October 2001
Beginner
528 pages
15h 20m
English
Content preview from Perl for Web Site Management
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Chapter 12. Running a CGI Guestbook
We’re going to return now to the subject of CGI scripting, in order to create a guestbook script so that visitors to our web site can leave a pithy comment for others to read. Although some people view web guestbooks as vain and silly, I’ve chosen to present one here for two reasons. First, plenty of people (myself included) think the Web’s greatest possibilities lie in the area of fostering two-way communication, and a guestbook is a nice (albeit simple) step in that direction. Second, a guestbook script will let us look at two issues that are very important to web programmers.
The first issue involves how to safely handle untrusted data. Letting
outside users submit data that will be stored in a file on the web
server and displayed to other visitors to our site creates several
security-related problems. Fortunately, Perl has a feature called
tainting that is very helpful in combating those
problems.
The second issue involves multiple users trying to update the same
data at the same time. In this chapter we’ll see how to use
something called file locking to solve that
problem.
The Guestbook Script
The flowchart in Figure 12-1 shows the sequence of
actions that our guestbook script, guestbook.cgi,
will take.
Figure 12-1. The sequence of actions taken by the guestbook.cgi script
As the flowchart shows, the program begins by printing the top of the ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.