/*
?*?canutils/canconfig.c
?*
?*?Copyright?（C）?2005?2008?Marc?Kleine-Budde??Pengutronix
?*?Copyright?（C）?2007?Juergen?Beisert??Pengutronix
?*
?*?This?program?is?free?software;?you?can?redistribute?it?and/or?modify
?*?it?under?the?terms?of?the?version?2?of?the?GNU?General?Public?License
?*?as?published?by?the?Free?Software?Foundation
?*
?*?This?program?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?this?program;?if?not?write?to?the?Free?Software
?*?Foundation?Inc.?59?Temple?Place?Suite?330?Boston?MA??02111-1307??USA
?*/

#include?
#include?
#include?
#include?
#include?
#include?
#include?

#include?
#include?
#include?

#ifndef?MIN
#define?MIN（a?b）?（（a）?#endif

#define?VALUE_MAX		256
#define?SYSFS_PATH_MAX		256
#define?SYSFS_MNT_PATH		“/sys“
#define?SYSFS_PATH_ENV		“SYSFS_PATH“

#define?CLASS_NET		“/class/net/“

static?char?sysfs_path[SYSFS_PATH_MAX];
static?const?char?*dev;
static?int?version;

enum?can_sysfs_version?{
	SV_0
	SV_1
	SV_MAX
};

enum?can_sysfs_entries?{
	SE_BITRATE
	SE_MAX
};


static?const?char?*can_sysfs[SV_MAX][SE_MAX]?=?{
	[SV_0][SE_BITRATE]?=?“can_bitrate“
	[SV_1][SE_BITRATE]?=?“can_bittiming/bitrate“
};

static?void?help（void）
{
	fprintf（stderr?“usage:\n\t“
		“canconfig??bitrate?{?BR?}\n\t\t“
		“BR?:=?\n\t\t“
		“canconfig??mode\n“
#if?0
		“MODE\n\t\t“
		“MODE?:=?{?start?}\n\t“
		“canconfig??setentry?[?VALs?]\n\t\t“
		“VALs?:=?\n\t\t“
		“?bitrate?\n\t\t“
		“?tq?\n\t\t“
		“?err?\n\t\t“
		“?prop_seg?\n\t\t“
		“?phase_seg1?\n\t\t“
		“?phase_seg2?		“?sjw?\n\t\t“
		“?sam?<1?|?0>?1?for?3?times?sampling?0?else\n“
#endif
		）;

	exit（EXIT_FAILURE）;
}


static?void?make_path（char?*key_path?const?char?*key?size_t?key_path_len）
{
	strncpy（key_path?sysfs_path?key_path_len）;
	strncat（key_path?key?key_path_len）;
	key_path[key_path_len?-?1]?=?0;
}


static?ssize_t?get_value（const?char*?key?char?*value?size_t?value_len）
{
	char?key_path[SYSFS_PATH_MAX];
	int?fd;
	ssize_t?len;

	make_path（key_path?key?sizeof（key_path））;

	fd?=?open（key_path?O_RDONLY）;
	if?（fd?==?-1）?{
		fprintf（stderr?“opening?‘%s‘?failed:?“
			key_path）;
		perror（NULL）;
		exit（EXIT_FAILURE）;
	}

	len?=?read（fd?value?value_len?-?1）;
	close（fd）;
	if?（len?		perror（“read“）;
		exit（EXIT_FAILURE）;
	}
	value[len]?=?0;

	/*?remove?trailing?newline（s）?*/
	while?（len?>?0?&&?value[len?-?1]?==?‘\n‘