Increase L2ARC write rate and headroom

[zfs.git] / scripts / cstyle.pl

#!/usr/bin/env perl
#
# CDDL HEADER START
#
# The contents of this file are subject to the terms of the
# Common Development and Distribution License (the "License").
# You may not use this file except in compliance with the License.
#
# You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
# or https://opensource.org/licenses/CDDL-1.0.
# See the License for the specific language governing permissions
# and limitations under the License.
#
# When distributing Covered Code, include this CDDL HEADER in each
# file and include the License file at usr/src/OPENSOLARIS.LICENSE.
# If applicable, add the following below this CDDL HEADER, with the
# fields enclosed by brackets "[]" replaced with your own identifying
# information: Portions Copyright [yyyy] [name of copyright owner]
#
# CDDL HEADER END
#
# Copyright 2016 Nexenta Systems, Inc.
#
# Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
# Use is subject to license terms.
#
# @(#)cstyle 1.58 98/09/09 (from shannon)
#ident  "%Z%%M% %I%     %E% SMI"
#
# cstyle - check for some common stylistic errors.
#
#       cstyle is a sort of "lint" for C coding style.
#       It attempts to check for the style used in the
#       kernel, sometimes known as "Bill Joy Normal Form".
#
#       There's a lot this can't check for, like proper indentation
#       of code blocks.  There's also a lot more this could check for.
#
#       A note to the non perl literate:
#
#               perl regular expressions are pretty much like egrep
#               regular expressions, with the following special symbols
#
#               \s      any space character
#               \S      any non-space character
#               \w      any "word" character [a-zA-Z0-9_]
#               \W      any non-word character
#               \d      a digit [0-9]
#               \D      a non-digit
#               \b      word boundary (between \w and \W)
#               \B      non-word boundary
#

require 5.0;
use warnings;
use IO::File;
use Getopt::Std;
use strict;

my $usage =
"usage: cstyle [-cgpvP] file...
        -c      check continuation indentation inside functions
        -g      print github actions' workflow commands
        -p      perform some of the more picky checks
        -v      verbose
        -P      check for use of non-POSIX types
";

my %opts;

if (!getopts("cghpvCP", \%opts)) {
        print $usage;
        exit 2;
}

my $check_continuation = $opts{'c'};
my $github_workflow = $opts{'g'} || $ENV{'CI'};
my $picky = $opts{'p'};
my $verbose = $opts{'v'};
my $check_posix_types = $opts{'P'};

my ($filename, $line, $prev);           # shared globals

my $fmt;
my $hdr_comment_start;

if ($verbose) {
        $fmt = "%s: %d: %s\n%s\n";
} else {
        $fmt = "%s: %d: %s\n";
}

$hdr_comment_start = qr/^\s*\/\*$/;

# Note, following must be in single quotes so that \s and \w work right.
my $typename = '(int|char|short|long|unsigned|float|double' .
    '|\w+_t|struct\s+\w+|union\s+\w+|FILE)';

# mapping of old types to POSIX compatible types
my %old2posix = (
        'unchar' => 'uchar_t',
        'ushort' => 'ushort_t',
        'uint' => 'uint_t',
        'ulong' => 'ulong_t',
        'u_int' => 'uint_t',
        'u_short' => 'ushort_t',
        'u_long' => 'ulong_t',
        'u_char' => 'uchar_t',
        'quad' => 'quad_t'
);

my $lint_re = qr/\/\*(?:
        NOTREACHED|LINTLIBRARY|VARARGS[0-9]*|
        CONSTCOND|CONSTANTCOND|CONSTANTCONDITION|EMPTY|
        FALLTHRU|FALLTHROUGH|LINTED.*?|PRINTFLIKE[0-9]*|
        PROTOLIB[0-9]*|SCANFLIKE[0-9]*|CSTYLED.*?
    )\*\//x;

my $warlock_re = qr/\/\*\s*(?:
        VARIABLES\ PROTECTED\ BY|
        MEMBERS\ PROTECTED\ BY|
        ALL\ MEMBERS\ PROTECTED\ BY|
        READ-ONLY\ VARIABLES:|
        READ-ONLY\ MEMBERS:|
        VARIABLES\ READABLE\ WITHOUT\ LOCK:|
        MEMBERS\ READABLE\ WITHOUT\ LOCK:|
        LOCKS\ COVERED\ BY|
        LOCK\ UNNEEDED\ BECAUSE|
        LOCK\ NEEDED:|
        LOCK\ HELD\ ON\ ENTRY:|
        READ\ LOCK\ HELD\ ON\ ENTRY:|
        WRITE\ LOCK\ HELD\ ON\ ENTRY:|
        LOCK\ ACQUIRED\ AS\ SIDE\ EFFECT:|
        READ\ LOCK\ ACQUIRED\ AS\ SIDE\ EFFECT:|
        WRITE\ LOCK\ ACQUIRED\ AS\ SIDE\ EFFECT:|
        LOCK\ RELEASED\ AS\ SIDE\ EFFECT:|
        LOCK\ UPGRADED\ AS\ SIDE\ EFFECT:|
        LOCK\ DOWNGRADED\ AS\ SIDE\ EFFECT:|
        FUNCTIONS\ CALLED\ THROUGH\ POINTER|
        FUNCTIONS\ CALLED\ THROUGH\ MEMBER|
        LOCK\ ORDER:
    )/x;

my $err_stat = 0;               # exit status

if ($#ARGV >= 0) {
        foreach my $arg (@ARGV) {
                my $fh = new IO::File $arg, "r";
                if (!defined($fh)) {
                        printf "%s: can not open\n", $arg;
                } else {
                        &cstyle($arg, $fh);
                        close $fh;
                }
        }
} else {
        &cstyle("<stdin>", *STDIN);
}
exit $err_stat;

my $no_errs = 0;                # set for CSTYLED-protected lines

sub err($) {
        my ($error) = @_;
        unless ($no_errs) {
                if ($verbose) {
                        printf $fmt, $filename, $., $error, $line;
                } else {
                        printf $fmt, $filename, $., $error;
                }
                if ($github_workflow) {
                        printf "::error file=%s,line=%s::%s\n", $filename, $., $error;
                }
                $err_stat = 1;
        }
}

sub err_prefix($$) {
        my ($prevline, $error) = @_;
        my $out = $prevline."\n".$line;
        unless ($no_errs) {
                if ($verbose) {
                        printf $fmt, $filename, $., $error, $out;
                } else {
                        printf $fmt, $filename, $., $error;
                }
                $err_stat = 1;
        }
}

sub err_prev($) {
        my ($error) = @_;
        unless ($no_errs) {
                if ($verbose) {
                        printf $fmt, $filename, $. - 1, $error, $prev;
                } else {
                        printf $fmt, $filename, $. - 1, $error;
                }
                $err_stat = 1;
        }
}

sub cstyle($$) {

my ($fn, $filehandle) = @_;
$filename = $fn;                        # share it globally

my $in_cpp = 0;
my $next_in_cpp = 0;

my $in_comment = 0;
my $comment_done = 0;
my $in_warlock_comment = 0;
my $in_function = 0;
my $in_function_header = 0;
my $function_header_full_indent = 0;
my $in_declaration = 0;
my $note_level = 0;
my $nextok = 0;
my $nocheck = 0;

my $in_string = 0;

my ($okmsg, $comment_prefix);

$line = '';
$prev = '';
reset_indent();

line: while (<$filehandle>) {
        s/\r?\n$//;     # strip return and newline

        # save the original line, then remove all text from within
        # double or single quotes, we do not want to check such text.

        $line = $_;

        #
        # C allows strings to be continued with a backslash at the end of
        # the line.  We translate that into a quoted string on the previous
        # line followed by an initial quote on the next line.
        #
        # (we assume that no-one will use backslash-continuation with character
        # constants)
        #
        $_ = '"' . $_           if ($in_string && !$nocheck && !$in_comment);

        #
        # normal strings and characters
        #
        s/'([^\\']|\\[^xX0]|\\0[0-9]*|\\[xX][0-9a-fA-F]*)'/''/g;
        s/"([^\\"]|\\.)*"/\"\"/g;

        #
        # detect string continuation
        #
        if ($nocheck || $in_comment) {
                $in_string = 0;
        } else {
                #
                # Now that all full strings are replaced with "", we check
                # for unfinished strings continuing onto the next line.
                #
                $in_string =
                    (s/([^"](?:"")*)"([^\\"]|\\.)*\\$/$1""/ ||
                    s/^("")*"([^\\"]|\\.)*\\$/""/);
        }

        #
        # figure out if we are in a cpp directive
        #
        $in_cpp = $next_in_cpp || /^\s*#/;      # continued or started
        $next_in_cpp = $in_cpp && /\\$/;        # only if continued

        # strip off trailing backslashes, which appear in long macros
        s/\s*\\$//;

        # an /* END CSTYLED */ comment ends a no-check block.
        if ($nocheck) {
                if (/\/\* *END *CSTYLED *\*\//) {
                        $nocheck = 0;
                } else {
                        reset_indent();
                        next line;
                }
        }

        # a /*CSTYLED*/ comment indicates that the next line is ok.
        if ($nextok) {
                if ($okmsg) {
                        err($okmsg);
                }
                $nextok = 0;
                $okmsg = 0;
                if (/\/\* *CSTYLED.*\*\//) {
                        /^.*\/\* *CSTYLED *(.*) *\*\/.*$/;
                        $okmsg = $1;
                        $nextok = 1;
                }
                $no_errs = 1;
        } elsif ($no_errs) {
                $no_errs = 0;
        }

        # check length of line.
        # first, a quick check to see if there is any chance of being too long.
        if (($line =~ tr/\t/\t/) * 7 + length($line) > 80) {
                # yes, there is a chance.
                # replace tabs with spaces and check again.
                my $eline = $line;
                1 while $eline =~
                    s/\t+/' ' x (length($&) * 8 - length($`) % 8)/e;
                if (length($eline) > 80) {
                        err("line > 80 characters");
                }
        }

        # ignore NOTE(...) annotations (assumes NOTE is on lines by itself).
        if ($note_level || /\b_?NOTE\s*\(/) { # if in NOTE or this is NOTE
                s/[^()]//g;                       # eliminate all non-parens
                $note_level += s/\(//g - length;  # update paren nest level
                next;
        }

        # a /* BEGIN CSTYLED */ comment starts a no-check block.
        if (/\/\* *BEGIN *CSTYLED *\*\//) {
                $nocheck = 1;
        }

        # a /*CSTYLED*/ comment indicates that the next line is ok.
        if (/\/\* *CSTYLED.*\*\//) {
                /^.*\/\* *CSTYLED *(.*) *\*\/.*$/;
                $okmsg = $1;
                $nextok = 1;
        }
        if (/\/\/ *CSTYLED/) {
                /^.*\/\/ *CSTYLED *(.*)$/;
                $okmsg = $1;
                $nextok = 1;
        }

        # universal checks; apply to everything
        if (/\t +\t/) {
                err("spaces between tabs");
        }
        if (/ \t+ /) {
                err("tabs between spaces");
        }
        if (/\s$/) {
                err("space or tab at end of line");
        }
        if (/[^ \t(]\/\*/ && !/\w\(\/\*.*\*\/\);/) {
                err("comment preceded by non-blank");
        }
        if (/ARGSUSED/) {
                err("ARGSUSED directive");
        }

        # is this the beginning or ending of a function?
        # (not if "struct foo\n{\n")
        if (/^\{$/ && $prev =~ /\)\s*(const\s*)?(\/\*.*\*\/\s*)?\\?$/) {
                $in_function = 1;
                $in_declaration = 1;
                $in_function_header = 0;
                $function_header_full_indent = 0;
                $prev = $line;
                next line;
        }
        if (/^\}\s*(\/\*.*\*\/\s*)*$/) {
                if ($prev =~ /^\s*return\s*;/) {
                        err_prev("unneeded return at end of function");
                }
                $in_function = 0;
                reset_indent();         # we don't check between functions
                $prev = $line;
                next line;
        }
        if ($in_function_header && ! /^    (\w|\.)/ ) {
                if (/^\{\}$/ # empty functions
                || /;/ #run function with multiline arguments
                || /#/ #preprocessor commands
                || /^[^\s\\]*\(.*\)$/ #functions without ; at the end
                || /^$/ #function declaration can't have empty line
                ) {
                        $in_function_header = 0;
                        $function_header_full_indent = 0;
                } elsif ($prev =~ /^__attribute__/) { #__attribute__((*))
                        $in_function_header = 0;
                        $function_header_full_indent = 0;
                        $prev = $line;
                        next line;
                } elsif ($picky && ! (/^\t/ && $function_header_full_indent != 0)) {

                        err("continuation line should be indented by 4 spaces");
                }
        }

        #
        # If this matches something of form "foo(", it's probably a function
        # definition, unless it ends with ") bar;", in which case it's a declaration
        # that uses a macro to generate the type.
        #
        if (/^\w+\(/ && !/\) \w+;/) {
                $in_function_header = 1;
                if (/\($/) {
                        $function_header_full_indent = 1;
                }
        }
        if ($in_function_header && /^\{$/) {
                $in_function_header = 0;
                $function_header_full_indent = 0;
                $in_function = 1;
        }
        if ($in_function_header && /\);$/) {
                $in_function_header = 0;
                $function_header_full_indent = 0;
        }
        if ($in_function_header && /\{$/ ) {
                if ($picky) {
                        err("opening brace on same line as function header");
                }
                $in_function_header = 0;
                $function_header_full_indent = 0;
                $in_function = 1;
                next line;
        }

        if ($in_warlock_comment && /\*\//) {
                $in_warlock_comment = 0;
                $prev = $line;
                next line;
        }

        # a blank line terminates the declarations within a function.
        # XXX - but still a problem in sub-blocks.
        if ($in_declaration && /^$/) {
                $in_declaration = 0;
        }

        if ($comment_done) {
                $in_comment = 0;
                $comment_done = 0;
        }
        # does this looks like the start of a block comment?
        if (/$hdr_comment_start/) {
                if (!/^\t*\/\*/) {
                        err("block comment not indented by tabs");
                }
                $in_comment = 1;
                /^(\s*)\//;
                $comment_prefix = $1;
                $prev = $line;
                next line;
        }
        # are we still in the block comment?
        if ($in_comment) {
                if (/^$comment_prefix \*\/$/) {
                        $comment_done = 1;
                } elsif (/\*\//) {
                        $comment_done = 1;
                        err("improper block comment close");
                } elsif (!/^$comment_prefix \*[ \t]/ &&
                    !/^$comment_prefix \*$/) {
                        err("improper block comment");
                }
        }

        # check for errors that might occur in comments and in code.

        # allow spaces to be used to draw pictures in all comments.
        if (/[^ ]     / && !/".*     .*"/ && !$in_comment) {
                err("spaces instead of tabs");
        }
        if (/^ / && !/^ \*[ \t\/]/ && !/^ \*$/ &&
            (!/^    (\w|\.)/ || $in_function != 0)) {
                err("indent by spaces instead of tabs");
        }
        if (/^\t+ [^ \t\*]/ || /^\t+  \S/ || /^\t+   \S/) {
                err("continuation line not indented by 4 spaces");
        }
        if (/$warlock_re/ && !/\*\//) {
                $in_warlock_comment = 1;
                $prev = $line;
                next line;
        }
        if (/^\s*\/\*./ && !/^\s*\/\*.*\*\// && !/$hdr_comment_start/) {
                err("improper first line of block comment");
        }

        if ($in_comment) {      # still in comment, don't do further checks
                $prev = $line;
                next line;
        }

        if ((/[^(]\/\*\S/ || /^\/\*\S/) && !/$lint_re/) {
                err("missing blank after open comment");
        }
        if (/\S\*\/[^)]|\S\*\/$/ && !/$lint_re/) {
                err("missing blank before close comment");
        }
        # check for unterminated single line comments, but allow them when
        # they are used to comment out the argument list of a function
        # declaration.
        if (/\S.*\/\*/ && !/\S.*\/\*.*\*\// && !/\(\/\*/) {
                err("unterminated single line comment");
        }

        if (/^(#else|#endif|#include)(.*)$/) {
                $prev = $line;
                if ($picky) {
                        my $directive = $1;
                        my $clause = $2;
                        # Enforce ANSI rules for #else and #endif: no noncomment
                        # identifiers are allowed after #endif or #else.  Allow
                        # C++ comments since they seem to be a fact of life.
                        if ((($1 eq "#endif") || ($1 eq "#else")) &&
                            ($clause ne "") &&
                            (!($clause =~ /^\s+\/\*.*\*\/$/)) &&
                            (!($clause =~ /^\s+\/\/.*$/))) {
                                err("non-comment text following " .
                                    "$directive (or malformed $directive " .
                                    "directive)");
                        }
                }
                next line;
        }

        #
        # delete any comments and check everything else.  Note that
        # ".*?" is a non-greedy match, so that we don't get confused by
        # multiple comments on the same line.
        #
        s/\/\*.*?\*\//\x01/g;
        s/\/\/(?:\s.*)?$/\x01/;    # Valid C++ comments

        # After stripping correctly spaced comments, check for (and strip) comments
        # without a blank.  By checking this after clearing out C++ comments that
        # correctly have a blank, we guarantee URIs in a C++ comment will not cause
        # an error.
        if (s!//.*$!\x01!) {               # C++ comments
                err("missing blank after start comment");
        }

        # delete any trailing whitespace; we have already checked for that.
        s/\s*$//;

        # following checks do not apply to text in comments.

        if (/[^<>\s][!<>=]=/ || /[^<>][!<>=]=[^\s,]/ ||
            (/[^->]>[^,=>\s]/ && !/[^->]>$/) ||
            (/[^<]<[^,=<\s]/ && !/[^<]<$/) ||
            /[^<\s]<[^<]/ || /[^->\s]>[^>]/) {
                err("missing space around relational operator");
        }
        if (/\S>>=/ || /\S<<=/ || />>=\S/ || /<<=\S/ || /\S[-+*\/&|^%]=/ ||
            (/[^-+*\/&|^%!<>=\s]=[^=]/ && !/[^-+*\/&|^%!<>=\s]=$/) ||
            (/[^!<>=]=[^=\s]/ && !/[^!<>=]=$/)) {
                # XXX - should only check this for C++ code
                # XXX - there are probably other forms that should be allowed
                if (!/\soperator=/) {
                        err("missing space around assignment operator");
                }
        }
        if (/[,;]\S/ && !/\bfor \(;;\)/) {
                err("comma or semicolon followed by non-blank");
        }
        # allow "for" statements to have empty "while" clauses
        if (/\s[,;]/ && !/^[\t]+;$/ && !/^\s*for \([^;]*; ;[^;]*\)/) {
                err("comma or semicolon preceded by blank");
        }
        if (/^\s*(&&|\|\|)/) {
                err("improper boolean continuation");
        }
        if (/\S   *(&&|\|\|)/ || /(&&|\|\|)   *\S/) {
                err("more than one space around boolean operator");
        }
        if (/\b(for|if|while|switch|sizeof|return|case)\(/) {
                err("missing space between keyword and paren");
        }
        if (/(\b(for|if|while|switch|return)\b.*){2,}/ && !/^#define/) {
                # multiple "case" and "sizeof" allowed
                err("more than one keyword on line");
        }
        if (/\b(for|if|while|switch|sizeof|return|case)\s\s+\(/ &&
            !/^#if\s+\(/) {
                err("extra space between keyword and paren");
        }
        # try to detect "func (x)" but not "if (x)" or
        # "#define foo (x)" or "int (*func)();"
        if (/\w\s\(/) {
                my $s = $_;
                # strip off all keywords on the line
                s/\b(for|if|while|switch|return|case|sizeof)\s\(/XXX(/g;
                s/#elif\s\(/XXX(/g;
                s/^#define\s+\w+\s+\(/XXX(/;
                # do not match things like "void (*f)();"
                # or "typedef void (func_t)();"
                s/\w\s\(+\*/XXX(*/g;
                s/\b($typename|void)\s+\(+/XXX(/og;
                if (/\w\s\(/) {
                        err("extra space between function name and left paren");
                }
                $_ = $s;
        }
        # try to detect "int foo(x)", but not "extern int foo(x);"
        # XXX - this still trips over too many legitimate things,
        # like "int foo(x,\n\ty);"
#               if (/^(\w+(\s|\*)+)+\w+\(/ && !/\)[;,](\s|\x01)*$/ &&
#                   !/^(extern|static)\b/) {
#                       err("return type of function not on separate line");
#               }
        # this is a close approximation
        if (/^(\w+(\s|\*)+)+\w+\(.*\)(\s|\x01)*$/ &&
            !/^(extern|static)\b/) {
                err("return type of function not on separate line");
        }
        if (/^#define /) {
                err("#define followed by space instead of tab");
        }
        if (/^\s*return\W[^;]*;/ && !/^\s*return\s*\(.*\);/) {
                err("unparenthesized return expression");
        }
        if (/\bsizeof\b/ && !/\bsizeof\s*\(.*\)/) {
                err("unparenthesized sizeof expression");
        }
        if (/\(\s/) {
                err("whitespace after left paren");
        }
        # Allow "for" statements to have empty "continue" clauses.
        # Allow right paren on its own line unless we're being picky (-p).
        if (/\s\)/ && !/^\s*for \([^;]*;[^;]*; \)/ && ($picky || !/^\s*\)/)) {
                err("whitespace before right paren");
        }
        if (/^\s*\(void\)[^ ]/) {
                err("missing space after (void) cast");
        }
        if (/\S\{/ && !/\{\{/) {
                err("missing space before left brace");
        }
        if ($in_function && /^\s+\{/ &&
            ($prev =~ /\)\s*$/ || $prev =~ /\bstruct\s+\w+$/)) {
                err("left brace starting a line");
        }
        if (/\}(else|while)/) {
                err("missing space after right brace");
        }
        if (/\}\s\s+(else|while)/) {
                err("extra space after right brace");
        }
        if (/\b_VOID\b|\bVOID\b|\bSTATIC\b/) {
                err("obsolete use of VOID or STATIC");
        }
        if (/\b$typename\*/o) {
                err("missing space between type name and *");
        }
        if (/^\s+#/) {
                err("preprocessor statement not in column 1");
        }
        if (/^#\s/) {
                err("blank after preprocessor #");
        }
        if (/!\s*(strcmp|strncmp|bcmp)\s*\(/) {
                err("don't use boolean ! with comparison functions");
        }

        #
        # We completely ignore, for purposes of indentation:
        #  * lines outside of functions
        #  * preprocessor lines
        #
        if ($check_continuation && $in_function && !$in_cpp) {
                process_indent($_);
        }
        if ($picky) {
                # try to detect spaces after casts, but allow (e.g.)
                # "sizeof (int) + 1", "void (*funcptr)(int) = foo;", and
                # "int foo(int) __NORETURN;"
                if ((/^\($typename( \*+)?\)\s/o ||
                    /\W\($typename( \*+)?\)\s/o) &&
                    !/sizeof\s*\($typename( \*)?\)\s/o &&
                    !/\($typename( \*+)?\)\s+=[^=]/o) {
                        err("space after cast");
                }
                if (/\b$typename\s*\*\s/o &&
                    !/\b$typename\s*\*\s+const\b/o) {
                        err("unary * followed by space");
                }
        }
        if ($check_posix_types) {
                # try to detect old non-POSIX types.
                # POSIX requires all non-standard typedefs to end in _t,
                # but historically these have been used.
                if (/\b(unchar|ushort|uint|ulong|u_int|u_short|u_long|u_char|quad)\b/) {
                        err("non-POSIX typedef $1 used: use $old2posix{$1} instead");
                }
        }
        if (/^\s*else\W/) {
                if ($prev =~ /^\s*\}$/) {
                        err_prefix($prev,
                            "else and right brace should be on same line");
                }
        }
        $prev = $line;
}

if ($prev eq "") {
        err("last line in file is blank");
}

}

#
# Continuation-line checking
#
# The rest of this file contains the code for the continuation checking
# engine.  It's a pretty simple state machine which tracks the expression
# depth (unmatched '('s and '['s).
#
# Keep in mind that the argument to process_indent() has already been heavily
# processed; all comments have been replaced by control-A, and the contents of
# strings and character constants have been elided.
#

my $cont_in;            # currently inside of a continuation
my $cont_off;           # skipping an initializer or definition
my $cont_noerr;         # suppress cascading errors
my $cont_start;         # the line being continued
my $cont_base;          # the base indentation
my $cont_first;         # this is the first line of a statement
my $cont_multiseg;      # this continuation has multiple segments

my $cont_special;       # this is a C statement (if, for, etc.)
my $cont_macro;         # this is a macro
my $cont_case;          # this is a multi-line case

my @cont_paren;         # the stack of unmatched ( and [s we've seen

sub
reset_indent()
{
        $cont_in = 0;
        $cont_off = 0;
}

sub
delabel($)
{
        #
        # replace labels with tabs.  Note that there may be multiple
        # labels on a line.
        #
        local $_ = $_[0];

        while (/^(\t*)( *(?:(?:\w+\s*)|(?:case\b[^:]*)): *)(.*)$/) {
                my ($pre_tabs, $label, $rest) = ($1, $2, $3);
                $_ = $pre_tabs;
                while ($label =~ s/^([^\t]*)(\t+)//) {
                        $_ .= "\t" x (length($2) + length($1) / 8);
                }
                $_ .= ("\t" x (length($label) / 8)).$rest;
        }

        return ($_);
}

sub
process_indent($)
{
        require strict;
        local $_ = $_[0];                       # preserve the global $_

        s/\x01//g; # No comments
        s/\s+$//;       # Strip trailing whitespace

        return                  if (/^$/);      # skip empty lines

        # regexps used below; keywords taking (), macros, and continued cases
        my $special = '(?:(?:\}\s*)?else\s+)?(?:if|for|while|switch)\b';
        my $macro = '[A-Z_][A-Z_0-9]*\(';
        my $case = 'case\b[^:]*$';

        # skip over enumerations, array definitions, initializers, etc.
        if ($cont_off <= 0 && !/^\s*$special/ &&
            (/(?:(?:\b(?:enum|struct|union)\s*[^\{]*)|(?:\s+=\s*))\{/ ||
            (/^\s*\{/ && $prev =~ /=\s*(?:\/\*.*\*\/\s*)*$/))) {
                $cont_in = 0;
                $cont_off = tr/{/{/ - tr/}/}/;
                return;
        }
        if ($cont_off) {
                $cont_off += tr/{/{/ - tr/}/}/;
                return;
        }

        if (!$cont_in) {
                $cont_start = $line;

                if (/^\t* /) {
                        err("non-continuation indented 4 spaces");
                        $cont_noerr = 1;                # stop reporting
                }
                $_ = delabel($_);       # replace labels with tabs

                # check if the statement is complete
                return          if (/^\s*\}?$/);
                return          if (/^\s*\}?\s*else\s*\{?$/);
                return          if (/^\s*do\s*\{?$/);
                return          if (/\{$/);
                return          if (/\}[,;]?$/);

                # Allow macros on their own lines
                return          if (/^\s*[A-Z_][A-Z_0-9]*$/);

                # cases we don't deal with, generally non-kosher
                if (/\{/) {
                        err("stuff after {");
                        return;
                }

                # Get the base line, and set up the state machine
                /^(\t*)/;
                $cont_base = $1;
                $cont_in = 1;
                @cont_paren = ();
                $cont_first = 1;
                $cont_multiseg = 0;

                # certain things need special processing
                $cont_special = /^\s*$special/? 1 : 0;
                $cont_macro = /^\s*$macro/? 1 : 0;
                $cont_case = /^\s*$case/? 1 : 0;
        } else {
                $cont_first = 0;

                # Strings may be pulled back to an earlier (half-)tabstop
                unless ($cont_noerr || /^$cont_base    / ||
                    (/^\t*(?:    )?(?:gettext\()?\"/ && !/^$cont_base\t/)) {
                        err_prefix($cont_start,
                            "continuation should be indented 4 spaces");
                }
        }

        my $rest = $_;                  # keeps the remainder of the line

        #
        # The split matches 0 characters, so that each 'special' character
        # is processed separately.  Parens and brackets are pushed and
        # popped off the @cont_paren stack.  For normal processing, we wait
        # until a ; or { terminates the statement.  "special" processing
        # (if/for/while/switch) is allowed to stop when the stack empties,
        # as is macro processing.  Case statements are terminated with a :
        # and an empty paren stack.
        #
        foreach $_ (split /[^\(\)\[\]\{\}\;\:]*/) {
                next            if (length($_) == 0);

                # rest contains the remainder of the line
                my $rxp = "[^\Q$_\E]*\Q$_\E";
                $rest =~ s/^$rxp//;

                if (/\(/ || /\[/) {
                        push @cont_paren, $_;
                } elsif (/\)/ || /\]/) {
                        my $cur = $_;
                        tr/\)\]/\(\[/;

                        my $old = (pop @cont_paren);
                        if (!defined($old)) {
                                err("unexpected '$cur'");
                                $cont_in = 0;
                                last;
                        } elsif ($old ne $_) {
                                err("'$cur' mismatched with '$old'");
                                $cont_in = 0;
                                last;
                        }

                        #
                        # If the stack is now empty, do special processing
                        # for if/for/while/switch and macro statements.
                        #
                        next            if (@cont_paren != 0);
                        if ($cont_special) {
                                if ($rest =~ /^\s*\{?$/) {
                                        $cont_in = 0;
                                        last;
                                }
                                if ($rest =~ /^\s*;$/) {
                                        err("empty if/for/while body ".
                                            "not on its own line");
                                        $cont_in = 0;
                                        last;
                                }
                                if (!$cont_first && $cont_multiseg == 1) {
                                        err_prefix($cont_start,
                                            "multiple statements continued ".
                                            "over multiple lines");
                                        $cont_multiseg = 2;
                                } elsif ($cont_multiseg == 0) {
                                        $cont_multiseg = 1;
                                }
                                # We've finished this section, start
                                # processing the next.
                                goto section_ended;
                        }
                        if ($cont_macro) {
                                if ($rest =~ /^$/) {
                                        $cont_in = 0;
                                        last;
                                }
                        }
                } elsif (/\;/) {
                        if ($cont_case) {
                                err("unexpected ;");
                        } elsif (!$cont_special) {
                                err("unexpected ;")     if (@cont_paren != 0);
                                if (!$cont_first && $cont_multiseg == 1) {
                                        err_prefix($cont_start,
                                            "multiple statements continued ".
                                            "over multiple lines");
                                        $cont_multiseg = 2;
                                } elsif ($cont_multiseg == 0) {
                                        $cont_multiseg = 1;
                                }
                                if ($rest =~ /^$/) {
                                        $cont_in = 0;
                                        last;
                                }
                                if ($rest =~ /^\s*special/) {
                                        err("if/for/while/switch not started ".
                                            "on its own line");
                                }
                                goto section_ended;
                        }
                } elsif (/\{/) {
                        err("{ while in parens/brackets") if (@cont_paren != 0);
                        err("stuff after {")            if ($rest =~ /[^\s}]/);
                        $cont_in = 0;
                        last;
                } elsif (/\}/) {
                        err("} while in parens/brackets") if (@cont_paren != 0);
                        if (!$cont_special && $rest !~ /^\s*(while|else)\b/) {
                                if ($rest =~ /^$/) {
                                        err("unexpected }");
                                } else {
                                        err("stuff after }");
                                }
                                $cont_in = 0;
                                last;
                        }
                } elsif (/\:/ && $cont_case && @cont_paren == 0) {
                        err("stuff after multi-line case") if ($rest !~ /$^/);
                        $cont_in = 0;
                        last;
                }
                next;
section_ended:
                # End of a statement or if/while/for loop.  Reset
                # cont_special and cont_macro based on the rest of the
                # line.
                $cont_special = ($rest =~ /^\s*$special/)? 1 : 0;
                $cont_macro = ($rest =~ /^\s*$macro/)? 1 : 0;
                $cont_case = 0;
                next;
        }
        $cont_noerr = 0                 if (!$cont_in);
}