1/*
2 * Intel MIC Platform Software Stack (MPSS)
3 *
4 * Copyright(c) 2013 Intel Corporation.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License, version 2, as
8 * published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * General Public License for more details.
14 *
15 * The full GNU General Public License is included in this distribution in
16 * the file called "COPYING".
17 *
18 * Intel MIC User Space Tools.
19 */
20
21#include "mpssd.h"
22
23#define PAGE_SIZE 4096
24
25char *
26readsysfs(char *dir, char *entry)
27{
28	char filename[PATH_MAX];
29	char value[PAGE_SIZE];
30	char *string = NULL;
31	int fd;
32	int len;
33
34	if (dir == NULL)
35		snprintf(filename, PATH_MAX, "%s/%s", MICSYSFSDIR, entry);
36	else
37		snprintf(filename, PATH_MAX,
38			 "%s/%s/%s", MICSYSFSDIR, dir, entry);
39
40	fd = open(filename, O_RDONLY);
41	if (fd < 0) {
42		mpsslog("Failed to open sysfs entry '%s': %s\n",
43			filename, strerror(errno));
44		return NULL;
45	}
46
47	len = read(fd, value, sizeof(value));
48	if (len < 0) {
49		mpsslog("Failed to read sysfs entry '%s': %s\n",
50			filename, strerror(errno));
51		goto readsys_ret;
52	}
53	if (len == 0)
54		goto readsys_ret;
55
56	value[len - 1] = '\0';
57
58	string = malloc(strlen(value) + 1);
59	if (string)
60		strcpy(string, value);
61
62readsys_ret:
63	close(fd);
64	return string;
65}
66
67int
68setsysfs(char *dir, char *entry, char *value)
69{
70	char filename[PATH_MAX];
71	char *oldvalue;
72	int fd, ret = 0;
73
74	if (dir == NULL)
75		snprintf(filename, PATH_MAX, "%s/%s", MICSYSFSDIR, entry);
76	else
77		snprintf(filename, PATH_MAX, "%s/%s/%s",
78			 MICSYSFSDIR, dir, entry);
79
80	oldvalue = readsysfs(dir, entry);
81
82	fd = open(filename, O_RDWR);
83	if (fd < 0) {
84		ret = errno;
85		mpsslog("Failed to open sysfs entry '%s': %s\n",
86			filename, strerror(errno));
87		goto done;
88	}
89
90	if (!oldvalue || strcmp(value, oldvalue)) {
91		if (write(fd, value, strlen(value)) < 0) {
92			ret = errno;
93			mpsslog("Failed to write new sysfs entry '%s': %s\n",
94				filename, strerror(errno));
95		}
96	}
97	close(fd);
98done:
99	if (oldvalue)
100		free(oldvalue);
101	return ret;
102}
103