mention portability caveat about C<use Errno 'EFOO'>

[perl5.git] / ext / Errno / Errno_pm.PL

diff --git a/ext/Errno/Errno_pm.PL b/ext/Errno/Errno_pm.PL
index 0d3ca75..e81afb2 100644 (file)
--- a/ext/Errno/Errno_pm.PL
+++ b/ext/Errno/Errno_pm.PL
@@ -21,7 +21,7 @@ unlink "errno.c" if -f "errno.c";
 sub process_file {
     my($file) = @_;
 
-    return unless defined $file;
+    return unless defined $file and -f $file;
 
     local *FH;
     if (($^O eq 'VMS') && ($Config{vms_cc_type} ne 'gnuc')) {
@@ -31,7 +31,7 @@ sub process_file {
        }     
     } else {
        unless(open(FH,"< $file")) {
-           # This file could be a temporay file created by cppstdin
+           # This file could be a temporary file created by cppstdin
            # so only warn under -w, and return
             warn "Cannot open '$file'" if $^W;
             return;
@@ -44,6 +44,24 @@ sub process_file {
    close(FH);
 }
 
+my $cppstdin;
+
+sub default_cpp {
+    unless (defined $cppstdin) {
+       use File::Spec;
+       $cppstdin = $Config{cppstdin};
+       my $upup_cppstdin = File::Spec->catfile(File::Spec->updir,
+                                               File::Spec->updir,
+                                               "cppstdin");
+       my $cppstdin_is_wrapper =
+           ($cppstdin eq 'cppstdin'
+               and -f $upup_cppstdin
+                   and -x $upup_cppstdin);
+       $cppstdin = $upup_cppstdin if $cppstdin_is_wrapper;
+    }
+    return "$cppstdin $Config{cppflags} $Config{cppminus}";
+}
+
 sub get_files {
     my %file = ();
     # VMS keeps its include files in system libraries (well, except for Gcc)
@@ -58,6 +76,9 @@ sub get_files {
     } elsif ($^O eq 'os390') {
        # OS/390 C compiler doesn't generate #file or #line directives
        $file{'/usr/include/errno.h'} = 1;
+    } elsif ($^O eq 'vmesa') {
+       # OS/390 C compiler doesn't generate #file or #line directives
+       $file{'../../vmesa/errno.h'} = 1;
     } else {
        open(CPPI,"> errno.c") or
            die "Cannot open errno.c";
@@ -71,7 +92,7 @@ sub get_files {
            open(CPPO,"$Config{cpprun} $Config{cppflags} errno.c |") or
                die "Cannot run '$Config{cpprun} $Config{cppflags} errno.c'";
        } else {
-           my $cpp = "$Config{cppstdin} $Config{cppflags} $Config{cppminus}";
+           my $cpp = default_cpp();
            open(CPPO,"$cpp < errno.c |") or
                die "Cannot exec $cpp";
        }
@@ -84,7 +105,16 @@ sub get_files {
            $pat = '^#(?:line)?\s*\d+\s+"([^"]+)"';
        }
        while(<CPPO>) {
-           $file{$1} = 1 if /$pat/o;
+           if ($^O eq 'os2' or $^O eq 'MSWin32') {
+               if (/$pat/o) {
+                  my $f = $1;
+                  $f =~ s,\\\\,/,g;
+                  $file{$f} = 1;
+               }
+           }
+           else {
+               $file{$1} = 1 if /$pat/o;
+           }
        }
        close(CPPO);
     }
@@ -94,6 +124,10 @@ sub get_files {
 sub write_errno_pm {
     my $err;
 
+    # quick sanity check
+
+    die "No error definitions found" unless keys %err;
+
     # create the CPP input
 
     open(CPPI,"> errno.c") or
@@ -118,7 +152,7 @@ sub write_errno_pm {
        open(CPPO,"$Config{cpprun} $Config{cppflags} errno.c |") or
            die "Cannot run '$Config{cpprun} $Config{cppflags} errno.c'";
     } else {
-       my $cpp = "$Config{cppstdin} $Config{cppflags} $Config{cppminus}";
+       my $cpp = default_cpp();
        open(CPPO,"$cpp < errno.c |")
            or die "Cannot exec $cpp";
     }
@@ -146,8 +180,9 @@ use Exporter ();
 use Config;
 use strict;
 
-\$Config{'myarchname'} eq "$Config{'myarchname'}" or
-       die "Errno architecture ($Config{'myarchname'}) does not match executable architecture (\$Config{'myarchname'})";
+"\$Config{'archname'}-\$Config{'osvers'}" eq
+"$Config{'archname'}-$Config{'osvers'}" or
+       die "Errno architecture ($Config{'archname'}-$Config{'osvers'}) does not match executable architecture (\$Config{'archname'}-\$Config{'osvers'})";
 
 \$VERSION = "$VERSION";
 \@ISA = qw(Exporter);
@@ -196,13 +231,14 @@ sub TIEHASH { bless [] }
 sub FETCH {
     my ($self, $errname) = @_;
     my $proto = prototype("Errno::$errname");
+    my $errno = "";
     if (defined($proto) && $proto eq "") {
        no strict 'refs';
-        return $! == &$errname;
+       $errno = &$errname;
+        $errno = 0 unless $! == $errno;
     }
-    require Carp;
-    Carp::confess("No errno $errname");
-} 
+    return $errno;
+}
 
 sub STORE {
     require Carp;
@@ -217,13 +253,12 @@ sub NEXTKEY {
     while(($k,$v) = each %Errno::) {
        my $proto = prototype("Errno::$k");
        last if (defined($proto) && $proto eq "");
-       
     }
     $k
 }
 
 sub FIRSTKEY {
-    my $s = scalar keys %Errno::;
+    my $s = scalar keys %Errno::;      # initialize iterator
     goto &NEXTKEY;
 }
 
@@ -252,8 +287,8 @@ C<Errno> defines and conditionally exports all the error constants
 defined in your system C<errno.h> include file. It has a single export
 tag, C<:POSIX>, which will export all POSIX defined error numbers.
 
-C<Errno> also makes C<%!> magic such that each element of C<%!> has a non-zero
-value only if C<$!> is set to that value, eg
+C<Errno> also makes C<%!> magic such that each element of C<%!> has a
+non-zero value only if C<$!> is set to that value. For example:
 
     use Errno;
     
@@ -265,6 +300,20 @@ value only if C<$!> is set to that value, eg
         } 
     } 
 
+If a specified constant C<EFOO> does not exist on the system, C<$!{EFOO}>
+returns C<"">.  You may use C<exists $!{EFOO}> to check whether the
+constant is available on the system.
+
+=head1 CAVEATS
+
+Importing a particular constant may not be very portable, because the
+import will fail on platforms that do not have that constant.  A more
+portable way to set C<$!> to a valid value is to use:
+
+    if (exists &Errno::EFOO) {
+        $! = &Errno::EFOO;
+    }
+
 =head1 AUTHOR
 
 Graham Barr <gbarr@pobox.com>