gistfile1.txt

#include <stdio.h>

#include <stdlib.h>

#define MAXLEN 80

#define EXTRA 5

/* 4 for field name "data", 1 for "=" */

#define MAXINPUT MAXLEN+EXTRA+2

/* 1 for added line break, 1 for trailing NUL */

#define DATAFILE "/srv/httpd/htdocs/data.txt"


void unencode(char *src, char *last, char *dest)

{

 for(; src != last; src++, dest++)

   if(*src == '+')

     *dest = ' ';

   else if(*src == '%') {

     int code;

     if(sscanf(src+1, "%2x", &code) != 1) code = '?';

     *dest = code;

     src +=2; }     

   else

     *dest = *src;

 *dest = '\n';

 *++dest = '\0';

}


int main(void)

{

char *lenstr;

char input[MAXINPUT], data[MAXINPUT];

long len;

printf("%s%c%c\n",

"Content-Type:text/html;charset=iso-8859-1",13,10);

printf("<TITLE>Response</TITLE>\n");

lenstr = getenv("CONTENT_LENGTH");

if(lenstr == NULL || sscanf(lenstr,"%ld",&len)!=1 || len > MAXLEN)

  printf("<P>Error in invocation - wrong FORM probably.");

else {

  FILE *f;

  fgets(input, len+1, stdin);

  unencode(input+EXTRA, input+len, data);

  f = fopen(DATAFILE, "a");

  if(f == NULL)

    printf("<P>Sorry, cannot store your data.");

  else

    fputs(data, f);

  fclose(f);

  printf("<P>Thank you! Your contribution has been stored.");

  }

return 0;

}