[mgp-users 01214] Patch for mgp.c

[Tim Maher <tim@consultix-inc.com>]

mgp.c isn't doing any error checking on its invocations 
of xwintoppm and pnmscale via system() functions.

IMHO, this is an overly optimistic policy for a
production program, as demonstrated by some related
problems I had this weekend, so I've provided a patch below.

-Tim
*------------------------------------------------------------*
| Tim Maher (206) 781-UNIX  (866) DOC-PERL  (866) DOC-UNIX   |
| CEO, JAWCAR ("Just Another White Camel Award Recipient")   |
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*------------------------------------------------------------*

Patch for mgp.c in Magicpoint 1.09a release

44a45,53
> /* tfm mod; for WEXITSTATUS */
> /* 
> Following #include unnecessary on Linux, although symbol defined there,
> and symbol not in that header file on Solaris. I'll leave it to somebody
> else to come up with the portable solution to defining WEXITSTATUS.
> 
> #include <stdlib.h>
> */
> 
496c505,511
< 		system(buf);	/*XXX security hole*/
---
> 
> 		/* <tfm modifications> */
> 		int err;
> 		err=system(buf);	/*XXX security hole*/
> 		exit_on_failure(err,buf);
> 		/* </tfm modifications> */
> 
502c517,520
< 		system(buf);	/*XXX security hole*/
---
> 		/* <tfm modifications> */
> 		err=system(buf);	/*XXX security hole*/
> 		exit_on_failure(err,buf);
> 		/* </tfm modifications> */
1346a1365,1399
> 
> 		/* <tfm modifications> */
> static void
> exit_on_failure(err, command)
> 	int err;
> 	char *command;
> /*
> 	Tim Maher, Mon Jun 23 06:01:25 PDT 2003
> 
> 	Wrote this because I spent the whole weekend trying to
> 	figure out why my image files were turning out corrupted,
> 	and eventually noticed the lack of error checking on system()
> 	calls, which was part of the problem.
> 
> 	Haven't written C-code in a few decades, but I think I've got
> 	it right! 8-}
> */
> 
> {
> 		if (err == -1 ) {
> 			fprintf(stderr,
> 				"\nsystem() failed for %s\n", command);
> 			exit (1);
> 		}
> 		else {
> 			err=WEXITSTATUS(err);
> 			if (err > 0) {
> 				fprintf(stderr,
> 				"\nCommand '%s' failed, with code %d\n",
> 					command, err);
> 				exit (err);
> 			}
> 		}
> }
> 		/* </tfm modifications> */