filename - handled incorrectly with inplace editing

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From @nwc10

Created by @nwc10

The filename - is not handled correctly by in place editing. The semantics
of in place editing were changed as part of this commit between perl-5.004
and perl-5.005​:

commit 85aff57
Author​: Chip Salzenberg <chip@​pobox.com>
Date​: Tue Feb 3 04​:16​:50 1998 -0500

  Some Chip patches (some tweaked to match _5x source)​:
  Subject​: [PATCH] local leakage
  Date​: Tue, 3 Feb 1998 09​:16​:50 -0500 (EST)
  Subject​: [PATCH] NULs in patterns
  Date​: Wed, 4 Feb 1998 01​:33​:51 -0500 (EST)
  Subject​: [PATCH] Configure on PerlIO
  Date​: Wed, 4 Feb 1998 01​:38​:43 -0500 (EST)
  Subject​: [PATCH] Avoid core dump on package alias
  Date​: Wed, 4 Feb 1998 15​:38​:42 -0500 (EST)
  Subject​: [PATCH] Fix name of $Foo​::{'Bar​::'}
  Date​: Wed, 4 Feb 1998 16​:37​:51 -0500 (EST)
 
  p4raw-id​: //depot/perl@​462

The change in question is this one​:

  As someone (?) recently observed, Perl's magical handling of filenames
  like "ls|" and "|tee foo bar" doesn't make a lot of sense in inplace
  editing mode (the -i command line option).
 
  This patch disables magic names in inplace mode. I tested it on a
  file named "echo abc|"; I ended up with files named "echo abc|" and
  "echo abc|~".

http​://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/1998-02/msg00419.html

The change makes sense. Pretty much every "magical" filename under 2-arg open
is either for input or for output, hence (specifically for in-place editing)
it's unambiguously not useful to treat filenames as per 2-arg open rules.
The only possible exception is -, which is meaningful in those contexts as
STDIN and STDOUT, but

1) I don't think that it's worth having super-global-extra-magical exception
  rule for -
2) I checked GNU sed in inplace mode, and it stops treating - as STDIN

However, a bug remains. With inplace editing perl is still treating '-' as
meaning "write to STDOUT". ie​:

$ echo 'This is a file' >-
$ /Sandpit/5005_03g/bin/perl5.00503 -i -pwe0 -- -
This is a file
$ ls ./-~
ls​: ./-~​: No such file or directory

Contrast with​:

$ /Sandpit/5005_03g/bin/perl5.00503 -i -pwe0 -- ./-
$ ls ./-~
./-~

The fix itself is simple​:

Inline Patch

diff --git a/doio.c b/doio.c
index e2bfda5..65caa67 100644
--- a/doio.c
+++ b/doio.c
@@ -845,11 +845,6 @@ Perl_nextargv(pTHX_ GV *gv)
                 Gid_t filegid;
 
 		TAINT_PROPER("inplace open");
-		if (oldlen == 1 && *PL_oldname == '-') {
-		    setdefout(gv_fetchpvs("STDOUT", GV_ADD|GV_NOTQUAL,
-					  SVt_PVIO));
-		    return IoIFP(GvIOp(gv));
-		}
 #ifndef FLEXFILENAMES
 		filedev = PL_statbuf.st_dev;
 		fileino = PL_statbuf.st_ino;

1) Would anyone like to add tests for this? 2\) I don't think that it's documented anywhere that inplace editing makes   \<> behave differently\.   Would anyone like to patch the documentation?   \(Or show me where I'm wrong\)

Nicholas Clark

Perl Info

Site configuration information for perl 5.00503:

Configured by nick at Tue Jun 14 12:35:58 BST 2011.

Summary of my perl5 (5.0 patchlevel 5 subversion 3) configuration:
  Platform:
    osname=darwin, osvers=10.7.0, archname=darwin
    uname='darwin mouse-mill.local 10.7.0 darwin kernel version 10.7.0: sat jan 29 15:17:16 pst 2011; root:xnu-1504.9.37~1release_i386 i386 '
    hint=recommended, useposix=true, d_sigaction=define
    usethreads=undef useperlio=undef d_sfio=undef
  Compiler:
    cc='ccache gcc', optimize='-g', gccversion=4.2.1 (Apple Inc. build 5666) (dot 3)
    cppflags='-DDEBUGGING -I/opt/local/include'
    ccflags ='-DDEBUGGING -I/opt/local/include'
    stdchar='char', d_stdstdio=undef, usevfork=true
    intsize=4, longsize=8, ptrsize=8, doublesize=8
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
    alignbytes=8, usemymalloc=n, prototype=define
  Linker and Libraries:
    ld='env MACOSX_DEPLOYMENT_TARGET=10.3 cc', ldflags =' -L/usr/local/lib -L/opt/local/lib'
    libpth=/usr/local/lib /opt/local/lib /usr/lib
    libs=-lgdbm -ldbm -ldl -lm -lc
    libc=/usr/lib/libc.dylib, so=dylib, useshrplib=false, libperl=libperl.a
  Dynamic Linking:
    dlsrc=dl_dyld.xs, dlext=bundle, d_dlsymun=undef, ccdlflags=' '
    cccdlflags=' ', lddlflags=' -bundle -undefined dynamic_lookup -L/usr/local/lib -L/opt/local/lib'

Locally applied patches:
    


@INC for perl 5.00503:
    /Volumes/Stuff/Sandpit/5005_03g/lib/perl5/5.00503/darwin
    /Volumes/Stuff/Sandpit/5005_03g/lib/perl5/5.00503
    /Volumes/Stuff/Sandpit/5005_03g/lib/perl5/site_perl/5.005/darwin
    /Volumes/Stuff/Sandpit/5005_03g/lib/perl5/site_perl/5.005
    .


Environment for perl 5.00503:
    HOME=/Users/nick
    LANG (unset)
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/opt/local/bin:/opt/local/sbin:/Users/nick/bin:/opt/local/bin:/opt/local/sbin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/X11/bin:/opt/local/bin:/opt/local/sbin:/Users/nick/bin:/usr/local/sbin:/usr/local/sbin:/sbin:/usr/sbin
    PERL_BADLANG (unset)
    SHELL=/bin/bash