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ShengYi Hung
749318f2ae
FreeBSD's libusb has three components: libusb01, libusb10, and libusb20. libusb20 handles communication with character devices. We now requires a backend context for libusb20. The backend context contains contains the capsicumized usbctrl fd and usb directory (/dev/usb) fd so that the library user can enter the capiblity mode safely while using libusb. libusb10 is updated to support capabilities via a context option. Since libusb allows general read/write access, we preserve all possible capabilities when passing backend context to libusb20. It is the responsibility of the libusb user to call cap_enter() at an appropriate time. All base system tools using libusb and libusb20 have been updated to support Capsicum. Reviewed by: adrian, markj Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D51865
70 lines
1.7 KiB
Plaintext
70 lines
1.7 KiB
Plaintext
.\"
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.\" Copyright (c) 2025 Rick Parrish <[email protected]>
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.\"
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.\" SPDX-License-Identifier: BSD-2-Clause
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.\"
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.Dd December 14, 2025
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.Dt LIBUSB20 3
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.Os
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.Sh NAME
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.Nm libusb20_dev_open
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.Nd open a USB device to retrieve descriptors and initiate transfers
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.Sh SYNOPSIS
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.Lb libusb
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.In libusb20.h
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.Ft int
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.Fn libusb20_dev_open "struct libusb20_device *pdev" "uin16_t transfer_max"
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.Sh DESCRIPTION
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The
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.Nm
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function opens a USB device to retrieve descriptors and initiate transfers.
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.Nm
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accepts a pointer as
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.Fa pdev
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to a libusb20_device obtained from
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.Nm libusb20_be_device_foreach .
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A zero for
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.Fa transfer_max
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limits the device to only control transfers.
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Call
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.Xr libusb20_dev_close 3
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to free resources taken by the open device handle.
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.Sh RETURN VALUES
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.Nm
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returns one of the following to report success or failure:
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.Pp
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.Bl -tag -width "LIBUSB20_ERROR_NO_DEVICE," -compact
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.It Er LIBUSB20_SUCCESS ,
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The operation succeeds.
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.It Er LIBUSB20_ERROR_BUSY ,
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The device is in use elsewhere.
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.It Er LIBUSB20_ERROR_ACCESS ,
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A permissions issue.
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.It Er LIBUSB20_ERROR_NO_DEVICE ,
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The device detached.
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.It Er LIBUSB20_ERROR_NO_MEM
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The library couldn't allocate memory.
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.El
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.Pp
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Errors not listed here may be found in
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.Xr libusb20 3
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and
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.In libusb20.h .
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.Sh EXAMPLES
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.Bd -literal
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#include <libusb20.h>
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struct libusb20_backend *be = libusb20_be_alloc_default(NULL);
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struct libusb20_device *device = NULL;
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while ( (device = libusb20_be_device_foreach(be, device)) != NULL ) {
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if (libusb20_dev_open(device, 0) == LIBUSB20_SUCCESS) {
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/* do something */
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libusb20_dev_close(device);
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}
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}
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libusb20_be_free(be);
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.Ed
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.Sh SEE ALSO
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.Xr libusb20 3 ,
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.Xr libusb20_be_device_foreach 3 ,
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.Xr libusb20_dev_close 3
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