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8d497515 CY |
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 * | |
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 | |
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 | } |