1 /* TODO merge/factor in debugfs.c here */
2
3 #include <ctype.h>
4 #include <errno.h>
5 #include <stdbool.h>
6 #include <stdio.h>
7 #include <stdlib.h>
8 #include <string.h>
9 #include <sys/vfs.h>
10 #include <sys/types.h>
11 #include <sys/stat.h>
12 #include <fcntl.h>
13 #include <unistd.h>
14
15 #include "debugfs.h"
16 #include "fs.h"
17
18 static const char * const sysfs__fs_known_mountpoints[] = {
19 "/sys",
20 0,
21 };
22
23 static const char * const procfs__known_mountpoints[] = {
24 "/proc",
25 0,
26 };
27
28 struct fs {
29 const char *name;
30 const char * const *mounts;
31 char path[PATH_MAX + 1];
32 bool found;
33 long magic;
34 };
35
36 enum {
37 FS__SYSFS = 0,
38 FS__PROCFS = 1,
39 };
40
41 static struct fs fs__entries[] = {
42 [FS__SYSFS] = {
43 .name = "sysfs",
44 .mounts = sysfs__fs_known_mountpoints,
45 .magic = SYSFS_MAGIC,
46 },
47 [FS__PROCFS] = {
48 .name = "proc",
49 .mounts = procfs__known_mountpoints,
50 .magic = PROC_SUPER_MAGIC,
51 },
52 };
53
fs__read_mounts(struct fs * fs)54 static bool fs__read_mounts(struct fs *fs)
55 {
56 bool found = false;
57 char type[100];
58 FILE *fp;
59
60 fp = fopen("/proc/mounts", "r");
61 if (fp == NULL)
62 return NULL;
63
64 while (!found &&
65 fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n",
66 fs->path, type) == 2) {
67
68 if (strcmp(type, fs->name) == 0)
69 found = true;
70 }
71
72 fclose(fp);
73 return fs->found = found;
74 }
75
fs__valid_mount(const char * fs,long magic)76 static int fs__valid_mount(const char *fs, long magic)
77 {
78 struct statfs st_fs;
79
80 if (statfs(fs, &st_fs) < 0)
81 return -ENOENT;
82 else if ((long)st_fs.f_type != magic)
83 return -ENOENT;
84
85 return 0;
86 }
87
fs__check_mounts(struct fs * fs)88 static bool fs__check_mounts(struct fs *fs)
89 {
90 const char * const *ptr;
91
92 ptr = fs->mounts;
93 while (*ptr) {
94 if (fs__valid_mount(*ptr, fs->magic) == 0) {
95 fs->found = true;
96 strcpy(fs->path, *ptr);
97 return true;
98 }
99 ptr++;
100 }
101
102 return false;
103 }
104
mem_toupper(char * f,size_t len)105 static void mem_toupper(char *f, size_t len)
106 {
107 while (len) {
108 *f = toupper(*f);
109 f++;
110 len--;
111 }
112 }
113
114 /*
115 * Check for "NAME_PATH" environment variable to override fs location (for
116 * testing). This matches the recommendation in Documentation/sysfs-rules.txt
117 * for SYSFS_PATH.
118 */
fs__env_override(struct fs * fs)119 static bool fs__env_override(struct fs *fs)
120 {
121 char *override_path;
122 size_t name_len = strlen(fs->name);
123 /* name + "_PATH" + '\0' */
124 char upper_name[name_len + 5 + 1];
125 memcpy(upper_name, fs->name, name_len);
126 mem_toupper(upper_name, name_len);
127 strcpy(&upper_name[name_len], "_PATH");
128
129 override_path = getenv(upper_name);
130 if (!override_path)
131 return false;
132
133 fs->found = true;
134 strncpy(fs->path, override_path, sizeof(fs->path));
135 return true;
136 }
137
fs__get_mountpoint(struct fs * fs)138 static const char *fs__get_mountpoint(struct fs *fs)
139 {
140 if (fs__env_override(fs))
141 return fs->path;
142
143 if (fs__check_mounts(fs))
144 return fs->path;
145
146 if (fs__read_mounts(fs))
147 return fs->path;
148
149 return NULL;
150 }
151
fs__mountpoint(int idx)152 static const char *fs__mountpoint(int idx)
153 {
154 struct fs *fs = &fs__entries[idx];
155
156 if (fs->found)
157 return (const char *)fs->path;
158
159 return fs__get_mountpoint(fs);
160 }
161
162 #define FS__MOUNTPOINT(name, idx) \
163 const char *name##__mountpoint(void) \
164 { \
165 return fs__mountpoint(idx); \
166 }
167
168 FS__MOUNTPOINT(sysfs, FS__SYSFS);
169 FS__MOUNTPOINT(procfs, FS__PROCFS);
170
filename__read_int(const char * filename,int * value)171 int filename__read_int(const char *filename, int *value)
172 {
173 char line[64];
174 int fd = open(filename, O_RDONLY), err = -1;
175
176 if (fd < 0)
177 return -1;
178
179 if (read(fd, line, sizeof(line)) > 0) {
180 *value = atoi(line);
181 err = 0;
182 }
183
184 close(fd);
185 return err;
186 }
187
sysctl__read_int(const char * sysctl,int * value)188 int sysctl__read_int(const char *sysctl, int *value)
189 {
190 char path[PATH_MAX];
191 const char *procfs = procfs__mountpoint();
192
193 if (!procfs)
194 return -1;
195
196 snprintf(path, sizeof(path), "%s/sys/%s", procfs, sysctl);
197
198 return filename__read_int(path, value);
199 }
200