#define _GNU_SOURCE#include <errno.h>#include <stdio.h>#include <stdlib.h>#include <string.h>#include <unistd.h>#include <stdbool.h>#include <sys/vfs.h>#include <sys/types.h>#include <sys/stat.h>#include <sys/mount.h>#include <linux/kernel.h> #include "debugfs.h" #ifndef DEBUGFS_DEFAULT_PATH#define DEBUGFS_DEFAULT_PATH		"/sys/kernel/debug"#endif char debugfs_mountpoint[PATH_MAX + 1] = DEBUGFS_DEFAULT_PATH; static const char * const debugfs_known_mountpoints[] = {	DEBUGFS_DEFAULT_PATH,	"/debug",	0,}; static bool debugfs_found; bool debugfs_configured(void){	return debugfs_find_mountpoint() != NULL;} /* find the path to the mounted debugfs */const char *debugfs_find_mountpoint(void){	const char *ret; 	if (debugfs_found)		return (const char *)debugfs_mountpoint; 	ret = find_mountpoint("debugfs", (long) DEBUGFS_MAGIC,			      debugfs_mountpoint, PATH_MAX + 1,			      debugfs_known_mountpoints);	if (ret)		debugfs_found = true; 	return ret;} /* 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())		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 = DEBUGFS_DEFAULT_PATH;	} 	if (mount(NULL, mountpoint, "debugfs", 0, NULL) < 0)		return NULL; 	/* save the mountpoint */	debugfs_found = true;	strncpy(debugfs_mountpoint, mountpoint, sizeof(debugfs_mountpoint));out:	return debugfs_mountpoint;} int debugfs__strerror_open(int err, char *buf, size_t size, const char *filename){	char sbuf[128]; 	switch (err) {	case ENOENT:		if (debugfs_found) {			snprintf(buf, size,				 "Error:\tFile %s/%s not found.\n"				 "Hint:\tPerhaps this kernel misses some CONFIG_ setting to enable this feature?.\n",				 debugfs_mountpoint, filename);			break;		}		snprintf(buf, size, "%s",			 "Error:\tUnable to find debugfs\n"			 "Hint:\tWas your kernel compiled with debugfs support?\n"			 "Hint:\tIs the debugfs filesystem mounted?\n"			 "Hint:\tTry 'sudo mount -t debugfs nodev /sys/kernel/debug'");		break;	case EACCES:		snprintf(buf, size,			 "Error:\tNo permissions to read %s/%s\n"			 "Hint:\tTry 'sudo mount -o remount,mode=755 %s'\n",			 debugfs_mountpoint, filename, debugfs_mountpoint);		break;	default:		snprintf(buf, size, "%s", strerror_r(err, sbuf, sizeof(sbuf)));		break;	} 	return 0;} int debugfs__strerror_open_tp(int err, char *buf, size_t size, const char *sys, const char *name){	char path[PATH_MAX]; 	snprintf(path, PATH_MAX, "tracing/events/%s/%s", sys, name ?: "*"); 	return debugfs__strerror_open(err, buf, size, path);}