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//=================================================================

//

//        usb_chmod.c

//

//        A utility to manipulate /proc/bus/usb access rights

//

//==========================================================================

// ####ECOSGPLCOPYRIGHTBEGIN####                                            

// -------------------------------------------                              

// This file is part of eCos, the Embedded Configurable Operating System.   

// Copyright (C) 1998, 1999, 2000, 2001, 2002 Free Software Foundation, Inc.

//

// eCos is free software; you can redistribute it and/or modify it under    

// the terms of the GNU General Public License as published by the Free     

// Software Foundation; either version 2 or (at your option) any later      

// version.                                                                 

//

// eCos is distributed in the hope that it will be useful, but WITHOUT      

// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or    

// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License    

// for more details.                                                        

//

// You should have received a copy of the GNU General Public License        

// along with eCos; if not, write to the Free Software Foundation, Inc.,    

// 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.            

//

// As a special exception, if other files instantiate templates or use      

// macros or inline functions from this file, or you compile this file      

// and link it with other works to produce a work based on this file,       

// this file does not by itself cause the resulting work to be covered by   

// the GNU General Public License. However the source code for this file    

// must still be made available in accordance with section (3) of the GNU   

// General Public License v2.                                               

//

// This exception does not invalidate any other reasons why a work based    

// on this file might be covered by the GNU General Public License.         

// -------------------------------------------                              

// ####ECOSGPLCOPYRIGHTEND####                                              

//==========================================================================

//#####DESCRIPTIONBEGIN####

//

// The Linux kernel allows raw access to USB devices via /proc/bus/usb.

// However, such access requires root privileges: this makes perfect

// sense for typical USB devices, but gets in the way of eCos USB

// testing. This utility runs suid and can be used to change the access

// rights to a specific and validated USB device.

//

// Author(s):     bartv

// Date:          2001-07-18

//####DESCRIPTIONEND####

//==========================================================================

#include <stdio.h>

#include <stdlib.h>

#include <limits.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <errno.h>

#include <string.h>

// Note: this code is duplicated in usbhost.c. Any changes here

// should be propagated. For now the routine is too small to warrant

// a separate source file.

#define USB_ROOT        "/proc/bus/usb/"

#define PRODUCT_STRING  "Red Hat eCos USB test"

static int

usb_scan_devices(int* bus, int* dev)

{

    FILE*       devs_file       = fopen(USB_ROOT "devices", "r");

    int         current_bus     = -1;

    int         current_dev     = -1;

    int         ch;

    if (NULL == devs_file) {

        fprintf(stderr, "Error: unable to access " USB_ROOT "devices\n");

        return 0;

    }

    ch = getc(devs_file);

    while (EOF != ch) {

        if ('T' == ch) {

            if (2 !=fscanf(devs_file, ":  Bus=%d %*[^D\n]Dev#=%d", &current_bus, &current_dev)) {

                current_bus = -1;

                current_dev = -1;

            }

        } else if ('S' == ch) {

            int start = 0, end = 0;

            if (EOF != fscanf(devs_file, ":  Product=%n" PRODUCT_STRING "%n", &start, &end)) {

                if (start < end) {

                    *bus = current_bus;

                    *dev = current_dev;

                    break;

                }

            }

        }

        // Move to the end of the current line.

        while ((EOF != ch) && ('\n' != ch)) {

            ch = getc(devs_file);

        }

        if (EOF != ch) {

            ch = getc(devs_file);

        }

    }

    fclose(devs_file);

    if ((-1 != *bus) && (-1 != *dev)) {

        return 1;

    }

    fprintf(stderr, "Error: failed to find a USB device \"" PRODUCT_STRING "\"\n");

    return 0;

}

int

main(int argc, char** argv)

{

    int         bus, dev;

    int         actual_bus  = 0;

    int         actual_dev  = 0;

    char        devname[_POSIX_PATH_MAX];

    long        strtol_tmp1;

    char*       strtol_tmp2;

    if (3 != argc) {

        fprintf(stderr, "usb_chmod: wrong number of arguments\n");

        fprintf(stderr, "         : usage, usb_chmod <bus> <dev>\n");

        exit(EXIT_FAILURE);

    }

    if (('\0' == argv[1][0]) || ('\0' == argv[2][0])) {

        fprintf(stderr, "usb_chmod: invalid arguments\n");

        exit(EXIT_FAILURE);

    }

    strtol_tmp1 = strtol(argv[1], &strtol_tmp2, 10);

    if ('\0' != *strtol_tmp2) {

        fprintf(stderr, "usbchmod: invalid first argument, not a number\n");

        exit(EXIT_FAILURE);

    }

    if (strtol_tmp1 > INT_MAX) {

        fprintf(stderr, "usbchmod: invalid first argument, number too large\n");

        exit(EXIT_FAILURE);

    }

    bus = (int) strtol_tmp1;

    strtol_tmp1 = strtol(argv[2], &strtol_tmp2, 10);

    if ('\0' != *strtol_tmp2) {

        fprintf(stderr, "usbchmod: invalid second argument, not a number\n");

        exit(EXIT_FAILURE);

    }

    if (strtol_tmp1 > INT_MAX) {

        fprintf(stderr, "usbchmod: invalid second argument, number too large\n");

        exit(EXIT_FAILURE);

    }

    dev = (int) strtol_tmp1;

    if (!usb_scan_devices(&actual_bus, &actual_dev)) {

        fprintf(stderr, "usb_chmod: failed to find eCos USB test application\n");

        exit(EXIT_FAILURE);

    }

    if ((bus != actual_bus) || (dev != actual_dev)) {

        fprintf(stderr, "usbchmod: mismatch between specified and actual USB identifiers.\n");

        fprintf(stderr, "         : eCos test application is at %03d/%03d, not %03d/%03d\n",

                actual_bus, actual_dev, bus, dev);

        exit(EXIT_FAILURE);

    }

    if (_POSIX_PATH_MAX == snprintf(devname, _POSIX_PATH_MAX, "/proc/bus/usb/" "%03d/%03d", actual_bus, actual_dev)) {

        fprintf(stderr, "usbchmod: internal error, buffer overflow\n");

        exit(EXIT_FAILURE);

    }

    if (0 != chmod(devname, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH)) {

        int old_errno = errno;

        fprintf(stderr, "usbchmod: failed to modify access rights on %s\n", devname);

        fprintf(stderr, "         : %s\n", strerror(old_errno));

        exit(EXIT_FAILURE);

    }

    return EXIT_SUCCESS;

}