0. What is cgihtml?

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cgihtml is a collection of routines for parsing World Wide Web (WWW) Common Gateway Interface (CGI) input and outputting HyperText Markup Language (HTML).

0.1. What are the advantages of cgihtml?

cgihtml simplifies the task of parsing CGI input and producing HTML output. Tasks which would normally require several lines of C can be reduced to just a few.

Additionally, I have attempted to include general routines which CGI programmers often find themselves using. Consequently, some of the complexities of CGI programming are hidden. On the other hand, if you want to know what's going on, source is included.

0.2. Why C?

The purpose of CGI programs is to take data and manipulate it as the web programmer desires. Since CGI programs are often dealing with text manipulation, Perl or other scripting languages is an ideal way of producing CGI scripts. (I highly recommend Steve Brenner's cgi-lib.pl package for Perl programmers interested in producing CGI scripts).

However, interpreted scripting languages tend to be relatively large. This rarely has a major effect on the performance of your server (unless you are a high-traffic site). However, if this is a concern of your's, a program written in C is often several times smaller than the equivalent program written in Perl. There's definitely a performance improvement when using CGI programs written in C, although the performance is not likely to be noticeable.

Additionally, some servers (notably Netsite and Apache) have APIs so that CGI programs can be written as extensions to the server, rather than as separate programs. This greatly improves performance, especially on high-traffic sites. The best way to take advantage of these APIs is to write your programs in C.

Or, you might fall under one of the following categories:

You don't know Perl
You don't like Perl
You like C

In which case, you will hopefully find cgihtml useful.

0.3. Changes from version 1.0

Renamed functions to use a more standard naming scheme. This will break old programs; make sure you search and replace to rename the appropriate functions.

     Old function name     New function name
     -----------------     -----------------
     ReadParse             read_cgi_input
     val                   cgi_val
     PrintHeader           html_header
     MethodGet             method_get
     PrintEntries          print_entries

read_cgi_input now returns a 1 if input is received, and a 0 otherwise. ReadParse in version 1.0 did just the opposite.
Used dynamically allocated strings rather than arrays of characters. There is now no theoretical limit to the size of item.name or item.value.
Added string-lib library:
- newstr()
- getstr()
New cgi-lib functions:
- accept_images() -- determines whether the client browser will accept images.
- escape_input() -- filter out shell metacharacters for security purposes
New html-lib functions:
- mime_header()
- no_parse_header()
- show_html_page()
- h1() ... h6()
Added two new example programs: index-sample.cgi and nph-ignore.cgi
Removed example: mailform.cgi
Included debug-cgi.sh, a shell script which runs CGI programs from the command line to help debug code.

0.4. Files included in this package

The following files are included in this package:

   README            - Read this first
   CHANGES           - version revision information
   TODO              - Things I want to eventually implement
   docs/             - Documentation directory
   debug-cgi.sh      - Shell script to help debug CGI code

   cgi-lib.c         - Source code
   html-lib.c
   llist.c
   string-lib.c

   cgi-lib.h         - Header files for routines
   html-lib.h
   llist.h
   string-lib.h

   query-results.c   - Example programs
   mail.cgi.c
   index-sample.cgi.c
   nph-ignore.cgi.c

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eekim@fas.harvard.edu

Last modified: Sun Aug 13 16:23:58 1995