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/* |
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qemu-start.c - Part of qemu-start, a package to start qemu nicely. |
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Copyright (c) 2006 Frodo Looijaard <frodo@frodo.looijaard.name> |
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|
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This program is free software; you can redistribute it and/or modify |
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it under the terms of the GNU General Public License as published by |
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the Free Software Foundation; either version 2 of the License, or |
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(at your option) any later version. |
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|
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This program is distributed in the hope that it will be useful, |
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but WITHOUT ANY WARRANTY; without even the implied warranty of |
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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GNU General Public License for more details. |
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|
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You should have received a copy of the GNU General Public License |
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along with this program; if not, write to the Free Software |
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. |
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*/ |
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|
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#define _GNU_SOURCE /* asprintf */ |
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#include <stdio.h> |
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#include <string.h> |
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#include <sys/types.h> |
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#include <pwd.h> |
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#include <grp.h> |
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#include <sys/stat.h> |
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#include <sys/ioctl.h> |
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#include <fcntl.h> |
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#include <unistd.h> |
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#include <stdlib.h> |
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#include <net/if.h> |
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#include <linux/if_tun.h> |
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#include <sys/wait.h> |
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#include <errno.h> |
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|
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/* Autogenerated by gengetopt */ |
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#include "cmdline.h" |
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|
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/* This define is present in recent glibc, it is not available on sarge */ |
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#ifndef HOST_NAME_MAX |
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#define HOST_NAME_MAX 64 |
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#endif |
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|
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#define QEMU "/usr/bin/qemu" |
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#define USER "qemu" |
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|
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/* |
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* This function merges the xauthority data of the current X context |
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* into the QEMU user's .Xauthority file. |
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*/ |
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void fix_xauthority(void) { |
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struct passwd *userdata; |
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int pfd[2]; |
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char *xauthfile; |
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char *display; |
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char *newdisplay; |
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char *hostname; |
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// int status1, status2; |
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int status,pid; |
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pid_t cpid1, cpid2; |
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|
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if (pipe(pfd)) { |
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perror("pipe failed"); |
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exit(1); |
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} |
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|
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cpid1 = fork(); |
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if (cpid1 < 0) { |
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perror("first fork failed"); |
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exit(1); |
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} |
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|
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/* Child: will execute the xauth extract */ |
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if (cpid1 == 0) { |
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/* Child may run as original process starter */ |
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if (setgroups(0, NULL)) { |
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perror("setgroups failed"); |
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exit(1); |
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} |
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if (setgid(getgid())) { |
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perror("setgid failed"); |
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exit(1); |
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} |
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if (setuid(getuid())) { |
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perror("setuid failed"); |
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exit(1); |
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} |
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|
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/* Write side of pipe corresponds to stdout */ |
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if (dup2(pfd[1],1) < 0) { |
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perror("dup2 failed"); |
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exit(1); |
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} |
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if (close(pfd[0])) { |
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perror("close of pfd[0] failed"); |
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exit(1); |
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} |
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if (close(pfd[1])) { |
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perror("close of pfd[1] failed"); |
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exit(1); |
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} |
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|
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userdata = getpwuid(getuid()); |
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if (!userdata) { |
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fprintf(stderr, "No user '%s'\n", USER); |
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exit(1); |
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} |
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|
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|
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/* Get xauthority file to use */ |
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if (! (xauthfile = getenv("XAUTHORITY"))) { |
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if (asprintf(&xauthfile,"%s/.Xauthority",userdata->pw_dir) < 1) { |
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perror("Constructing xauthority filename failed"); |
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exit(1); |
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} |
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} |
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|
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/* Get display */ |
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if (! (display = getenv("DISPLAY"))) { |
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perror("No DISPLAY variable found\n"); |
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exit(1); |
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} |
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|
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/* Substitution: if display starts with `localhost', substitute |
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`localhost' by `HOSTNAME/unix'. */ |
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if (strstr(display,"localhost") == display) { |
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hostname = malloc(HOST_NAME_MAX+1); |
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if (gethostname(hostname,HOST_NAME_MAX+1)) { |
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perror("Getting hostname failed"); |
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exit(1); |
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} |
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|
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if (!(newdisplay = malloc(strlen(hostname) + 5 + strlen(display)-9 + 1))) { |
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perror("Allocating new display failed"); |
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exit(1); |
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} |
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strcpy(newdisplay,hostname); |
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strcpy(newdisplay + strlen(hostname),"/unix"); |
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strcpy(newdisplay + strlen(hostname) + 5, display + 9); |
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display = newdisplay; |
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} else if (! (display = strdup(display))) { |
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perror("strdup DISPLAY failed"); |
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exit(1); |
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} |
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|
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execl("/usr/bin/X11/xauth","/usr/bin/X11/xauth","-f",xauthfile,"extract","-",display,NULL); |
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exit(1); |
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} |
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|
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|
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cpid2 = fork(); |
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if (cpid2 < 0) { |
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perror("second fork failed"); |
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exit(1); |
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} |
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|
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/* Child: will execute the xauth merge */ |
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if (cpid2 == 0) { |
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/* Get userid data. */ |
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userdata = getpwnam(USER); |
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if (!userdata) { |
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fprintf(stderr, "No user '%s'\n", USER); |
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exit(1); |
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} |
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|
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if (setgroups(0, NULL)) { |
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perror("setgroups failed"); |
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exit(1); |
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} |
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|
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/* Child may run as qemu user */ |
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if (setgid(userdata->pw_gid)) { |
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perror("setgid failed"); |
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exit(1); |
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} |
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if (setuid(userdata->pw_uid)) { |
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perror("setuid failed"); |
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exit(1); |
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} |
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/* Read side of pipe is stdin */ |
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if (dup2(pfd[0],0) < 0) { |
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perror("dup2 failed"); |
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exit(1); |
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} |
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if (close(pfd[0])) { |
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perror("close of pfd[0] failed"); |
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exit(1); |
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} |
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if (close(pfd[1])) { |
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perror("close of pfd[1] failed"); |
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exit(1); |
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} |
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|
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if (asprintf(&xauthfile,"%s/.Xauthority",userdata->pw_dir) < 1) { |
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perror("Constructing xauthority filename failed"); |
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exit(1); |
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} |
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|
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execl("/usr/bin/X11/xauth","/usr/bin/X11/xauth","-f",xauthfile,"merge","-",NULL); |
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exit(1); |
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} |
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|
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if (close(pfd[0])) { |
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perror("close of pfd[0] failed"); |
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exit(1); |
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} |
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if (close(pfd[1])) { |
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perror("close of pfd[1] failed"); |
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exit(1); |
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} |
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|
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while(1) { |
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|
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pid = wait(&status); |
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if ((pid < 1) && (errno == ECHILD)) |
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break; |
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if (pid < 1) { |
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perror("wait failed"); |
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exit(1); |
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} |
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if (! WIFEXITED(status) || WEXITSTATUS(status)) { |
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fprintf(stderr,"Child returned error\n"); |
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exit(1); |
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} |
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} |
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} |
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|
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|
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/* Tiny code to open tap/tun device, and hand the fd to qemu. |
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Run as root, drops to given user. */ |
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int main(int argc, char *argv[]) |
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{ |
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struct ifreq ifr; |
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struct passwd *userdata; |
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char *newargs[argc + 2]; |
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int fd,vlan,tapnr; |
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unsigned int i; |
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unsigned new_arg_count = 5; |
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struct gengetopt_args_info args_info; |
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char *display; |
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char *system; |
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char *topleft; |
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|
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/* Ugly fix because gengetopt 2.18 does not have the `usage' option */ |
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gengetopt_args_info_usage = "qemu-start [OPTIONS] -- [OPTIONS for QEMU]"; |
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|
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if (cmdline_parser(argc, argv, &args_info)) |
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exit(1); |
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|
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/* parameter: TAPDEVNR */ |
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tapnr = args_info.tapnr_arg; |
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|
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/* parameter: VLAN */ |
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vlan = args_info.vlan_arg; |
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|
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/* parameter: System type */ |
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if (args_info.system_given) { |
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if (index(args_info.system_arg,'/')) { |
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fprintf(stderr, "Invalid value `%s' for system (may not contain a slash character)\n", args_info.system_arg); |
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exit(1); |
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} |
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asprintf(&system, "%s", args_info.system_arg); |
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} |
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|
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/* parameters: Window location */ |
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if (args_info.window_left_given || args_info.window_top_given) { |
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if (!(args_info.window_left_given && args_info.window_top_given)) { |
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fprintf(stderr,("If either window-left (x) or window-top (y) are given, then both must be given\n")); |
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exit(1); |
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} |
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if (asprintf(&topleft, "%d,%d",args_info.window_left_arg,args_info.window_top_arg) < 0) { |
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perror("Preparing top-left environment value string failed"); |
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exit(1); |
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} |
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} |
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|
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/* Export the xauth data */ |
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fix_xauthority(); |
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|
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/* Open /dev/net/tun */ |
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fd = open("/dev/net/tun", O_RDWR); |
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if (fd < 0) { |
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perror("Could not open /dev/net/tun"); |
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exit(1); |
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} |
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|
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/* Bind to the right tap device */ |
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memset(&ifr, 0, sizeof(ifr)); |
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ifr.ifr_flags = IFF_TAP | IFF_NO_PI; |
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snprintf(ifr.ifr_name,IFNAMSIZ,"tap%d",tapnr); |
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|
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if (ioctl(fd, TUNSETIFF, (void *) &ifr) != 0) { |
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perror("Could not get tap device"); |
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exit(1); |
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} |
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|
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/* Get userid data. */ |
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userdata = getpwnam(USER); |
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if (!userdata) { |
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fprintf(stderr, "No user '%s'\n", USER); |
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exit(1); |
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} |
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|
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/* Change to QEMU user */ |
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if (setgroups(0, NULL)) { |
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perror("setgroups failed"); |
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exit(1); |
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} |
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if (setgid(userdata->pw_gid)) { |
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perror("setgid failed"); |
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exit(1); |
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} |
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if (setuid(userdata->pw_uid)) { |
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perror("setuid failed"); |
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exit(1); |
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} |
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|
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/* Clean the environment */ |
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if(!(display=getenv("DISPLAY"))) { |
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perror("Getting DISPLAY failed"); |
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exit(1); |
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} |
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if(clearenv()) { |
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perror("Clearing environment failed"); |
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exit(1); |
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} |
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if(setenv("HOME",userdata->pw_dir,1) || |
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setenv("DISPLAY",display,1) || |
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setenv("PATH","/usr/bin:/bin:/usr/local/bin",1) || |
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setenv("LOGNAME",userdata->pw_name,1) || |
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setenv("USER",userdata->pw_name,1)) { |
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perror("Setting environment failed"); |
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exit(1); |
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} |
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if (args_info.window_left_given || args_info.window_top_given) { |
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if (setenv("SDL_VIDEO_WINDOW_POS", topleft, 1)) { |
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perror("Setting top-left environment value failed"); |
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exit(1); |
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} |
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} |
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|
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/* Create the right qemu invocation */ |
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if (!args_info.system_given) |
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newargs[0] = QEMU; |
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else if (asprintf(&newargs[0],"%s-system-%s",QEMU,args_info.system_arg) < 0) { |
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perror("Preparing qemu executable filename failed"); |
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exit(1); |
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} |
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newargs[1] = "-net"; |
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if (asprintf(&newargs[2],"nic,vlan=%d",vlan) < 0) { |
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perror("Preparing nic argument failed"); |
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exit(1); |
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} |
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if (args_info.macaddr_given) { |
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if (asprintf(&newargs[2], "%s,mac=%s", newargs[2], args_info.macaddr_arg) < 0) { |
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perror("Adding macaddress to nic argument failed"); |
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} |
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} |
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if (args_info.nic_model_given) { |
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if (asprintf(&newargs[2], "%s,model=%s", newargs[2], args_info.nic_model_arg) < 0) { |
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perror("Adding nic model to nic argument failed"); |
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} |
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} |
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newargs[3] = "-net"; |
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if (asprintf(&newargs[4],"tap,fd=%d,vlan=%d",fd,vlan) < 0) { |
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perror("Preparing tap argument failed"); |
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exit(1); |
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} |
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for (i = 0; i < args_info.inputs_num; i++) { |
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newargs[i+5] = args_info.inputs[i]; |
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new_arg_count++; |
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} |
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newargs[new_arg_count] = NULL; |
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|
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execvp(newargs[0], newargs); |
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perror("Execution of qemu failed"); |
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exit(1); |
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} |
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