From mpyne@purinchu.net

Created by mpyne@purinchu.net

When running a script that I write (kdesvn-build) I noticed that a recent
change to my script to add more error checking when creating lock files was
always reporting errors. I've reduced the problem to the following test case​:

use strict;
use Fcntl;

my $file = '.lockfile';

$! = 0;
sysopen(LOCK, $file, O_CREAT|O_WRONLY|O_EXCL);
print "Result​: $!\n"; # Prints Result​: inappropriate ioctl for device
close LOCK;
unlink $file;

---------------------------------

strace output (partial)​:

ioctl(5, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fff565581b0) = -1 ENOTTY (Inappropriate ioctl for device)
lseek(5, 0, SEEK_CUR) = 0
read(5, "package Exporter;\n\nrequire 5.006;"..., 4096) = 4096
brk(0x2459000) = 0x2459000
lseek(5, 2217, SEEK_SET) = 2217
lseek(5, 0, SEEK_CUR) = 2217
close(5) = 0
stat("/usr/lib64/perl5/5.8.8/x86_64-linux/auto/Fcntl/Fcntl.so", {st_mode=S_IFREG|0555, st_size=14296, ...}) = 0
stat("/usr/lib64/perl5/5.8.8/x86_64-linux/auto/Fcntl/Fcntl.bs", {st_mode=S_IFREG|0444, st_size=0, ...}) = 0
futex(0x34d8e0310c, FUTEX_WAKE, 2147483647) = 0
open("/usr/lib64/perl5/5.8.8/x86_64-linux/auto/Fcntl/Fcntl.so", O_RDONLY) = 5
read(5, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\0\v\0\0\0\0\0\0@​"..., 832) = 832
fstat(5, {st_mode=S_IFREG|0555, st_size=14296, ...}) = 0
mmap(NULL, 2109568, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 5, 0) = 0x7f234e1aa000
mprotect(0x7f234e1ad000, 2093056, PROT_NONE) = 0
mmap(0x7f234e3ac000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 5, 0x2000) = 0x7f234e3ac000
close(5) = 0
mprotect(0x7f234e3ac000, 4096, PROT_READ) = 0
read(3, ""..., 4096) = 0

---------------------------------

I've tried different combinations of flags to sysopen() (O_RDWR instead of
O_WRONLY and removing O_EXCL) but the problem remains.

One thing I've noted is that exporting PERLIO=​:stdio before running the script
results in expected behavior (i.e. no errors).

I've downloaded the 5.8.8 source code and browsed through but I can't find
where sysopen is defined in order to ease stepping through in gdb. I know
that 5.8.9 is now out but it is not packaged by my distro and I was unable to
get the make to start (something about missing build rule; probably a separate
problem on my end)

My Googling around seems to indicate that the problem is still present for
some people running 5.10.0 even and perldelta-5.8.9 didn't have anything leap
out to me as probably solving the bug.

I have a debug-enabled build of perl now so I'm standing by to assist as
necessary.

Flags:
    category=core
    severity=low

Site configuration information for perl v5.8.8:

Configured by Gentoo at Sun Jan  4 20:23:38 EST 2009.

Summary of my perl5 (revision 5 version 8 subversion 8) configuration:
  Platform:
    osname=linux, osvers=2.6.27.10, archname=x86_64-linux
    uname='linux midna 2.6.27.10 #1 smp preempt tue dec 23 00:05:35 est 2008 x86_64 amd athlon(tm) 64 x2 dual core processor 3800+ authenticamd gnulinux '
    config_args='-des -Darchname=x86_64-linux -Dcccdlflags=-fPIC -Dccdlflags=-rdynamic -Dcc=x86_64-pc-linux-gnu-gcc -Dprefix=/usr -Dvendorprefix=/usr -Dsiteprefix=/usr -Dlocincpth=  -Doptimize=-march=athlon64 -O2 -pipe -msse3 -g -Duselargefiles -Dd_semctl_semun -Dscriptdir=/usr/bin -Dman1dir=/usr/share/man/man1 -Dman3dir=/usr/share/man/man3 -Dinstallman1dir=/usr/share/man/man1 -Dinstallman3dir=/usr/share/man/man3 -Dman1ext=1 -Dman3ext=3pm -Dinc_version_list=5.8.0 5.8.0/x86_64-linux 5.8.2 5.8.2/x86_64-linux 5.8.4 5.8.4/x86_64-linux 5.8.5 5.8.5/x86_64-linux 5.8.6 5.8.6/x86_64-linux 5.8.7 5.8.7/x86_64-linux  -Dcf_by=Gentoo -Ud_csh -Dusenm -Di_ndbm -Di_gdbm -Di_db -DDEBUGGING -Dusrinc=/usr/include/gentoo-multilib/amd64 -Dlibpth=/usr/local/lib64 /lib64 /usr/lib64'
    hint=recommended, useposix=true, d_sigaction=define
    usethreads=undef use5005threads=undef useithreads=undef usemultiplicity=undef
    useperlio=define d_sfio=undef uselargefiles=define usesocks=undef
    use64bitint=define use64bitall=define uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='x86_64-pc-linux-gnu-gcc', ccflags ='-DDEBUGGING -fno-strict-aliasing -pipe -Wdeclaration-after-statement -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -I/usr/include/gdbm',
    optimize='-march=athlon64 -O2 -pipe -msse3 -g',
    cppflags='-DDEBUGGING -fno-strict-aliasing -pipe -Wdeclaration-after-statement -I/usr/include/gdbm'
    ccversion='', gccversion='4.2.4 (Gentoo 4.2.4 p1.0)', gccosandvers=''
    intsize=4, longsize=8, ptrsize=8, doublesize=8, byteorder=12345678
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
    ivtype='long', ivsize=8, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='x86_64-pc-linux-gnu-gcc', ldflags =' -L/usr/local/lib64'
    libpth=/usr/local/lib64 /lib64 /usr/lib64
    libs=-lpthread -lnsl -lgdbm -ldb -ldl -lm -lcrypt -lutil -lc
    perllibs=-lpthread -lnsl -ldl -lm -lcrypt -lutil -lc
    libc=/lib/libc-2.6.1.so, so=so, useshrplib=false, libperl=libperl.a
    gnulibc_version='2.6.1'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-rdynamic'
    cccdlflags='-fPIC', lddlflags='-shared -L/usr/local/lib64'

Locally applied patches:
    


@INC for perl v5.8.8:
    /etc/perl
    /usr/lib64/perl5/vendor_perl/5.8.8/x86_64-linux
    /usr/lib64/perl5/vendor_perl/5.8.8
    /usr/lib64/perl5/vendor_perl
    /usr/lib64/perl5/site_perl/5.8.8/x86_64-linux
    /usr/lib64/perl5/site_perl/5.8.8
    /usr/lib64/perl5/site_perl
    /usr/lib64/perl5/5.8.8/x86_64-linux
    /usr/lib64/perl5/5.8.8
    /usr/local/lib/site_perl
    .


Environment for perl v5.8.8:
    HOME=/home/kde-svn
    LANG=en_US.UTF-8
    LANGUAGE=
    LD_LIBRARY_PATH=/home/kde-svn/kde-4/lib:/home/kde-svn/qt4/lib:
    LOGDIR (unset)
    PATH=/home/kde-svn/kde4/kdesdk/scripts:/home/kde-svn/cmake/bin:/home/kde-svn/kde4/kdesdk/scripts:/usr/lib/ccache/bin:/home/kde-svn/qt4/bin:/home/kde-svn/kde-4/bin:/usr/local/bin:/usr/bin:/bin:/opt/bin:/usr/x86_64-pc-linux-gnu/gcc-bin/4.2.4:/opt/blackdown-jdk-1.4.2.03/bin:/opt/blackdown-jdk-1.4.2.03/jre/bin:/usr/games/bin:/var/qmail/bin
    PERL_BADLANG (unset)
    SHELL=/bin/bash

From ben@morrow.me.uk

Quoth mpyne@​purinchu.net​:

When running a script that I write (kdesvn-build) I noticed that a recent
change to my script to add more error checking when creating lock files was
always reporting errors. I've reduced the problem to the following test case​:

use strict;
use Fcntl;

my $file = '.lockfile';

$! = 0;
sysopen(LOCK, $file, O_CREAT|O_WRONLY|O_EXCL);
print "Result​: $!\n"; # Prints Result​: inappropriate ioctl for device

This is not a bug. $! only has a useful value after a syscall has
failed​: to check for errors you need to check the return value of
sysopen, and only then check $!. Setting $! to 0 and checking it
afterwards is *not* sufficient.

Ben

The RT System itself - Status changed from 'new' to 'open'

From @dcollinsn

From perldoc perlvar​:

Many system or library calls set errno if they fail, to indicate the cause of failure. They usually do not set errno to zero if they succeed. This means errno , hence $! , is meaningful only immediately after a failure​:

Further details in the docs. sysopen() indicates failure by returning undef. If it does not return undef, $! is meaningless.

Closing rejected notabug.

--
Respectfully,
Dan Collins

@dcollinsn - Status changed from 'open' to 'rejected'