/*
 * blunder -- detect and fix misues of strncpy and strncat.
 *
 * 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 <stdlib.h>	/* For putenv. */
#include <strings.h>	/* For strncpy/strncat. */
#include <string.h>	/* For strncpy/strncat. */
#include <unistd.h>	/* For gepid(). */
#include <stdio.h>	/* For fprintf(). */
#include <stdarg.h>	/* For vsnprintf(). */
#ifdef undef
#include <dlfcn.h>	/* For dlopen(). */
#include <link.h>
#endif

static char *ProgName = "blunder.so.1";
void reportError(void);
#define MAXLINE 1024



/*
 * strncpy -- copy strings up to N characters
 */
 char *
strncpy(char *dest, const char *src, size_t destsize) {
	unsigned len;

	if ((len = strlcpy(dest, src, destsize)) >= destsize) {
		(void) fprintf(stderr, "%s: "
			"error in strncpy(0x%p, \"%s\", %d)\n",
			ProgName, (void *)dest, src, destsize);
		if (len == destsize) {
			(void) fprintf(stderr, "    "
				"Attempt to create a "
				"string exactly %d long, "
				"which will be unterminated.\n",
				destsize);
		}
		else {
			(void) fprintf(stderr, "    "
				"Atempt to overflow dest string.\n");
		}
		(void) fprintf(stderr, "    "
			"Truncated to %d characters and "
			"null-terminated.\n", destsize-1);

		(void) reportError();
	}
	return dest;
}

/*
 * strncat -- concatente strings up to N characters.
 */
 char *
strncat(char *dest, const char *src, size_t destsize) {
	int	len;

	if ((len = strlcat(dest, src, destsize)) >= destsize) {
		(void) fprintf(stderr, "%s: "
			"error in strncat(0x%p, \"%s\", %d)\n",
			ProgName, (void *)dest, src, destsize);
		if (len == destsize) {
			(void) fprintf(stderr, "    "
				"Attempt to create a "
				"string exactly %d long, "
				"which will be unterminated.\n",
				destsize);
		}
		else {
			(void) fprintf(stderr, "    "
				"Atempt to overflow dest string.\n");
		}
		(void) fprintf(stderr, "    "
			"Truncated to %d characters and "
			"null-terminated.\n", destsize-1);

		reportError();
	}
	return dest;
}

/*
 * strnprintf -- just do the reporting, as the size limitation
 *	is already done.
 */
 int
snprintf(char *place, unsigned int size, const char *format, ...) {
	va_list ap;
	int	rc;

	va_start(ap, format);
	if ((rc = vsnprintf(place, size, format, ap)) >= size) {
		(void) fprintf(stderr, "%s: snprintf just tried "
			"to overflow the dest string.\n"
			"    Truncated to %d characters and "
			"null-terminated.\n", 
			ProgName, size-1);
		reportError();
	}
	va_end(ap);
	return rc;
}


/*
 * reportError -- tell the world what hapened and where.
 */
 static void
reportError(void) {
	pid_t	pid;
	char	procCmd[MAXLINE],
		oldEnv[MAXLINE];
	static int nCores = 1;

	pid = getpid();
	(void) snprintf(oldEnv, MAXLINE, "LD_PRELOAD=%s", 
		getenv("LD_PRELOAD"));
	(void) putenv("LD_PRELOAD=");

	(void) fprintf(stderr, "%s: attempted string overflow in "
		" process %ld.\n"
		"    Information follows, and a core will be\n"
		"    written to /usr/tmp/blunder_core.%d.%ld\n", 
		ProgName, pid, nCores, pid);

	(void) fprintf(stderr, "\npstack:\n");
	(void) snprintf(procCmd, (int)sizeof(procCmd), 
		"pstack %ld 1>&2'", pid);
	(void) system(procCmd);
	
	(void) fprintf(stderr, "\npmap:\n");
	(void) snprintf(procCmd, (int)sizeof(procCmd), 
		"pmap -x %ld 1>&2", pid);
	(void) system(procCmd);
	
	(void) fprintf(stderr, "\npsig:\n");
	(void) snprintf(procCmd, (int)sizeof(procCmd), 
		"psig %ld 1>&2", pid);
	(void) system(procCmd);

        (void) fprintf(stderr, "\npfiles:\n");
	(void) snprintf(procCmd, (int)sizeof(procCmd), 
		"pfiles %ld 1>&2", pid);
	(void) system(procCmd);

        (void) fprintf(stderr, "\npwdx:\n");
	(void) snprintf(procCmd, (int)sizeof(procCmd), 
		"pwdx %ld 1>&2", pid);
	(void) system(procCmd);

        (void) fprintf(stderr, "\nptree:\n");
	(void) snprintf(procCmd, (int)sizeof(procCmd), 
		"ptree %ld 1>&2", pid);
	(void) system(procCmd);

	(void) fprintf(stderr, 
		"\nsaving core to /var/tmp/blunder_core.%d.%ld\n", nCores, pid);
	(void) snprintf(procCmd, (int)sizeof(procCmd), 
		"gcore -o /var/tmp/blunder_core.%d %ld 1>&2", nCores, pid);
	(void) system(procCmd);
	(void) fprintf(stderr, "\n");

	nCores++;
	(void) putenv(oldEnv);

	return;
}