linux/tools/perf/util/util.c

// SPDX-License-Identifier: GPL-2.0
#include "util.h"
#include "debug.h"
#include "event.h"
#include <api/fs/fs.h>
#include <sys/stat.h>
#include <sys/utsname.h>
#include <dirent.h>
#include <fcntl.h>
#include <inttypes.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <limits.h>
#include <linux/capability.h>
#include <linux/kernel.h>
#include <linux/log2.h>
#include <linux/time64.h>
#include <linux/overflow.h>
#include <unistd.h>
#include "cap.h"
#include "strlist.h"
#include "string2.h"

/*
 * XXX We need to find a better place for these things...
 */

bool perf_singlethreaded = true;

void perf_set_singlethreaded(void)
{
	perf_singlethreaded = true;
}

void perf_set_multithreaded(void)
{
	perf_singlethreaded = false;
}

int sysctl_perf_event_max_stack = PERF_MAX_STACK_DEPTH;
int sysctl_perf_event_max_contexts_per_stack = PERF_MAX_CONTEXTS_PER_STACK;

int sysctl__max_stack(void)
{
	int value;

	if (sysctl__read_int("kernel/perf_event_max_stack", &value) == 0)
		sysctl_perf_event_max_stack = value;

	if (sysctl__read_int("kernel/perf_event_max_contexts_per_stack", &value) == 0)
		sysctl_perf_event_max_contexts_per_stack = value;

	return sysctl_perf_event_max_stack;
}

bool sysctl__nmi_watchdog_enabled(void)
{
	static bool cached;
	static bool nmi_watchdog;
	int value;

	if (cached)
		return nmi_watchdog;

	if (sysctl__read_int("kernel/nmi_watchdog", &value) < 0)
		return false;

	nmi_watchdog = (value > 0) ? true : false;
	cached = true;

	return nmi_watchdog;
}

bool test_attr__enabled;

bool perf_host  = true;
bool perf_guest = false;

void event_attr_init(struct perf_event_attr *attr)
{
	if (!perf_host)
		attr->exclude_host  = 1;
	if (!perf_guest)
		attr->exclude_guest = 1;
	/* to capture ABI version */
	attr->size = sizeof(*attr);
}

int mkdir_p(char *path, mode_t mode)
{
	struct stat st;
	int err;
	char *d = path;

	if (*d != '/')
		return -1;

	if (stat(path, &st) == 0)
		return 0;

	while (*++d == '/');

	while ((d = strchr(d, '/'))) {
		*d = '\0';
		err = stat(path, &st) && mkdir(path, mode);
		*d++ = '/';
		if (err)
			return -1;
		while (*d == '/')
			++d;
	}
	return (stat(path, &st) && mkdir(path, mode)) ? -1 : 0;
}

static bool match_pat(char *file, const char **pat)
{
	int i = 0;

	if (!pat)
		return true;

	while (pat[i]) {
		if (strglobmatch(file, pat[i]))
			return true;

		i++;
	}

	return false;
}

/*
 * The depth specify how deep the removal will go.
 * 0       - will remove only files under the 'path' directory
 * 1 .. x  - will dive in x-level deep under the 'path' directory
 *
 * If specified the pat is array of string patterns ended with NULL,
 * which are checked upon every file/directory found. Only matching
 * ones are removed.
 *
 * The function returns:
 *    0 on success
 *   -1 on removal failure with errno set
 *   -2 on pattern failure
 */
static int rm_rf_depth_pat(const char *path, int depth, const char **pat)
{
	DIR *dir;
	int ret;
	struct dirent *d;
	char namebuf[PATH_MAX];
	struct stat statbuf;

	/* Do not fail if there's no file. */
	ret = lstat(path, &statbuf);
	if (ret)
		return 0;

	/* Try to remove any file we get. */
	if (!(statbuf.st_mode & S_IFDIR))
		return unlink(path);

	/* We have directory in path. */
	dir = opendir(path);
	if (dir == NULL)
		return -1;

	while ((d = readdir(dir)) != NULL && !ret) {

		if (!strcmp(d->d_name, ".") || !strcmp(d->d_name, ".."))
			continue;

		if (!match_pat(d->d_name, pat)) {
			ret =  -2;
			break;
		}

		scnprintf(namebuf, sizeof(namebuf), "%s/%s",
			  path, d->d_name);

		/* We have to check symbolic link itself */
		ret = lstat(namebuf, &statbuf);
		if (ret < 0) {
			pr_debug("stat failed: %s\n", namebuf);
			break;
		}

		if (S_ISDIR(statbuf.st_mode))
			ret = depth ? rm_rf_depth_pat(namebuf, depth - 1, pat) : 0;
		else
			ret = unlink(namebuf);
	}
	closedir(dir);

	if (ret < 0)
		return ret;

	return rmdir(path);
}

static int rm_rf_a_kcore_dir(const char *path, const char *name)
{
	char kcore_dir_path[PATH_MAX];
	const char *pat[] = {
		"kcore",
		"kallsyms",
		"modules",
		NULL,
	};

	snprintf(kcore_dir_path, sizeof(kcore_dir_path), "%s/%s", path, name);

	return rm_rf_depth_pat(kcore_dir_path, 0, pat);
}

static bool kcore_dir_filter(const char *name __maybe_unused, struct dirent *d)
{
	const char *pat[] = {
		"kcore_dir",
		"kcore_dir__[1-9]*",
		NULL,
	};

	return match_pat(d->d_name, pat);
}

static int rm_rf_kcore_dir(const char *path)
{
	struct strlist *kcore_dirs;
	struct str_node *nd;
	int ret;

	kcore_dirs = lsdir(path, kcore_dir_filter);

	if (!kcore_dirs)
		return 0;

	strlist__for_each_entry(nd, kcore_dirs) {
		ret = rm_rf_a_kcore_dir(path, nd->s);
		if (ret)
			return ret;
	}

	strlist__delete(kcore_dirs);

	return 0;
}

int rm_rf_perf_data(const char *path)
{
	const char *pat[] = {
		"data",
		"data.*",
		NULL,
	};

	rm_rf_kcore_dir(path);

	return rm_rf_depth_pat(path, 0, pat);
}

int rm_rf(const char *path)
{
	return rm_rf_depth_pat(path, INT_MAX, NULL);
}

/* A filter which removes dot files */
bool lsdir_no_dot_filter(const char *name __maybe_unused, struct dirent *d)
{
	return d->d_name[0] != '.';
}

/* lsdir reads a directory and store it in strlist */
struct strlist *lsdir(const char *name,
		      bool (*filter)(const char *, struct dirent *))
{
	struct strlist *list = NULL;
	DIR *dir;
	struct dirent *d;

	dir = opendir(name);
	if (!dir)
		return NULL;

	list = strlist__new(NULL, NULL);
	if (!list) {
		errno = ENOMEM;
		goto out;
	}

	while ((d = readdir(dir)) != NULL) {
		if (!filter || filter(name, d))
			strlist__add(list, d->d_name);
	}

out:
	closedir(dir);
	return list;
}

size_t hex_width(u64 v)
{
	size_t n = 1;

	while ((v >>= 4))
		++n;

	return n;
}

int perf_event_paranoid(void)
{
	int value;

	if (sysctl__read_int("kernel/perf_event_paranoid", &value))
		return INT_MAX;

	return value;
}

bool perf_event_paranoid_check(int max_level)
{
	return perf_cap__capable(CAP_SYS_ADMIN) ||
			perf_cap__capable(CAP_PERFMON) ||
			perf_event_paranoid() <= max_level;
}

static int
fetch_ubuntu_kernel_version(unsigned int *puint)
{
	ssize_t len;
	size_t line_len = 0;
	char *ptr, *line = NULL;
	int version, patchlevel, sublevel, err;
	FILE *vsig;

	if (!puint)
		return 0;

	vsig = fopen("/proc/version_signature", "r");
	if (!vsig) {
		pr_debug("Open /proc/version_signature failed: %s\n",
			 strerror(errno));
		return -1;
	}

	len = getline(&line, &line_len, vsig);
	fclose(vsig);
	err = -1;
	if (len <= 0) {
		pr_debug("Reading from /proc/version_signature failed: %s\n",
			 strerror(errno));
		goto errout;
	}

	ptr = strrchr(line, ' ');
	if (!ptr) {
		pr_debug("Parsing /proc/version_signature failed: %s\n", line);
		goto errout;
	}

	err = sscanf(ptr + 1, "%d.%d.%d",
		     &version, &patchlevel, &sublevel);
	if (err != 3) {
		pr_debug("Unable to get kernel version from /proc/version_signature '%s'\n",
			 line);
		goto errout;
	}

	*puint = (version << 16) + (patchlevel << 8) + sublevel;
	err = 0;
errout:
	free(line);
	return err;
}

int
fetch_kernel_version(unsigned int *puint, char *str,
		     size_t str_size)
{
	struct utsname utsname;
	int version, patchlevel, sublevel, err;
	bool int_ver_ready = false;

	if (access("/proc/version_signature", R_OK) == 0)
		if (!fetch_ubuntu_kernel_version(puint))
			int_ver_ready = true;

	if (uname(&utsname))
		return -1;

	if (str && str_size) {
		strncpy(str, utsname.release, str_size);
		str[str_size - 1] = '\0';
	}

	if (!puint || int_ver_ready)
		return 0;

	err = sscanf(utsname.release, "%d.%d.%d",
		     &version, &patchlevel, &sublevel);

	if (err != 3) {
		pr_debug("Unable to get kernel version from uname '%s'\n",
			 utsname.release);
		return -1;
	}

	*puint = (version << 16) + (patchlevel << 8) + sublevel;
	return 0;
}

int perf_tip(char **strp, const char *dirpath)
{
	struct strlist *tips;
	struct str_node *node;
	struct strlist_config conf = {
		.dirname = dirpath,
		.file_only = true,
	};
	int ret = 0;

	*strp = NULL;
	tips = strlist__new("tips.txt", &conf);
	if (tips == NULL)
		return -errno;

	if (strlist__nr_entries(tips) == 0)
		goto out;

	node = strlist__entry(tips, random() % strlist__nr_entries(tips));
	if (asprintf(strp, "Tip: %s", node->s) < 0)
		ret = -ENOMEM;

out:
	strlist__delete(tips);

	return ret;
}

char *perf_exe(char *buf, int len)
{
	int n = readlink("/proc/self/exe", buf, len);
	if (n > 0) {
		buf[n] = 0;
		return buf;
	}
	return strcpy(buf, "perf");
}

void perf_debuginfod_setup(struct perf_debuginfod *di)
{
	/*
	 * By default '!di->set' we clear DEBUGINFOD_URLS, so debuginfod
	 * processing is not triggered, otherwise we set it to 'di->urls'
	 * value. If 'di->urls' is "system" we keep DEBUGINFOD_URLS value.
	 */
	if (!di->set)
		setenv("DEBUGINFOD_URLS", "", 1);
	else if (di->urls && strcmp(di->urls, "system"))
		setenv("DEBUGINFOD_URLS", di->urls, 1);

	pr_debug("DEBUGINFOD_URLS=%s\n", getenv("DEBUGINFOD_URLS"));

#ifndef HAVE_DEBUGINFOD_SUPPORT
	if (di->set)
		pr_warning("WARNING: debuginfod support requested, but perf is not built with it\n");
#endif
}

/*
 * Return a new filename prepended with task's root directory if it's in
 * a chroot.  Callers should free the returned string.
 */
char *filename_with_chroot(int pid, const char *filename)
{
	char buf[PATH_MAX];
	char proc_root[32];
	char *new_name = NULL;
	int ret;

	scnprintf(proc_root, sizeof(proc_root), "/proc/%d/root", pid);
	ret = readlink(proc_root, buf, sizeof(buf) - 1);
	if (ret <= 0)
		return NULL;

	/* readlink(2) does not append a null byte to buf */
	buf[ret] = '\0';

	if (!strcmp(buf, "/"))
		return NULL;

	if (strstr(buf, "(deleted)"))
		return NULL;

	if (asprintf(&new_name, "%s/%s", buf, filename) < 0)
		return NULL;

	return new_name;
}

/*
 * Reallocate an array *arr of size *arr_sz so that it is big enough to contain
 * x elements of size msz, initializing new entries to *init_val or zero if
 * init_val is NULL
 */
int do_realloc_array_as_needed(void **arr, size_t *arr_sz, size_t x, size_t msz, const void *init_val)
{
	size_t new_sz = *arr_sz;
	void *new_arr;
	size_t i;

	if (!new_sz)
		new_sz = msz >= 64 ? 1 : roundup(64, msz); /* Start with at least 64 bytes */
	while (x >= new_sz) {
		if (check_mul_overflow(new_sz, (size_t)2, &new_sz))
			return -ENOMEM;
	}
	if (new_sz == *arr_sz)
		return 0;
	new_arr = calloc(new_sz, msz);
	if (!new_arr)
		return -ENOMEM;
	memcpy(new_arr, *arr, *arr_sz * msz);
	if (init_val) {
		for (i = *arr_sz; i < new_sz; i++)
			memcpy(new_arr + (i * msz), init_val, msz);
	}
	*arr = new_arr;
	*arr_sz = new_sz;
	return 0;
}