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1#!/bin/sh
2
3# Copyright 2015 The Chromium OS Authors. All rights reserved.
4# Use of this source code is governed by a BSD-style license that can be
5# found in the LICENSE file.
6
7# Generates a header file with a named constant table made up of "name", value
8# entries by including several build target header files and emitting the list
9# of defines.  Use of the preprocessor is needed to recursively include all
10# relevant headers.
11
12set -e
13
14if [ $# -ne 1 ] && [ $# -ne 2 ]; then
15  echo "Usage: $(basename "$0") OUTFILE"
16  echo "Usage: $(basename "$0") CC OUTFILE"
17  exit 1
18fi
19
20if [ $# -eq 2 ]; then
21  CC="$1"
22  shift
23fi
24OUTFILE="$1"
25
26INCLUDES='
27#include <errno.h>
28#include <fcntl.h>
29#include <linux/prctl.h>
30#include <linux/sched.h>
31#include <stddef.h>
32#include <signal.h>
33#include <sys/stat.h>
34#include <sys/types.h>'
35
36# Generate a dependency file which helps the build tool to see when it
37# should regenerate ${OUTFILE}.
38echo "${INCLUDES}" | ${CC} - -E -M -MF "${OUTFILE}.d.tmp"
39# Correct the output filename.
40(echo "${OUTFILE}: \\" ; sed -e 's/^-\.o://' -e 's/^-://' "${OUTFILE}.d.tmp") \
41  > "${OUTFILE}.d"
42rm "${OUTFILE}.d.tmp"
43
44# sed expression which extracts constants and converts them from:
45#   #define AT_FDWCD foo
46# to:
47# #ifdef AT_FDCWD
48#   { "AT_FDWCD", AT_FDCWD },
49# endif
50SED_MULTILINE='s@#define ([[:upper:]][[:upper:]0-9_]*).*@#ifdef \1\
51  { "\1", (unsigned long) \1 },\
52#endif  // \1@'
53
54# Passes the previous list of #includes to the C preprocessor and prints out
55# all #defines whose name is all-caps.  Excludes a few symbols that are known
56# macro functions that don't evaluate to a constant.
57cat <<-EOF > "${OUTFILE}"
58/* GENERATED BY MAKEFILE */
59$INCLUDES
60
61#include "libconstants.h"
62const struct constant_entry constant_table[] = {
63$(echo "$INCLUDES" | \
64  ${CC} -dD - -E | \
65  grep -E '^#define [[:upper:]][[:upper:]0-9_]*(\s)+[[:alnum:]]' | \
66  grep -Ev '(SIGRTMAX|SIGRTMIN|SIG_|NULL)' | \
67  sort -u | \
68  sed -Ee "${SED_MULTILINE}")
69  { NULL, 0 },
70};
71EOF
72