trunk/rdesktop/rdesktop.c

/* -*- c-basic-offset: 8 -*-
   rdesktop: A Remote Desktop Protocol client.
   Entrypoint and utility functions
   Copyright (C) Matthew Chapman 1999-2003

   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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include <stdarg.h>             /* va_list va_start va_end */
#include <unistd.h>             /* read close getuid getgid getpid getppid gethostname */
#include <fcntl.h>              /* open */
#include <pwd.h>                /* getpwuid */
#include <termios.h>            /* tcgetattr tcsetattr */
#include <sys/stat.h>           /* stat */
#include <sys/time.h>           /* gettimeofday */
#include <sys/times.h>          /* times */
#include <ctype.h>              /* toupper */
#include <errno.h>
#include "rdesktop.h"

#ifdef EGD_SOCKET
#include <sys/socket.h>         /* socket connect */
#include <sys/un.h>             /* sockaddr_un */
#endif

#ifdef WITH_OPENSSL
#include <openssl/md5.h>
#else
#include "crypto/md5.h"
#endif

char g_title[64] = "";
char g_username[64];
char hostname[16];
char keymapname[16];
int keylayout = 0x409;          /* Defaults to US keyboard layout */

int g_width = 800;              /* width is special: If 0, the
                                   geometry will be fetched from
                                   _NET_WORKAREA. If negative,
                                   absolute value specifies the
                                   percent of the whole screen. */
int g_height = 600;
int tcp_port_rdp = TCP_PORT_RDP;
int g_server_bpp = 8;
int g_win_button_size = 0;      /* If zero, disable single app mode */
BOOL g_bitmap_compression = True;
BOOL g_sendmotion = True;
BOOL g_orders = True;
BOOL g_encryption = True;
BOOL packet_encryption = True;
BOOL g_desktop_save = True;
BOOL g_fullscreen = False;
BOOL g_grab_keyboard = True;
BOOL g_hide_decorations = False;
BOOL g_use_rdp5 = True;
BOOL g_console_session = False;
BOOL g_numlock_sync = False;
extern BOOL g_owncolmap;
extern BOOL g_ownbackstore;
extern uint32 g_embed_wnd;

#ifdef WITH_RDPSND
BOOL g_rdpsnd = False;
#endif

extern RDPDR_DEVICE g_rdpdr_device[];
extern uint32 g_num_devices;

#ifdef RDP2VNC
extern int rfb_port;
extern int defer_time;
void
rdp2vnc_connect(char *server, uint32 flags, char *domain, char *password,
                char *shell, char *directory);
#endif
/* Display usage information */
static void
usage(char *program)
{
        fprintf(stderr, "rdesktop: A Remote Desktop Protocol client.\n");
        fprintf(stderr, "Version " VERSION ". Copyright (C) 1999-2003 Matt Chapman.\n");
        fprintf(stderr, "See http://www.rdesktop.org/ for more information.\n\n");

        fprintf(stderr, "Usage: %s [options] server[:port]\n", program);
#ifdef RDP2VNC
        fprintf(stderr, "   -V: vnc port\n");
        fprintf(stderr, "   -Q: defer time (ms)\n");
#endif
        fprintf(stderr, "   -u: user name\n");
        fprintf(stderr, "   -d: domain\n");
        fprintf(stderr, "   -s: shell\n");
        fprintf(stderr, "   -c: working directory\n");
        fprintf(stderr, "   -p: password (- to prompt)\n");
        fprintf(stderr, "   -n: client hostname\n");
        fprintf(stderr, "   -k: keyboard layout on server (en-us, de, sv, etc.)\n");
        fprintf(stderr, "   -g: desktop geometry (WxH)\n");
        fprintf(stderr, "   -f: full-screen mode\n");
        fprintf(stderr, "   -b: force bitmap updates\n");
        fprintf(stderr, "   -B: use BackingStore of X-server (if available)\n");
        fprintf(stderr, "   -e: disable encryption (French TS)\n");
        fprintf(stderr, "   -E: disable encryption from client to server\n");
        fprintf(stderr, "   -m: do not send motion events\n");
        fprintf(stderr, "   -C: use private colour map\n");
        fprintf(stderr, "   -D: hide window manager decorations\n");
        fprintf(stderr, "   -K: keep window manager key bindings\n");
        fprintf(stderr, "   -S: caption button size (single application mode)\n");
        fprintf(stderr, "   -T: window title\n");
        fprintf(stderr, "   -N: enable numlock syncronization\n");
        fprintf(stderr, "   -X: embed into another window with a given id.\n");
        fprintf(stderr, "   -a: connection colour depth\n");
        fprintf(stderr, "   -r: enable specified device redirection (this flag can be repeated)\n");
        fprintf(stderr,
                "         '-r comport:COM1=/dev/ttyS0': enable serial redirection of /dev/ttyS0 to COM1\n");
        fprintf(stderr, "             or      COM1=/dev/ttyS0,COM2=/dev/ttyS1\n");
        fprintf(stderr,
                "         '-r disk:A=/mnt/floppy': enable redirection of /mnt/floppy to A:\n");
        fprintf(stderr, "             or   A=/mnt/floppy,D=/mnt/cdrom'\n");
        fprintf(stderr,
                "         '-r lptport:LPT1=/dev/lp0': enable parallel redirection of /dev/lp0 to LPT1\n");
        fprintf(stderr, "             or      LPT1=/dev/lp0,LPT2=/dev/lp1\n");
        fprintf(stderr, "         '-r printer:mydeskjet': enable printer redirection\n");
        fprintf(stderr,
                "             or      mydeskjet=\"HP LaserJet IIIP\" to enter server driver as well\n");
        fprintf(stderr, "         '-r sound:[local|off|remote]': enable sound redirection\n");
        fprintf(stderr, "                     remote would leave sound on server\n");
        fprintf(stderr, "   -0: attach to console\n");
        fprintf(stderr, "   -4: use RDP version 4\n");
        fprintf(stderr, "   -5: use RDP version 5 (default)\n");
}

static BOOL
read_password(char *password, int size)
{
        struct termios tios;
        BOOL ret = False;
        int istty = 0;
        char *p;

        if (tcgetattr(STDIN_FILENO, &tios) == 0)
        {
                fprintf(stderr, "Password: ");
                tios.c_lflag &= ~ECHO;
                tcsetattr(STDIN_FILENO, TCSANOW, &tios);
                istty = 1;
        }

        if (fgets(password, size, stdin) != NULL)
        {
                ret = True;

                /* strip final newline */
                p = strchr(password, '\n');
                if (p != NULL)
                        *p = 0;
        }

        if (istty)
        {
                tios.c_lflag |= ECHO;
                tcsetattr(STDIN_FILENO, TCSANOW, &tios);
                fprintf(stderr, "\n");
        }

        return ret;
}

static void
parse_server_and_port(char *server)
{
        char *p;
#ifdef IPv6
        int addr_colons;
#endif

#ifdef IPv6
        p = server;
        addr_colons = 0;
        while (*p)
                if (*p++ == ':')
                        addr_colons++;
        if (addr_colons >= 2)
        {
                /* numeric IPv6 style address format - [1:2:3::4]:port */
                p = strchr(server, ']');
                if (*server == '[' && p != NULL)
                {
                        if (*(p + 1) == ':' && *(p + 2) != '\0')
                                tcp_port_rdp = strtol(p + 2, NULL, 10);
                        /* remove the port number and brackets from the address */
                        *p = '\0';
                        strncpy(server, server + 1, strlen(server));
                }
        }
        else
        {
                /* dns name or IPv4 style address format - server.example.com:port or 1.2.3.4:port */
                p = strchr(server, ':');
                if (p != NULL)
                {
                        tcp_port_rdp = strtol(p + 1, NULL, 10);
                        *p = 0;
                }
        }
#else /* no IPv6 support */
        p = strchr(server, ':');
        if (p != NULL)
        {
                tcp_port_rdp = strtol(p + 1, NULL, 10);
                *p = 0;
        }
#endif /* IPv6 */

}

/* Client program */
int
main(int argc, char *argv[])
{
        char server[64];
        char fullhostname[64];
        char domain[16];
        char password[64];
        char shell[128];
        char directory[32];
        BOOL prompt_password, rdp_retval = False;
        struct passwd *pw;
        uint32 flags;
        char *p;
        int c;

        int username_option = 0;

        flags = RDP_LOGON_NORMAL;
        prompt_password = False;
        domain[0] = password[0] = shell[0] = directory[0] = 0;
        strcpy(keymapname, "en-us");
        g_embed_wnd = 0;

        g_num_devices = 0;

#ifdef RDP2VNC
#define VNCOPT "V:Q:"
#else
#define VNCOPT
#endif

        while ((c = getopt(argc, argv, VNCOPT "u:d:s:c:p:n:k:g:fbBeEmCDKS:T:NX:a:r:045h?")) != -1)
        {
                switch (c)
                {
#ifdef RDP2VNC
                        case 'V':
                                rfb_port = strtol(optarg, NULL, 10);
                                if (rfb_port < 100)
                                        rfb_port += 5900;
                                break;

                        case 'Q':
                                defer_time = strtol(optarg, NULL, 10);
                                if (defer_time < 0)
                                        defer_time = 0;
                                break;
#endif

                        case 'u':
                                STRNCPY(g_username, optarg, sizeof(g_username));
                                username_option = 1;
                                break;

                        case 'd':
                                STRNCPY(domain, optarg, sizeof(domain));
                                break;

                        case 's':
                                STRNCPY(shell, optarg, sizeof(shell));
                                break;

                        case 'c':
                                STRNCPY(directory, optarg, sizeof(directory));
                                break;

                        case 'p':
                                if ((optarg[0] == '-') && (optarg[1] == 0))
                                {
                                        prompt_password = True;
                                        break;
                                }

                                STRNCPY(password, optarg, sizeof(password));
                                flags |= RDP_LOGON_AUTO;

                                /* try to overwrite argument so it won't appear in ps */
                                p = optarg;
                                while (*p)
                                        *(p++) = 'X';
                                break;

                        case 'n':
                                STRNCPY(hostname, optarg, sizeof(hostname));
                                break;

                        case 'k':
                                STRNCPY(keymapname, optarg, sizeof(keymapname));
                                break;

                        case 'g':
                                g_fullscreen = False;
                                if (!strcmp(optarg, "workarea"))
                                {
                                        g_width = g_height = 0;
                                        break;
                                }

                                g_width = strtol(optarg, &p, 10);
                                if (g_width <= 0)
                                {
                                        error("invalid geometry\n");
                                        return 1;
                                }

                                if (*p == 'x')
                                        g_height = strtol(p + 1, NULL, 10);

                                if (g_height <= 0)
                                {
                                        error("invalid geometry\n");
                                        return 1;
                                }

                                if (*p == '%')
                                        g_width = -g_width;

                                break;

                        case 'f':
                                g_fullscreen = True;
                                break;

                        case 'b':
                                g_orders = False;
                                break;

                        case 'B':
                                g_ownbackstore = False;
                                break;

                        case 'e':
                                g_encryption = False;
                                break;
                        case 'E':
                                packet_encryption = False;
                                break;
                        case 'm':
                                g_sendmotion = False;
                                break;

                        case 'C':
                                g_owncolmap = True;
                                break;

                        case 'D':
                                g_hide_decorations = True;
                                break;

                        case 'K':
                                g_grab_keyboard = False;
                                break;

                        case 'S':
                                if (!strcmp(optarg, "standard"))
                                {
                                        g_win_button_size = 18;
                                        break;
                                }

                                g_win_button_size = strtol(optarg, &p, 10);

                                if (*p)
                                {
                                        error("invalid button size\n");
                                        return 1;
                                }

                                break;

                        case 'T':
                                STRNCPY(g_title, optarg, sizeof(g_title));
                                break;

                        case 'N':
                                g_numlock_sync = True;
                                break;

                        case 'X':
                                g_embed_wnd = strtol(optarg, NULL, 10);
                                break;
                                
                        case 'a':
                                g_server_bpp = strtol(optarg, NULL, 10);
                                if (g_server_bpp != 8 && g_server_bpp != 16 && g_server_bpp != 15
                                    && g_server_bpp != 24)
                                {
                                        error("invalid server bpp\n");
                                        return 1;
                                }
                                break;

                        case 'r':

                                if (strncmp("sound", optarg, 5) == 0)
                                {
                                        optarg += 5;

                                        if (*optarg == ':')
                                        {
                                                *optarg++;
                                                while ((p = next_arg(optarg, ',')))
                                                {
                                                        if (strncmp("remote", optarg, 6) == 0)
                                                                flags |= RDP_LOGON_LEAVE_AUDIO;

                                                        if (strncmp("local", optarg, 5) == 0)
#ifdef WITH_RDPSND
                                                                g_rdpsnd = True;
#else
                                                                warning("Not compiled with sound support");
#endif

                                                        if (strncmp("off", optarg, 3) == 0)
                                                                g_rdpsnd = False;

                                                        optarg = p;
                                                }
                                        }
                                        else
                                        {
#ifdef WITH_RDPSND
                                                g_rdpsnd = True;
#else
                                                warning("Not compiled with sound support");
#endif
                                        }
                                }
                                else if (strncmp("disk", optarg, 4) == 0)
                                {
                                        /* -r disk:h:=/mnt/floppy */
                                        disk_enum_devices(&g_num_devices, optarg + 4);
                                }
                                else if (strncmp("comport", optarg, 7) == 0)
                                {
                                        serial_enum_devices(&g_num_devices, optarg + 7);
                                }
                                else if (strncmp("lptport", optarg, 7) == 0)
                                {
                                        parallel_enum_devices(&g_num_devices, optarg + 7);
                                }
                                else if (strncmp("printer", optarg, 7) == 0)
                                {
                                        printer_enum_devices(&g_num_devices, optarg + 7);
                                }
                                else
                                {
                                        warning("Unknown -r argument\n\n\tPossible arguments are: comport, disk, lptport, printer, sound\n");
                                }
                                break;

                        case '0':
                                g_console_session = True;
                                break;

                        case '4':
                                g_use_rdp5 = False;
                                break;

                        case '5':
                                g_use_rdp5 = True;
                                break;

                        case 'h':
                        case '?':
                        default:
                                usage(argv[0]);
                                return 1;
                }
        }

        if (argc - optind != 1)
        {
                usage(argv[0]);
                return 1;
        }

        STRNCPY(server, argv[optind], sizeof(server));
        parse_server_and_port(server);

        if (!username_option)
        {
                pw = getpwuid(getuid());
                if ((pw == NULL) || (pw->pw_name == NULL))
                {
                        error("could not determine username, use -u\n");
                        return 1;
                }

                STRNCPY(g_username, pw->pw_name, sizeof(g_username));
        }

        if (hostname[0] == 0)
        {
                if (gethostname(fullhostname, sizeof(fullhostname)) == -1)
                {
                        error("could not determine local hostname, use -n\n");
                        return 1;
                }

                p = strchr(fullhostname, '.');
                if (p != NULL)
                        *p = 0;

                STRNCPY(hostname, fullhostname, sizeof(hostname));
        }

        if (prompt_password && read_password(password, sizeof(password)))
                flags |= RDP_LOGON_AUTO;

        if (g_title[0] == 0)
        {
                strcpy(g_title, "rdesktop - ");
                strncat(g_title, server, sizeof(g_title) - sizeof("rdesktop - "));
        }

#ifdef RDP2VNC
        rdp2vnc_connect(server, flags, domain, password, shell, directory);
        return 0;
#else

        if (!ui_init())
                return 1;

#ifdef WITH_RDPSND
        if (g_rdpsnd)
                rdpsnd_init();
#endif
        rdpdr_init();

        if (!rdp_connect(server, flags, domain, password, shell, directory))
                return 1;

        /* By setting encryption to False here, we have an encrypted login 
           packet but unencrypted transfer of other packets */
        if (!packet_encryption)
                g_encryption = False;


        DEBUG(("Connection successful.\n"));
        memset(password, 0, sizeof(password));

        if (ui_create_window())
        {
                rdp_retval = rdp_main_loop();
                ui_destroy_window();
        }

        DEBUG(("Disconnecting...\n"));
        rdp_disconnect();
        ui_deinit();

        if (True == rdp_retval)
                return 0;
        else
                return 2;

#endif

}

#ifdef EGD_SOCKET
/* Read 32 random bytes from PRNGD or EGD socket (based on OpenSSL RAND_egd) */
static BOOL
generate_random_egd(uint8 * buf)
{
        struct sockaddr_un addr;
        BOOL ret = False;
        int fd;

        fd = socket(AF_UNIX, SOCK_STREAM, 0);
        if (fd == -1)
                return False;

        addr.sun_family = AF_UNIX;
        memcpy(addr.sun_path, EGD_SOCKET, sizeof(EGD_SOCKET));
        if (connect(fd, (struct sockaddr *) &addr, sizeof(addr)) == -1)
                goto err;

        /* PRNGD and EGD use a simple communications protocol */
        buf[0] = 1;             /* Non-blocking (similar to /dev/urandom) */
        buf[1] = 32;            /* Number of requested random bytes */
        if (write(fd, buf, 2) != 2)
                goto err;

        if ((read(fd, buf, 1) != 1) || (buf[0] == 0))   /* Available? */
                goto err;

        if (read(fd, buf, 32) != 32)
                goto err;

        ret = True;

      err:
        close(fd);
        return ret;
}
#endif

/* Generate a 32-byte random for the secure transport code. */
void
generate_random(uint8 * random)
{
        struct stat st;
        struct tms tmsbuf;
        MD5_CTX md5;
        uint32 *r;
        int fd, n;

        /* If we have a kernel random device, try that first */
        if (((fd = open("/dev/urandom", O_RDONLY)) != -1)
            || ((fd = open("/dev/random", O_RDONLY)) != -1))
        {
                n = read(fd, random, 32);
                close(fd);
                if (n == 32)
                        return;
        }

#ifdef EGD_SOCKET
        /* As a second preference use an EGD */
        if (generate_random_egd(random))
                return;
#endif

        /* Otherwise use whatever entropy we can gather - ideas welcome. */
        r = (uint32 *) random;
        r[0] = (getpid()) | (getppid() << 16);
        r[1] = (getuid()) | (getgid() << 16);
        r[2] = times(&tmsbuf);  /* system uptime (clocks) */
        gettimeofday((struct timeval *) &r[3], NULL);   /* sec and usec */
        stat("/tmp", &st);
        r[5] = st.st_atime;
        r[6] = st.st_mtime;
        r[7] = st.st_ctime;

        /* Hash both halves with MD5 to obscure possible patterns */
        MD5_Init(&md5);
        MD5_Update(&md5, random, 16);
        MD5_Final(random, &md5);
        MD5_Update(&md5, random + 16, 16);
        MD5_Final(random + 16, &md5);
}

/* malloc; exit if out of memory */
void *
xmalloc(int size)
{
        void *mem = malloc(size);
        if (mem == NULL)
        {
                error("xmalloc %d\n", size);
                exit(1);
        }
        return mem;
}

/* realloc; exit if out of memory */
void *
xrealloc(void *oldmem, int size)
{
        void *mem = realloc(oldmem, size);
        if (mem == NULL)
        {
                error("xrealloc %d\n", size);
                exit(1);
        }
        return mem;
}

/* free */
void
xfree(void *mem)
{
        free(mem);
}

/* report an error */
void
error(char *format, ...)
{
        va_list ap;

        fprintf(stderr, "ERROR: ");

        va_start(ap, format);
        vfprintf(stderr, format, ap);
        va_end(ap);
}

/* report a warning */
void
warning(char *format, ...)
{
        va_list ap;

        fprintf(stderr, "WARNING: ");

        va_start(ap, format);
        vfprintf(stderr, format, ap);
        va_end(ap);
}

/* report an unimplemented protocol feature */
void
unimpl(char *format, ...)
{
        va_list ap;

        fprintf(stderr, "NOT IMPLEMENTED: ");

        va_start(ap, format);
        vfprintf(stderr, format, ap);
        va_end(ap);
}

/* produce a hex dump */
void
hexdump(unsigned char *p, unsigned int len)
{
        unsigned char *line = p;
        int i, thisline, offset = 0;

        while (offset < len)
        {
                printf("%04x ", offset);
                thisline = len - offset;
                if (thisline > 16)
                        thisline = 16;

                for (i = 0; i < thisline; i++)
                        printf("%02x ", line[i]);

                for (; i < 16; i++)
                        printf("   ");

                for (i = 0; i < thisline; i++)
                        printf("%c", (line[i] >= 0x20 && line[i] < 0x7f) ? line[i] : '.');

                printf("\n");
                offset += thisline;
                line += thisline;
        }
}

/*
  input: src is the string we look in for needle.
         Needle may be escaped by a backslash, in
         that case we ignore that particular needle.
  return value: returns next src pointer, for
        succesive executions, like in a while loop
        if retval is 0, then there are no more args.
  pitfalls:
        src is modified. 0x00 chars are inserted to
        terminate strings.
        return val, points on the next val chr after ins
        0x00

        example usage:
        while( (pos = next_arg( optarg, ',')) ){
                printf("%s\n",optarg);
                optarg=pos;
        }

*/
char *
next_arg(char *src, char needle)
{
        char *nextval;
        char *p;
        char *mvp = 0;

        /* EOS */
        if (*src == (char) 0x00)
                return 0;

        p = src;
        /*  skip escaped needles */
        while ((nextval = strchr(p, needle)))
        {
                mvp = nextval - 1;
                /* found backslashed needle */
                if (*mvp == '\\' && (mvp > src))
                {
                        /* move string one to the left */
                        while (*(mvp + 1) != (char) 0x00)
                        {
                                *mvp = *(mvp + 1);
                                *mvp++;
                        }
                        *mvp = (char) 0x00;
                        p = nextval;
                }
                else
                {
                        p = nextval + 1;
                        break;
                }

        }

        /* more args available */
        if (nextval)
        {
                *nextval = (char) 0x00;
                return ++nextval;
        }

        /* no more args after this, jump to EOS */
        nextval = src + strlen(src);
        return nextval;
}


void
toupper_str(char *p)
{
        while (*p)
        {
                if ((*p >= 'a') && (*p <= 'z'))
                        *p = toupper((int) *p);
                p++;
        }
}


/* not all clibs got ltoa */
#define LTOA_BUFSIZE (sizeof(long) * 8 + 1)

char *
l_to_a(long N, int base)
{
        static char ret[LTOA_BUFSIZE];

        char *head = ret, buf[LTOA_BUFSIZE], *tail = buf + sizeof(buf);

        register int divrem;

        if (base < 36 || 2 > base)
                base = 10;

        if (N < 0)
        {
                *head++ = '-';
                N = -N;
        }

        tail = buf + sizeof(buf);
        *--tail = 0;

        do
        {
                divrem = N % base;
                *--tail = (divrem <= 9) ? divrem + '0' : divrem + 'a' - 10;
                N /= base;
        }
        while (N);

        strcpy(head, tail);
        return ret;
}


int
load_licence(unsigned char **data)
{
        char *home, *path;
        struct stat st;
        int fd, length;

        home = getenv("HOME");
        if (home == NULL)
                return -1;

        path = (char *) xmalloc(strlen(home) + strlen(hostname) + sizeof("/.rdesktop/licence."));
        sprintf(path, "%s/.rdesktop/licence.%s", home, hostname);

        fd = open(path, O_RDONLY);
        if (fd == -1)
                return -1;

        if (fstat(fd, &st))
                return -1;

        *data = (uint8 *) xmalloc(st.st_size);
        length = read(fd, *data, st.st_size);
        close(fd);
        xfree(path);
        return length;
}

void
save_licence(unsigned char *data, int length)
{
        char *home, *path, *tmppath;
        int fd;

        home = getenv("HOME");
        if (home == NULL)
                return;

        path = (char *) xmalloc(strlen(home) + strlen(hostname) + sizeof("/.rdesktop/licence."));

        sprintf(path, "%s/.rdesktop", home);
        if ((mkdir(path, 0700) == -1) && errno != EEXIST)
        {
                perror(path);
                return;
        }

        /* write licence to licence.hostname.new, then atomically rename to licence.hostname */

        sprintf(path, "%s/.rdesktop/licence.%s", home, hostname);
        tmppath = (char *) xmalloc(strlen(path) + sizeof(".new"));
        strcpy(tmppath, path);
        strcat(tmppath, ".new");

        fd = open(tmppath, O_WRONLY | O_CREAT | O_TRUNC, 0600);
        if (fd == -1)
        {
                perror(tmppath);
                return;
        }

        if (write(fd, data, length) != length)
        {
                perror(tmppath);
                unlink(tmppath);
        }
        else if (rename(tmppath, path) == -1)
        {
                perror(path);
                unlink(tmppath);
        }

        close(fd);
        xfree(tmppath);
        xfree(path);
}