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[MacPerl] newbie problem: Why can't I write to a file?
I'm new to MacPerl and so far am impressed with its power. However, I am
having a problem with a practice script I got from the book CGI Programming
by Shishir Gundavaram.
This is from his guestbook example. It requires that submitted
information be appended to a file (I call it guestbook.html). All my paths
seem to be correct. It just seems that the script can't open the file.
Another possible problem, before I start showing you code, is that I'm
using NetPresenz. I set it up guests to have read only access through
Netpresenz set-up, and I only allow guests 'see-folders' and 'read-files'
in my folder that has the cgi script and the html file (I don't allow them
to 'make-changes'). A third possible non-code problem is that the
guestbook.html file is just a plain text file created by Simpletext (also,
it is completely empty). Do the files that MacPerl scripts write to have to
be a certain creator type?
Ok, onto the problem. I apologize for posting all of the code, but I'm
not sure what to include and it is fairly short. I removed all of the
comments and added new comments at the point where I get my error.
(The program is able to execute the first time you access it. In my case I
use
http://host-41.subnet-96.med.umich.edu/test/guestbook.cgi?add and that runs
through the appropriate code. However, this code doesn't require that any
files be opened. After presenting me a form to fill out, I fill this out
and hit submit. It then runs until it gets to the point that it has to open
the file and insteads gives me an error.)
#!/usr/local/bin/perl
$webmaster = "comrade\@umich\.edu";
$method = $ENV{'REQUEST_METHOD'};
$script = $ENV{'SCRIPT_NAME'};
$query = $ENV{'QUERY_STRING'};
$document_root = "Pod People/Pub/www/test";
$guest_file = "/guestbook.html";
$full_path = $document_root . $guest_file;
$exclusive_lock = 2;
$unlock = 8;
if ($method eq "GET") {
if ($query eq "add") {
$date_time = &get_date_time();
&MIME_header ("text/html", "Robert Decker's guestbook");
print <<End_Of_Guestbook_Form;
<P>
The current time is: $date_time
<HR>
<FORM METHOD="POST">
<PRE>
<EM>Full name</EM>: <INPUT TYPE="text" NAME="name" SIZE=40>
<EM>Email Address</EM>: <INPUT TYPE="text" NAME="from" SIZE=40>
<EM>WWW Server</EM>: <INPUT TYPE="text" NAME="www" SIZE=40>
</PRE>
<P>
<EM>Please enter the information that you'd like to add:</EM><BR>
<TEXTAREA ROWS=3 COLS=60 NAME="comments"></TEXTAREA><P>
<INPUT TYPE="submit" VALUE="Add to Guestbook">
<INPUT TYPE="reset" VALUE="Clear Information"><BR>
<P>
</FORM>
<HR>
End_Of_Guestbook_Form
} else {
if (open(GUESTBOOK, "<" . $full_path) ) {
flock (GUESTBOOK, $exclusive_lock);
&MIME_header ("text/html", "Here is my guestbook!");
while (<GUESTBOOK>) {
print;
}
flock (GUESTBOOK, $unlock);
close(GUESTBOOK);
} else {
&return_error (500, "Guestbook File Error",
"Cannot read from the guestbook file [$full_path].");
}
}
#The next few lines are where the problem occurs. I understand that the
">>" lets MacPerl know that I want to open the file to have information
appended to it. However, it can't seem to open it and instead goes down to
the error message below.
} elsif ($method eq "POST") {
if ( open (GUESTBOOK, ">>" . $full_path) ) {
flock (GUESTBOOK, $exclusive_lock);
$date_time = &get_date_time();
&parse_form_data (*FORM);
$FORM{'name'} = "Anonymous User" if !$FORM{'name'};
$FORM{'from'} = $ENV{'REMOTE_HOST'} if !$FORM{'from'};
$FORM{'comments'} =~ s/\n/<BR>/g;
print GUESTBOOK <<End_Of_Write;
<P>
<B>$date_time:</B><BR>
Message from <EM>$FORM{'name'}</EM> at <EM>$FORM{'from'}</EM>:
</P>
$FORM{'comments'}
End_Of_Write
if ($FORM{'www'}) {
print GUESTBOOK <<End_of_Web_Address;
<P>
$FORM{'name'} can also be reached at:
<A HREF="$FORM{'www'}">$FORM{'www'}</A>
End_of_Web_Address
}
print GUESTBOOK "<P><HR>";
flock (GUESTBOOK, $unlock);
close(GUESTBOOK);
&MIME_header ("text/html", "Thank You!");
print <<End_of_Thanks;
Thanks for visiting my guestbook. If you would like to see the
guestbook,
click <A HREF="$guest_file">here</A> (actual guestbook file),
or <A HREF="$script">here</A> (guestbook script without a query).
End_of_Thanks
} else {
&return_error (500, "Guestbook File Error",
"Cannot write to the guestbook file [$full_path].")
}
} else {
&return_error (500, "Server Error",
"Server uses unsupported method");
}
exit(0);
sub MIME_header
{
local ($mime_type, $title_string, $header) = @_;
if (!$header) {
$header = $title_string;
}
print "Content-type: ", $mime_type, "\n\n";
print "<HTML>", "\n";
print "<HEAD><TITLE>", $title_string, "</TITLE></HEAD>", "\n";
print "<BODY>", "\n";
print "<H1>", $header, "</H1>";
print "<HR>";
}
sub get_date_time
{
$months = "January/Febraury/March/April/May/June/July/" .
"August/September/October/November/December";
$weekdays = "Sunday/Monday/Tuesday/Wednesday/Thursday/Friday/Saturday";
local ($sec, $min, $hour, $day, $nmonth, $year, $wday, $yday, $isdst)
= localtime(time);
if ($hour > 12) {
$hour -= 12;
$ampm = "pm";
} else {
$ampm = "am";
}
if ($hour == 0) {
$hour = 12;
}
$year += 1900;
$week = (split("/", $weekdays))[$wday];
$month = (split("/", $months))[$nmonth];
$time_string = sprintf("%s, %s, %s, %s, - %02d:%02d:%02d %s",
$week, $month, $day, $year, $hour, $min, $sec, $ampm);
return ($time_string);
}
sub parse_form_data
{
local (*FORM_DATA) = @_;
local ( $request_method, $post_info, @key_value_pairs,
$key_value, $key, $value);
read (STDIN, $post_info, $ENV{'CONTENT_LENGTH'});
@key_value_pairs = split (/&/, $post_info);
foreach $key_value (@key_value_pairs) {
($key, $value) = split (/=/, $key_value);
$value =~ s/%([\dA-Fa-f][\dA-Fa-f])/pack ("C", hex ($1))/eg;
if (defined($FORM_DATA{$key})) {
$FORM_DATA{$key} = join ("\0", $FORM_DATA{$key}, $value);
} else {
$FORM_DATA{$key} = $value;
}
}
}
sub return_error
{
local ($status, $keyword, $message) = @_;
print "Content-type: text/html", "\n";
print "Status: ", $status, " ", $keyword, "\n\n";
print <<End_of_Error;
<title>CGI Program - Unexpected Error</title>
<h1>$keyword</h1>
<hr>$message</hr>
Please contact $webmaster for more information.
End_of_Error
exit(1);
}
-- G
/\ /\ /\ /\ /\ /\ /\ /\ /\ /\ /\ / T A
001\/1100\/10\/1010\/0110\/00\/1111\/0111\/CT\/TCGA\/GTAC\/C A \C
110/\0011/\01/\0101/\1001/\11/\0000/\1000/\GA/\AGCT/\CATG/\GA / G
\/ \/ \/ \/ \/ \/ \/ \/ \/ \/ \/ \/ \ T
Robert A. Decker voice: (313) 936-9779 A T
Computer Consultant I
Department of Radiology "...millionaire stuntman - half jackalope."
University of Michigan -Chris Elliott