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[perl #55420] No warnings when reading from a file only opened for appending.

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From:
Paul Fenwick
Date:
June 7, 2008 01:47
Subject:
[perl #55420] No warnings when reading from a file only opened for appending.
Message ID:
rt-3.6.HEAD-21199-1212797208-806.55420-75-0@perl.org
# New Ticket Created by  Paul Fenwick 
# Please include the string:  [perl #55420]
# in the subject line of all future correspondence about this issue. 
# <URL: http://rt.perl.org/rt3/Ticket/Display.html?id=55420 >



This is a bug report for perl from pjf@cpan.org,
generated with the help of perlbug 1.35 running under perl v5.8.8.


-----------------------------------------------------------------
[Please enter your report here]

G'day p5p and readers of perlbugs,

Under all versions of Perl I have on my laptop (5.8.4, 5.8.8, 5.10.0, and
5.11.0) the following produces a warning:

	open(FOO, '>', 'foo.txt');
	<FOO>;

However writing a file for appending doesn't:

	open(FOO, '>>', 'foo.txt');
	<FOO>;

I thought this would be easy enough to fix:

diff --git a/pp_hot.c b/pp_hot.c
index 64b5fc5..bc0d5fe 100644
--- a/pp_hot.c
+++ b/pp_hot.c
@@ -1586,7 +1586,8 @@ Perl_do_readline(pTHX)
         }
         else if (type == OP_GLOB)
             SP--;
-       else if (ckWARN(WARN_IO) && IoTYPE(io) == IoTYPE_WRONLY) {
+       else if (ckWARN(WARN_IO) && ( IoTYPE(io) == IoTYPE_WRONLY ||
+                                     IoTYPE(io) == IoTYPE_APPEND)) {
             report_evil_fh(PL_last_in_gv, io, OP_phoney_OUTPUT_ONLY);
         }
      }

However it looks like IoTYPE_APPEND also applies to files opened with mode
'+>>', and we certainly don't want to be warning there.

Am I missing an IoTYPE that signifies a file is open for appending
only, or is the reason this bug is still around because we can't
easily spot the difference between the two?

Many thanks,

	Paul

-- 
Paul Fenwick <pjf@perltraining.com.au> | http://perltraining.com.au/
Director of Training                   | Ph:  +61 3 9354 6001
Perl Training Australia                | Fax: +61 3 9354 2681



[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags:
     category=core
     severity=low
---
Site configuration information for perl v5.8.8:

Configured by rurban at Sun Jul  8 19:08:44 GMT 2007.

Summary of my perl5 (revision 5 version 8 subversion 8) configuration:
   Platform:
     osname=cygwin, osvers=1.5.24(0.15642), archname=cygwin-thread-multi-64int
     uname='cygwin_nt-5.1 reini 1.5.24(0.15642) 2007-01-31 10:57 i686 cygwin '
     config_args='-de -Dmksymlinks -Duse64bitint -Dusethreads -Uusemymalloc
-Doptimize=-O3 -Dman3ext=3pm -Dusesitecustomize -Dusedevel'
     hint=recommended, useposix=true, d_sigaction=define
     usethreads=define use5005threads=undef useithreads=define
usemultiplicity=define
     useperlio=define d_sfio=undef uselargefiles=define usesocks=undef
     use64bitint=define use64bitall=undef uselongdouble=undef
     usemymalloc=n, bincompat5005=undef
   Compiler:
     cc='gcc', ccflags ='-DPERL_USE_SAFE_PUTENV -fno-strict-aliasing -pipe
-Wdeclaration-after-statement',
     optimize='-O3',
     cppflags='-DPERL_USE_SAFE_PUTENV -fno-strict-aliasing -pipe
-Wdeclaration-after-statement'
     ccversion='', gccversion='3.4.4 (cygming special, gdc 0.12, using dmd
0.125)', gccosandvers=''
     intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=12345678
     d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
     ivtype='long long', ivsize=8, nvtype='double', nvsize=8, Off_t='off_t',
lseeksize=8
     alignbytes=8, prototype=define
   Linker and Libraries:
     ld='ld2', ldflags =' -s -L/usr/local/lib'
     libpth=/usr/local/lib /usr/lib /lib
     libs=-lgdbm -ldb -ldl -lcrypt -lgdbm_compat
     perllibs=-ldl -lcrypt -lgdbm_compat
     libc=/usr/lib/libc.a, so=dll, useshrplib=true, libperl=libperl.a
     gnulibc_version=''
   Dynamic Linking:
     dlsrc=dl_dlopen.xs, dlext=dll, d_dlsymun=undef, ccdlflags=' -s'
     cccdlflags=' ', lddlflags=' -s -L/usr/local/lib'

Locally applied patches:
     CYG01 - hints.cygwin.sh ldflags -s
     CYG02 - lib-ExtUtils-Embed insensitive against leading \\s
     CYG03 - lib-Test-Harness-Straps $ENV{PERL5LIB} = ''
     CYG04 - major.version.cygwin.sh cygperl-5_8.dll and not cygperl-5_8_x.dll
     CYG05 - add Win32CORE to core
     CYG07 - File-Spec-Cygwin-TMPDIR.patch
     Bug#38628 - allow legacy Cwd->cwd()
     Bug#40103 - File-Spec-case_tolerant.patch from 5.9.5

---
@INC for perl v5.8.8:
     /usr/lib/perl5/5.8/cygwin
     /usr/lib/perl5/5.8
     /usr/lib/perl5/site_perl/5.8/cygwin
     /usr/lib/perl5/site_perl/5.8
     /usr/lib/perl5/site_perl/5.8
     /usr/lib/perl5/vendor_perl/5.8/cygwin
     /usr/lib/perl5/vendor_perl/5.8
     /usr/lib/perl5/vendor_perl/5.8
     .

---
Environment for perl v5.8.8:
     HOME=/home/pjf
     LANG (unset)
     LANGUAGE (unset)
     LD_LIBRARY_PATH (unset)
     LOGDIR (unset)

PATH=/usr/local/bin:/usr/bin:/bin:/usr/X11R6/bin:/cygdrive/c/PROGRA~1/PerlEdit:/cygdrive/c/Perl/site/bin:/cygdrive/c/Perl/bin:/cygdrive/c/Perl/bin/:/cygdrive/c/WINDOWS/system32:/cygdrive/c/WINDOWS:/cygdrive/c/WINDOWS/System32/Wbem:/cygdrive/c/Program
Files/VDMSound/:/cygdrive/c/Program Files/Common
Files/GTK/2.0/bin:/cygdrive/c/MinGW/bin:/cygdrive/c/Program
Files/gs/gs8.54/bin:/cygdrive/c/Program
Files/QuickTime/QTSystem/:/usr/local/bin/netpbm
     PERL_BADLANG (unset)
     SHELL (unset)


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