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Workaround missing functions in other libc

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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 <stgraber@ubuntu.com>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
This commit is contained in:
Stéphane Graber
2013-01-03 12:24:14 -05:00
parent 6ff05e18a3
commit 2d76d1d7e5
3 changed files with 53 additions and 7 deletions
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3
configure.ac
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@@ -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([openpty])
AC_CHECK_FUNCS([getline],

26
src/lxc/attach.c
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@@ -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

31
src/lxc/conf.c
View File

@@ -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 {