Translate code from PERL to C - image files

Posted on 1997-06-03
Last Modified: 2010-04-15
I have the following PERL script that works fine. It sends a
picture to a browser as a response to a
<img src="http://www.***.com/cgi-bin/">
tag with the picture number is passed as shown.

Can you please show me how can one do the same thing using a
CGI script in C that can be compiled. Just in case you need,
here is info about the server:

server software is Apache/1.2b10
Perl version is 5.003
server protocol is HTTP/1.0
Common Gateway Interface (CGI) version is CGI/1.1.

Also, how do I go about compiling?

Thank you for your help.
Sincerely yours,
Laurentiu Traineanu






sub DisplayPicture
    print "Content-type: image/gif\r\n";
    print "\r\n";

Question by:neis
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Author Comment

ID: 1250734
Edited text of question

Expert Comment

ID: 1250735
Yes I will code it for you, but that's more worth than 100 points...

Author Comment

ID: 1250736
Ok, how much?
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Expert Comment

ID: 1250737
250 incl. the source - because you have to compile it on your system. I think it's a UNIX-box (Apache)?!?

Accepted Solution

julio011597 earned 100 total points
ID: 1250738
Sorry for the intrusion, but i think 100 points are enough:)

Here is the code:

/* sendpic.c */

#include <stdlib.h>
#include <stdio.h>

#define PIC_PATH "/usr/local/etc/httpd/cgi-bin"

int main(int argc, char **argv)
  char buff[BUFSIZ];
  FILE *pgif;

  /* look at fread(3): give items_read the type */
  /* returned by fread (size_t on my system) */
  register size_t items_read;

  /* let's print the header */
  fputs("Content-Type: image/gif\n\n", stdout);

  if(argc == 1) {
    /* in C, first argument is the command run */
    /* so, handle no parameter passed: */
    /* maybe show a default picture */
    /* then exit saying: the cgi didn't fail! */
    return EXIT_SUCCESS;

  /* let's put file name in buff */
  sprintf(buff, "%s/%s.gif", PIC_PATH, *(argv+1));

  if(!(pgif = fopen(buff, "r"))) {
    /* gif not found: again, maybe show a default image */
    return EXIT_SUCCESS;

  while(items_read = fread((void *)buff, sizeof(char), BUFSIZ, pgif))
    fwrite((void *)buff, sizeof(char), items_read, stdout);

  return EXIT_SUCCESS;

Compile it with:

$ cc -o sendpic.cgi sendpic.c

Note that in C/Unix you handle binary files with fread() and fwrite() - don't need to specify binary mode.
Also, you needn't unbuffer stdout in this case, because you are sending a self-standing buch of data; also, unbuffering makes things slower.

Rgds, julio

Expert Comment

ID: 1250739
Give him the points, learn C and you will not have to give points away for such easy problems. To julio: I only wanted to clear this section from complete-program-searchers. This is for special C-problems.

Expert Comment

ID: 1250740
Hello beckers,

i may agree with you, this forum is mainly intended for advice, not for ready products.

Anyway, there's not such a strong rule about this, so, to show my position:

i never ask homeworks;
i sometimes give complete programs, because - say - Mr.neis doesn't care about becoming a programmer: he's just 'paying' for some help.

BTW, you would have answered this for 250 points, so what's indeed your point? ;)

Cheers, julio

Author Comment

ID: 1250741
Thank you julio for your help. It is exactly what I was looking for. You are right, I don't care to become a C programmer, I just need to replace the PERL program with a C one.

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