/*
 * thud.c -- start a program with the thud.so library preloaded.
 *
 * Copyright (C) 2004  David Collier-Brown
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of your choice of the GNU Lesser (Library) General 
 *   Public License or the Sun Common Development and Distribution License.
 */
#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/wait.h>	/* For wait(). */
#include <signal.h>	/* For sigation. */
#include <siginfo.h>	/* For sigaction(). */
#include <errno.h>	/* For errno. */
#include <string.h>	/* For strerro(). */
#include <sys/stat.h>
#include "thud.h"       /* Just debugging code. */

#define MAXLINE 1024
static char *ProgName = "thud";
static pid_t Child;
static int AllSignals = 0;

 int
main(int argc, char *argv[]) {
	pid_t	rc;
	int	i, j, childRc;
	struct stat buf;
	char	putenvLine[MAXLINE];

	if (argc < 2) {
		(void) fprintf(stderr, "%s: you must supply a "
			"full path to a command to be checked.\n", ProgName);
		(void) fprintf(stderr, "Usage: %s program args ...\n",
			argv[0]);
		(void) exit(1);
	}
       
	for (i=1; i <argc; i++) {
		if (argv[i][0] == '-') {
			switch (argv[i][1]) {
			case 'a': /* All signals */
				AllSignals = 1;
				break;
			default:
				(void) fprintf(stderr, "%s: unrecognized "
					"option -%c ignored.\n",
					ProgName, argv[i][1]);
				break;
			}
		}
		else {
			/* The program to run */
			break;
		}
	}
		
	/* Remove thud and opts from the command line. */
	for (j=0; (i+j) < argc; j++) {
		argv[j] = argv[i+j];
	}
	argv[j] = NULL;;


	/* Find library:  we're being cautious. */
	if (stat("./libthud.so.1", &buf) == 0) {
		(void) snprintf(putenvLine, sizeof(putenvLine)-1,
			"LD_PRELOAD=./libthud.so.1");
	}
	else if (stat("/usr/lib/libthud.so.1", &buf) == 0) {
		(void) snprintf(putenvLine, sizeof(putenvLine)-1,
			"LD_PRELOAD=/usr/lib/libthud.so.1"); 
	}
	else {
		(void) fprintf(stderr, "%s: can't find either "
			"./libthud.so.1 or /usr/lib/libthud.so.1: "
			"fatal error, not running %s.\n",
			ProgName, argv[0]);
			(void) exit(2);
	}

	if (AllSignals == 1) {
		(void) fprintf(stderr, "%s: starting %s with extra "
			"error reporting.\n", ProgName, argv[0]);
	}
	else {
	  	(void) fprintf(stderr, "%s: starting %s with null-pointer "
			"protection.\n", ProgName, argv[0]);
	}

	rc = fork();
	if (rc == 0) {
		/* We're the child. */
		/* load library */
		(void) putenv(putenvLine);

		if (AllSignals == 1) {
			(void) putenv("THUD=-a");
		}
		else {
			(void) unsetenv("THUD");
		}

		/* exec the rest of the command-line */
		(void) sleep(1);
		rc = execv(argv[0], argv);
		/* But if we return from exec ... */
		(void) fprintf(stderr, "%s: exec %s failed, "
			"rc = %ld, errno = %d (%s)\n",
			ProgName, argv[0], rc, errno, strerror(errno));
		_exit(3);
	}
	else if (rc == (pid_t)-1) {
		(void) fprintf(stderr, "%s: fork failed.\n",  ProgName);
		exit(4);
	}
	else {
		/* Otherwise we're the parent, wait for a signal */
		Child = rc;
		(void) fprintf(stderr, "%s: in parent, child=%ld.\n",
			 ProgName, Child);
		if ((rc = wait(&childRc)) != -1) {
			(void) fprintf(stderr, "%s: child "
				"returned %d\n",
				ProgName, WEXITSTATUS(childRc));
		}
		else {
			(void) fprintf(stderr, "%s: child "
				"returned after handling signals "
				"with errno = %d (%s)\n",
				ProgName, errno, strerror(errno));
		}
		exit(0);
	}
	return 0;
}