src/lxc/lxc_attach.c

   1 /*
   2  * lxc: linux Container library
   3  *
   4  * (C) Copyright IBM Corp. 2007, 2010
   5  *
   6  * Authors:
   7  * Daniel Lezcano <dlezcano at fr.ibm.com>
   8  *
   9  * This library is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public
  11  * License as published by the Free Software Foundation; either
  12  * version 2.1 of the License, or (at your option) any later version.
  13  *
  14  * This library is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with this library; if not, write to the Free Software
  21  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  22  */
  23
  24 #define _GNU_SOURCE
  25 #include <unistd.h>
  26 #include <errno.h>
  27 #include <pwd.h>
  28 #include <stdlib.h>
  29 #include <sys/param.h>
  30 #include <sys/types.h>
  31 #include <sys/wait.h>
  32
  33 #include "commands.h"
  34 #include "arguments.h"
  35 #include "namespace.h"
  36 #include "log.h"
  37
  38 lxc_log_define(lxc_attach_ui, lxc);
  39
  40 static const struct option my_longopts[] = {
  41         LXC_COMMON_OPTIONS
  42 };
  43
  44 static struct lxc_arguments my_args = {
  45         .progname = "lxc-attach",
  46         .help     = "\
  47 --name=NAME\n\
  48 \n\
  49 Execute the specified command - enter the container NAME\n\
  50 \n\
  51 Options :\n\
  52   -n, --name=NAME   NAME for name of the container\n",
  53         .options  = my_longopts,
  54         .parser   = NULL,
  55         .checker  = NULL,
  56 };
  57
  58 int main(int argc, char *argv[], char *envp[])
  59 {
  60         int ret;
  61         pid_t pid;
  62         struct passwd *passwd;
  63         uid_t uid;
  64         char *curdir;
  65
  66         ret = lxc_arguments_parse(&my_args, argc, argv);
  67         if (ret)
  68                 return ret;
  69
  70         ret = lxc_log_init(my_args.log_file, my_args.log_priority,
  71                            my_args.progname, my_args.quiet);
  72         if (ret)
  73                 return ret;
  74
  75         pid = get_init_pid(my_args.name);
  76         if (pid < 0) {
  77                 ERROR("failed to get the init pid");
  78                 return -1;
  79         }
  80
  81         curdir = get_current_dir_name();
  82
  83         ret = lxc_attach(pid);
  84         if (ret < 0) {
  85                 ERROR("failed to enter the namespace");
  86                 return -1;
  87         }
  88
  89         if (curdir && chdir(curdir))
  90                 WARN("could not change directory to '%s'", curdir);
  91
  92         free(curdir);
  93
  94         pid = fork();
  95
  96         if (pid < 0) {
  97                 SYSERROR("failed to fork");
  98                 return -1;
  99         }
 100
 101         if (pid) {
 102                 int status;
 103
 104         again:
 105                 if (waitpid(pid, &status, 0) < 0) {
 106                         if (errno == EINTR)
 107                                 goto again;
 108                         SYSERROR("failed to wait '%d'", pid);
 109                         return -1;
 110                 }
 111
 112                 if (WIFEXITED(status))
 113                         return WEXITSTATUS(status);
 114
 115                 return -1;
 116         }
 117
 118         if (!pid) {
 119
 120                 if (my_args.argc) {
 121                         execve(my_args.argv[0], my_args.argv, envp);
 122                         SYSERROR("failed to exec '%s'", my_args.argv[0]);
 123                         return -1;
 124                 }
 125
 126                 uid = getuid();
 127
 128                 passwd = getpwuid(uid);
 129                 if (!passwd) {
 130                         SYSERROR("failed to get passwd "                \
 131                                  "entry for uid '%d'", uid);
 132                         return -1;
 133                 }
 134
 135                 {
 136                         char *const args[] = {
 137                                 passwd->pw_shell,
 138                                 NULL,
 139                         };
 140
 141                         execve(args[0], args, envp);
 142                         SYSERROR("failed to exec '%s'", args[0]);
 143                         return -1;
 144                 }
 145
 146         }
 147
 148         return 0;
 149 }