[dpdk-dev] [PATCH v1 1/5] devtools: script to remove unused headers includes

[Sean Morrissey <sean.morrissey@intel.com>]

This script can be used for removing headers flagged for removal by the
include-what-you-use (IWYU) tool. The script has the ability to remove
headers from specified sub-directories or dpdk as a whole.

example usages:

Remove headers flagged by iwyu_tool output file
$ ./devtools/process_iwyu.py iwyu.out -b build

Remove headers flagged by iwyu_tool output file from sub-directory
$ ./devtools/process_iwyu.py iwyu.out -b build -d lib/kvargs

Remove headers directly piped from the iwyu_tool
$ iwyu_tool -p build | ./devtools/process_iwyu.py - -b build

Signed-off-by: Sean Morrissey <sean.morrissey@intel.com>
Signed-off-by: Conor Fogarty <conor.fogarty@intel.com>
---
 devtools/process_iwyu.py | 109 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 109 insertions(+)
 create mode 100755 devtools/process_iwyu.py

diff --git a/devtools/process_iwyu.py b/devtools/process_iwyu.py
new file mode 100755
index 0000000000..ddc4ceafa4
--- /dev/null
+++ b/devtools/process_iwyu.py
@@ -0,0 +1,109 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: BSD-3-Clause
+# Copyright(c) 2021 Intel Corporation
+#
+
+import argparse
+import fileinput
+import sys
+from os.path import abspath, relpath, join
+from pathlib import Path
+from mesonbuild import mesonmain
+
+def args_parse():
+    parser = argparse.ArgumentParser(description='This script can be used to remove includes which are not in use\n')
+    parser.add_argument('-b', '--build_dir', type=str, help='Name of the build directory in which the IWYU tool was used in.', default="build")
+    parser.add_argument('-d', '--sub_dir', type=str, help='The sub-directory to remove headers from.', default="")
+    parser.add_argument('file', type=Path, help='The path to the IWYU log file or output from stdin.')
+
+    args = parser.parse_args()
+
+    return args
+
+
+def run_meson(args):
+    "Runs a meson command logging output to process.log"
+    with open('process.log', 'a') as sys.stdout:
+        ret = mesonmain.run(args, abspath('meson'))
+    sys.stdout = sys.__stdout__
+    return ret
+
+
+def remove_includes(filename, include, dpdk_dir, build_dir):
+    # Load in file - readlines()
+    # loop through list once in mem -> make cpy of list with line removed
+    # write cpy  -> stored in memory so write cpy to file then check
+    # run test build -> call ninja on the build folder, ninja -C build, subprocess
+    # if fails -> write original back to file otherwise continue on
+    # newlist = [ln for ln in lines if not ln.startswith(...)] filters out one element
+    filepath = filename
+
+    with open(filepath, 'r+') as f:
+        lines = f.readlines()  # Read lines when file is opened
+
+    with open(filepath, 'w') as f:
+        for ln in lines:  # Removes the include passed in
+            if ln.strip("\n") != include:
+                f.write(ln)
+
+    ret = run_meson(['compile', '-C', join(dpdk_dir, build_dir)])
+    if (ret == 0):  # Include is not needed -> build is successful
+        print('SUCCESS')
+    else:
+        # failed, catch the error
+        # return file to original state
+        with open(filepath, 'w') as f:
+            f.writelines(lines)
+            print('FAILED')
+
+
+def get_build_config(builddir, condition):
+    "returns contents of rte_build_config.h"
+    with open(join(builddir, 'rte_build_config.h')) as f:
+        return [ln for ln in f.readlines() if condition(ln)]
+
+
+def uses_libbsd(builddir):
+    "return whether the build uses libbsd or not"
+    return bool(get_build_config(builddir, lambda ln: 'RTE_USE_LIBBSD' in ln))
+
+
+def process(args):
+    filename = None
+    build_dir = args.build_dir
+    dpdk_dir = abspath(__file__).split('/devtools')[0]
+    directory = args.sub_dir
+    # Use stdin if no iwyu_tool out file given
+    logfile = abspath(args.file) if str(args.file) != '-' else args.file
+
+    keep_str_fns = uses_libbsd(join(dpdk_dir, build_dir)) # check for libbsd
+    if keep_str_fns:
+        print('Warning: libbsd is present, build will fail to detect incorrect removal of rte_string_fns.h',
+              file=sys.stderr)
+    run_meson(['configure', dpdk_dir + "/" + build_dir, '-Dwerror=true'])  # turn on werror
+
+    for line in fileinput.input(logfile):
+        if 'should remove' in line:
+            # If the file path in the iwyu_tool output is an absolute path
+            # it means the file is outside of the dpdk directory, therefore ignore it
+            # Also check to see if the file is within the specified sub directory
+            if line.split()[0] != abspath(line.split()[0]) and directory in line.split()[0]:
+                filename = relpath(join(build_dir, line.split()[0]))
+        elif line.startswith('-') and filename:
+            include = '#include ' + line.split()[2]
+            print(f"Remove {include} from {filename} ... ", end='', flush=True)
+            if keep_str_fns and '<rte_string_fns.h>' in include:
+                print('skipped')
+                continue
+            remove_includes(filename, include, dpdk_dir, build_dir)
+        else:
+            filename = None
+
+
+def main():
+    args = args_parse()
+    process(args)
+
+
+if __name__ == '__main__':
+    main()
-- 
2.25.1