last.c

sysvinit--linux系统下的init

/*
 * last.c	Re-implementation of the 'last' command, this time
 *		for Linux. Yes I know there is BSD last, but I
 *		just felt like writing this. No thanks :-).
 *		Also, this version gives lots more info (especially with -x)
 *
 * Author:	Miquel van Smoorenburg, [e-mail]
 *
 * Version:	@(#)last  2.85  30-Jul-2004  [e-mail]
 *
 *		This file is part of the sysvinit suite,
 *		Copyright 1991-2004 Miquel van Smoorenburg.
 *
 *		This program is free software; you can redistribute it and/or
 *		modify it under the terms of the GNU General Public License
 *		as published by the Free Software Foundation; either version
 *		2 of the License, or (at your option) any later version.
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/fcntl.h>
#include <time.h>
#include <stdio.h>
#include <ctype.h>
#include <utmp.h>
#include <errno.h>
#include <malloc.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <signal.h>
#include <getopt.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>
#include "oldutmp.h"

#ifndef SHUTDOWN_TIME
#  define SHUTDOWN_TIME 254
#endif

char *Version = "@(#) last 2.85 31-Apr-2004 miquels";

#define CHOP_DOMAIN	0	/* Define to chop off local domainname. */
#define NEW_UTMP	1	/* Fancy & fast utmp read code. */
#define UCHUNKSIZE	16384	/* How much we read at once. */

/* Double linked list of struct utmp's */
struct utmplist {
  struct utmp ut;
  struct utmplist *next;
  struct utmplist *prev;
};
struct utmplist *utmplist = NULL;

/* Types of listing */
#define R_CRASH		1 /* No logout record, system boot in between */
#define R_DOWN		2 /* System brought down in decent way */
#define R_NORMAL	3 /* Normal */
#define R_NOW		4 /* Still logged in */
#define R_REBOOT	5 /* Reboot record. */
#define R_PHANTOM	6 /* No logout record but session is stale. */
#define R_TIMECHANGE	7 /* NEW_TIME or OLD_TIME */

/* Global variables */
int maxrecs = 0;	/* Maximum number of records to list. */
int recsdone = 0;	/* Number of records listed */
int showhost = 1;	/* Show hostname too? */
int altlist = 0;	/* Show hostname at the end. */
int usedns = 0;		/* Use DNS to lookup the hostname. */
int useip = 0;		/* Print IP address in number format */
int oldfmt = 0;		/* Use old libc5 format? */
char **show = NULL;	/* What do they want us to show */
char *ufile;		/* Filename of this file */
time_t lastdate;	/* Last date we've seen */
char *progname;		/* Name of this program */
#if CHOP_DOMAIN
char hostname[256];	/* For gethostbyname() */
char *domainname;	/* Our domainname. */
#endif

/*
 *	Convert old utmp format to new.
 */
void uconv(struct oldutmp *oldut, struct utmp *utn)
{
	memset(utn, 0, sizeof(struct utmp));
	utn->ut_type = oldut->ut_type;
	utn->ut_pid  = oldut->ut_pid;
	utn->ut_time = oldut->ut_oldtime;
	utn->ut_addr = oldut->ut_oldaddr;
	strncpy(utn->ut_line, oldut->ut_line, OLD_LINESIZE);
	strncpy(utn->ut_user, oldut->ut_user, OLD_NAMESIZE);
	strncpy(utn->ut_host, oldut->ut_host, OLD_HOSTSIZE);
}

#if NEW_UTMP
/*
 *	Read one utmp entry, return in new format.
 *	Automatically reposition file pointer.
 */
int uread(FILE *fp, struct utmp *u, int *quit)
{
	static int utsize;
	static char buf[UCHUNKSIZE];
	char tmp[1024];
	static off_t fpos;
	static int bpos;
	struct oldutmp uto;
	int r;
	off_t o;

	if (quit == NULL && u != NULL) {
		/*
		 *	Normal read.
		 */
		if (oldfmt) {
			r = fread(&uto, sizeof(uto), 1, fp);
			uconv(&uto, u);
		} else
			r = fread(u, sizeof(struct utmp), 1, fp);
		return r;
	}

	if (u == NULL) {
		/*
		 *	Initialize and position.
		 */
		utsize = oldfmt ? sizeof(uto) : sizeof(struct utmp);
		fseeko(fp, 0, SEEK_END);
		fpos = ftello(fp);
		if (fpos == 0)
			return 0;
		o = ((fpos - 1) / UCHUNKSIZE) * UCHUNKSIZE;
		if (fseeko(fp, o, SEEK_SET) < 0) {
			fprintf(stderr, "%s: seek failed!\n", progname);
			return 0;
		}
		bpos = (int)(fpos - o);
		if (fread(buf, bpos, 1, fp) != 1) {
			fprintf(stderr, "%s: read failed!\n", progname);
			return 0;
		}
		fpos = o;
		return 1;
	}

	/*
	 *	Read one struct. From the buffer if possible.
	 */
	bpos -= utsize;
	if (bpos >= 0) {
		if (oldfmt)
			uconv((struct oldutmp *)(buf + bpos), u);
		else
			memcpy(u, buf + bpos, sizeof(struct utmp));
		return 1;
	}

	/*
	 *	Oops we went "below" the buffer. We should be able to
	 *	seek back UCHUNKSIZE bytes.
	 */
	fpos -= UCHUNKSIZE;
	if (fpos < 0)
		return 0;

	/*
	 *	Copy whatever is left in the buffer.
	 */
	memcpy(tmp + (-bpos), buf, utsize + bpos);
	if (fseeko(fp, fpos, SEEK_SET) < 0) {
		perror("fseek");
		return 0;
	}

	/*
	 *	Read another UCHUNKSIZE bytes.
	 */
	if (fread(buf, UCHUNKSIZE, 1, fp) != 1) {
		perror("fread");
		return 0;
	}

	/*
	 *	The end of the UCHUNKSIZE byte buffer should be the first
	 *	few bytes of the current struct utmp.
	 */
	memcpy(tmp, buf + UCHUNKSIZE + bpos, -bpos);
	bpos += UCHUNKSIZE;

	if (oldfmt)
		uconv((struct oldutmp *)tmp, u);
	else
		memcpy(u, tmp, sizeof(struct utmp));

	return 1;
}

#else /* NEW_UTMP */

/*
 *	Read one utmp entry, return in new format.
 *	Automatically reposition file pointer.
 */
int uread(FILE *fp, struct utmp *u, int *quit)
{
	struct oldutmp uto;
	off_t r;

	if (u == NULL) {
		r = oldfmt ? sizeof(struct oldutmp) : sizeof(struct utmp);
		fseek(fp, -1 * r, SEEK_END);
		return 1;
	}

	if (!oldfmt) {
		r = fread(u, sizeof(struct utmp), 1, fp);
		if (r == 1) {
			if (fseeko(fp, -2 * sizeof(struct utmp), SEEK_CUR) < 0)
				if (quit) *quit = 1;
		}
		return r;
	}
	r = fread(&uto, sizeof(struct oldutmp), 1, fp);
	if (r == 1) {
		if (fseeko(fp, -2 * sizeof(struct oldutmp), SEEK_CUR) < 0)
			if (quit) *quit = 1;
		uconv(&uto, u);
	}

	return r;
}
#endif

/*
 *	Try to be smart about the location of the BTMP file
 */
#ifndef BTMP_FILE
#define BTMP_FILE getbtmp()
char *getbtmp()
{
	static char btmp[128];
	char *p;

	strcpy(btmp, WTMP_FILE);
	if ((p = strrchr(btmp, '/')) == NULL)
		p = btmp;
	else
		p++;
	*p = 0;
	strcat(btmp, "btmp");
	return btmp;
}
#endif

/*
 *	Print a short date.
 */
char *showdate()
{
	char *s = ctime(&lastdate);
	s[16] = 0;
	return s;
}

/*
 *	SIGINT handler
 */
void int_handler()
{
	printf("Interrupted %s\n", showdate());
	exit(1);
}

/*
 *	SIGQUIT handler
 */
void quit_handler()
{
	printf("Interrupted %s\n", showdate());
	signal(SIGQUIT, quit_handler);
}

/*
 *	Get the basename of a filename
 */
char *mybasename(char *s)
{
	char *p;

	if ((p = strrchr(s, '/')) != NULL)
		p++;
	else
		p = s;
	return p;
}

/*
 *	Lookup a host with DNS.
 */
int dns_lookup(char *result, int size, int useip, int32_t *a)
{
	struct sockaddr_in	sin;
	struct sockaddr_in6	sin6;
	struct sockaddr		*sa;
	int			salen, flags;
	unsigned int		topnibble;
	int			mapped = 0;

	flags = useip ? NI_NUMERICHOST : 0;

	/*
	 *	IPv4 or IPv6 ? We use 2 heuristics:
	 *	1. Current IPv6 range uses 2000-3fff. Outside of
	 *	   that is illegal and must be IPv4.
	 *	2. If last 3 bytes are 0, must be IPv4
	 *	3. If IPv6 in IPv4, handle as IPv4
	 *
	 *	Ugly.
	 */
	if (a[0] == 0 && a[1] == 0 && a[2] == htonl (0xffff))
		mapped = 1;
	topnibble = ntohl((unsigned int)a[0]) >> 28;
	if (topnibble < 2 || topnibble > 3 || mapped ||
	    (a[1] == 0 && a[2] == 0 && a[3] == 0)) {
		/* IPv4 */
		sin.sin_family = AF_INET;
		sin.sin_port = 0;
		sin.sin_addr.s_addr = mapped ? a[3] : a[0];
		sa = (struct sockaddr *)&sin;
		salen = sizeof(sin);
	} else {
		/* IPv6 */
		memset(&sin6, 0, sizeof(sin6));
		sin6.sin6_family = AF_INET6;
		sin6.sin6_port = 0;
		memcpy(sin6.sin6_addr.s6_addr, a, 16);
		sa = (struct sockaddr *)&sin6;
		salen = sizeof(sin6);
	}

	return getnameinfo(sa, salen, result, size, NULL, 0, flags);
}

/*
 *	Show one line of information on screen
 */
int list(struct utmp *p, time_t t, int what)
{
	time_t		secs, tmp;
	char		logintime[32];
	char		logouttime[32];
	char		length[32];
	char		final[128];
	char		utline[UT_LINESIZE+1];
	char		domain[256];
	char		*s, **walk;
	int		mins, hours, days;
	int		r, len;

	/*
	 *	uucp and ftp have special-type entries
	 */
	utline[0] = 0;
	strncat(utline, p->ut_line, UT_LINESIZE);
	if (strncmp(utline, "ftp", 3) == 0 && isdigit(utline[3]))
		utline[3] = 0;
	if (strncmp(utline, "uucp", 4) == 0 && isdigit(utline[4]))
		utline[4] = 0;

	/*
	 *	Is this something we wanna show?
	 */
	if (show) {
		for (walk = show; *walk; walk++) {
			if (strncmp(p->ut_name, *walk, UT_NAMESIZE) == 0 ||
			    strcmp(utline, *walk) == 0 ||
			    (strncmp(utline, "tty", 3) == 0 &&
			     strcmp(utline + 3, *walk) == 0)) break;
		}
		if (*walk == NULL) return 0;
	}

	/*
	 *	Calculate times
	 */
	tmp = (time_t)p->ut_time;
	strcpy(logintime, ctime(&tmp));
	logintime[16] = 0;
	sprintf(logouttime, "- %s", ctime(&t) + 11);
	logouttime[7] = 0;
	secs = t - p->ut_time;
	mins  = (secs / 60) % 60;
	hours = (secs / 3600) % 24;
	days  = secs / 86400;
	if (days)
		sprintf(length, "(%d+%02d:%02d)", days, hours, mins);
	else
		sprintf(length, " (%02d:%02d)", hours, mins);

	switch(what) {
		case R_CRASH:
			sprintf(logouttime, "- crash");
			break;
		case R_DOWN:
			sprintf(logouttime, "- down ");
			break;
		case R_NOW:
			length[0] = 0;
			sprintf(logouttime, "  still");
			sprintf(length, "logged in");
			break;
		case R_PHANTOM:
			length[0] = 0;
			sprintf(logouttime, "   gone");
			sprintf(length, "- no logout");
			break;
		case R_REBOOT:
			logouttime[0] = 0;      /* Print machine uptime */
			break;
		case R_TIMECHANGE:
			logouttime[0] = 0;
			length[0] = 0;
			break;
		case R_NORMAL:
			break;
 	}

	/*
	 *	Look up host with DNS if needed.
	 */
	r = -1;
	if (usedns || useip)
		r = dns_lookup(domain, sizeof(domain), useip, p->ut_addr_v6);
	if (r < 0) {
		len = UT_HOSTSIZE;