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debugfs.c
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debugfs.c
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/*
* Copyright (C) 2009 Clark Williams <[email protected]>
* Copyright (C) 2009 Xiao Guangrong <[email protected]>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of version 2 of the GNU General Public
* License as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA
*
*/
#include "debugfs.h"
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/statfs.h>
#ifndef DEBUGFS_MAGIC
#define DEBUGFS_MAGIC 0x64626720
#endif
static int debugfs_premounted;
static char debugfs_mountpoint[MAX_PATH+1];
static const char *debugfs_find_mountpoint(void);
static int debugfs_valid_mountpoint(const char *debugfs);
static const char *debugfs_known_mountpoints[] = {
"/sys/kernel/debug/",
"/debug/",
NULL,
};
/* construct a full path to a debugfs element */
int debugfs_make_path(const char *fmt, const char *mesh_iface, char *buffer,
int size)
{
int len;
if (strlen(debugfs_mountpoint) == 0) {
buffer[0] = '\0';
return -1;
}
len = strlen(debugfs_mountpoint) + strlen(fmt) + 1;
if (len >= size)
return len+1;
snprintf(buffer, size-1, fmt, debugfs_mountpoint, mesh_iface);
return 0;
}
static int debugfs_found;
/* find the path to the mounted debugfs */
static 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;
strncpy(debugfs_mountpoint, *ptr,
sizeof(debugfs_mountpoint));
debugfs_mountpoint[sizeof(debugfs_mountpoint) - 1] = 0;
return debugfs_mountpoint;
}
ptr++;
}
/* give up and parse /proc/mounts */
fp = fopen("/proc/mounts", "r");
if (fp == NULL) {
perror("Error - can't open /proc/mounts for read");
return NULL;
}
while (fscanf(fp, "%*s %"
STR(MAX_PATH)
"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 */
static 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;
}
/* 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;
return debugfs_mountpoint;
}
/* if not mounted and no argument */
if (mountpoint == NULL)
mountpoint = "/sys/kernel/debug";
if (mount(NULL, mountpoint, "debugfs", 0, NULL) < 0)
return NULL;
/* save the mountpoint */
strncpy(debugfs_mountpoint, mountpoint, sizeof(debugfs_mountpoint));
debugfs_mountpoint[sizeof(debugfs_mountpoint) - 1] = '\0';
debugfs_found = 1;
return debugfs_mountpoint;
}