[darcs-users] patches to darcs.cgi

[Ben Crowell]

Here are some patches to darcs.cgi that improve its error handling,
and fix a problem with the use of the -T pragma with $ENV{'PATH'}.
I'd intended to submit the patches via darcs, but I've given up
on trying to use darcs.

============================================================

38a39
> use File::Spec::Functions;
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< ## "/etc/cgi.conf".  The syntax accepts equals signs or simply
---
> ## "cgi.conf".  The syntax accepts equals signs or simply
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> our $conf_file = ''; # global variable for use by read_conf()
> foreach my $possible_conf_file(
>     '/etc/darcs/cgi.conf', # typical Linux location
>     '/usr/local/etc/darcs/darcs/cgi.conf', # FreeBSD location
>   ) {
>   if (-r $possible_conf_file) {
>     $conf_file = $possible_conf_file;
>     last;
>   }
> }
> die_with_error("unable to locate cgi.conf in any of the likely places")
>   if !$conf_file;
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< $ENV{'PATH'} = read_conf('PATH', $ENV{'PATH'});
---
> # The following used to be $ENV{'PATH'} = read_conf('PATH',$ENV{'PATH'}),
> # but that was insecure, and caused an error due to taint checking.
> my $new_path = read_conf('PATH','/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/bin:/usr/local/sbin');
> if ($new_path =~ m@^([:/\w]+)$@) {
>   # The result of the pattern match, $1, is untainted. Really the reason we trust it is that we
>   # assume cgi.conf is trustworthy.
>   $ENV{'PATH'} = $1;
> }
> else {
>   die_with_error("path $new_path contains illegal characters");
> }
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> die_if_program_not_available($darcs_program);
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> die_if_program_not_available($xslt_program);
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> die_with_error("directory $repository_root does not exist") if !-d $repository_root;
> die_with_error("directory $repository_root is not readable") if !-r $repository_root;
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> die_with_error("directory $template_root does not exist") if !-d $template_root;
> die_with_error("directory $template_root is not readable") if !-r $template_root;
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< 
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> foreach my $xslt_file($xslt_annotate,$xslt_browse,$xslt_patches,$xslt_repos,$xslt_rss,$xslt_errors) {
>   die_if_file_not_available($xslt_file);
> }
> 
68c100
< # path, not a local file system path. The default will caues darcs.cgi
---
> # path, not a local file system path. The default will cause darcs.cgi
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> # Don't check for existence, not a local filesystem path.
74a108
> die_if_file_not_available($css_styles);
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> die_if_file_not_available($xml_errors);
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<   if (open(CGI_CONF, "/etc/darcs/cgi.conf")) {
---
>   if (open(CGI_CONF, "<$conf_file")) {
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>   else {
>     die_with_error("Error opening file $conf_file for input, $!");
>   }
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<     open $pipe, "| $xslt_program $args $xslt -";
---
>     open $pipe, "| $xslt_program $args $xslt -" 
>              or die_with_error("error opening pipe to $xslt_program");
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<     open(DARCS, "$darcs_program '$cmd' $args $target|");
---
>     open(DARCS, "$darcs_program '$cmd' $args $target|")
>          or die "error running $darcs_program";
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> }
> 
> # Write an error message to the web server's log file.
> sub log_error {
>   my $message = shift;
>   print STDERR "$message\n";
> }
> 
> sub die_with_error {
>   my $message = shift;
>   log_error($message);
>   exit;  
> }
> 
> sub die_if_file_not_available {
>   my $file = shift;
>   die_with_error("file $file does not exist, check the file $conf_file") if !-e $file;
>   die_with_error("file $file is not readable, check the file $conf_file") if !-r $file;
> }
> 
> sub die_if_program_not_available {
>   my $program = shift;
>   # In the following line, the first clause is meant for the case where the full path to
>   # the program has been given explicitly in cgi.conf, while the second clause is for
>   # the case where it has to be found in $ENV{PATH}.
> 	my $available = -x $program ||
>              grep -x File::Spec::Functions::catfile( $_, $program ), File::Spec::Functions::path;
>   die_with_error(<<ERR) if !$available;
>     program $program not found in
>        $ENV{PATH}   ;
>     If it's not installed, please install it. If it is installed, please 
>     give an explicit path to it in cgi.conf, e.g.,
>        xsltproc=/path/to/xsltproc
>     or
>        darcs=/path/to/darcs
> ERR