[hurd] 05/17: utils/settrans: improve --chroot functionality

[Samuel Thibault]

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sthibault pushed a commit to branch upstream
in repository hurd.

commit 35ae0168bbdae2eb7029262f49d394046a67860f
Author: Justus Winter <address@hidden>
Date:   Fri Jan 15 18:56:25 2016 +0100

    utils/settrans: improve --chroot functionality
    
    Add an option '--chroot-chdir' to settrans and make it chdir to this
    directory before executing the target program.  Also, look up the
    executable in PATH.
    
    With these changes we no longer need to use the shell inside the
    chroot in the convenience scripts, and hence do not require it to be
    installed inside the chroot.
    
    * utils/fakeroot.sh: Simplify using the new option.
    * utils/remap.sh: Likewise.
    * utils/settrans.c (OPT_CHROOT_CHDIR): New constant.
    (options): New option 'chroot-chdir'.
    (main): Handle new option. Search for target executable in PATH.
    * utils/fakeauth.c (main): Likewise.
---
 utils/fakeauth.c  |  6 +++++-
 utils/fakeroot.sh | 15 ++++++---------
 utils/remap.sh    | 14 ++++++--------
 utils/settrans.c  | 32 ++++++++++++++++++++++++++++++--
 4 files changed, 47 insertions(+), 20 deletions(-)

diff --git a/utils/fakeauth.c b/utils/fakeauth.c
index ba6a3ee..004cc46 100644
--- a/utils/fakeauth.c
+++ b/utils/fakeauth.c
@@ -402,9 +402,13 @@ believe it has restricted them to different identities or 
no identity at all.\
   {
     task_t newtask;
     process_t proc;
-    file_t execfile = file_name_lookup (argv[argi], O_EXEC, 0);
+    char *prefixed_name;
+    file_t execfile = file_name_path_lookup (argv[argi], getenv ("PATH"),
+                                            O_EXEC, 0, &prefixed_name);
     if (execfile == MACH_PORT_NULL)
       error (3, errno, "%s", argv[argi]);
+    if (prefixed_name)
+      argv[0] = prefixed_name;
 
     err = task_create (mach_task_self (),
 #ifdef KERN_INVALID_LEDGER
diff --git a/utils/fakeroot.sh b/utils/fakeroot.sh
index 6993365..7bc5dc7 100644
--- a/utils/fakeroot.sh
+++ b/utils/fakeroot.sh
@@ -54,12 +54,9 @@ if [ $# -eq 0 ]; then
   set -- ${SHELL:-/bin/sh}
 fi
 
-# We exec settrans, which execs the "fakeauth" command in the chroot context.
-# The `pwd` is evaluated here and now, and that result interpreted inside
-# the shell running under fakeauth to chdir there inside the chroot world.
-# That shell then execs our arguments as a command line.
-exec /bin/settrans --chroot \
-     /bin/fakeauth \
-     /bin/sh -c 'cd "$1" || exit ; shift ; exec "$@"' \
-     "$1" "$PWD" "$@" \
-     -- / /hurd/fakeroot
+# We exec settrans, which execs the "fakeauth" command in the chroot
+# context provided by /hurd/fakeroot.
+exec /bin/settrans \
+     --chroot-chdir "$PWD" \
+     --chroot /bin/fakeauth "$@" -- \
+     / /hurd/fakeroot
diff --git a/utils/remap.sh b/utils/remap.sh
index f24ed0e..40c2d76 100644
--- a/utils/remap.sh
+++ b/utils/remap.sh
@@ -57,11 +57,9 @@ if [ $# -eq 0 ]; then
   set -- ${SHELL:-/bin/sh}
 fi
 
-# We exec settrans, which execs the "fakeauth" command in the chroot context.
-# The `pwd` is evaluated here and now, and that result interpreted inside
-# the shell running under fakeauth to chdir there inside the chroot world.
-# That shell then execs our arguments as a command line.
-exec /bin/settrans --chroot \
-     /bin/sh -c 'cd "$1" || exit ; shift ; exec "$@"' \
-     "$1" "$PWD" "$@" \
-     -- / /hurd/remap $MAPPED
+# We exec settrans, which execs the target command in the chroot
+# context provided by /hurd/remap.
+exec /bin/settrans \
+     --chroot-chdir "$PWD" \
+     --chroot "$@" -- \
+     / /hurd/remap $MAPPED
diff --git a/utils/settrans.c b/utils/settrans.c
index cd40c56..00cc358 100644
--- a/utils/settrans.c
+++ b/utils/settrans.c
@@ -18,6 +18,7 @@
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
 
+#include <assert.h>
 #include <hurd.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -45,6 +46,8 @@ const char *argp_program_version = STANDARD_HURD_VERSION 
(settrans);
 #define _STRINGIFY(arg) #arg
 #define STRINGIFY(arg) _STRINGIFY (arg)
 
+#define OPT_CHROOT_CHDIR       -1
+
 static struct argp_option options[] =
 {
   {"active",      'a', 0, 0, "Start TRANSLATOR and set it as NODE's active 
translator" },
@@ -65,6 +68,9 @@ static struct argp_option options[] =
   {"chroot",      'C', 0, 0,
    "Instead of setting the node's translator, take following arguments up to"
    " `--' and run that command chroot'd to the translated node."},
+  {"chroot-chdir",      OPT_CHROOT_CHDIR, "DIR", 0,
+   "Change to DIR before running the chrooted command.  "
+   "DIR must be an absolute path."},
 
   {0,0,0,0, "When setting the passive translator, if there's an active 
translator:"},
   {"goaway",      'g', 0, 0, "Ask the active translator to go away"},
@@ -114,6 +120,7 @@ main(int argc, char *argv[])
   int excl = 0;
   int timeout = DEFAULT_TIMEOUT * 1000; /* ms */
   char **chroot_command = 0;
+  char *chroot_chdir = "/";
 
   /* Parse our options...  */
   error_t parse_opt (int key, char *arg, struct argp_state *state)
@@ -183,6 +190,12 @@ main(int argc, char *argv[])
          argp_error (state, "--chroot command must be terminated with `--'");
          return EINVAL;
 
+       case OPT_CHROOT_CHDIR:
+         if (arg[0] != '/')
+           argp_error (state, "--chroot-chdir must be absolute");
+         chroot_chdir = arg;
+         break;
+
        case 'c': lookup_flags |= O_CREAT; break;
        case 'L': lookup_flags &= ~O_NOTRANS; break;
 
@@ -325,6 +338,8 @@ main(int argc, char *argv[])
          char retry_name[1024];        /* XXX */
          retry_type do_retry;
          mach_port_t root;
+         file_t executable;
+         char *prefixed_name;
          err = fsys_getroot (active_control,
                              MACH_PORT_NULL, MACH_MSG_TYPE_COPY_SEND,
                              NULL, 0, NULL, 0, 0,
@@ -341,8 +356,21 @@ main(int argc, char *argv[])
          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");
+         if (chdir (chroot_chdir))
+           error (8, errno, "%s", chroot_chdir);
+
+         /* Lookup executable in PATH.  */
+         executable = file_name_path_lookup (chroot_command[0],
+                                             getenv ("PATH"),
+                                             O_EXEC, 0,
+                                             &prefixed_name);
+         if (MACH_PORT_VALID (executable))
+           {
+             err = mach_port_deallocate (mach_task_self (), executable);
+             assert_perror (err);
+             if (prefixed_name)
+               chroot_command[0] = prefixed_name;
+           }
 
          execvp (chroot_command[0], chroot_command);
          error (8, errno, "cannot execute %s", chroot_command[0]);

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