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.
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
