[hurd] 76/98: utils/settrans: fix the teardown of chrooted environments

[Samuel Thibault]

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sthibault pushed a commit to branch upstream
in repository hurd.

commit 77ba38a61492799cc3c615f0f622f34fc10de826
Author: Justus Winter <address@hidden>
Date:   Tue Dec 10 15:31:36 2013 +0100

    utils/settrans: fix the teardown of chrooted environments
    
    Previously, settrans --chroot would just exec the target.  Create a
    new process for that purpose.  Wait for its completion, then ask the
    translator (nicely by default) to go away.  If it refuses with EBUSY,
    it might be because some process has daemonized inside the chrooted
    environment.
    
    This fixes the following bug when settrans is used with fakeroot:
    
    % fakeroot-hurd /bin/true 2>&1 | tee
    <hangs>
    
    Here, fakeroot-hurd execs settrans with --chroot, settrans execs
    /hurd/fakeauth which will eventually exec the target /bin/true.  When
    true terminates, it will close its stdout and stderr.  But
    /hurd/fakeroot's stderr is also connected to tee's stdin, preventing
    tee from exiting.
    
    * utils/settrans.c (main): Fix the teardown of chrooted environments.
---
 utils/settrans.c | 69 ++++++++++++++++++++++++++++++++++++--------------------
 1 file changed, 44 insertions(+), 25 deletions(-)

diff --git a/utils/settrans.c b/utils/settrans.c
index d13e7c4..ecc6d75 100644
--- a/utils/settrans.c
+++ b/utils/settrans.c
@@ -25,6 +25,7 @@
 #include <error.h>
 #include <fcntl.h>
 #include <unistd.h>
+#include <sys/wait.h>
 
 #include <error.h>
 #include <argz.h>
@@ -279,33 +280,51 @@ main(int argc, char *argv[])
 
   if (chroot_command)
     {
-      /* We will act as the parent filesystem would for a lookup
-        of the active translator's root node, then use this port
-        as our root directory while we exec the command.  */
-
-      char retry_name[1024];   /* XXX */
-      retry_type do_retry;
-      mach_port_t root;
-      err = fsys_getroot (active_control,
-                         MACH_PORT_NULL, MACH_MSG_TYPE_COPY_SEND,
-                         NULL, 0, NULL, 0, 0, &do_retry, retry_name, &root);
-      mach_port_deallocate (mach_task_self (), active_control);
-      if (err)
-       error (6, err, "fsys_getroot");
-      err = hurd_file_name_lookup_retry (&_hurd_ports_use, &getdport, 0,
-                                        do_retry, retry_name, 0, 0,
-                                        &root);
-      if (err)
-       error (6, err, "cannot resolve root port");
+      pid_t pid;
+      switch ((pid = fork ()))
+       {
+       case -1:
+         error (6, errno, "fork");
+
+       case 0:; /* Child.  */
+         /* We will act as the parent filesystem would for a lookup
+            of the active translator's root node, then use this port
+            as our root directory while we exec the command.  */
+
+         char retry_name[1024];        /* XXX */
+         retry_type do_retry;
+         mach_port_t root;
+         err = fsys_getroot (active_control,
+                             MACH_PORT_NULL, MACH_MSG_TYPE_COPY_SEND,
+                             NULL, 0, NULL, 0, 0,
+                             &do_retry, retry_name, &root);
+         mach_port_deallocate (mach_task_self (), active_control);
+         if (err)
+           error (6, err, "fsys_getroot");
+         err = hurd_file_name_lookup_retry (&_hurd_ports_use, &getdport, 0,
+                                            do_retry, retry_name, 0, 0,
+                                            &root);
+         if (err)
+           error (6, err, "cannot resolve root port");
+
+         if (setcrdir (root))
+           error (7, errno, "cannot install root port");
+         mach_port_deallocate (mach_task_self (), root);
+         if (chdir ("/"))
+           error (8, errno, "cannot chdir to new root");
+
+         execvp (chroot_command[0], chroot_command);
+         error (8, errno, "cannot execute %s", chroot_command[0]);
+         break;
 
-      if (setcrdir (root))
-       error (7, errno, "cannot install root port");
-      mach_port_deallocate (mach_task_self (), root);
-      if (chdir ("/"))
-       error (8, errno, "cannot chdir to new root");
+       default: /* Parent.  */
+         if (waitpid (pid, NULL, 0) == -1)
+           error (8, errno, "waitpid");
 
-      execvp (chroot_command[0], chroot_command);
-      error (8, errno, "cannot execute %s", chroot_command[0]);
+         err = fsys_goaway (active_control, goaway_flags);
+         if (err && err != EBUSY)
+           error (9, err, "fsys_goaway");
+       }
     }
 
   return 0;

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