// SPDX-License-Identifier: GPL-2.0#include <assert.h>#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 <pthread.h>#include <unistd.h>#include <sys/mount.h> #include "fs.h"#include "../io.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__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 *		 const name;	const char * const *	 const mounts;	char			*path;	pthread_mutex_t		 mount_mutex;	const long		 magic;}; #ifndef TRACEFS_MAGIC#define TRACEFS_MAGIC 0x74726163#endif static void fs__init_once(struct fs *fs);static const char *fs__mountpoint(const struct fs *fs);static const char *fs__mount(struct fs *fs); #define FS(lower_name, fs_name, upper_name)		\static struct fs fs__##lower_name = {			\	.name = #fs_name,				\	.mounts = lower_name##__known_mountpoints,	\	.magic = upper_name##_MAGIC,			\	.mount_mutex = PTHREAD_MUTEX_INITIALIZER,	\};							\							\static void lower_name##_init_once(void)		\{							\	struct fs *fs = &fs__##lower_name;		\							\	fs__init_once(fs);				\}							\							\const char *lower_name##__mountpoint(void)		\{							\	static pthread_once_t init_once = PTHREAD_ONCE_INIT;	\	struct fs *fs = &fs__##lower_name;		\							\	pthread_once(&init_once, lower_name##_init_once);	\	return fs__mountpoint(fs);			\}							\							\const char *lower_name##__mount(void)			\{							\	const char *mountpoint = lower_name##__mountpoint();	\	struct fs *fs = &fs__##lower_name;		\							\	if (mountpoint)					\		return mountpoint;			\							\	return fs__mount(fs);				\}							\							\bool lower_name##__configured(void)			\{							\	return lower_name##__mountpoint() != NULL;	\} FS(sysfs, sysfs, SYSFS);FS(procfs, procfs, PROC_SUPER);FS(debugfs, debugfs, DEBUGFS);FS(tracefs, tracefs, TRACEFS);FS(hugetlbfs, hugetlbfs, HUGETLBFS);FS(bpf_fs, bpf, BPF_FS); static bool fs__read_mounts(struct fs *fs){	char type[100];	FILE *fp;	char path[PATH_MAX + 1]; 	fp = fopen("/proc/mounts", "r");	if (fp == NULL)		return false; 	while (fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n",		      path, type) == 2) { 		if (strcmp(type, fs->name) == 0) {			fs->path = strdup(path);			fclose(fp);			return fs->path != NULL;		}	}	fclose(fp);	return false;} 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->path = strdup(*ptr);			if (!fs->path)				return false;			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/admin-guide/sysfs-rules.rst * 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->path = strdup(override_path);	if (!fs->path)		return false;	return true;} static void fs__init_once(struct fs *fs){	if (!fs__env_override(fs) &&	    !fs__check_mounts(fs) &&	    !fs__read_mounts(fs)) {		assert(!fs->path);	} else {		assert(fs->path);	}} static const char *fs__mountpoint(const struct fs *fs){	return fs->path;} 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, sizeof(upper_name), "PERF_%s_ENVIRONMENT", fs->name);	mem_toupper(upper_name, strlen(upper_name)); 	return getenv(upper_name) ?: *fs->mounts;} static const char *fs__mount(struct fs *fs){	const char *mountpoint; 	pthread_mutex_lock(&fs->mount_mutex); 	/* Check if path found inside the mutex to avoid races with other callers of mount. */	mountpoint = fs__mountpoint(fs);	if (mountpoint)		goto out; 	mountpoint = mount_overload(fs); 	if (mount(NULL, mountpoint, fs->name, 0, NULL) == 0 &&	    fs__valid_mount(mountpoint, fs->magic) == 0) {		fs->path = strdup(mountpoint);		mountpoint = fs->path;	}out:	pthread_mutex_unlock(&fs->mount_mutex);	return mountpoint;} int filename__read_int(const char *filename, int *value){	char line[64];	int fd = open(filename, O_RDONLY), err = -1;	ssize_t n; 	if (fd < 0)		return -errno; 	n = read(fd, line, sizeof(line) - 1);	if (n > 0) {		line[n] = '\0';		*value = atoi(line);		err = 0;	} 	close(fd);	return err;} static int filename__read_ull_base(const char *filename,				   unsigned long long *value, int base){	char line[64];	int fd = open(filename, O_RDONLY), err = -1;	ssize_t n; 	if (fd < 0)		return -errno; 	n = read(fd, line, sizeof(line) - 1);	if (n > 0) {		line[n] = '\0';		*value = strtoull(line, NULL, base);		if (*value != ULLONG_MAX)			err = 0;	} 	close(fd);	return err;} /* * Parses @value out of @filename with strtoull. * By using 16 for base to treat the number as hex. */int filename__read_xll(const char *filename, unsigned long long *value){	return filename__read_ull_base(filename, value, 16);} /* * 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){	return filename__read_ull_base(filename, value, 0);} int filename__read_str(const char *filename, char **buf, size_t *sizep){	struct io io;	char bf[128];	int err; 	io.fd = open(filename, O_RDONLY);	if (io.fd < 0)		return -errno;	io__init(&io, io.fd, bf, sizeof(bf));	*buf = NULL;	err = io__getdelim(&io, buf, sizep, /*delim=*/-1);	if (err < 0) {		free(*buf);		*buf = NULL;	} else		err = 0;	close(io.fd);	return err;} int filename__write_int(const char *filename, int value){	int fd = open(filename, O_WRONLY), err = -1;	char buf[64];	int len; 	if (fd < 0)		return -errno; 	len = sprintf(buf, "%d", value);	if (write(fd, buf, len) == len)		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);} static int sysfs__read_ull_base(const char *entry,				unsigned long long *value, int base){	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_base(path, value, base);} int sysfs__read_xll(const char *entry, unsigned long long *value){	return sysfs__read_ull_base(entry, value, 16);} int sysfs__read_ull(const char *entry, unsigned long long *value){	return sysfs__read_ull_base(entry, value, 0);} 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){	struct io io;	char bf[16];	int ret = 0;	char path[PATH_MAX];	const char *sysfs = sysfs__mountpoint(); 	if (!sysfs)		return -1; 	snprintf(path, sizeof(path), "%s/%s", sysfs, entry);	io.fd = open(path, O_RDONLY);	if (io.fd < 0)		return -errno; 	io__init(&io, io.fd, bf, sizeof(bf));	switch (io__get_char(&io)) {	case '1':	case 'y':	case 'Y':		*value = true;		break;	case '0':	case 'n':	case 'N':		*value = false;		break;	default:		ret = -1;	}	close(io.fd); 	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);

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