#include <ctype.h>#include <errno.h>#include <limits.h>#include <stdbool.h>#include <stdio.h>#include <stdlib.h>#include <string.h>#include <sys/vfs.h>#include <sys/types.h>#include <sys/stat.h>#include <fcntl.h>#include <unistd.h>#include <sys/mount.h> #include "fs.h"#include "debug-internal.h" #define _STR(x) #x#define STR(x) _STR(x) #ifndef SYSFS_MAGIC#define SYSFS_MAGIC            0x62656572#endif #ifndef PROC_SUPER_MAGIC#define PROC_SUPER_MAGIC       0x9fa0#endif #ifndef DEBUGFS_MAGIC#define DEBUGFS_MAGIC          0x64626720#endif #ifndef TRACEFS_MAGIC#define TRACEFS_MAGIC          0x74726163#endif #ifndef HUGETLBFS_MAGIC#define HUGETLBFS_MAGIC        0x958458f6#endif #ifndef BPF_FS_MAGIC#define BPF_FS_MAGIC           0xcafe4a11#endif static const char * const sysfs__fs_known_mountpoints[] = {	"/sys",	0,}; static const char * const procfs__known_mountpoints[] = {	"/proc",	0,}; #ifndef DEBUGFS_DEFAULT_PATH#define DEBUGFS_DEFAULT_PATH "/sys/kernel/debug"#endif static const char * const debugfs__known_mountpoints[] = {	DEBUGFS_DEFAULT_PATH,	"/debug",	0,};  #ifndef TRACEFS_DEFAULT_PATH#define TRACEFS_DEFAULT_PATH "/sys/kernel/tracing"#endif static const char * const tracefs__known_mountpoints[] = {	TRACEFS_DEFAULT_PATH,	"/sys/kernel/debug/tracing",	"/tracing",	"/trace",	0,}; static const char * const hugetlbfs__known_mountpoints[] = {	0,}; static const char * const bpf_fs__known_mountpoints[] = {	"/sys/fs/bpf",	0,}; struct fs {	const char		*name;	const char * const	*mounts;	char			 path[PATH_MAX];	bool			 found;	long			 magic;}; enum {	FS__SYSFS   = 0,	FS__PROCFS  = 1,	FS__DEBUGFS = 2,	FS__TRACEFS = 3,	FS__HUGETLBFS = 4,	FS__BPF_FS = 5,}; #ifndef TRACEFS_MAGIC#define TRACEFS_MAGIC 0x74726163#endif static struct fs fs__entries[] = {	[FS__SYSFS] = {		.name	= "sysfs",		.mounts	= sysfs__fs_known_mountpoints,		.magic	= SYSFS_MAGIC,	},	[FS__PROCFS] = {		.name	= "proc",		.mounts	= procfs__known_mountpoints,		.magic	= PROC_SUPER_MAGIC,	},	[FS__DEBUGFS] = {		.name	= "debugfs",		.mounts	= debugfs__known_mountpoints,		.magic	= DEBUGFS_MAGIC,	},	[FS__TRACEFS] = {		.name	= "tracefs",		.mounts	= tracefs__known_mountpoints,		.magic	= TRACEFS_MAGIC,	},	[FS__HUGETLBFS] = {		.name	= "hugetlbfs",		.mounts = hugetlbfs__known_mountpoints,		.magic	= HUGETLBFS_MAGIC,	},	[FS__BPF_FS] = {		.name	= "bpf",		.mounts = bpf_fs__known_mountpoints,		.magic	= BPF_FS_MAGIC,	},}; static bool fs__read_mounts(struct fs *fs){	bool found = false;	char type[100];	FILE *fp; 	fp = fopen("/proc/mounts", "r");	if (fp == NULL)		return NULL; 	while (!found &&	       fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n",		      fs->path, type) == 2) { 		if (strcmp(type, fs->name) == 0)			found = true;	} 	fclose(fp);	return fs->found = found;} static int fs__valid_mount(const char *fs, long magic){	struct statfs st_fs; 	if (statfs(fs, &st_fs) < 0)		return -ENOENT;	else if ((long)st_fs.f_type != magic)		return -ENOENT; 	return 0;} static bool fs__check_mounts(struct fs *fs){	const char * const *ptr; 	ptr = fs->mounts;	while (*ptr) {		if (fs__valid_mount(*ptr, fs->magic) == 0) {			fs->found = true;			strcpy(fs->path, *ptr);			return true;		}		ptr++;	} 	return false;} static void mem_toupper(char *f, size_t len){	while (len) {		*f = toupper(*f);		f++;		len--;	}} /* * Check for "NAME_PATH" environment variable to override fs location (for * testing). This matches the recommendation in Documentation/sysfs-rules.txt * for SYSFS_PATH. */static bool fs__env_override(struct fs *fs){	char *override_path;	size_t name_len = strlen(fs->name);	/* name + "_PATH" + '\0' */	char upper_name[name_len + 5 + 1];	memcpy(upper_name, fs->name, name_len);	mem_toupper(upper_name, name_len);	strcpy(&upper_name[name_len], "_PATH"); 	override_path = getenv(upper_name);	if (!override_path)		return false; 	fs->found = true;	strncpy(fs->path, override_path, sizeof(fs->path));	return true;} static const char *fs__get_mountpoint(struct fs *fs){	if (fs__env_override(fs))		return fs->path; 	if (fs__check_mounts(fs))		return fs->path; 	if (fs__read_mounts(fs))		return fs->path; 	return NULL;} static const char *fs__mountpoint(int idx){	struct fs *fs = &fs__entries[idx]; 	if (fs->found)		return (const char *)fs->path; 	return fs__get_mountpoint(fs);} static const char *mount_overload(struct fs *fs){	size_t name_len = strlen(fs->name);	/* "PERF_" + name + "_ENVIRONMENT" + '\0' */	char upper_name[5 + name_len + 12 + 1]; 	snprintf(upper_name, name_len, "PERF_%s_ENVIRONMENT", fs->name);	mem_toupper(upper_name, name_len); 	return getenv(upper_name) ?: *fs->mounts;} static const char *fs__mount(int idx){	struct fs *fs = &fs__entries[idx];	const char *mountpoint; 	if (fs__mountpoint(idx))		return (const char *)fs->path; 	mountpoint = mount_overload(fs); 	if (mount(NULL, mountpoint, fs->name, 0, NULL) < 0)		return NULL; 	return fs__check_mounts(fs) ? fs->path : NULL;} #define FS(name, idx)				\const char *name##__mountpoint(void)		\{						\	return fs__mountpoint(idx);		\}						\						\const char *name##__mount(void)			\{						\	return fs__mount(idx);			\}						\						\bool name##__configured(void)			\{						\	return name##__mountpoint() != NULL;	\} FS(sysfs,   FS__SYSFS);FS(procfs,  FS__PROCFS);FS(debugfs, FS__DEBUGFS);FS(tracefs, FS__TRACEFS);FS(hugetlbfs, FS__HUGETLBFS);FS(bpf_fs, FS__BPF_FS); int filename__read_int(const char *filename, int *value){	char line[64];	int fd = open(filename, O_RDONLY), err = -1; 	if (fd < 0)		return -1; 	if (read(fd, line, sizeof(line)) > 0) {		*value = atoi(line);		err = 0;	} 	close(fd);	return err;} /* * Parses @value out of @filename with strtoull. * By using 0 for base, the strtoull detects the * base automatically (see man strtoull). */int filename__read_ull(const char *filename, unsigned long long *value){	char line[64];	int fd = open(filename, O_RDONLY), err = -1; 	if (fd < 0)		return -1; 	if (read(fd, line, sizeof(line)) > 0) {		*value = strtoull(line, NULL, 0);		if (*value != ULLONG_MAX)			err = 0;	} 	close(fd);	return err;} #define STRERR_BUFSIZE  128     /* For the buffer size of strerror_r */ int filename__read_str(const char *filename, char **buf, size_t *sizep){	size_t size = 0, alloc_size = 0;	void *bf = NULL, *nbf;	int fd, n, err = 0;	char sbuf[STRERR_BUFSIZE]; 	fd = open(filename, O_RDONLY);	if (fd < 0)		return -errno; 	do {		if (size == alloc_size) {			alloc_size += BUFSIZ;			nbf = realloc(bf, alloc_size);			if (!nbf) {				err = -ENOMEM;				break;			} 			bf = nbf;		} 		n = read(fd, bf + size, alloc_size - size);		if (n < 0) {			if (size) {				pr_warning("read failed %d: %s\n", errno,					 strerror_r(errno, sbuf, sizeof(sbuf)));				err = 0;			} else				err = -errno; 			break;		} 		size += n;	} while (n > 0); 	if (!err) {		*sizep = size;		*buf   = bf;	} else		free(bf); 	close(fd);	return err;} int filename__write_int(const char *filename, int value){	int fd = open(filename, O_WRONLY), err = -1;	char buf[64]; 	if (fd < 0)		return err; 	sprintf(buf, "%d", value);	if (write(fd, buf, sizeof(buf)) == sizeof(buf))		err = 0; 	close(fd);	return err;} int procfs__read_str(const char *entry, char **buf, size_t *sizep){	char path[PATH_MAX];	const char *procfs = procfs__mountpoint(); 	if (!procfs)		return -1; 	snprintf(path, sizeof(path), "%s/%s", procfs, entry); 	return filename__read_str(path, buf, sizep);} int sysfs__read_ull(const char *entry, unsigned long long *value){	char path[PATH_MAX];	const char *sysfs = sysfs__mountpoint(); 	if (!sysfs)		return -1; 	snprintf(path, sizeof(path), "%s/%s", sysfs, entry); 	return filename__read_ull(path, value);} int sysfs__read_int(const char *entry, int *value){	char path[PATH_MAX];	const char *sysfs = sysfs__mountpoint(); 	if (!sysfs)		return -1; 	snprintf(path, sizeof(path), "%s/%s", sysfs, entry); 	return filename__read_int(path, value);} int sysfs__read_str(const char *entry, char **buf, size_t *sizep){	char path[PATH_MAX];	const char *sysfs = sysfs__mountpoint(); 	if (!sysfs)		return -1; 	snprintf(path, sizeof(path), "%s/%s", sysfs, entry); 	return filename__read_str(path, buf, sizep);} int sysfs__read_bool(const char *entry, bool *value){	char *buf;	size_t size;	int ret; 	ret = sysfs__read_str(entry, &buf, &size);	if (ret < 0)		return ret; 	switch (buf[0]) {	case '1':	case 'y':	case 'Y':		*value = true;		break;	case '0':	case 'n':	case 'N':		*value = false;		break;	default:		ret = -1;	} 	free(buf); 	return ret;}int sysctl__read_int(const char *sysctl, int *value){	char path[PATH_MAX];	const char *procfs = procfs__mountpoint(); 	if (!procfs)		return -1; 	snprintf(path, sizeof(path), "%s/sys/%s", procfs, sysctl); 	return filename__read_int(path, value);} int sysfs__write_int(const char *entry, int value)

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