support/scripts/check-package: new script

Create the infra to check the style of new packages before submitting.
The overall function of the script is described inside a txt file.
It is designed to process the actual files and NOT the patch files
generated by git format-patch.

Also add the first check function, to warn if a file (Config.*, *.mk,
*.hash, *.patch) has no newline at the last line of the file, see [1].

Basic usage for simple packages:
support/scripts/check-package -vvv package/newpackage/*

Basic usage for packages with subdirs:
support/scripts/check-package -vvv $(find package/newpackage/ -type f)

See "checkpackage" in [2].

[1] http://patchwork.ozlabs.org/patch/631129/
[2] http://elinux.org/Buildroot#Todo_list

Signed-off-by: Ricardo Martincoski <ricardo.martincoski@gmail.com>
Cc: Thomas De Schampheleire <patrickdepinguin@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

DEVELOPERS

@@ -1312,6 +1312,9 @@ F:	package/atop/
 N:	Rhys Williams <github@wilberforce.co.nz>
 F:	package/lirc-tools/
 
+N:	Ricardo Martincoski <ricardo.martincoski@gmail.com>
+F:	support/scripts/check*package*
+
 N:	Richard Braun <rbraun@sceen.net>
 F:	package/curlftpfs/
 F:	package/tzdata/

support/scripts/check-package

@@ -0,0 +1,144 @@
+#!/usr/bin/env python
+# See support/scripts/check-package.txt before editing this file.
+
+from __future__ import print_function
+import argparse
+import inspect
+import re
+import sys
+
+import checkpackagelib_config
+import checkpackagelib_hash
+import checkpackagelib_mk
+import checkpackagelib_patch
+
+VERBOSE_LEVEL_TO_SHOW_IGNORED_FILES = 3
+flags = None  # Command line arguments.
+
+
+def parse_args():
+    parser = argparse.ArgumentParser()
+
+    # Do not use argparse.FileType("r") here because only files with known
+    # format will be open based on the filename.
+    parser.add_argument("files", metavar="F", type=str, nargs="*",
+                        help="list of files")
+
+    parser.add_argument("--manual-url", action="store",
+                        default="http://nightly.buildroot.org/",
+                        help="default: %(default)s")
+    parser.add_argument("--verbose", "-v", action="count", default=0)
+
+    # Now the debug options in the order they are processed.
+    parser.add_argument("--include-only", dest="include_list", action="append",
+                        help="run only the specified functions (debug)")
+    parser.add_argument("--exclude", dest="exclude_list", action="append",
+                        help="do not run the specified functions (debug)")
+    parser.add_argument("--dry-run", action="store_true", help="print the "
+                        "functions that would be called for each file (debug)")
+
+    return parser.parse_args()
+
+
+CONFIG_IN_FILENAME = re.compile("/Config\.\S*$")
+FILE_IS_FROM_A_PACKAGE = re.compile("package/[^/]*/")
+
+
+def get_lib_from_filename(fname):
+    if FILE_IS_FROM_A_PACKAGE.search(fname) is None:
+        return None
+    if CONFIG_IN_FILENAME.search(fname):
+        return checkpackagelib_config
+    if fname.endswith(".hash"):
+        return checkpackagelib_hash
+    if fname.endswith(".mk"):
+        return checkpackagelib_mk
+    if fname.endswith(".patch"):
+        return checkpackagelib_patch
+    return None
+
+
+def is_a_check_function(m):
+    if not inspect.isclass(m):
+        return False
+    # do not call the base class
+    if m.__name__.startswith("_"):
+        return False
+    if flags.include_list and m.__name__ not in flags.include_list:
+        return False
+    if flags.exclude_list and m.__name__ in flags.exclude_list:
+        return False
+    return True
+
+
+def print_warnings(warnings):
+    # Avoid the need to use 'return []' at the end of every check function.
+    if warnings is None:
+        return 0  # No warning generated.
+
+    for level, message in enumerate(warnings):
+        if flags.verbose >= level:
+            print(message.replace("\t", "< tab  >").rstrip())
+    return 1  # One more warning to count.
+
+
+def check_file_using_lib(fname):
+    # Count number of warnings generated and lines processed.
+    nwarnings = 0
+    nlines = 0
+
+    lib = get_lib_from_filename(fname)
+    if not lib:
+        if flags.verbose >= VERBOSE_LEVEL_TO_SHOW_IGNORED_FILES:
+            print("{}: ignored".format(fname))
+        return nwarnings, nlines
+    classes = inspect.getmembers(lib, is_a_check_function)
+
+    if flags.dry_run:
+        functions_to_run = [c[0] for c in classes]
+        print("{}: would run: {}".format(fname, functions_to_run))
+        return nwarnings, nlines
+
+    objects = [c[1](fname, flags.manual_url) for c in classes]
+
+    for cf in objects:
+        nwarnings += print_warnings(cf.before())
+    for lineno, text in enumerate(open(fname, "r").readlines()):
+        nlines += 1
+        for cf in objects:
+            nwarnings += print_warnings(cf.check_line(lineno + 1, text))
+    for cf in objects:
+        nwarnings += print_warnings(cf.after())
+
+    return nwarnings, nlines
+
+
+def __main__():
+    global flags
+    flags = parse_args()
+
+    if len(flags.files) == 0:
+        print("No files to check style")
+        sys.exit(1)
+
+    # Accumulate number of warnings generated and lines processed.
+    total_warnings = 0
+    total_lines = 0
+
+    for fname in flags.files:
+        nwarnings, nlines = check_file_using_lib(fname)
+        total_warnings += nwarnings
+        total_lines += nlines
+
+    # The warning messages are printed to stdout and can be post-processed
+    # (e.g. counted by 'wc'), so for stats use stderr. Wait all warnings are
+    # printed, for the case there are many of them, before printing stats.
+    sys.stdout.flush()
+    print("{} lines processed".format(total_lines), file=sys.stderr)
+    print("{} warnings generated".format(total_warnings), file=sys.stderr)
+
+    if total_warnings > 0:
+        sys.exit(1)
+
+
+__main__()

support/scripts/check-package.txt

@@ -0,0 +1,76 @@
+How the scripts are structured:
+- check-package is the main engine, called by the user.
+  For each input file, this script decides which parser should be used and it
+  collects all classes declared in the library file and instantiates them.
+  The main engine opens the input files and it serves each raw line (including
+  newline!) to the method check_line() of every check object.
+  Two special methods before() and after() are used to call the initialization
+  of variables (for the case it needs to keep data across calls) and the
+  equivalent finalization (e.g. for the case a warning must be issued if some
+  pattern is not in the input file).
+- checkpackagebase.py contains the base class for all check functions.
+- checkpackagelib.py contains the classes for common check functions.
+  Each check function is explicitly included in a given type-parsing library.
+  Do not include every single check function in this file, a class that will
+  only parse hash files should be implemented in the hash-parsing library.
+  When a warning must be issued, the check function returns an array of strings.
+  Each string is a warning message and is displayed if the corresponding verbose
+  level is active. When the script is called without --verbose only the first
+  warning in the returned array is printed; when called with --verbose both
+  first and second warnings are printed; when called with -vv until the third
+  warning is printed; an so on.
+  Helper functions can be defined and will not be called by the main script.
+- checkpackagelib_type.py contains check functions specific to files of this
+  type.
+
+Some hints when changing this code:
+- prefer O(n) algorithms, where n is the total number of lines in the files
+  processed.
+- when there is no other reason for ordering, use alphabetical order (e.g. keep
+  the check functions in alphabetical order, keep the imports in alphabetical
+  order, and so on).
+- use pyflakes to detect and fix potential problems.
+- use pep8 formatting.
+- keep in mind that for every class the method before() will be called before
+  any line is served to be checked by the method check_line(). A class that
+  checks the filename should only implement the method before(). A function that
+  needs to keep data across calls (e.g. keep the last line before the one being
+  processed) should initialize all variables using this method.
+- keep in mind that for every class the method after() will be called after all
+  lines were served to be checked by the method check_line(). A class that
+  checks the absence of a pattern in the file will need to use this method.
+- try to avoid false warnings. It's better to not issue a warning message to a
+  corner case than have too many false warnings. The second can make users stop
+  using the script.
+- do not check spacing in the input line in every single function. Trailing
+  whitespace and wrong indentation should be checked by separate functions.
+- avoid duplicate tests. Try to test only one thing in each function.
+- in the warning message, include the url to a section from the manual, when
+  applicable. It potentially will make more people know the manual.
+- use short sentences in the warning messages. A complete explanation can be
+  added to show when --verbose is used.
+- when testing, verify the error message is displayed when the error pattern is
+  found, but also verify the error message is not displayed for few
+  well-formatted packages... there are many of these, just pick your favorite
+  as golden package that should not trigger any warning message.
+- check the url displayed by the warning message works.
+
+Usage examples:
+- to get a list of check functions that would be called without actually
+  calling them you can use the --dry-run option:
+$ support/scripts/check-package --dry-run package/yourfavorite/*
+
+- when you just added a new check function, e.g. Something, check how it behaves
+  for all current packages:
+$ support/scripts/check-package --include-only Something $(find package -type f)
+
+- the effective processing time (when the .pyc were already generated and all
+  files to be processed are cached in the RAM) should stay in the order of few
+  seconds:
+$ support/scripts/check-package $(find package -type f) >/dev/null ; \
+  time support/scripts/check-package $(find package -type f) >/dev/null
+
+- vim users can navigate the warnings (most editors probably have similar
+  function) since warnings are generated in the form 'path/file:line: warning':
+$ find package/ -name 'Config.*' > filelist && vim -c \
+  'set makeprg=support/scripts/check-package\ $(cat\ filelist)' -c make -c copen

support/scripts/checkpackagebase.py

@@ -0,0 +1,16 @@
+# See support/scripts/check-package.txt before editing this file.
+
+
+class _CheckFunction(object):
+    def __init__(self, filename, url_to_manual):
+        self.filename = filename
+        self.url_to_manual = url_to_manual
+
+    def before(self):
+        pass
+
+    def check_line(self, lineno, text):
+        pass
+
+    def after(self):
+        pass

support/scripts/checkpackagelib.py

@@ -0,0 +1,19 @@
+# See support/scripts/check-package.txt before editing this file.
+
+from checkpackagebase import _CheckFunction
+
+
+class NewlineAtEof(_CheckFunction):
+    def before(self):
+        self.lastlineno = 0
+        self.lastline = "\n"
+
+    def check_line(self, lineno, text):
+        self.lastlineno = lineno
+        self.lastline = text
+
+    def after(self):
+        if self.lastline == self.lastline.rstrip("\r\n"):
+            return ["{}:{}: missing newline at end of file"
+                    .format(self.filename, self.lastlineno),
+                    self.lastline]

support/scripts/checkpackagelib_config.py

@@ -0,0 +1,7 @@
+# See support/scripts/check-package.txt before editing this file.
+# Kconfig generates errors if someone introduces a typo like "boool" instead of
+# "bool", so below check functions don't need to check for things already
+# checked by running "make menuconfig".
+
+# Notice: ignore 'imported but unused' from pyflakes for check functions.
+from checkpackagelib import NewlineAtEof

support/scripts/checkpackagelib_hash.py

@@ -0,0 +1,7 @@
+# See support/scripts/check-package.txt before editing this file.
+# The validity of the hashes itself is checked when building, so below check
+# functions don't need to check for things already checked by running
+# "make package-dirclean package-source".
+
+# Notice: ignore 'imported but unused' from pyflakes for check functions.
+from checkpackagelib import NewlineAtEof

support/scripts/checkpackagelib_mk.py

@@ -0,0 +1,8 @@
+# See support/scripts/check-package.txt before editing this file.
+# There are already dependency checks during the build, so below check
+# functions don't need to check for things already checked by exploring the
+# menu options using "make menuconfig" and by running "make" with appropriate
+# packages enabled.
+
+# Notice: ignore 'imported but unused' from pyflakes for check functions.
+from checkpackagelib import NewlineAtEof

support/scripts/checkpackagelib_patch.py

@@ -0,0 +1,7 @@
+# See support/scripts/check-package.txt before editing this file.
+# The format of the patch files is tested during the build, so below check
+# functions don't need to check for things already checked by running
+# "make package-dirclean package-patch".
+
+# Notice: ignore 'imported but unused' from pyflakes for check functions.
+from checkpackagelib import NewlineAtEof