20/31: daemon: Do not use clone on the Hurd.

[guix-commits]

janneke pushed a commit to branch wip-hurd
in repository guix.

commit 6cb6411c1c5f06522c3885736a14fcb4b2e13c1a
Author: Manolis Ragkousis <address@hidden>
AuthorDate: Sun Aug 7 17:48:30 2016 +0300

    daemon: Do not use clone on the Hurd.
    
    Checking for CLONE_NEWNS is only needed for using tha Linux specific 
clone(2),
    otherwise we can use fork(2).  Using clone on the Hurd needs some work, only
    support LINUX for now.  See
    https://lists.gnu.org/archive/html/guix-devel/2020-03/msg00190.html
    
    * nix/libstore/build.cc (CHROOT_ENABLED): Break into CHROOT_ENABLED
    and CLONE_ENABLED.
    (DerivationGoal::startBuilder): Replace CHROOT_ENABLED with __linux__.
    (DerivationGoal::runChild): Only define pivot_root() if SYS_pivot_root is
    defined.
    
    Co-authored-by: Jan Nieuwenhuizen <address@hidden>
---
 nix/libstore/build.cc | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/nix/libstore/build.cc b/nix/libstore/build.cc
index 17e92c6..29266f1 100644
--- a/nix/libstore/build.cc
+++ b/nix/libstore/build.cc
@@ -52,7 +52,12 @@
 #endif
 
 
-#define CHROOT_ENABLED HAVE_CHROOT && HAVE_SYS_MOUNT_H && defined(MS_BIND) && 
defined(MS_PRIVATE) && defined(CLONE_NEWNS) && defined(SYS_pivot_root)
+#define CHROOT_ENABLED HAVE_CHROOT && HAVE_SYS_MOUNT_H && defined(MS_BIND) && 
defined(MS_PRIVATE)
+#define CLONE_ENABLED defined(CLONE_NEWNS)
+
+#if defined(SYS_pivot_root)
+#define pivot_root(new_root, put_old) (syscall(SYS_pivot_root, 
new_root,put_old))
+#endif
 
 #if CHROOT_ENABLED
 #include <sys/socket.h>
@@ -2005,7 +2010,7 @@ void DerivationGoal::startBuilder()
        - The UTS namespace ensures that builders see a hostname of
          localhost rather than the actual hostname.
     */
-#if CHROOT_ENABLED
+#if __linux__
     if (useChroot) {
        char stack[32 * 1024];
        int flags = CLONE_NEWPID | CLONE_NEWNS | CLONE_NEWIPC | CLONE_NEWUTS | 
SIGCHLD;
@@ -2186,10 +2191,8 @@ void DerivationGoal::runChild()
             if (mkdir("real-root", 0) == -1)
                 throw SysError("cannot create real-root directory");
 
-#define pivot_root(new_root, put_old) (syscall(SYS_pivot_root, new_root, 
put_old))
             if (pivot_root(".", "real-root") == -1)
                 throw SysError(format("cannot pivot old root directory onto 
'%1%'") % (chrootRootDir + "/real-root"));
-#undef pivot_root
 
             if (chroot(".") == -1)
                 throw SysError(format("cannot change root directory to '%1%'") 
% chrootRootDir);