--- name: "fido_dev_cancel" section: "3" platform: "linux" package: "libfido2" version: "1.17.0-1" release: "Arch Linux 2026-11-01" platforms: ["linux"] url: "https://new.carta.tech/fido_dev_open" --- # fido\_dev\_cancel(3) FIDO2 device open/close and related functions Part of [fido\_dev\_open(3)](/fido_dev_open/3.md). ## NAME **fido\_dev\_open**, **fido\_dev\_open\_with\_info**, **fido\_dev\_close**, **fido\_dev\_cancel**, **fido\_dev\_new**, **fido\_dev\_new\_with\_info**, **fido\_dev\_free**, **fido\_dev\_force\_fido2**, **fido\_dev\_force\_u2f**, **fido\_dev\_is\_fido2**, **fido\_dev\_is\_winhello**, **fido\_dev\_supports\_credman**, **fido\_dev\_supports\_cred\_prot**, **fido\_dev\_supports\_permissions**, **fido\_dev\_supports\_pin**, **fido\_dev\_supports\_uv**, **fido\_dev\_has\_pin**, **fido\_dev\_has\_uv**, **fido\_dev\_protocol**, **fido\_dev\_build**, **fido\_dev\_flags**, **fido\_dev\_major**, **fido\_dev\_minor** – FIDO2 device open/close and related functions ## SYNOPSIS **#include \** *int*\ **fido\_dev\_open**(*fido\_dev\_t \*dev*, *const char \*path*); *int*\ **fido\_dev\_open\_with\_info**(*fido\_dev\_t \*dev*); *int*\ **fido\_dev\_close**(*fido\_dev\_t \*dev*); *int*\ **fido\_dev\_cancel**(*fido\_dev\_t \*dev*); *fido\_dev\_t* *\**\ **fido\_dev\_new**(*void*); *fido\_dev\_t* *\**\ **fido\_dev\_new\_with\_info**(*const fido\_dev\_info\_t \**); *void*\ **fido\_dev\_free**(*fido\_dev\_t \*\*dev\_p*); *void*\ **fido\_dev\_force\_fido2**(*fido\_dev\_t \*dev*); *void*\ **fido\_dev\_force\_u2f**(*fido\_dev\_t \*dev*); *bool*\ **fido\_dev\_is\_fido2**(*const fido\_dev\_t \*dev*); *bool*\ **fido\_dev\_is\_winhello**(*const fido\_dev\_t \*dev*); *bool*\ **fido\_dev\_supports\_credman**(*const fido\_dev\_t \*dev*); *bool*\ **fido\_dev\_supports\_cred\_prot**(*const fido\_dev\_t \*dev*); *bool*\ **fido\_dev\_supports\_permissions**(*const fido\_dev\_t \*dev*); *bool*\ **fido\_dev\_supports\_pin**(*const fido\_dev\_t \*dev*); *bool*\ **fido\_dev\_supports\_uv**(*const fido\_dev\_t \*dev*); *bool*\ **fido\_dev\_has\_pin**(*const fido\_dev\_t \*dev*); *bool*\ **fido\_dev\_has\_uv**(*const fido\_dev\_t \*dev*); *uint8\_t*\ **fido\_dev\_protocol**(*const fido\_dev\_t \*dev*); *uint8\_t*\ **fido\_dev\_build**(*const fido\_dev\_t \*dev*); *uint8\_t*\ **fido\_dev\_flags**(*const fido\_dev\_t \*dev*); *uint8\_t*\ **fido\_dev\_major**(*const fido\_dev\_t \*dev*); *uint8\_t*\ **fido\_dev\_minor**(*const fido\_dev\_t \*dev*); ## DESCRIPTION The **fido\_dev\_open**() function opens the device pointed to by *path*, where *dev* is a freshly allocated or otherwise closed *fido\_dev\_t*. If *dev* claims to be FIDO2, *libfido2* will attempt to speak FIDO2 to *dev*. If that fails, *libfido2* will fallback to U2F unless the FIDO\_DISABLE\_U2F\_FALLBACK flag was set in [fido\_init(3)](/fido_init/3.md). The **fido\_dev\_open\_with\_info**() function opens *dev* as previously allocated using **fido\_dev\_new\_with\_info**(). The **fido\_dev\_close**() function closes the device represented by *dev*. If *dev* is already closed, **fido\_dev\_close**() is a NOP. The **fido\_dev\_cancel**() function cancels any pending requests on *dev*. The **fido\_dev\_new**() function returns a pointer to a newly allocated, empty *fido\_dev\_t*. If memory cannot be allocated, NULL is returned. The **fido\_dev\_new\_with\_info**() function returns a pointer to a newly allocated *fido\_dev\_t* with *fido\_dev\_info\_t* parameters, for use with [fido\_dev\_info\_manifest(3)](/fido_dev_info_manifest/3.md) and **fido\_dev\_open\_with\_info**(). If memory cannot be allocated, NULL is returned. The **fido\_dev\_free**() function releases the memory backing *\*dev\_p*, where *\*dev\_p* must have been previously allocated by **fido\_dev\_new**(). On return, *\*dev\_p* is set to NULL. Either *dev\_p* or *\*dev\_p* may be NULL, in which case **fido\_dev\_free**() is a NOP. The **fido\_dev\_force\_fido2**() function can be used to force CTAP2 communication with *dev*, where *dev* is an open device. The **fido\_dev\_force\_u2f**() function can be used to force CTAP1 (U2F) communication with *dev*, where *dev* is an open device. The **fido\_dev\_is\_fido2**() function returns true if *dev* is a FIDO2 device. The **fido\_dev\_is\_winhello**() function returns true if *dev* is a Windows Hello device. The **fido\_dev\_supports\_credman**() function returns true if *dev* supports CTAP 2.1 Credential Management. The **fido\_dev\_supports\_cred\_prot**() function returns true if *dev* supports CTAP 2.1 Credential Protection. The **fido\_dev\_supports\_permissions**() function returns true if *dev* supports CTAP 2.1 UV token permissions. The **fido\_dev\_supports\_pin**() function returns true if *dev* supports CTAP 2.0 Client PINs. The **fido\_dev\_supports\_uv**() function returns true if *dev* supports a built-in user verification method. The **fido\_dev\_has\_pin**() function returns true if *dev* has a CTAP 2.0 Client PIN set. The **fido\_dev\_has\_uv**() function returns true if *dev* supports built-in user verification and its user verification feature is configured. The **fido\_dev\_protocol**() function returns the CTAPHID protocol version identifier of *dev*. The **fido\_dev\_build**() function returns the CTAPHID build version number of *dev*. The **fido\_dev\_flags**() function returns the CTAPHID capabilities flags of *dev*. The **fido\_dev\_major**() function returns the CTAPHID major version number of *dev*. The **fido\_dev\_minor**() function returns the CTAPHID minor version number of *dev*. For the format and meaning of the CTAPHID parameters returned by functions above, please refer to the FIDO Client to Authenticator Protocol (CTAP) specification. ## RETURN VALUES On success, **fido\_dev\_open**(), **fido\_dev\_open\_with\_info**(), and **fido\_dev\_close**() return FIDO\_OK. On error, a different error code defined in ⟨fido/err.h⟩ is returned. ## SEE ALSO [fido\_dev\_info\_manifest(3)](/fido_dev_info_manifest/3.md), [fido\_dev\_set\_io\_functions(3)](/fido_dev_set_io_functions/3.md), [fido\_init(3)](/fido_init/3.md)