Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1#include "util.h"
2#include "debugfs.h"
3#include "cache.h"
4
5static int debugfs_premounted;
6static char debugfs_mountpoint[MAX_PATH+1];
7
8static const char *debugfs_known_mountpoints[] = {
9 "/sys/kernel/debug/",
10 "/debug/",
11 0,
12};
13
14/* use this to force a umount */
15void debugfs_force_cleanup(void)
16{
17 debugfs_find_mountpoint();
18 debugfs_premounted = 0;
19 debugfs_umount();
20}
21
22/* construct a full path to a debugfs element */
23int debugfs_make_path(const char *element, char *buffer, int size)
24{
25 int len;
26
27 if (strlen(debugfs_mountpoint) == 0) {
28 buffer[0] = '\0';
29 return -1;
30 }
31
32 len = strlen(debugfs_mountpoint) + strlen(element) + 1;
33 if (len >= size)
34 return len+1;
35
36 snprintf(buffer, size-1, "%s/%s", debugfs_mountpoint, element);
37 return 0;
38}
39
40static int debugfs_found;
41
42/* find the path to the mounted debugfs */
43const char *debugfs_find_mountpoint(void)
44{
45 const char **ptr;
46 char type[100];
47 FILE *fp;
48
49 if (debugfs_found)
50 return (const char *) debugfs_mountpoint;
51
52 ptr = debugfs_known_mountpoints;
53 while (*ptr) {
54 if (debugfs_valid_mountpoint(*ptr) == 0) {
55 debugfs_found = 1;
56 strcpy(debugfs_mountpoint, *ptr);
57 return debugfs_mountpoint;
58 }
59 ptr++;
60 }
61
62 /* give up and parse /proc/mounts */
63 fp = fopen("/proc/mounts", "r");
64 if (fp == NULL)
65 die("Can't open /proc/mounts for read");
66
67 while (fscanf(fp, "%*s %"
68 STR(MAX_PATH)
69 "s %99s %*s %*d %*d\n",
70 debugfs_mountpoint, type) == 2) {
71 if (strcmp(type, "debugfs") == 0)
72 break;
73 }
74 fclose(fp);
75
76 if (strcmp(type, "debugfs") != 0)
77 return NULL;
78
79 debugfs_found = 1;
80
81 return debugfs_mountpoint;
82}
83
84/* verify that a mountpoint is actually a debugfs instance */
85
86int debugfs_valid_mountpoint(const char *debugfs)
87{
88 struct statfs st_fs;
89
90 if (statfs(debugfs, &st_fs) < 0)
91 return -ENOENT;
92 else if (st_fs.f_type != (long) DEBUGFS_MAGIC)
93 return -ENOENT;
94
95 return 0;
96}
97
98
99int debugfs_valid_entry(const char *path)
100{
101 struct stat st;
102
103 if (stat(path, &st))
104 return -errno;
105
106 return 0;
107}
108
109/* mount the debugfs somewhere if it's not mounted */
110
111char *debugfs_mount(const char *mountpoint)
112{
113 /* see if it's already mounted */
114 if (debugfs_find_mountpoint()) {
115 debugfs_premounted = 1;
116 return debugfs_mountpoint;
117 }
118
119 /* if not mounted and no argument */
120 if (mountpoint == NULL) {
121 /* see if environment variable set */
122 mountpoint = getenv(PERF_DEBUGFS_ENVIRONMENT);
123 /* if no environment variable, use default */
124 if (mountpoint == NULL)
125 mountpoint = "/sys/kernel/debug";
126 }
127
128 if (mount(NULL, mountpoint, "debugfs", 0, NULL) < 0)
129 return NULL;
130
131 /* save the mountpoint */
132 strncpy(debugfs_mountpoint, mountpoint, sizeof(debugfs_mountpoint));
133 debugfs_found = 1;
134
135 return debugfs_mountpoint;
136}
137
138/* umount the debugfs */
139
140int debugfs_umount(void)
141{
142 char umountcmd[128];
143 int ret;
144
145 /* if it was already mounted, leave it */
146 if (debugfs_premounted)
147 return 0;
148
149 /* make sure it's a valid mount point */
150 ret = debugfs_valid_mountpoint(debugfs_mountpoint);
151 if (ret)
152 return ret;
153
154 snprintf(umountcmd, sizeof(umountcmd),
155 "/bin/umount %s", debugfs_mountpoint);
156 return system(umountcmd);
157}
158
159int debugfs_write(const char *entry, const char *value)
160{
161 char path[MAX_PATH+1];
162 int ret, count;
163 int fd;
164
165 /* construct the path */
166 snprintf(path, sizeof(path), "%s/%s", debugfs_mountpoint, entry);
167
168 /* verify that it exists */
169 ret = debugfs_valid_entry(path);
170 if (ret)
171 return ret;
172
173 /* get how many chars we're going to write */
174 count = strlen(value);
175
176 /* open the debugfs entry */
177 fd = open(path, O_RDWR);
178 if (fd < 0)
179 return -errno;
180
181 while (count > 0) {
182 /* write it */
183 ret = write(fd, value, count);
184 if (ret <= 0) {
185 if (ret == EAGAIN)
186 continue;
187 close(fd);
188 return -errno;
189 }
190 count -= ret;
191 }
192
193 /* close it */
194 close(fd);
195
196 /* return success */
197 return 0;
198}
199
200/*
201 * read a debugfs entry
202 * returns the number of chars read or a negative errno
203 */
204int debugfs_read(const char *entry, char *buffer, size_t size)
205{
206 char path[MAX_PATH+1];
207 int ret;
208 int fd;
209
210 /* construct the path */
211 snprintf(path, sizeof(path), "%s/%s", debugfs_mountpoint, entry);
212
213 /* verify that it exists */
214 ret = debugfs_valid_entry(path);
215 if (ret)
216 return ret;
217
218 /* open the debugfs entry */
219 fd = open(path, O_RDONLY);
220 if (fd < 0)
221 return -errno;
222
223 do {
224 /* read it */
225 ret = read(fd, buffer, size);
226 if (ret == 0) {
227 close(fd);
228 return EOF;
229 }
230 } while (ret < 0 && errno == EAGAIN);
231
232 /* close it */
233 close(fd);
234
235 /* make *sure* there's a null character at the end */
236 buffer[ret] = '\0';
237
238 /* return the number of chars read */
239 return ret;
240}