Unlink connect function handler

Prototype:

int (*unlink) ( resmgr_context_t *ctp,
               io_unlink_t *msg,
               RESMGR_HANDLE_T *handle,
               void *reserved ) 

Classification:

Connect

Default handler:

none

Helper functions:

iofunc_unlink()

Client function:

unlink(), unlinkat()

Messages:

_IO_CONNECT with subtype _IO_CONNECT_UNLINK

Data structure:

struct _io_connect {
  // internal fields (as described above)
  uint16_t path_len;
  uint8_t  extra_type;
  uint16_t extra_len;
  char     path [1];
};

struct _io_connect_link_reply {
  uint32_t reserved1;
  uint32_t file_type;
  uint8_t  eflag;
  uint8_t  reserved2[1];
  uint16_t chroot_len;
  uint32_t umask;
  uint16_t nentries;
  uint16_t path_len;
};

struct _io_connect_ftype_reply {
  uint16_t status;      /* Typically an errno */
  uint16_t reserved;
  uint32_t file_type;   /* _FTYPE_? in sys/ftype.h */
};

typedef union {
  struct _io_connect             connect;
  struct _io_connect_link_reply  link_reply;
  struct _io_connect_ftype_reply ftype_reply;
} io_unlink_t;

Description:

Responsible for unlinking the file whose pathname is passed in the input message structure's path member.

Returns:

The status via the helper macro _RESMGR_STATUS().

Referenced by:

resmgr_connect_funcs_t connect table

Permission checking:

When you override the default function, QNX recommends that you call iofunc_unlink(), which verifies the following conditions before it updates the link counts:

• The client has write permission on the directory that contains the entity being unlinked.
• The entity being unlinked is not “.” or “..”.
• If it is a directory that is being unlinked, that the directory is empty.
• If it is a directory that is being unlinked, that the client is user ID (UID) 0 and the filesystem allows root to unlink directories (IOFUNC_PC_LINK_DIR; see iofunc_mount_t in the C Library Reference).
• If the sticky bit is set, the client is the owner of the entity being unlinked.
• It is a writable filesystem.

If you need to allow users other than UID 0 to unlink directories, re-implement all these checks yourself in your resource manager.