web services in c with cgi

I was trying to setup a simply webservice to reply to POST requests. Earlier this was being done in tomcat which seem a little overkill to me since I already had a webserver up and running. So, a quick c program to respond to request is all that I needed. And here is the result.

/*
 * =====================================================================================
 *
 *       Filename:  Login.cpp
 *
 *    Description:
 *
 *        Version:  1.0

 *       Revision:  none
 *       Compiler:  gcc
 *
 *         Author:  Amit Agarwal (),
 *   Organization:
*
* == == == == == == == == == == == == == == == == == == == == == == == == == == == == == == == == == == == == == == == == == == =
    */
#include 
#include 
#include 


#define MAXLEN 1024

#ifdef DBG
#define DEBUG(a,b) fprintf(stderr, a, b);
#else
#define DEBUG(a,b) 
#endif

#define HEAD "n"
#define TAIL ""

int main(void)
{

    char input[MAXLEN];
    char * data;
    char*lenstr;
    long len;


    printf("%s%c%cnn",
           "Content-Type:text/xml;charset=iso-8859-1", 13, 10);

    // len = getenv("QUERY_STRING"); // This is for GET
    lenstr = getenv("CONTENT_LENGTH");
    DEBUG( "Length string is %sn", lenstr);

    if(lenstr == NULL || sscanf(lenstr,"%ld",&len)!=1 || len > MAXLEN)
        printf("Error in invocation - wrong FORM probably.");
DEBUG( "Length is %ldn", len);
{
int count=0;
while ( count < len )
input[count++] = getchar();
input[count]='?';
DEBUG ( "Read characters = %dn", count)
}

//fprintf(stderr, "VAlue is %sn", input);
///unencode(input + 5 , input + len, data);

data = input;
DEBUG("Data value is %sn", data);

printf(HEAD);
printf("Everything else goes heren");
printf(TAIL);

fprintf(stderr, "Sent resp: tid[%s], eaid[%s], tcode[%s]n", tid, eaid, tcode);
}

Additionally, the makefile:

all:
gcc -o Login Login.c -Wall

debug:
gcc -o Login Login.c -Wall -DDBG=1

And finally, compile this with make command and put in the cgi-bin folder and that is all that you need ūüôā

colorgcc – Color your compiler output on Fedora

Lets start with installing colorgcc :

sudo yum install colorgcc

Now once that is done, you will need to ensure that the call to g++, gcc and others that you want to use, you will need to create a link in the “~/bin” directory, like so:

for i in g++ gcc c++ cc 
do
    ln -s $(which colorgcc) ~/bin/$i
done

The one liner above will create the links for colorgcc as your favourite compiler in your homedir. Don’t forget to add the bin diretory to your PATH variable:

export PATH=~/bin:$PATH

And now finally the ~/.colorgccrc file taken from Ubuntu for your reference:

#
# colorgcc configuration file
#
# $Id: colorgccrc,v 1.1.1.1 1999/04/25 15:24:03 jamoyers Exp $
#
# This file should be named $HOME/.colorgccrc
#
#
# The following groups of attributes may be combined for a given color:
#
# clear         black      on_black
# reset            red        on_red
# bold            green      on_green
# underline     yellow     on_yellow
# underscore    blue       on_blue
# blink            magenta    on_magenta
# reverse       cyan       on_cyan
# concealed     white      on_white
#
# For example, srcColor: bold cyan on_yellow
#

# gccVersion: if defined, append "-" to the compiler paths
# defined hereunder. Otherwise, those paths remains as is set
# gccVersion: 4.1.1

# Define the paths to the actual location of the various compilers.
# (Currently, colorgcc only understands these: g++ gcc c++ cc g77 f77 gcj)
g++: /usr/bin/g++
gcc: /usr/bin/gcc
c++: /usr/bin/g++
cc:  /usr/bin/gcc
#g77: /usr/bin/g77
#f77: /usr/bin/g77
#gcj: /usr/bin/gcj

# Don't do color if our terminal type ($TERM) is one of these.
# (List all terminal types on one line, seperated by whitespace.)
nocolor: dumb emacs

# Text between ` and ' is usually source code.
srcColor: bold cyan

# Text other than a warning or error.
introColor: reset

# Warnings and errors both have similar formats:
#    filename:999:Message
# Each field may be assigned a different color.

# Warnings
warningFileNameColor: reset
warningNumberColor:   blue
warningMessageColor:  yellow

# Errors
errorFileNameColor: reset
errorNumberColor:   blue
errorMessageColor:  bold red

# Possible translations, if you use localized compiler.
# (List all translations on one line, seperated by whitespace.)
warningTranslations:
errorTranslations:
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Inotify Example: Introduction to Inotify with a C Program Example


Inotify Example: Introduction to Inotify with a C Program Example:

inotify utility is an effective tool to monitor and notify filesystem changes. You can specify a list of files and directories that needs to be monitored by inotify. This library is used by various other programs. For example, CPAN module Linux::Inotify is developed based on this library.
iNotify Execution Flow

On a high-level, you do the following with inotify utility.

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