caller() filenames broken by "use"

[p5pRT]

Migrated from rt.perl.org#68712 (status was 'resolved')

Searchable as RT68712$

[p5pRT]

From zefram@fysh.org

Created by zefram@fysh.org

I'm looking at the stack, with caller(), during compilation. (Not just
for kicks, I have real reasons to do this.) Here's an unexpected result​:

$ cat x0.pm
package x0;
no warnings;
sub import {
  for(my$i=0;;$i++) {
  my @​c = caller($i);
  last unless @​c;
  print join(",", @​c), "\n";
  }
}
1;
$ perl -e 'use x0'
main,-e,1,x0​::import,1,0,,,0,,
main,x0.pm,1,main​::BEGIN,1,0,,,0,,
main,x0.pm,1,(eval),0,0,,,0,,

Observe that the direct caller of x0​::import is correctly ascribed the
filename "-e", but *its* callers, also located in the -e string, are
shown as being in x0.pm, which has just been read. This effect only
occurs if the "use" that invokes x0​::import is also the one in which
x0.pm was actually read. Subsequent "use" statements work fine​:

$ perl -e 'use x0 (); use x0'
main,-e,1,x0​::import,1,0,,,256,,
main,-e,1,main​::BEGIN,1,0,,,256,,
main,-e,1,(eval),0,0,,,256,,

A bit of deconstruction reveals that it's actually just one (implicit)
BEGIN block that's tainted​:

$ perl -e 'BEGIN { require x0; x0->import }'
main,-e,1,x0​::import,1,0,,,0,,
main,x0.pm,1,main​::BEGIN,1,0,,,0,,
main,x0.pm,1,(eval),0,0,,,0,,
$ perl -e 'BEGIN { require x0 } BEGIN { x0->import }'
main,-e,1,x0​::import,1,0,,,0,,
main,-e,1,main​::BEGIN,1,0,,,0,,
main,-e,1,(eval),0,0,,,0,,

This is annoying because I wanted to use caller() to get at the lexical
state of the code being compiled, distinct from the lexical state inside
the BEGIN block that invoked my compile-time code. This bug means that
the right caller() frame for me to use may have the wrong filename.
I can work around it by merging the two frames.

Perl Info

Flags:
    category=core
    severity=low

Site configuration information for perl 5.10.0:

Configured by Debian Project at Thu Jan  1 12:43:38 UTC 2009.

Summary of my perl5 (revision 5 version 10 subversion 0) configuration:
  Platform:
    osname=linux, osvers=2.6.26-1-686, archname=i486-linux-gnu-thread-multi
    uname='linux rebekka 2.6.26-1-686 #1 smp mon dec 15 18:15:07 utc 2008 i686 gnulinux '
    config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN -Dcccdlflags=-fPIC -Darchname=i486-linux-gnu -Dprefix=/usr -Dprivlib=/usr/share/perl/5.10 -Darchlib=/usr/lib/perl/5.10 -Dvendorprefix=/usr -Dvendorlib=/usr/share/perl5 -Dvendorarch=/usr/lib/perl5 -Dsiteprefix=/usr/local -Dsitelib=/usr/local/share/perl/5.10.0 -Dsitearch=/usr/local/lib/perl/5.10.0 -Dman1dir=/usr/share/man/man1 -Dman3dir=/usr/share/man/man3 -Dsiteman1dir=/usr/local/man/man1 -Dsiteman3dir=/usr/local/man/man3 -Dman1ext=1 -Dman3ext=3perl -Dpager=/usr/bin/sensible-pager -Uafs -Ud_csh -Ud_ualarm -Uusesfio -Uusenm -DDEBUGGING=-g -Doptimize=-O2 -Duseshrplib -Dlibperl=libperl.so.5.10.0 -Dd_dosuid -des'
    hint=recommended, useposix=true, d_sigaction=define
    useithreads=define, usemultiplicity=define
    useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
    use64bitint=undef, use64bitall=undef, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fno-strict-aliasing -pipe -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
    optimize='-O2 -g',
    cppflags='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fno-strict-aliasing -pipe -I/usr/local/include'
    ccversion='', gccversion='4.3.2', gccosandvers=''
    intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
    ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
    alignbytes=4, prototype=define
  Linker and Libraries:
    ld='cc', ldflags =' -L/usr/local/lib'
    libpth=/usr/local/lib /lib /usr/lib /usr/lib64
    libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt
    perllibs=-ldl -lm -lpthread -lc -lcrypt
    libc=/lib/libc-2.7.so, so=so, useshrplib=true, libperl=libperl.so.5.10.0
    gnulibc_version='2.7'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
    cccdlflags='-fPIC', lddlflags='-shared -O2 -g -L/usr/local/lib'

Locally applied patches:
    


@INC for perl 5.10.0:
    /etc/perl
    /usr/local/lib/perl/5.10.0
    /usr/local/share/perl/5.10.0
    /usr/lib/perl5
    /usr/share/perl5
    /usr/lib/perl/5.10
    /usr/share/perl/5.10
    /usr/local/lib/site_perl
    .


Environment for perl 5.10.0:
    HOME=/home/zefram
    LANG (unset)
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/home/zefram/pub/i686-pc-linux-gnu/bin:/home/zefram/pub/common/bin:/usr/bin:/usr/X11R6/bin:/bin:/usr/local/bin:/usr/games
    PERL_BADLANG (unset)
    SHELL=/usr/bin/zsh

[p5pRT]

From zefram@fysh.org

I wrote​:

Observe that the direct caller of x0​::import is correctly ascribed the
filename "-e", but *its* callers, also located in the -e string, are
shown as being in x0.pm, which has just been read.

Additional information​: this bug is present in every perl version at least
back to 5.004 (which is the earliest that I have available for testing).

-zefram

[p5pRT]

From p5p@perl.wizbit.be

I'm looking at the stack, with caller(), during compilation. (Not just
for kicks, I have real reasons to do this.) Here's an unexpected result​:

$ cat x0.pm
package x0;
no warnings;
sub import {
for(my$i=0;;$i++) {
my @​c = caller($i);
last unless @​c;
print join(",", @​c), "\n";
}
}
1;
$ perl -e 'use x0'
main,-e,1,x0​::import,1,0,,,0,,
main,x0.pm,1,main​::BEGIN,1,0,,,0,,
main,x0.pm,1,(eval),0,0,,,0,,

Observe that the direct caller of x0​::import is correctly ascribed the
filename "-e", but *its* callers, also located in the -e string, are
shown as being in x0.pm, which has just been read. This effect only
occurs if the "use" that invokes x0​::import is also the one in which
x0.pm was actually read. Subsequent "use" statements work fine​:

$ perl -e 'use x0 (); use x0'
main,-e,1,x0​::import,1,0,,,256,,
main,-e,1,main​::BEGIN,1,0,,,256,,
main,-e,1,(eval),0,0,,,256,,

A bit of deconstruction reveals that it's actually just one (implicit)
BEGIN block that's tainted​:

[snip]

That does not seem to be the case​:

$ cat x1.pm
1;

$ cat rt-68712-1.pl
#!/usr/bin/perl -l

BEGIN {
  require x1;

  for(my$i=0;;$i++) {
  my @​c = caller($i);
  last unless @​c;
  print join(",", @​c);
  }
}

BEGIN {
  print "-" x 80;
  delete $INC{'x1.pm'};
  require x1;

  for(my$i=0;;$i++) {
  my @​c = caller($i);
  last unless @​c;
  print join(",", @​c);
  }
}
__END__
main,x1.pm,11,main​::BEGIN,1,0,,,0,
main,x1.pm,11,(eval),0,0,,,0,

---

main,x1.pm,23,main​::BEGIN,1,0,,,0,
main,x1.pm,23,(eval),0,0,,,0,

$ cat rt-68712-2.pl
#!/usr/bin/perl -l

BEGIN {
  do "x1.pm";

  for(my$i=0;;$i++) {
  my @​c = caller($i);
  last unless @​c;
  print join(",", @​c);
  }
}

BEGIN {
  print "-" x 80;
  do "x1.pm";

  for(my$i=0;;$i++) {
  my @​c = caller($i);
  last unless @​c;
  print join(",", @​c);
  }
}

__END__
main,x1.pm,11,main​::BEGIN,1,0,,,0,
main,x1.pm,11,(eval),0,0,,,0,

---

main,x1.pm,22,main​::BEGIN,1,0,,,0,
main,x1.pm,22,(eval),0,0,,,0,

Adding the require x1 or do "x1.pm" in a separate block also seems to work​:

#!/usr/bin/perl -l

BEGIN {
  {
  require x1;
  }

  for(my$i=0;;$i++) {
  my @​c = caller($i);
  last unless @​c;
  print join(",", @​c);
  }
}

BEGIN {
  print "-" x 80;
  {
  delete $INC{'x1.pm'};
  require x1;
  }

  for(my$i=0;;$i++) {
  my @​c = caller($i);
  last unless @​c;
  print join(",", @​c);
  }
}
__END__
main,rt-68712-3.pl,13,main​::BEGIN,1,0,,,0,
main,rt-68712-3.pl,13,(eval),0,0,,,0,

---

main,rt-68712-3.pl,27,main​::BEGIN,1,0,,,0,
main,rt-68712-3.pl,27,(eval),0,0,,,0,

(same output for { do "x0.pm" })

Best regards,

Bram

[p5pRT]

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

[p5pRT]

From @cpansprout

Fixed by b2ef6d4.

[p5pRT]

@cpansprout - Status changed from 'open' to 'resolved'