On Tue, Sep 01, 2015 at 10:27:33PM +0200, Laurent Vivier wrote: > This patch allows to run example given by open_by_handle_at(2): > > The following shell session demonstrates the use of these two programs: > > $ echo 'Can you please think about it?' > cecilia.txt > $ ./t_name_to_handle_at cecilia.txt > fh > $ ./t_open_by_handle_at < fh > open_by_handle_at: Operation not permitted > $ sudo ./t_open_by_handle_at < fh # Need CAP_SYS_ADMIN > Read 31 bytes > $ rm cecilia.txt > > Now we delete and (quickly) re-create the file so that it has the same > content and (by chance) the same inode.[...] > > $ stat --printf="%i\n" cecilia.txt # Display inode number > 4072121 > $ rm cecilia.txt > $ echo 'Can you please think about it?' > cecilia.txt > $ stat --printf="%i\n" cecilia.txt # Check inode number > 4072121 > $ sudo ./t_open_by_handle_at < fh > open_by_handle_at: Stale NFS file handle > > See the man page for source code.
Applied to linux-user, Thanks > Signed-off-by: Laurent Vivier <laur...@vivier.eu> > --- > v2: Rename function parameters, swap fh->handle_type in both functions, > When I have re-tested the patch I have found a bug in the size of > the data, so I fix this too (handle_bytes is the size of f_handle[] > only, not of the whole structure) > > linux-user/syscall.c | 98 > ++++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 98 insertions(+) > > diff --git a/linux-user/syscall.c b/linux-user/syscall.c > index f62c698..8a17351 100644 > --- a/linux-user/syscall.c > +++ b/linux-user/syscall.c > @@ -5246,6 +5246,94 @@ static int do_futex(target_ulong uaddr, int op, int > val, target_ulong timeout, > return -TARGET_ENOSYS; > } > } > +#if defined(TARGET_NR_name_to_handle_at) && defined(CONFIG_OPEN_BY_HANDLE) > +static abi_long do_name_to_handle_at(abi_long dirfd, abi_long pathname, > + abi_long handle, abi_long mount_id, > + abi_long flags) > +{ > + struct file_handle *target_fh; > + struct file_handle *fh; > + int mid = 0; > + abi_long ret; > + char *name; > + unsigned int size, total_size; > + > + if (get_user_s32(size, handle)) { > + return -TARGET_EFAULT; > + } > + > + name = lock_user_string(pathname); > + if (!name) { > + return -TARGET_EFAULT; > + } > + > + total_size = sizeof(struct file_handle) + size; > + target_fh = lock_user(VERIFY_WRITE, handle, total_size, 0); > + if (!target_fh) { > + unlock_user(name, pathname, 0); > + return -TARGET_EFAULT; > + } > + > + fh = g_malloc0(total_size); > + fh->handle_bytes = size; > + > + ret = get_errno(name_to_handle_at(dirfd, path(name), fh, &mid, flags)); > + unlock_user(name, pathname, 0); > + > + /* man name_to_handle_at(2): > + * Other than the use of the handle_bytes field, the caller should treat > + * the file_handle structure as an opaque data type > + */ > + > + memcpy(target_fh, fh, total_size); > + target_fh->handle_bytes = tswap32(fh->handle_bytes); > + target_fh->handle_type = tswap32(fh->handle_type); > + g_free(fh); > + unlock_user(target_fh, handle, total_size); > + > + if (put_user_s32(mid, mount_id)) { > + return -TARGET_EFAULT; > + } > + > + return ret; > + > +} > +#endif > + > +#if defined(TARGET_NR_open_by_handle_at) && defined(CONFIG_OPEN_BY_HANDLE) > +static abi_long do_open_by_handle_at(abi_long mount_fd, abi_long handle, > + abi_long flags) > +{ > + struct file_handle *target_fh; > + struct file_handle *fh; > + unsigned int size, total_size; > + abi_long ret; > + > + if (get_user_s32(size, handle)) { > + return -TARGET_EFAULT; > + } > + > + total_size = sizeof(struct file_handle) + size; > + target_fh = lock_user(VERIFY_READ, handle, total_size, 1); > + if (!target_fh) { > + return -TARGET_EFAULT; > + } > + > + fh = g_malloc0(total_size); > + memcpy(fh, target_fh, total_size); > + fh->handle_bytes = size; > + fh->handle_type = tswap32(target_fh->handle_type); > + > + ret = get_errno(open_by_handle_at(mount_fd, fh, > + target_to_host_bitmask(flags, fcntl_flags_tbl))); > + > + g_free(fh); > + > + unlock_user(target_fh, handle, total_size); > + > + return ret; > +} > +#endif > > /* Map host to target signal numbers for the wait family of syscalls. > Assume all other status bits are the same. */ > @@ -5655,6 +5743,16 @@ abi_long do_syscall(void *cpu_env, int num, abi_long > arg1, > arg4)); > unlock_user(p, arg2, 0); > break; > +#if defined(TARGET_NR_name_to_handle_at) && defined(CONFIG_OPEN_BY_HANDLE) > + case TARGET_NR_name_to_handle_at: > + ret = do_name_to_handle_at(arg1, arg2, arg3, arg4, arg5); > + break; > +#endif > +#if defined(TARGET_NR_open_by_handle_at) && defined(CONFIG_OPEN_BY_HANDLE) > + case TARGET_NR_open_by_handle_at: > + ret = do_open_by_handle_at(arg1, arg2, arg3); > + break; > +#endif > case TARGET_NR_close: > ret = get_errno(close(arg1)); > break; > -- > 2.4.3 > >