5 static int debugfs_premounted;
6 static char debugfs_mountpoint[MAX_PATH+1];
8 static const char *debugfs_known_mountpoints[] = {
14 /* use this to force a umount */
15 void debugfs_force_cleanup(void)
17 debugfs_find_mountpoint();
18 debugfs_premounted = 0;
22 /* construct a full path to a debugfs element */
23 int debugfs_make_path(const char *element, char *buffer, int size)
27 if (strlen(debugfs_mountpoint) == 0) {
32 len = strlen(debugfs_mountpoint) + strlen(element) + 1;
36 snprintf(buffer, size-1, "%s/%s", debugfs_mountpoint, element);
40 static int debugfs_found;
42 /* find the path to the mounted debugfs */
43 const char *debugfs_find_mountpoint(void)
50 return (const char *) debugfs_mountpoint;
52 ptr = debugfs_known_mountpoints;
54 if (debugfs_valid_mountpoint(*ptr) == 0) {
56 strcpy(debugfs_mountpoint, *ptr);
57 return debugfs_mountpoint;
62 /* give up and parse /proc/mounts */
63 fp = fopen("/proc/mounts", "r");
65 die("Can't open /proc/mounts for read");
67 while (fscanf(fp, "%*s %"
69 "s %99s %*s %*d %*d\n",
70 debugfs_mountpoint, type) == 2) {
71 if (strcmp(type, "debugfs") == 0)
76 if (strcmp(type, "debugfs") != 0)
81 return debugfs_mountpoint;
84 /* verify that a mountpoint is actually a debugfs instance */
86 int debugfs_valid_mountpoint(const char *debugfs)
90 if (statfs(debugfs, &st_fs) < 0)
92 else if (st_fs.f_type != (long) DEBUGFS_MAGIC)
99 int debugfs_valid_entry(const char *path)
109 /* mount the debugfs somewhere */
111 int debugfs_mount(const char *mountpoint)
115 /* see if it's already mounted */
116 if (debugfs_find_mountpoint()) {
117 debugfs_premounted = 1;
121 /* if not mounted and no argument */
122 if (mountpoint == NULL) {
123 /* see if environment variable set */
124 mountpoint = getenv(PERF_DEBUGFS_ENVIRONMENT);
125 /* if no environment variable, use default */
126 if (mountpoint == NULL)
127 mountpoint = "/sys/kernel/debug";
130 /* save the mountpoint */
131 strncpy(debugfs_mountpoint, mountpoint, sizeof(debugfs_mountpoint));
134 snprintf(mountcmd, sizeof(mountcmd),
135 "/bin/mount -t debugfs debugfs %s", mountpoint);
136 return system(mountcmd);
139 /* umount the debugfs */
141 int debugfs_umount(void)
146 /* if it was already mounted, leave it */
147 if (debugfs_premounted)
150 /* make sure it's a valid mount point */
151 ret = debugfs_valid_mountpoint(debugfs_mountpoint);
155 snprintf(umountcmd, sizeof(umountcmd),
156 "/bin/umount %s", debugfs_mountpoint);
157 return system(umountcmd);
160 int debugfs_write(const char *entry, const char *value)
162 char path[MAX_PATH+1];
166 /* construct the path */
167 snprintf(path, sizeof(path), "%s/%s", debugfs_mountpoint, entry);
169 /* verify that it exists */
170 ret = debugfs_valid_entry(path);
174 /* get how many chars we're going to write */
175 count = strlen(value);
177 /* open the debugfs entry */
178 fd = open(path, O_RDWR);
184 ret = write(fd, value, count);
202 * read a debugfs entry
203 * returns the number of chars read or a negative errno
205 int debugfs_read(const char *entry, char *buffer, size_t size)
207 char path[MAX_PATH+1];
211 /* construct the path */
212 snprintf(path, sizeof(path), "%s/%s", debugfs_mountpoint, entry);
214 /* verify that it exists */
215 ret = debugfs_valid_entry(path);
219 /* open the debugfs entry */
220 fd = open(path, O_RDONLY);
226 ret = read(fd, buffer, size);
231 } while (ret < 0 && errno == EAGAIN);
236 /* make *sure* there's a null character at the end */
239 /* return the number of chars read */