merge changes from SQUID_2_3 branch

[thirdparty/squid.git] / src / tools.cc

/*
 * $Id: tools.cc,v 1.188 1999/12/30 17:37:01 wessels Exp $
 *
 * DEBUG: section 21    Misc Functions
 * AUTHOR: Harvest Derived
 *
 * SQUID Internet Object Cache  http://squid.nlanr.net/Squid/
 * ----------------------------------------------------------
 *
 *  Squid is the result of efforts by numerous individuals from the
 *  Internet community.  Development is led by Duane Wessels of the
 *  National Laboratory for Applied Network Research and funded by the
 *  National Science Foundation.  Squid is Copyrighted (C) 1998 by
 *  Duane Wessels and the University of California San Diego.  Please
 *  see the COPYRIGHT file for full details.  Squid incorporates
 *  software developed and/or copyrighted by other sources.  Please see
 *  the CREDITS file for full details.
 *
 *  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.
 *  
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *  
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
 *
 */

#include "squid.h"

#define DEAD_MSG "\
The Squid Cache (version %s) died.\n\
\n\
You've encountered a fatal error in the Squid Cache version %s.\n\
If a core file was created (possibly in the swap directory),\n\
please execute 'gdb squid core' or 'dbx squid core', then type 'where',\n\
and report the trace back to squid-bugs@ircache.net.\n\
\n\
Thanks!\n"

static void fatal_common(const char *);
static void fatalvf(const char *fmt, va_list args);
static void mail_warranty(void);
#if MEM_GEN_TRACE
extern void log_trace_done();
extern void log_trace_init(char *);
#endif

extern void (*failure_notify) (const char *);

void
releaseServerSockets(void)
{
    int i;
    /* Release the main ports as early as possible */
    for (i = 0; i < NHttpSockets; i++) {
	if (HttpSockets[i] >= 0)
	    close(HttpSockets[i]);
    }
    if (theInIcpConnection >= 0)
	close(theInIcpConnection);
    if (theOutIcpConnection >= 0 && theOutIcpConnection != theInIcpConnection)
	close(theOutIcpConnection);
}

static char *
dead_msg(void)
{
    LOCAL_ARRAY(char, msg, 1024);
    snprintf(msg, 1024, DEAD_MSG, version_string, version_string);
    return msg;
}

static void
mail_warranty(void)
{
    FILE *fp = NULL;
    char *filename;
    static char command[256];
    if ((filename = tempnam(NULL, appname)) == NULL)
	return;
    if ((fp = fopen(filename, "w")) == NULL)
	return;
    fprintf(fp, "From: %s\n", appname);
    fprintf(fp, "To: %s\n", Config.adminEmail);
    fprintf(fp, "Subject: %s\n", dead_msg());
    fclose(fp);
    snprintf(command, 256, "mail %s < %s", Config.adminEmail, filename);
    system(command);		/* XXX should avoid system(3) */
    unlink(filename);
}

void
dumpMallocStats(void)
{
#if HAVE_MSTATS && HAVE_GNUMALLOC_H
    struct mstats ms = mstats();
    fprintf(debug_log, "\ttotal space in arena:  %6d KB\n",
	(int) (ms.bytes_total >> 10));
    fprintf(debug_log, "\tTotal free:            %6d KB %d%%\n",
	(int) (ms.bytes_free >> 10),
	percent(ms.bytes_free, ms.bytes_total));
#elif HAVE_MALLINFO && HAVE_STRUCT_MALLINFO
    struct mallinfo mp;
    int t;
    if (!do_mallinfo)
	return;
    mp = mallinfo();
    fprintf(debug_log, "Memory usage for %s via mallinfo():\n", appname);
    fprintf(debug_log, "\ttotal space in arena:  %6d KB\n",
	mp.arena >> 10);
    fprintf(debug_log, "\tOrdinary blocks:       %6d KB %6d blks\n",
	mp.uordblks >> 10, mp.ordblks);
    fprintf(debug_log, "\tSmall blocks:          %6d KB %6d blks\n",
	mp.usmblks >> 10, mp.smblks);
    fprintf(debug_log, "\tHolding blocks:        %6d KB %6d blks\n",
	mp.hblkhd >> 10, mp.hblks);
    fprintf(debug_log, "\tFree Small blocks:     %6d KB\n",
	mp.fsmblks >> 10);
    fprintf(debug_log, "\tFree Ordinary blocks:  %6d KB\n",
	mp.fordblks >> 10);
    t = mp.uordblks + mp.usmblks + mp.hblkhd;
    fprintf(debug_log, "\tTotal in use:          %6d KB %d%%\n",
	t >> 10, percent(t, mp.arena));
    t = mp.fsmblks + mp.fordblks;
    fprintf(debug_log, "\tTotal free:            %6d KB %d%%\n",
	t >> 10, percent(t, mp.arena));
#if HAVE_EXT_MALLINFO
    fprintf(debug_log, "\tmax size of small blocks:\t%d\n",
	mp.mxfast);
    fprintf(debug_log, "\tnumber of small blocks in a holding block:\t%d\n",
	mp.nlblks);
    fprintf(debug_log, "\tsmall block rounding factor:\t%d\n",
	mp.grain);
    fprintf(debug_log, "\tspace (including overhead) allocated in ord. blks:\t%d\n",
	mp.uordbytes);
    fprintf(debug_log, "\tnumber of ordinary blocks allocated:\t%d\n",
	mp.allocated);
    fprintf(debug_log, "\tbytes used in maintaining the free tree:\t%d\n",
	mp.treeoverhead);
#endif /* HAVE_EXT_MALLINFO */
#endif /* HAVE_MALLINFO */
}

void
squid_getrusage(struct rusage *r)
{
    memset(r, '\0', sizeof(struct rusage));
#if HAVE_GETRUSAGE && defined(RUSAGE_SELF)
#ifdef _SQUID_SOLARIS_
    /* Solaris 2.5 has getrusage() permission bug -- Arjan de Vet */
    enter_suid();
#endif
    getrusage(RUSAGE_SELF, r);
#ifdef _SQUID_SOLARIS_
    leave_suid();
#endif
#endif
}

double
rusage_cputime(struct rusage *r)
{
    return (double) r->ru_stime.tv_sec +
	(double) r->ru_utime.tv_sec +
	(double) r->ru_stime.tv_usec / 1000000.0 +
	(double) r->ru_utime.tv_usec / 1000000.0;
}

/* Hack for some HP-UX preprocessors */
#ifndef HAVE_GETPAGESIZE
#define HAVE_GETPAGESIZE 0
#endif

int
rusage_maxrss(struct rusage *r)
{
#if defined(_SQUID_SGI_) && _ABIAPI
    return r->ru_pad[0];
#elif defined(_SQUID_SGI_)
    return r->ru_maxrss;
#elif defined(_SQUID_OSF_)
    return r->ru_maxrss;
#elif defined(BSD4_4)
    return r->ru_maxrss;
#elif defined(HAVE_GETPAGESIZE) && HAVE_GETPAGESIZE != 0
    return (r->ru_maxrss * getpagesize()) >> 10;
#elif defined(PAGESIZE)
    return (r->ru_maxrss * PAGESIZE) >> 10;
#else
    return r->ru_maxrss;
#endif
}

int
rusage_pagefaults(struct rusage *r)
{
#if defined(_SQUID_SGI_) && _ABIAPI
    return r->ru_pad[5];
#else
    return r->ru_majflt;
#endif
}


void
PrintRusage(void)
{
    struct rusage rusage;
    squid_getrusage(&rusage);
    fprintf(debug_log, "CPU Usage: %.3f seconds = %.3f user + %.3f sys\n",
	rusage_cputime(&rusage),
	rusage.ru_utime.tv_sec + ((double) rusage.ru_utime.tv_usec / 1000000.0),
	rusage.ru_stime.tv_sec + ((double) rusage.ru_stime.tv_usec / 1000000.0));
    fprintf(debug_log, "Maximum Resident Size: %d KB\n",
	rusage_maxrss(&rusage));
    fprintf(debug_log, "Page faults with physical i/o: %d\n",
	rusage_pagefaults(&rusage));
}


void
death(int sig)
{
    if (sig == SIGSEGV)
	fprintf(debug_log, "FATAL: Received Segment Violation...dying.\n");
    else if (sig == SIGBUS)
	fprintf(debug_log, "FATAL: Received Bus Error...dying.\n");
    else
	fprintf(debug_log, "FATAL: Received signal %d...dying.\n", sig);

#ifdef PRINT_STACK_TRACE
#ifdef _SQUID_HPUX_
    {
	extern void U_STACK_TRACE(void);	/* link with -lcl */
	fflush(debug_log);
	dup2(fileno(debug_log), 2);
	U_STACK_TRACE();
    }
#endif /* _SQUID_HPUX_ */
#ifdef _SQUID_SOLARIS_
    {				/* get ftp://opcom.sun.ca/pub/tars/opcom_stack.tar.gz and */
	extern void opcom_stack_trace(void);	/* link with -lopcom_stack */
	fflush(debug_log);
	dup2(fileno(debug_log), fileno(stdout));
	opcom_stack_trace();
	fflush(stdout);
    }
#endif /* _SQUID_SOLARIS_ */
#endif /* PRINT_STACK_TRACE */

#if SA_RESETHAND == 0
    signal(SIGSEGV, SIG_DFL);
    signal(SIGBUS, SIG_DFL);
    signal(sig, SIG_DFL);
#endif
    releaseServerSockets();
    storeDirWriteCleanLogs(0);
    PrintRusage();
    dumpMallocStats();
    if (squid_curtime - SQUID_RELEASE_TIME < 864000) {
	/* skip if more than 10 days old */
	if (Config.adminEmail)
	    mail_warranty();
	else
	    puts(dead_msg());
    }
    abort();
}


void
sigusr2_handle(int sig)
{
    static int state = 0;
    /* no debug() here; bad things happen if the signal is delivered during _db_print() */
    if (state == 0) {
#ifndef MEM_GEN_TRACE
	_db_init(Config.Log.log, "ALL,10");
#else
	log_trace_done();
#endif
	state = 1;
    } else {
#ifndef MEM_GEN_TRACE
	_db_init(Config.Log.log, Config.debugOptions);
#else
	log_trace_init("/tmp/squid.alloc");
#endif
	state = 0;
    }
#if !HAVE_SIGACTION
    signal(sig, sigusr2_handle);	/* reinstall */
#endif
}

static void
fatal_common(const char *message)
{
#if HAVE_SYSLOG
    syslog(LOG_ALERT, "%s", message);
#endif
    fprintf(debug_log, "FATAL: %s\n", message);
    if (opt_debug_stderr > 0 && debug_log != stderr)
	fprintf(stderr, "FATAL: %s\n", message);
    fprintf(debug_log, "Squid Cache (Version %s): Terminated abnormally.\n",
	version_string);
    fflush(debug_log);
    PrintRusage();
    dumpMallocStats();
}

/* fatal */
void
fatal(const char *message)
{
    releaseServerSockets();
    /* check for store_dirs_rebuilding because fatal() is often
     * used in early initialization phases, long before we ever
     * get to the store log. */
    if (0 == store_dirs_rebuilding)
	storeDirWriteCleanLogs(0);
    fatal_common(message);
    exit(shutting_down ? 0 : 1);
}

/* printf-style interface for fatal */
#if STDC_HEADERS
void
fatalf(const char *fmt,...)
{
    va_list args;
    va_start(args, fmt);
#else
void
fatalf(va_alist)
     va_dcl
{
    va_list args;
    const char *fmt = NULL;
    va_start(args);
    fmt = va_arg(args, char *);
#endif
    fatalvf(fmt, args);
    va_end(args);
}


/* used by fatalf */
static void
fatalvf(const char *fmt, va_list args)
{
    static char fatal_str[BUFSIZ];
    vsnprintf(fatal_str, sizeof(fatal_str), fmt, args);
    fatal(fatal_str);
}

/* fatal with dumping core */
void
fatal_dump(const char *message)
{
    failure_notify = NULL;
    releaseServerSockets();
    if (message)
	fatal_common(message);
    if (opt_catch_signals)
	storeDirWriteCleanLogs(0);
    abort();
}

void
debug_trap(const char *message)
{
    if (!opt_catch_signals)
	fatal_dump(message);
    _db_print("WARNING: %s\n", message);
}

void
sig_child(int sig)
{
#ifdef _SQUID_NEXT_
    union wait status;
#else
    int status;
#endif
    pid_t pid;

    do {
#ifdef _SQUID_NEXT_
	pid = wait3(&status, WNOHANG, NULL);
#else
	pid = waitpid(-1, &status, WNOHANG);
#endif
	/* no debug() here; bad things happen if the signal is delivered during _db_print() */
#if HAVE_SIGACTION
    } while (pid > 0);
#else
    } while (pid > 0 || (pid < 0 && errno == EINTR));
    signal(sig, sig_child);
#endif
}

const char *
getMyHostname(void)
{
    LOCAL_ARRAY(char, host, SQUIDHOSTNAMELEN + 1);
    static int present = 0;
    const struct hostent *h = NULL;
    if (Config.visibleHostname != NULL)
	return Config.visibleHostname;
    if (present) {
	(void) 0;
    } else if (Config.Sockaddr.http->s.sin_addr.s_addr != any_addr.s_addr) {
	/*
	 * If the first http_port address has a specific address, try a
	 * reverse DNS lookup on it.
	 */
	host[0] = '\0';
	h = gethostbyaddr((char *) &Config.Sockaddr.http->s.sin_addr,
	    sizeof(Config.Sockaddr.http->s.sin_addr), AF_INET);
	if (h != NULL) {
	    /* DNS lookup successful */
	    /* use the official name from DNS lookup */
	    strcpy(host, h->h_name);
	    debug(50, 4) ("getMyHostname: resolved tcp_incoming_addr to '%s'\n",
		host);
	    present = 1;
	} else {
	    debug(50, 6) ("getMyHostname: failed to resolve tcp_incoming_addr\n");
	}
    } else {
	/*
	 * Get the host name and store it in host to return
	 */
	host[0] = '\0';
	if (gethostname(host, SQUIDHOSTNAMELEN) == -1) {
	    debug(50, 1) ("getMyHostname: gethostname failed: %s\n",
		xstrerror());
	} else {
	    if ((h = gethostbyname(host)) != NULL) {
		debug(50, 6) ("getMyHostname: '%s' resolved into '%s'\n",
		    host, h->h_name);
		/* DNS lookup successful */
		/* use the official name from DNS lookup */
		strcpy(host, h->h_name);
	    }
	}
	present = 1;
    }
    return present ? host : NULL;
}

const char *
uniqueHostname(void)
{
    return Config.uniqueHostname ? Config.uniqueHostname : getMyHostname();
}

void
safeunlink(const char *s, int quiet)
{
    Counter.syscalls.disk.unlinks++;
    if (unlink(s) < 0 && !quiet)
	debug(50, 1) ("safeunlink: Couldn't delete %s: %s\n", s, xstrerror());
}

/* leave a privilegied section. (Give up any privilegies)
 * Routines that need privilegies can rap themselves in enter_suid()
 * and leave_suid()
 * To give upp all posibilites to gain privilegies use no_suid()
 */
void
leave_suid(void)
{
    struct passwd *pwd = NULL;
    struct group *grp = NULL;
    debug(21, 3) ("leave_suid: PID %d called\n", getpid());
    if (geteuid() != 0)
	return;
    /* Started as a root, check suid option */
    if (Config.effectiveUser == NULL)
	return;
    if ((pwd = getpwnam(Config.effectiveUser)) == NULL)
	return;
    if (Config.effectiveGroup && (grp = getgrnam(Config.effectiveGroup))) {
	if (setgid(grp->gr_gid) < 0)
	    debug(50, 1) ("leave_suid: setgid: %s\n", xstrerror());
    } else {
	if (setgid(pwd->pw_gid) < 0)
	    debug(50, 1) ("leave_suid: setgid: %s\n", xstrerror());
    }
    debug(21, 3) ("leave_suid: PID %d giving up root, becoming '%s'\n",
	getpid(), pwd->pw_name);
#if HAVE_SETRESUID
    if (setresuid(pwd->pw_uid, pwd->pw_uid, 0) < 0)
	debug(50, 1) ("leave_suid: setresuid: %s\n", xstrerror());
#elif HAVE_SETEUID
    if (seteuid(pwd->pw_uid) < 0)
	debug(50, 1) ("leave_suid: seteuid: %s\n", xstrerror());
#else
    if (setuid(pwd->pw_uid) < 0)
	debug(50, 1) ("leave_suid: setuid: %s\n", xstrerror());
#endif
}

/* Enter a privilegied section */
void
enter_suid(void)
{
    debug(21, 3) ("enter_suid: PID %d taking root priveleges\n", getpid());
#if HAVE_SETRESUID
    setresuid(-1, 0, -1);
#else
    setuid(0);
#endif
}

/* Give up the posibility to gain privilegies.
 * this should be used before starting a sub process
 */
void
no_suid(void)
{
    uid_t uid;
    leave_suid();
    uid = geteuid();
    debug(21, 3) ("leave_suid: PID %d giving up root priveleges forever\n", getpid());
#if HAVE_SETRESUID
    if (setresuid(uid, uid, uid) < 0)
	debug(50, 1) ("no_suid: setresuid: %s\n", xstrerror());
#else
    setuid(0);
    if (setuid(uid) < 0)
	debug(50, 1) ("no_suid: setuid: %s\n", xstrerror());
#endif
}

void
writePidFile(void)
{
    int fd;
    const char *f = NULL;
    mode_t old_umask;
    char buf[32];
    if ((f = Config.pidFilename) == NULL)
	return;
    if (!strcmp(Config.pidFilename, "none"))
	return;
    enter_suid();
    old_umask = umask(022);
    fd = file_open(f, O_WRONLY | O_CREAT | O_TRUNC);
    umask(old_umask);
    leave_suid();
    if (fd < 0) {
	debug(50, 0) ("%s: %s\n", f, xstrerror());
	debug_trap("Could not write pid file");
	return;
    }
    snprintf(buf, 32, "%d\n", (int) getpid());
    write(fd, buf, strlen(buf));
    file_close(fd);
}


pid_t
readPidFile(void)
{
    FILE *pid_fp = NULL;
    const char *f = Config.pidFilename;
    pid_t pid = -1;
    int i;

    if (f == NULL || !strcmp(Config.pidFilename, "none")) {
	fprintf(stderr, "%s: ERROR: No pid file name defined\n", appname);
	exit(1);
    }
    pid_fp = fopen(f, "r");
    if (pid_fp != NULL) {
	pid = 0;
	if (fscanf(pid_fp, "%d", &i) == 1)
	    pid = (pid_t) i;
	fclose(pid_fp);
    } else {
	if (errno != ENOENT) {
	    fprintf(stderr, "%s: ERROR: Could not read pid file\n", appname);
	    fprintf(stderr, "\t%s: %s\n", f, xstrerror());
	    exit(1);
	}
    }
    return pid;
}


void
setMaxFD(void)
{
#if HAVE_SETRLIMIT
    /* try to use as many file descriptors as possible */
    /* System V uses RLIMIT_NOFILE and BSD uses RLIMIT_OFILE */
    struct rlimit rl;
#if defined(RLIMIT_NOFILE)
    if (getrlimit(RLIMIT_NOFILE, &rl) < 0) {
	debug(50, 0) ("setrlimit: RLIMIT_NOFILE: %s\n", xstrerror());
    } else {
	rl.rlim_cur = Squid_MaxFD;
	if (rl.rlim_cur > rl.rlim_max)
	    Squid_MaxFD = rl.rlim_cur = rl.rlim_max;
	if (setrlimit(RLIMIT_NOFILE, &rl) < 0) {
	    snprintf(tmp_error_buf, ERROR_BUF_SZ,
		"setrlimit: RLIMIT_NOFILE: %s", xstrerror());
	    fatal_dump(tmp_error_buf);
	}
    }
#elif defined(RLIMIT_OFILE)
    if (getrlimit(RLIMIT_OFILE, &rl) < 0) {
	debug(50, 0) ("setrlimit: RLIMIT_NOFILE: %s\n", xstrerror());
    } else {
	rl.rlim_cur = Squid_MaxFD;
	if (rl.rlim_cur > rl.rlim_max)
	    Squid_MaxFD = rl.rlim_cur = rl.rlim_max;
	if (setrlimit(RLIMIT_OFILE, &rl) < 0) {
	    snprintf(tmp_error_buf, ERROR_BUF_SZ,
		"setrlimit: RLIMIT_OFILE: %s", xstrerror());
	    fatal_dump(tmp_error_buf);
	}
    }
#endif
#else /* HAVE_SETRLIMIT */
    debug(21, 1) ("setMaxFD: Cannot increase: setrlimit() not supported on this system\n");
#endif /* HAVE_SETRLIMIT */

#if HAVE_SETRLIMIT && defined(RLIMIT_DATA)
    if (getrlimit(RLIMIT_DATA, &rl) < 0) {
	debug(50, 0) ("getrlimit: RLIMIT_DATA: %s\n", xstrerror());
    } else if (rl.rlim_max > rl.rlim_cur) {
	rl.rlim_cur = rl.rlim_max;	/* set it to the max */
	if (setrlimit(RLIMIT_DATA, &rl) < 0) {
	    snprintf(tmp_error_buf, ERROR_BUF_SZ,
		"setrlimit: RLIMIT_DATA: %s", xstrerror());
	    fatal_dump(tmp_error_buf);
	}
    }
#endif /* RLIMIT_DATA */
#if HAVE_SETRLIMIT && defined(RLIMIT_VMEM)
    if (getrlimit(RLIMIT_VMEM, &rl) < 0) {
	debug(50, 0) ("getrlimit: RLIMIT_VMEM: %s\n", xstrerror());
    } else if (rl.rlim_max > rl.rlim_cur) {
	rl.rlim_cur = rl.rlim_max;	/* set it to the max */
	if (setrlimit(RLIMIT_VMEM, &rl) < 0) {
	    snprintf(tmp_error_buf, ERROR_BUF_SZ,
		"setrlimit: RLIMIT_VMEM: %s", xstrerror());
	    fatal_dump(tmp_error_buf);
	}
    }
#endif /* RLIMIT_VMEM */
}

time_t
getCurrentTime(void)
{
#if GETTIMEOFDAY_NO_TZP
    gettimeofday(&current_time);
#else
    gettimeofday(&current_time, NULL);
#endif
    current_dtime = (double) current_time.tv_sec +
	(double) current_time.tv_usec / 1000000.0;
    return squid_curtime = current_time.tv_sec;
}

int
percent(int a, int b)
{
    return b ? ((int) (100.0 * a / b + 0.5)) : 0;
}

double
dpercent(double a, double b)
{
    return b ? (100.0 * a / b) : 0.0;
}

void
squid_signal(int sig, SIGHDLR * func, int flags)
{
#if HAVE_SIGACTION
    struct sigaction sa;
    sa.sa_handler = func;
    sa.sa_flags = flags;
    sigemptyset(&sa.sa_mask);
    if (sigaction(sig, &sa, NULL) < 0)
	debug(50, 0) ("sigaction: sig=%d func=%p: %s\n", sig, func, xstrerror());
#else
    signal(sig, func);
#endif
}

struct in_addr
inaddrFromHostent(const struct hostent *hp)
{
    struct in_addr s;
    xmemcpy(&s.s_addr, hp->h_addr, sizeof(s.s_addr));
    return s;
}

double
doubleAverage(double cur, double new, int N, int max)
{
    if (N > max)
	N = max;
    return (cur * (N - 1.0) + new) / N;
}

int
intAverage(int cur, int new, int n, int max)
{
    if (n > max)
	n = max;
    return (cur * (n - 1) + new) / n;
}

void
logsFlush(void)
{
    if (debug_log)
	fflush(debug_log);
    if (cache_useragent_log)
	fflush(cache_useragent_log);
}

char *
checkNullString(char *p)
{
    return p ? p : "(NULL)";
}

void
dlinkAdd(void *data, dlink_node * m, dlink_list * list)
{
    m->data = data;
    m->prev = NULL;
    m->next = list->head;
    if (list->head)
	list->head->prev = m;
    list->head = m;
    if (list->tail == NULL)
	list->tail = m;
}

void
dlinkAddTail(void *data, dlink_node * m, dlink_list * list)
{
    m->data = data;
    m->next = NULL;
    m->prev = list->tail;
    if (list->tail)
	list->tail->next = m;
    list->tail = m;
    if (list->head == NULL)
	list->head = m;
}

void
dlinkDelete(dlink_node * m, dlink_list * list)
{
    if (m->next)
	m->next->prev = m->prev;
    if (m->prev)
	m->prev->next = m->next;
    if (m == list->head)
	list->head = m->next;
    if (m == list->tail)
	list->tail = m->prev;
    m->next = m->prev = NULL;
}

void
kb_incr(kb_t * k, size_t v)
{
    k->bytes += v;
    k->kb += (k->bytes >> 10);
    k->bytes &= 0x3FF;
}

void
gb_flush(gb_t * g)
{
    g->gb += (g->bytes >> 30);
    g->bytes &= (1 << 30) - 1;
}

double
gb_to_double(const gb_t * g)
{
    return ((double) g->gb) * ((double) (1 << 30)) + ((double) g->bytes);
}

const char *
gb_to_str(const gb_t * g)
{
    /*
     * it is often convenient to call gb_to_str several times for _one_ printf
     */
#define max_cc_calls 5
    typedef char GbBuf[32];
    static GbBuf bufs[max_cc_calls];
    static int call_id = 0;
    double value = gb_to_double(g);
    char *buf = bufs[call_id++];
    if (call_id >= max_cc_calls)
	call_id = 0;
    /* select format */
    if (value < 1e9)
	snprintf(buf, sizeof(GbBuf), "%.2f MB", value / 1e6);
    else if (value < 1e12)
	snprintf(buf, sizeof(GbBuf), "%.2f GB", value / 1e9);
    else
	snprintf(buf, sizeof(GbBuf), "%.2f TB", value / 1e12);
    return buf;
}

void
debugObj(int section, int level, const char *label, void *obj, ObjPackMethod pm)
{
    MemBuf mb;
    Packer p;
    assert(label && obj && pm);
    memBufDefInit(&mb);
    packerToMemInit(&p, &mb);
    (*pm) (obj, &p);
    debug(section, level) ("%s%s", label, mb.buf);
    packerClean(&p);
    memBufClean(&mb);
}

int
stringHasWhitespace(const char *s)
{
    return (strcspn(s, w_space) != strlen(s));
}

void
linklistPush(link_list ** L, void *p)
{
    link_list *l = xmalloc(sizeof(*l));
    l->next = NULL;
    l->ptr = p;
    while (*L)
	L = &(*L)->next;
    *L = l;
}

void *
linklistShift(link_list ** L)
{
    void *p;
    link_list *l;
    if (NULL == *L)
	return NULL;
    l = *L;
    p = l->ptr;
    *L = (*L)->next;
    xfree(l);
    return p;
}

/*
 * Same as rename(2) but complains if something goes wrong;
 * the caller is responsible for handing and explaining the 
 * consequences of errors.
 */
int
xrename(const char *from, const char *to)
{
    debug(21, 2) ("xrename: renaming %s to %s\n", from, to);
    if (0 == rename(from, to))
	return 0;
    debug(21, errno == ENOENT ? 2 : 1) ("xrename: Cannot rename %s to %s: %s\n",
	from, to, xstrerror());
    return -1;
}

int
stringHasCntl(const char *s)
{
    unsigned char c;
    while ((c = (unsigned char) *s++) != '\0') {
	if (c <= 0x1f)
	    return 1;
	if (c >= 0x7f && c <= 0x9f)
	    return 1;
    }
    return 0;
}