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#include "util.h"
#include "debugfs.h"
#include "cache.h"
#include <linux/kernel.h>
#include <sys/mount.h>
static int debugfs_premounted;
char debugfs_mountpoint[PATH_MAX + 1] = "/sys/kernel/debug";
char tracing_events_path[PATH_MAX + 1] = "/sys/kernel/debug/tracing/events";
static const char *debugfs_known_mountpoints[] = {
"/sys/kernel/debug/",
"/debug/",
0,
};
/* use this to force a umount */
void debugfs_force_cleanup(void)
{
debugfs_find_mountpoint();
debugfs_premounted = 0;
debugfs_umount();
}
/* construct a full path to a debugfs element */
int debugfs_make_path(const char *element, char *buffer, int size)
{
int len;
if (strlen(debugfs_mountpoint) == 0) {
buffer[0] = '\0';
return -1;
}
len = strlen(debugfs_mountpoint) + strlen(element) + 1;
if (len >= size)
return len+1;
snprintf(buffer, size-1, "%s/%s", debugfs_mountpoint, element);
return 0;
}
static int debugfs_found;
/* find the path to the mounted debugfs */
const char *debugfs_find_mountpoint(void)
{
const char **ptr;
char type[100];
FILE *fp;
if (debugfs_found)
return (const char *) debugfs_mountpoint;
ptr = debugfs_known_mountpoints;
while (*ptr) {
if (debugfs_valid_mountpoint(*ptr) == 0) {
debugfs_found = 1;
strcpy(debugfs_mountpoint, *ptr);
return debugfs_mountpoint;
}
ptr++;
}
/* give up and parse /proc/mounts */
fp = fopen("/proc/mounts", "r");
if (fp == NULL)
return NULL;
while (fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n",
debugfs_mountpoint, type) == 2) {
if (strcmp(type, "debugfs") == 0)
break;
}
fclose(fp);
if (strcmp(type, "debugfs") != 0)
return NULL;
debugfs_found = 1;
return debugfs_mountpoint;
}
/* verify that a mountpoint is actually a debugfs instance */
int debugfs_valid_mountpoint(const char *debugfs)
{
struct statfs st_fs;
if (statfs(debugfs, &st_fs) < 0)
return -ENOENT;
else if (st_fs.f_type != (long) DEBUGFS_MAGIC)
return -ENOENT;
return 0;
}
int debugfs_valid_entry(const char *path)
{
struct stat st;
if (stat(path, &st))
return -errno;
return 0;
}
static void debugfs_set_tracing_events_path(const char *mountpoint)
{
snprintf(tracing_events_path, sizeof(tracing_events_path), "%s/%s",
mountpoint, "tracing/events");
}
/* mount the debugfs somewhere if it's not mounted */
char *debugfs_mount(const char *mountpoint)
{
/* see if it's already mounted */
if (debugfs_find_mountpoint()) {
debugfs_premounted = 1;
goto out;
}
/* if not mounted and no argument */
if (mountpoint == NULL) {
/* see if environment variable set */
mountpoint = getenv(PERF_DEBUGFS_ENVIRONMENT);
/* if no environment variable, use default */
if (mountpoint == NULL)
mountpoint = "/sys/kernel/debug";
}
if (mount(NULL, mountpoint, "debugfs", 0, NULL) < 0)
return NULL;
/* save the mountpoint */
debugfs_found = 1;
strncpy(debugfs_mountpoint, mountpoint, sizeof(debugfs_mountpoint));
out:
debugfs_set_tracing_events_path(debugfs_mountpoint);
return debugfs_mountpoint;
}
void debugfs_set_path(const char *mountpoint)
{
snprintf(debugfs_mountpoint, sizeof(debugfs_mountpoint), "%s", mountpoint);
debugfs_set_tracing_events_path(mountpoint);
}
/* umount the debugfs */
int debugfs_umount(void)
{
char umountcmd[128];
int ret;
/* if it was already mounted, leave it */
if (debugfs_premounted)
return 0;
/* make sure it's a valid mount point */
ret = debugfs_valid_mountpoint(debugfs_mountpoint);
if (ret)
return ret;
snprintf(umountcmd, sizeof(umountcmd),
"/bin/umount %s", debugfs_mountpoint);
return system(umountcmd);
}
int debugfs_write(const char *entry, const char *value)
{
char path[PATH_MAX + 1];
int ret, count;
int fd;
/* construct the path */
snprintf(path, sizeof(path), "%s/%s", debugfs_mountpoint, entry);
/* verify that it exists */
ret = debugfs_valid_entry(path);
if (ret)
return ret;
/* get how many chars we're going to write */
count = strlen(value);
/* open the debugfs entry */
fd = open(path, O_RDWR);
if (fd < 0)
return -errno;
while (count > 0) {
/* write it */
ret = write(fd, value, count);
if (ret <= 0) {
if (ret == EAGAIN)
continue;
close(fd);
return -errno;
}
count -= ret;
}
/* close it */
close(fd);
/* return success */
return 0;
}
/*
* read a debugfs entry
* returns the number of chars read or a negative errno
*/
int debugfs_read(const char *entry, char *buffer, size_t size)
{
char path[PATH_MAX + 1];
int ret;
int fd;
/* construct the path */
snprintf(path, sizeof(path), "%s/%s", debugfs_mountpoint, entry);
/* verify that it exists */
ret = debugfs_valid_entry(path);
if (ret)
return ret;
/* open the debugfs entry */
fd = open(path, O_RDONLY);
if (fd < 0)
return -errno;
do {
/* read it */
ret = read(fd, buffer, size);
if (ret == 0) {
close(fd);
return EOF;
}
} while (ret < 0 && errno == EAGAIN);
/* close it */
close(fd);
/* make *sure* there's a null character at the end */
buffer[ret] = '\0';
/* return the number of chars read */
return ret;
}
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