lib/Autom4te/XFile.pm

   1 # Copyright (C) 2001-2012 Free Software Foundation, Inc.
   2
   3 # This program is free software; you can redistribute it and/or modify
   4 # it under the terms of the GNU General Public License as published by
   5 # the Free Software Foundation; either version 2, or (at your option)
   6 # any later version.
   7
   8 # This program is distributed in the hope that it will be useful,
   9 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  10 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11 # GNU General Public License for more details.
  12
  13 # You should have received a copy of the GNU General Public License
  14 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
  15
  16 # Written by Akim Demaille <akim@freefriends.org>.
  17
  18 ###############################################################
  19 # The main copy of this file is in Automake's git repository. #
  20 # Updates should be sent to automake-patches@gnu.org.         #
  21 ###############################################################
  22
  23 package Autom4te::XFile;
  24
  25 =head1 NAME
  26
  27 Autom4te::XFile - supply object methods for filehandles with error handling
  28
  29 =head1 SYNOPSIS
  30
  31     use Autom4te::XFile;
  32
  33     $fh = new Autom4te::XFile;
  34     $fh->open ("< file");
  35     # No need to check $FH: we died if open failed.
  36     print <$fh>;
  37     $fh->close;
  38     # No need to check the return value of close: we died if it failed.
  39
  40     $fh = new Autom4te::XFile "> file";
  41     # No need to check $FH: we died if new failed.
  42     print $fh "bar\n";
  43     $fh->close;
  44
  45     $fh = new Autom4te::XFile "file", "r";
  46     # No need to check $FH: we died if new failed.
  47     defined $fh
  48     print <$fh>;
  49     undef $fh;   # automatically closes the file and checks for errors.
  50
  51     $fh = new Autom4te::XFile "file", O_WRONLY | O_APPEND;
  52     # No need to check $FH: we died if new failed.
  53     print $fh "corge\n";
  54
  55     $pos = $fh->getpos;
  56     $fh->setpos ($pos);
  57
  58     undef $fh;   # automatically closes the file and checks for errors.
  59
  60     autoflush STDOUT 1;
  61
  62 =head1 DESCRIPTION
  63
  64 C<Autom4te::XFile> inherits from C<IO::File>.  It provides the method
  65 C<name> returning the file name.  It provides dying versions of the
  66 methods C<close>, C<lock> (corresponding to C<flock>), C<new>,
  67 C<open>, C<seek>, and C<truncate>.  It also overrides the C<getline>
  68 and C<getlines> methods to translate C<\r\n> to C<\n>.
  69
  70 =cut
  71
  72 require 5.000;
  73 use strict;
  74 use vars qw($VERSION @EXPORT @EXPORT_OK $AUTOLOAD @ISA);
  75 use Carp;
  76 use Errno;
  77 use IO::File;
  78 use File::Basename;
  79 use Autom4te::ChannelDefs;
  80 use Autom4te::Channels qw(msg);
  81 use Autom4te::FileUtils;
  82
  83 require Exporter;
  84 require DynaLoader;
  85
  86 @ISA = qw(IO::File Exporter DynaLoader);
  87
  88 $VERSION = "1.2";
  89
  90 @EXPORT = @IO::File::EXPORT;
  91
  92 eval {
  93   # Make all Fcntl O_XXX and LOCK_XXX constants available for importing
  94   require Fcntl;
  95   my @O = grep /^(LOCK|O)_/, @Fcntl::EXPORT, @Fcntl::EXPORT_OK;
  96   Fcntl->import (@O);  # first we import what we want to export
  97   push (@EXPORT, @O);
  98 };
  99
 100 =head2 Methods
 101
 102 =over
 103
 104 =item C<$fh = new Autom4te::XFile ([$expr, ...]>
 105
 106 Constructor a new XFile object.  Additional arguments
 107 are passed to C<open>, if any.
 108
 109 =cut
 110
 111 sub new
 112 {
 113   my $type = shift;
 114   my $class = ref $type || $type || "Autom4te::XFile";
 115   my $fh = $class->SUPER::new ();
 116   if (@_)
 117     {
 118       $fh->open (@_);
 119     }
 120   $fh;
 121 }
 122
 123 =item C<$fh-E<gt>open ([$file, ...])>
 124
 125 Open a file, passing C<$file> and further arguments to C<IO::File::open>.
 126 Die if opening fails.  Store the name of the file.  Use binmode for writing.
 127
 128 =cut
 129
 130 sub open
 131 {
 132   my $fh = shift;
 133   my ($file) = @_;
 134
 135   # WARNING: Gross hack: $FH is a typeglob: use its hash slot to store
 136   # the 'name' of the file we are opening.  See the example with
 137   # io_socket_timeout in IO::Socket for more, and read Graham's
 138   # comment in IO::Handle.
 139   ${*$fh}{'autom4te_xfile_file'} = "$file";
 140
 141   if (!$fh->SUPER::open (@_))
 142     {
 143       fatal "cannot open $file: $!";
 144     }
 145
 146   # In case we're running under MSWindows, don't write with CRLF.
 147   # (This circumvents a bug in at least Cygwin bash where the shell
 148   # parsing fails on lines ending with the continuation character '\'
 149   # and CRLF).
 150   binmode $fh if $file =~ /^\s*>/;
 151 }
 152
 153 =item C<$fh-E<gt>close>
 154
 155 Close the file, handling errors.
 156
 157 =cut
 158
 159 sub close
 160 {
 161   my $fh = shift;
 162   if (!$fh->SUPER::close (@_))
 163     {
 164       my $file = $fh->name;
 165       Autom4te::FileUtils::handle_exec_errors $file
 166         unless $!;
 167       fatal "cannot close $file: $!";
 168     }
 169 }
 170
 171 =item C<$line = $fh-E<gt>getline>
 172
 173 Read and return a line from the file.  Ensure C<\r\n> is translated to
 174 C<\n> on input files.
 175
 176 =cut
 177
 178 # Some native Windows/perl installations fail to translate \r\n to \n on
 179 # input so we do that here.
 180 sub getline
 181 {
 182   local $_ = $_[0]->SUPER::getline;
 183   # Perform a _global_ replacement: $_ may can contains many lines
 184   # in slurp mode ($/ = undef).
 185   s/\015\012/\n/gs if defined $_;
 186   return $_;
 187 }
 188
 189 =item C<@lines = $fh-E<gt>getlines>
 190
 191 Slurp lines from the files.
 192
 193 =cut
 194
 195 sub getlines
 196 {
 197   my @res = ();
 198   my $line;
 199   push @res, $line while $line = $_[0]->getline;
 200   return @res;
 201 }
 202
 203 =item C<$name = $fh-E<gt>name>
 204
 205 Return the name of the file.
 206
 207 =cut
 208
 209 sub name
 210 {
 211   my $fh = shift;
 212   return ${*$fh}{'autom4te_xfile_file'};
 213 }
 214
 215 =item C<$fh-E<gt>lock>
 216
 217 Lock the file using C<flock>.  If locking fails for reasons other than
 218 C<flock> being unsupported, then error out if C<$ENV{'MAKEFLAGS'}> indicates
 219 that we are spawned from a parallel C<make>.
 220
 221 =cut
 222
 223 sub lock
 224 {
 225   my ($fh, $mode) = @_;
 226   # Cannot use @_ here.
 227
 228   # Unless explicitly configured otherwise, Perl implements its 'flock' with the
 229   # first of flock(2), fcntl(2), or lockf(3) that works.  These can fail on
 230   # NFS-backed files, with ENOLCK (GNU/Linux) or EOPNOTSUPP (FreeBSD); we
 231   # usually ignore these errors.  If $ENV{MAKEFLAGS} suggests that a parallel
 232   # invocation of 'make' has invoked the tool we serve, report all locking
 233   # failures and abort.
 234   #
 235   # On Unicos, flock(2) and fcntl(2) over NFS hang indefinitely when 'lockd' is
 236   # not running.  NetBSD NFS clients silently grant all locks.  We do not
 237   # attempt to defend against these dangers.
 238   #
 239   # -j is for parallel BSD make, -P is for parallel HP-UX make.
 240   if (!flock ($fh, $mode))
 241     {
 242       my $make_j = (exists $ENV{'MAKEFLAGS'}
 243                     && " -$ENV{'MAKEFLAGS'}" =~ / (-[BdeikrRsSw]*[jP]|--[jP]|---?jobs)/);
 244       my $note = "\nforgo \"make -j\" or use a file system that supports locks";
 245       my $file = $fh->name;
 246
 247       msg ($make_j ? 'fatal' : 'unsupported',
 248            "cannot lock $file with mode $mode: $!" . ($make_j ? $note : ""))
 249         if $make_j || !($!{ENOLCK} || $!{EOPNOTSUPP});
 250     }
 251 }
 252
 253 =item C<$fh-E<gt>seek ($position, [$whence])>
 254
 255 Seek file to C<$position>.  Die if seeking fails.
 256
 257 =cut
 258
 259 sub seek
 260 {
 261   my $fh = shift;
 262   # Cannot use @_ here.
 263   if (!seek ($fh, $_[0], $_[1]))
 264     {
 265       my $file = $fh->name;
 266       fatal "cannot rewind $file with @_: $!";
 267     }
 268 }
 269
 270 =item C<$fh-E<gt>truncate ($len)>
 271
 272 Truncate the file to length C<$len>.  Die on failure.
 273
 274 =cut
 275
 276 sub truncate
 277 {
 278   my ($fh, $len) = @_;
 279   if (!truncate ($fh, $len))
 280     {
 281       my $file = $fh->name;
 282       fatal "cannot truncate $file at $len: $!";
 283     }
 284 }
 285
 286 =back
 287
 288 =head1 SEE ALSO
 289
 290 L<perlfunc>,
 291 L<perlop/"I/O Operators">,
 292 L<IO::File>
 293 L<IO::Handle>
 294 L<IO::Seekable>
 295
 296 =head1 HISTORY
 297
 298 Derived from IO::File.pm by Akim Demaille E<lt>F<akim@freefriends.org>E<gt>.
 299
 300 =cut
 301
 302 1;
 303
 304 ### Setup "GNU" style for perl-mode and cperl-mode.
 305 ## Local Variables:
 306 ## perl-indent-level: 2
 307 ## perl-continued-statement-offset: 2
 308 ## perl-continued-brace-offset: 0
 309 ## perl-brace-offset: 0
 310 ## perl-brace-imaginary-offset: 0
 311 ## perl-label-offset: -2
 312 ## cperl-indent-level: 2
 313 ## cperl-brace-offset: 0
 314 ## cperl-continued-brace-offset: 0
 315 ## cperl-label-offset: -2
 316 ## cperl-extra-newline-before-brace: t
 317 ## cperl-merge-trailing-else: nil
 318 ## cperl-continued-statement-offset: 2
 319 ## End: