Perl
Bug: File::Spec->path() doesn't keep trailing empty elements
Module: File::Spec
Description
Tested on Linux, but likely an issue on other platforms as well.
File::Spec->path() accidentally trims trailing empty elements in $PATH due to it's use of split() without a LIMIT.
Steps to Reproduce
> export PATH=/some/path/: # Note trailing colon
> /usr/bin/perl -e 'require File::Spec; print join(":", File::Spec->path());'
/some/path
> export PATH=:::/some/path/:::: # Leading colons are kept
> /usr/bin/perl -e 'require File::Spec; print join(":", File::Spec->path());'
.:.:.:/usr/bin/
> export PATH=: # This should be the same as '.'
> /usr/bin/perl -e 'require File::Spec; print join(":", File::Spec->path());'
> export PATH=:::::: # Technically all trailing
> /usr/bin/perl -e 'require File::Spec; print join(":", File::Spec->path());'
Expected behavior
File::Spec->path() should include trailing empty elements.
Perl configuration
Summary of my perl5 (revision 5 version 38 subversion 2) configuration:
Platform:
osname=linux
osvers=5.12.15-arch1-1
archname=x86_64-linux-thread-multi
uname='archlinux'
config_args='-des -Dusethreads -Duseshrplib -Doptimize=-march=x86-64 -mtune=generic -O2 -pipe -fno-plt -fexceptions -Wp,-D_FORTIFY_SOURCE=2 -Wformat -Werror=format-security -fstack-clash-protection -fcf-protection -g -ffile-prefix-map=/build/perl/src=/usr/src/debug/perl -flto=auto -Dprefix=/usr -Dvendorprefix=/usr -Dprivlib=/usr/share/perl5/core_perl -Darchlib=/usr/lib/perl5/5.38/core_perl -Dsitelib=/usr/share/perl5/site_perl -Dsitearch=/usr/lib/perl5/5.38/site_perl -Dvendorlib=/usr/share/perl5/vendor_perl -Dvendorarch=/usr/lib/perl5/5.38/vendor_perl -Dscriptdir=/usr/bin/core_perl -Dsitescript=/usr/bin/site_perl -Dvendorscript=/usr/bin/vendor_perl -Dinc_version_list=none -Dman1ext=1perl -Dman3ext=3perl -Dlddlflags=-shared -Wl,-O1 -Wl,--sort-common -Wl,--as-needed -Wl,-z,relro -Wl,-z,now -Wl,-z,pack-relative-relocs -flto=auto -Dldflags=-Wl,-O1 -Wl,--sort-common -Wl,--as-needed -Wl,-z,relro -Wl,-z,now -Wl,-z,pack-relative-relocs -flto=auto -Dloclibpth=/usr/lib/db5.3 -Dlocincpth=/usr/include/db5.3'
hint=recommended
useposix=true
d_sigaction=define
useithreads=define
usemultiplicity=define
use64bitint=define
use64bitall=define
uselongdouble=undef
usemymalloc=n
default_inc_excludes_dot=define
Compiler:
cc='cc'
ccflags ='-D_REENTRANT -D_GNU_SOURCE -fwrapv -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/include/db5.3 -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64'
optimize='-march=x86-64 -mtune=generic -O2 -pipe -fno-plt -fexceptions -Wp,-D_FORTIFY_SOURCE=2 -Wformat -Werror=format-security -fstack-clash-protection -fcf-protection -g -ffile-prefix-map=/build/perl/src=/usr/src/debug/perl -flto=auto'
cppflags='-D_REENTRANT -D_GNU_SOURCE -fwrapv -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/include/db5.3'
ccversion=''
gccversion='13.2.1 20230801'
gccosandvers=''
intsize=4
longsize=8
ptrsize=8
doublesize=8
byteorder=12345678
doublekind=3
d_longlong=define
longlongsize=8
d_longdbl=define
longdblsize=16
longdblkind=3
ivtype='long'
ivsize=8
nvtype='double'
nvsize=8
Off_t='off_t'
lseeksize=8
alignbytes=8
prototype=define
Linker and Libraries:
ld='cc'
ldflags ='-Wl,-O1 -Wl,--sort-common -Wl,--as-needed -Wl,-z,relro -Wl,-z,now -Wl,-z,pack-relative-relocs -flto=auto -fstack-protector-strong -L/usr/lib/db5.3'
libpth=/usr/local/lib /usr/lib /usr/lib/db5.3
libs=-lpthread -lgdbm -ldb -ldl -lm -lcrypt -lutil -lc -lgdbm_compat
perllibs=-lpthread -ldl -lm -lcrypt -lutil -lc
libc=/lib/../lib/libc.so.6
so=so
useshrplib=true
libperl=libperl.so
gnulibc_version='2.39'
Dynamic Linking:
dlsrc=dl_dlopen.xs
dlext=so
d_dlsymun=undef
ccdlflags='-Wl,-E -Wl,-rpath,/usr/lib/perl5/5.38/core_perl/CORE'
cccdlflags='-fPIC'
lddlflags='-shared -Wl,-O1 -Wl,--sort-common -Wl,--as-needed -Wl,-z,relro -Wl,-z,now -Wl,-z,pack-relative-relocs -flto=auto -L/usr/lib/db5.3 -fstack-protector-strong'
Characteristics of this binary (from libperl):
Compile-time options:
HAS_LONG_DOUBLE
HAS_STRTOLD
HAS_TIMES
MULTIPLICITY
PERLIO_LAYERS
PERL_COPY_ON_WRITE
PERL_DONT_CREATE_GVSV
PERL_HASH_FUNC_SIPHASH13
PERL_HASH_USE_SBOX32
PERL_MALLOC_WRAP
PERL_OP_PARENT
PERL_PRESERVE_IVUV
PERL_USE_SAFE_PUTENV
USE_64_BIT_ALL
USE_64_BIT_INT
USE_ITHREADS
USE_LARGE_FILES
USE_LOCALE
USE_LOCALE_COLLATE
USE_LOCALE_CTYPE
USE_LOCALE_NUMERIC
USE_LOCALE_TIME
USE_PERLIO
USE_PERL_ATOF
USE_REENTRANT_API
USE_THREAD_SAFE_LOCALE
Built under linux
Compiled at Feb 11 2024 19:15:41
@INC:
/usr/lib/perl5/5.38/site_perl
/usr/share/perl5/site_perl
/usr/lib/perl5/5.38/vendor_perl
/usr/share/perl5/vendor_perl
/usr/lib/perl5/5.38/core_perl
/usr/share/perl5/core_perl
This bug is in ..../File/Spec/Unix.pm https://github.com/Perl/perl5/blob/bb1192d2e523bf790d192a2003e3bc9d81f9f8da/dist/PathTools/lib/File/Spec/Unix.pm#L256
Here, split should be passed a negative value for LIMIT: If LIMIT is negative, it is treated as if it were instead arbitrarily large; as many fields as possible are produced.
According to the POSIX Specifications for PATH, trailing colons are counted as empty elements: A zero-length prefix is a legacy feature that indicates the current working directory. It appears as two adjacent <colon> characters ( "::" ), as an initial <colon> preceding the rest of the list, or as a trailing <colon> following the rest of the list
I am willing to create a PR to fix this, however I'm not sure which other platforms this bug affects.
OS2.pm, Win32.pm, and Unix.pm all use split() to split the $PATH variable and as such are likely susceptible to this bug.
I'm not sure the conventions on Windows or OS2, so I am going to wait until I recieve feedback to start a PR.
Windows searches the current directory first by default anyway:
# argv.exe just dumps argv
C:\Users\Tony\dev\perl\git>copy argv.exe jar.exe
1 file(s) copied.
C:\Users\Tony\dev\perl\git>jar
0: 'jar'
C:\Users\Tony\dev\perl\git>del jar.exe
C:\Users\Tony\dev\perl\git>jar
Usage: jar [OPTION...] [ [--release VERSION] [-C dir] files] ...
Try `jar --help' for more information.
jar.exe is in the first directory in PATH
So I don't think it matters on Win32.
I am willing to create a PR to fix this, however I'm not sure which other platforms this bug affects. OS2.pm, Win32.pm, and Unix.pm all use
split()to split the$PATHvariable and as such are likely susceptible to this bug.I'm not sure the conventions on Windows or OS2, so I am going to wait until I recieve feedback to start a PR.
Based on @tonycoz's feedback, I recommend creating a pull request consisting of 2 commits.
The first commit should adjust that split line in lib/File/Spec/Unix.pm as you suggest. It should add tests, probably to dist/PathTools/t/Spec.t that would fail if run today but will pass after your code changes. This first commit should also increment $VERSION in all .pm files in the dist/PathTools/ tree in the core distribution (including Cwd.pm). Please make sure that all the tests in dist/PathTools/t/*.t PASS, and please make sure that make test_porting also PASSes.
The second commit should adjust the split line in lib/File/Spec/OS2.pm. I'm suggesting that you do that in a second commit because we probably don't have an OS2 available for testing and if we need to back that change out in the future, it will be easier to have it in a commit of its own.
Also, in the first of the two commits, please run perl Porting/updateAUTHORS.pl to add your name and preferred email address.
@jkeenan Should the second commit (changing OS2.pm) also increment $VERSION? Or should $VERSION only be incremented once?
@jkeenan Should the second commit (changing
OS2.pm) also increment$VERSION? Or should$VERSIONonly be incremented once?
$VERSION should only be incremented once, and it should be the same in all *.pm files in the distribution.
Okay, I'll update them to match. Out of curiosity, why don't the $VERSION values match in bleed?
> git sw -q blead && grep -r 'our \$VERSION =' dist/PathTools/
dist/PathTools/Cwd.pm:our $VERSION = '3.90';
dist/PathTools/lib/File/Spec.pm:our $VERSION = '3.90';
dist/PathTools/lib/File/Spec/Cygwin.pm:our $VERSION = '3.91';
dist/PathTools/lib/File/Spec/Epoc.pm:our $VERSION = '3.91';
dist/PathTools/lib/File/Spec/VMS.pm:our $VERSION = '3.91';
dist/PathTools/lib/File/Spec/Functions.pm:our $VERSION = '3.91';
dist/PathTools/lib/File/Spec/AmigaOS.pm:our $VERSION = '3.91';
dist/PathTools/lib/File/Spec/Win32.pm:our $VERSION = '3.91';
dist/PathTools/lib/File/Spec/Mac.pm:our $VERSION = '3.91';
dist/PathTools/lib/File/Spec/OS2.pm:our $VERSION = '3.91';
dist/PathTools/lib/File/Spec/Unix.pm:our $VERSION = '3.91';
Okay, I'll update them to match. Out of curiosity, why don't the
$VERSIONvalues match inbleed?> git sw -q blead && grep -r 'our \$VERSION =' dist/PathTools/ dist/PathTools/Cwd.pm:our $VERSION = '3.90'; dist/PathTools/lib/File/Spec.pm:our $VERSION = '3.90'; dist/PathTools/lib/File/Spec/Cygwin.pm:our $VERSION = '3.91'; dist/PathTools/lib/File/Spec/Epoc.pm:our $VERSION = '3.91'; dist/PathTools/lib/File/Spec/VMS.pm:our $VERSION = '3.91'; dist/PathTools/lib/File/Spec/Functions.pm:our $VERSION = '3.91'; dist/PathTools/lib/File/Spec/AmigaOS.pm:our $VERSION = '3.91'; dist/PathTools/lib/File/Spec/Win32.pm:our $VERSION = '3.91'; dist/PathTools/lib/File/Spec/Mac.pm:our $VERSION = '3.91'; dist/PathTools/lib/File/Spec/OS2.pm:our $VERSION = '3.91'; dist/PathTools/lib/File/Spec/Unix.pm:our $VERSION = '3.91';
Error on our part. I have submitted https://github.com/Perl/perl5/pull/22404 to correct. Thanks for spotting that.