Extensive documentation patch redux

[perl5.git] / lib / Cwd.pm

diff --git a/lib/Cwd.pm b/lib/Cwd.pm
index 680fc3e..7f8ef65 100644 (file)
--- a/lib/Cwd.pm
+++ b/lib/Cwd.pm
@@ -38,6 +38,8 @@ Returns the current working directory.
 
 Re-implements the getcwd(3) (or getwd(3)) functions in Perl.
 
+Taint-safe.
+
 =item cwd
 
     my $cwd = cwd();
@@ -46,7 +48,7 @@ The cwd() is the most natural form for the current architecture. For
 most systems it is identical to `pwd` (but without the trailing line
 terminator).
 
-Unfortunately, cwd() tends to break if called under taint mode.
+Taint-safe.
 
 =item fastcwd
 
@@ -87,18 +89,25 @@ Uses the same algorithm as getcwd().  Symbolic links and relative-path
 components ("." and "..") are resolved to return the canonical
 pathname, just like realpath(3).
 
+Taint-safe.
+
 =item realpath
 
   my $abs_path = realpath($file);
 
 A synonym for abs_path().
 
+Taint-safe.
+
 =item fast_abs_path
 
-  my $abs_path = abs_path($file);
+  my $abs_path = fast_abs_path($file);
 
 A more dangerous, but potentially faster version of abs_path.
 
+This function is B<Not> taint-safe : you can't use it in programs
+that work under taint mode.
+
 =back
 
 =head2 $ENV{PWD}
@@ -183,13 +192,24 @@ foreach my $try (qw(/bin/pwd /usr/bin/pwd)) {
         last;
     }
 }
-$pwd_cmd ||= 'pwd';
+unless ($pwd_cmd) {
+    if (-x '/QOpenSys/bin/pwd') { # OS/400 PASE.
+        $pwd_cmd = '/QOpenSys/bin/pwd' ;
+    } else {
+        # Isn't this wrong?  _backtick_pwd() will fail if somenone has
+        # pwd in their path but it is not /bin/pwd or /usr/bin/pwd?
+        # See [perl #16774]. --jhi
+        $pwd_cmd = 'pwd';
+    }
+}
 
 # The 'natural and safe form' for UNIX (pwd may be setuid root)
 sub _backtick_pwd {
+    local @ENV{qw(PATH IFS CDPATH ENV BASH_ENV)};
     my $cwd = `$pwd_cmd`;
-    # `pwd` may fail e.g. if the disk is full
+    # Belt-and-suspenders in case someone said "undef $/".
     local $/ = "\n";
+    # `pwd` may fail e.g. if the disk is full
     chomp($cwd) if defined $cwd;
     $cwd;
 }
@@ -199,7 +219,9 @@ sub _backtick_pwd {
 
 unless(defined &cwd) {
     # The pwd command is not available in some chroot(2)'ed environments
-    if($^O eq 'MacOS' || grep { -x "$_/pwd" } split(':', $ENV{PATH})) {
+    if( $^O eq 'MacOS' || (defined $ENV{PATH} && 
+                           grep { -x "$_/pwd" } split(':', $ENV{PATH})) ) 
+    {
        *cwd = \&_backtick_pwd;
     }
     else {
@@ -258,9 +280,9 @@ sub fastcwd {
     $path = '/' . join('/', @path);
     if ($^O eq 'apollo') { $path = "/".$path; }
     # At this point $path may be tainted (if tainting) and chdir would fail.
-    # To be more useful we untaint it then check that we landed where we started.
-    $path = $1 if $path =~ /^(.*)\z/s; # untaint
-    CORE::chdir($path) || return undef;
+    # Untaint it then check that we landed where we started.
+    $path =~ /^(.*)\z/s                # untaint
+       && CORE::chdir($1) or return undef;
     ($cdev, $cino) = stat('.');
     die "Unstable directory path, current directory changed unexpectedly"
        if $cdev != $orig_cdev || $cino != $orig_cino;
@@ -403,9 +425,10 @@ sub fast_abs_path {
     my $cwd = getcwd();
     require File::Spec;
     my $path = @_ ? shift : File::Spec->curdir;
-    CORE::chdir($path) || croak "Cannot chdir to $path:$!";
+    CORE::chdir($path) || croak "Cannot chdir to $path: $!";
     my $realpath = getcwd();
-    CORE::chdir($cwd)  || croak "Cannot chdir back to $cwd:$!";
+    -d $cwd && CORE::chdir($cwd) ||
+       croak "Cannot chdir back to $cwd: $!";
     $realpath;
 }
 
@@ -465,12 +488,18 @@ sub _dos_cwd {
 }
 
 sub _qnx_cwd {
+       local $ENV{PATH} = '';
+       local $ENV{CDPATH} = '';
+       local $ENV{ENV} = '';
     $ENV{'PWD'} = `/usr/bin/fullpath -t`;
     chop $ENV{'PWD'};
     return $ENV{'PWD'};
 }
 
 sub _qnx_abs_path {
+       local $ENV{PATH} = '';
+       local $ENV{CDPATH} = '';
+       local $ENV{ENV} = '';
     my $path = @_ ? shift : '.';
     my $realpath=`/usr/bin/fullpath -t $path`;
     chop $realpath;