Some libc implementation (bionic) is lacking some of the syscall functions
that are present in the glibc.
For those, detect at build time the they are missing and implement a minimal
syscall() wrapper that will essentially give the same result as the glibc
function.
Signed-off-by: Stéphane Graber <stgra...@ubuntu.com>
Acked-by: Serge E. Hallyn <serge.hal...@ubuntu.com>
---
configure.ac | 3 +++
src/lxc/attach.c | 26 +++++++++++++++++++++-----
src/lxc/conf.c | 31 +++++++++++++++++++++++++++++--
3 files changed, 53 insertions(+), 7 deletions(-)
diff --git a/configure.ac b/configure.ac
index 6c0db3c..bc2ddc4 100644
--- a/configure.ac
+++ b/configure.ac
@@ -223,6 +223,9 @@ AC_CHECK_DECLS([PR_CAPBSET_DROP], [], [], [#include
<sys/prctl.h>])
# Check for some headers
AC_CHECK_HEADERS([sys/signalfd.h pty.h sys/capability.h sys/personality.h])
+# Check for some syscalls functions
+AC_CHECK_FUNCS([setns pivot_root sethostname unshare])
+
# Check for some functions
AC_CHECK_FUNCS([getline fgetln openpty])
diff --git a/src/lxc/attach.c b/src/lxc/attach.c
index 9b7efbc..b86d2f4 100644
--- a/src/lxc/attach.c
+++ b/src/lxc/attach.c
@@ -47,15 +47,31 @@
lxc_log_define(lxc_attach, lxc);
-int setns(int fd, int nstype)
+/* Define setns() if missing from the C library */
+#ifndef HAVE_SETNS
+static int setns(int fd, int nstype)
{
-#ifndef __NR_setns
- errno = ENOSYS;
- return -1;
+#ifdef __NR_setns
+return syscall(__NR_setns, fd, nstype);
#else
- return syscall(__NR_setns, fd, nstype);
+errno = ENOSYS;
+return -1;
#endif
}
+#endif
+
+/* Define unshare() if missing from the C library */
+#ifndef HAVE_UNSHARE
+static int unshare(int flags)
+{
+#ifdef __NR_unshare
+return syscall(__NR_unshare, flags);
+#else
+errno = ENOSYS;
+return -1;
+#endif
+}
+#endif
/* Define getline() if missing from the C library */
#ifndef HAVE_GETLINE
diff --git a/src/lxc/conf.c b/src/lxc/conf.c
index 2136feb..4a2fd22 100644
--- a/src/lxc/conf.c
+++ b/src/lxc/conf.c
@@ -31,6 +31,7 @@
#include <mntent.h>
#include <unistd.h>
#include <sys/wait.h>
+#include <sys/syscall.h>
#if HAVE_PTY_H
#include <pty.h>
@@ -132,11 +133,37 @@ lxc_log_define(lxc_conf, lxc);
#define LO_FLAGS_AUTOCLEAR 4
#endif
+/* Define pivot_root() if missing from the C library */
+#ifndef HAVE_PIVOT_ROOT
+static int pivot_root(const char * new_root, const char * put_old)
+{
+#ifdef __NR_pivot_root
+return syscall(__NR_pivot_root, new_root, put_old);
+#else
+errno = ENOSYS;
+return -1;
+#endif
+}
+#else
+extern int pivot_root(const char * new_root, const char * put_old);
+#endif
+
+/* Define sethostname() if missing from the C library */
+#ifndef HAVE_SETHOSTNAME
+static int sethostname(const char * name, size_t len)
+{
+#ifdef __NR_sethostname
+return syscall(__NR_sethostname, name, len);
+#else
+errno = ENOSYS;
+return -1;
+#endif
+}
+#endif
+
char *lxchook_names[NUM_LXC_HOOKS] = {
"pre-start", "pre-mount", "mount", "start", "post-stop" };
-extern int pivot_root(const char * new_root, const char * put_old);
-
typedef int (*instanciate_cb)(struct lxc_handler *, struct lxc_netdev *);
struct mount_opt {
--
1.8.0
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