qemu-start/trunk/qemu-start.c

/*
    qemu-start.c - Part of qemu-start, a package to start qemu nicely.
    Copyright (c) 2006  Frodo Looijaard <frodo@frodo.looijaard.name>

    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.
*/

#define _GNU_SOURCE /* asprintf */
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <pwd.h>
#include <grp.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <net/if.h>
#include <linux/if_tun.h>

#define QEMU "/usr/bin/qemu"
#define USER "qemu"

/* Tiny code to open tap/tun device, and hand the fd to qemu.
   Run as root, drops to given user. */
int main(int argc, char *argv[])
{
        struct ifreq ifr;
        struct passwd *userdata;
        char *newargs[argc + 2];
        int i,fd,vlan,tapnr;
        char *ptr;
        char *command;
        char *display;

        /* Check parameters */
        if (argc < 4) {
                fprintf(stderr, "Usage: qemu-start TAPDEVNR VLAN SYSTEM <qemu options>...\n");
                fprintf(stderr, "  A device tapTAPDEVNR must have been configured.\n");
                fprintf(stderr, "  VLAN is the Virtual LAN number (just use 0 if unsure).\n");
                fprintf(stderr, "  SYSTEM is the system to emulate. Use \"\" for the current architecture\n");
                fprintf(stderr, "  (uses /usr/bin/qemm); else a binary /usr/bin/qemu-system-SYSTEM is used.\n");
                exit(1);
        }

        /* First parameter: TAPDEVNR */
        tapnr = strtol(argv[1],&ptr,0);
        if (*ptr) {
                fprintf(stderr, "Invalid value for TAPDEVNR parameter (use a number!)\n");
                exit(1);
        }

        /* Second parameter: VLAN */
        vlan = strtol(argv[2],&ptr,0);
        if (*ptr) {
                fprintf(stderr, "Invalid value for VLAN parameter (use a number!)\n");
                exit(1);
        }

        /* Open /dev/net/tun */
        fd = open("/dev/net/tun", O_RDWR);
        if (fd < 0) {
                perror("Could not open /dev/net/tun");
                exit(1);
        }

        /* Bind to the right tap device */
        memset(&ifr, 0, sizeof(ifr));
        ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
        snprintf(ifr.ifr_name,IFNAMSIZ,"tap%d",tapnr);

        if (ioctl(fd, TUNSETIFF, (void *) &ifr) != 0) {
                perror("Could not get tap device");
                exit(1);
        }

        /* Fix X-display */
        userdata = getpwuid(getuid());
        setuid(0);
        setgid(0);
        asprintf(&command,"xauth -f ~%s/.Xauthority extract - $(echo $DISPLAY|sed \"s,^localhost,$(hostname)/unix,\") | xauth -f ~%s/.Xauthority merge -; chown %s: ~%s/.Xauthority",userdata->pw_name,USER,USER,USER);
        system(command);

        /* Set correct userid. */
        userdata = getpwnam(USER);
        if (!userdata) {
                fprintf(stderr, "No user '%s'\n", USER);
                exit(1);
        }
        setgroups(0, NULL);
        setgid(userdata->pw_gid);
        if (setuid(userdata->pw_uid) != 0) {
                perror("setting uid");
                exit(1);
        }

        /* Clean the environment */
        display=getenv("DISPLAY");
        clearenv();
        setenv("HOME",userdata->pw_dir,1);
        setenv("DISPLAY",display,1);
        setenv("PATH","/usr/bin:/bin:/usr/local/bin",1);
        setenv("LOGNAME",userdata->pw_name,1);
        setenv("USER",userdata->pw_name,1);

        /* Create the right qemu invocation */
        if (!strlen(argv[3]))
                newargs[0] = QEMU;
        else
                asprintf(&newargs[0],"%s-system-%s",QEMU,argv[3]);
        newargs[1] = "-net";
        asprintf(&newargs[2],"nic,vlan=%d",vlan);
        newargs[3] = "-net";
        asprintf(&newargs[4],"tap,fd=%d,vlan=%d",fd,vlan);
        for (i = 4; i <= argc; i++)
                newargs[i+1] = argv[i];

        execvp(newargs[0], newargs);
        exit(1);
}
1	/*
2	qemu-start.c - Part of qemu-start, a package to start qemu nicely.
3	Copyright (c) 2006 Frodo Looijaard <frodo@frodo.looijaard.name>
4
5	This program is free software; you can redistribute it and/or modify
6	it under the terms of the GNU General Public License as published by
7	the Free Software Foundation; either version 2 of the License, or
8	(at your option) any later version.
9
10	This program is distributed in the hope that it will be useful,
11	but WITHOUT ANY WARRANTY; without even the implied warranty of
12	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13	GNU General Public License for more details.
14
15	You should have received a copy of the GNU General Public License
16	along with this program; if not, write to the Free Software
17	Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
18	*/
19
20	#define _GNU_SOURCE /* asprintf */
21	#include <stdio.h>
22	#include <string.h>
23	#include <sys/types.h>
24	#include <pwd.h>
25	#include <grp.h>
26	#include <sys/stat.h>
27	#include <sys/ioctl.h>
28	#include <fcntl.h>
29	#include <unistd.h>
30	#include <stdlib.h>
31	#include <net/if.h>
32	#include <linux/if_tun.h>
33
34	#define QEMU "/usr/bin/qemu"
35	#define USER "qemu"
36
37	/* Tiny code to open tap/tun device, and hand the fd to qemu.
38	Run as root, drops to given user. */
39	int main(int argc, char *argv[])
40	{
41	struct ifreq ifr;
42	struct passwd *userdata;
43	char *newargs[argc + 2];
44	int i,fd,vlan,tapnr;
45	char *ptr;
46	char *command;
47	char *display;
48
49	/* Check parameters */
50	if (argc < 4) {
51	fprintf(stderr, "Usage: qemu-start TAPDEVNR VLAN SYSTEM <qemu options>...\n");
52	fprintf(stderr, " A device tapTAPDEVNR must have been configured.\n");
53	fprintf(stderr, " VLAN is the Virtual LAN number (just use 0 if unsure).\n");
54	fprintf(stderr, " SYSTEM is the system to emulate. Use \"\" for the current architecture\n");
55	fprintf(stderr, " (uses /usr/bin/qemm); else a binary /usr/bin/qemu-system-SYSTEM is used.\n");
56	exit(1);
57	}
58
59	/* First parameter: TAPDEVNR */
60	tapnr = strtol(argv[1],&ptr,0);
61	if (*ptr) {
62	fprintf(stderr, "Invalid value for TAPDEVNR parameter (use a number!)\n");
63	exit(1);
64	}
65
66	/* Second parameter: VLAN */
67	vlan = strtol(argv[2],&ptr,0);
68	if (*ptr) {
69	fprintf(stderr, "Invalid value for VLAN parameter (use a number!)\n");
70	exit(1);
71	}
72
73	/* Open /dev/net/tun */
74	fd = open("/dev/net/tun", O_RDWR);
75	if (fd < 0) {
76	perror("Could not open /dev/net/tun");
77	exit(1);
78	}
79
80	/* Bind to the right tap device */
81	memset(&ifr, 0, sizeof(ifr));
82	ifr.ifr_flags = IFF_TAP \| IFF_NO_PI;
83	snprintf(ifr.ifr_name,IFNAMSIZ,"tap%d",tapnr);
84
85	if (ioctl(fd, TUNSETIFF, (void *) &ifr) != 0) {
86	perror("Could not get tap device");
87	exit(1);
88	}
89
90	/* Fix X-display */
91	userdata = getpwuid(getuid());
92	setuid(0);
93	setgid(0);
94	asprintf(&command,"xauth -f ~%s/.Xauthority extract - $(echo $DISPLAY\|sed \"s,^localhost,$(hostname)/unix,\") \| xauth -f ~%s/.Xauthority merge -; chown %s: ~%s/.Xauthority",userdata->pw_name,USER,USER,USER);
95	system(command);
96
97	/* Set correct userid. */
98	userdata = getpwnam(USER);
99	if (!userdata) {
100	fprintf(stderr, "No user '%s'\n", USER);
101	exit(1);
102	}
103	setgroups(0, NULL);
104	setgid(userdata->pw_gid);
105	if (setuid(userdata->pw_uid) != 0) {
106	perror("setting uid");
107	exit(1);
108	}
109
110	/* Clean the environment */
111	display=getenv("DISPLAY");
112	clearenv();
113	setenv("HOME",userdata->pw_dir,1);
114	setenv("DISPLAY",display,1);
115	setenv("PATH","/usr/bin:/bin:/usr/local/bin",1);
116	setenv("LOGNAME",userdata->pw_name,1);
117	setenv("USER",userdata->pw_name,1);
118
119	/* Create the right qemu invocation */
120	if (!strlen(argv[3]))
121	newargs[0] = QEMU;
122	else
123	asprintf(&newargs[0],"%s-system-%s",QEMU,argv[3]);
124	newargs[1] = "-net";
125	asprintf(&newargs[2],"nic,vlan=%d",vlan);
126	newargs[3] = "-net";
127	asprintf(&newargs[4],"tap,fd=%d,vlan=%d",fd,vlan);
128	for (i = 4; i <= argc; i++)
129	newargs[i+1] = argv[i];
130
131	execvp(newargs[0], newargs);
132	exit(1);
133	}
frodo@frodo.looijaard.name	ViewVC Help
Powered by ViewVC 1.1.26