
+
+
+SHORT_OPTIONS = "h"
+LONG_OPTIONS = ["help"]
+
+TOPLEVEL_CMD = ["git", "rev-parse", "--show-toplevel"]
+DIFF_CMD = ["git", "diff-index", "-u", "--cached", "HEAD", "--"]
+SHOW_CMD = ["git", "show"]
+CPPLINT_FILTERS = ["-readability/casting", "-runtime/int"]
+
+
+class Usage(Exception):
+    pass
+
+
+class SubprocessException(Exception):
+    def __init__(self, args):
+        msg = "Failed to execute '%s'"%(" ".join(args))
+        super(SubprocessException, self).__init__(msg)
+
+
+class Subprocess(subprocess.Popen):
+    """Adds the notion of an expected returncode to Popen."""
+
+    def __init__(self, args, expected_returncode=0, **kwargs):
+        self._args = args
+        self._expected_returncode = expected_returncode
+        super(Subprocess, self).__init__(args, **kwargs)
+
+    def communicate(self, *args, **kwargs):
+        result = super(Subprocess, self).communicate(*args, **kwargs)
+        if self._expected_returncode is not None:
+            try:
+                ok = self.returncode in self._expected_returncode
+            except TypeError:
+                ok = self.returncode == self._expected_returncode
+            if not ok:
+                raise SubprocessException(self._args)
+        return result
+
+
+def main(argv=None):
+    if argv is None:
+        argv = sys.argv
+    try:
+        try:
+            opts, _ = getopt.getopt(argv[1:], SHORT_OPTIONS, LONG_OPTIONS)
+        except getopt.error, msg:
+            raise Usage(msg)
+
+        # process options
+        for o, _ in opts:
+            if o in ("-h", "--help"):
+                print __doc__
+                sys.exit(0)
+
+        # Find the fully qualified path to the root of the tree
+        tl = Subprocess(TOPLEVEL_CMD, stdout=subprocess.PIPE)
+        tl = tl.communicate()[0].strip()
+
+        # Build the command line to execute cpplint
+        cpplint_cmd = [os.path.join(tl, "tools", "cpplint.py"),
+                       "--filter=" + ",".join(CPPLINT_FILTERS),
+                       "-"]
+
+        # Get a list of all affected lines
+        file_affected_line_map = {}
+        p = Subprocess(DIFF_CMD, stdout=subprocess.PIPE)
+        stdout = p.communicate()[0]
+        for hunk in diff.ParseDiffHunks(StringIO.StringIO(stdout)):
+            filename = hunk.right.filename[2:]
+            if filename not in file_affected_line_map:
+                file_affected_line_map[filename] = set()
+            file_affected_line_map[filename].update(hunk.right.delta_line_nums)
+
+        # Run each affected file through cpplint
+        lint_failed = False
+        for filename, affected_lines in file_affected_line_map.iteritems():
+            if filename.split(".")[-1] not in ("c", "h", "cc"):
+                continue
+            show_cmd = SHOW_CMD + [":" + filename]
+            show = Subprocess(show_cmd, stdout=subprocess.PIPE)
+            lint = Subprocess(cpplint_cmd, expected_returncode=(0, 1),
+                              stdin=show.stdout, stderr=subprocess.PIPE)
+            lint_out = lint.communicate()[1]
+            if lint.returncode == 1:
+                lint_failed = True
+
+            for line in lint_out.split("\n"):
+                fields = line.split(":")
+                if fields[0] != "-":
+                    continue
+                warning_line_num = int(fields[1])
+                if warning_line_num in affected_lines:
+                    print "%s:%d:%s"%(filename, warning_line_num,
+                                      ":".join(fields[2:]))
+
+        # Propagate lint's exit status
+        if lint_failed:
+            return 1
+
+    except Usage, err:
+        print >>sys.stderr, err
+        print >>sys.stderr, "for help use --help"
+        return 2
+
+if __name__ == "__main__":
+    sys.exit(main())