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
25 char *
readsysfs(char * dir,char * entry)26 readsysfs(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
62 readsys_ret:
63 close(fd);
64 return string;
65 }
66
67 int
setsysfs(char * dir,char * entry,char * value)68 setsysfs(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);
98 done:
99 if (oldvalue)
100 free(oldvalue);
101 return ret;
102 }
103