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Systemd/src/basic/util.c

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/* SPDX-License-Identifier: LGPL-2.1+ */
#include <alloca.h>
#include <errno.h>
#include <fcntl.h>
#include <sched.h>
#include <signal.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/prctl.h>
#include <sys/statfs.h>
#include <sys/sysmacros.h>
#include <sys/types.h>
#include <unistd.h>
#include "alloc-util.h"
#include "btrfs-util.h"
#include "build.h"
#include "cgroup-util.h"
#include "def.h"
#include "device-nodes.h"
#include "dirent-util.h"
#include "fd-util.h"
#include "fileio.h"
#include "format-util.h"
#include "hashmap.h"
#include "hostname-util.h"
#include "log.h"
#include "macro.h"
#include "missing.h"
#include "parse-util.h"
#include "path-util.h"
#include "process-util.h"
#include "procfs-util.h"
#include "set.h"
#include "signal-util.h"
#include "stat-util.h"
#include "string-util.h"
#include "strv.h"
#include "time-util.h"
#include "umask-util.h"
#include "user-util.h"
#include "util.h"
#include "virt.h"
int saved_argc = 0;
char **saved_argv = NULL;
static int saved_in_initrd = -1;
size_t page_size(void) {
static thread_local size_t pgsz = 0;
long r;
if (_likely_(pgsz > 0))
return pgsz;
r = sysconf(_SC_PAGESIZE);
assert(r > 0);
pgsz = (size_t) r;
return pgsz;
}
bool plymouth_running(void) {
return access("/run/plymouth/pid", F_OK) >= 0;
}
bool display_is_local(const char *display) {
assert(display);
return
display[0] == ':' &&
display[1] >= '0' &&
display[1] <= '9';
}
bool kexec_loaded(void) {
_cleanup_free_ char *s = NULL;
if (read_one_line_file("/sys/kernel/kexec_loaded", &s) < 0)
return false;
return s[0] == '1';
}
int prot_from_flags(int flags) {
switch (flags & O_ACCMODE) {
case O_RDONLY:
return PROT_READ;
case O_WRONLY:
return PROT_WRITE;
case O_RDWR:
return PROT_READ|PROT_WRITE;
default:
return -EINVAL;
}
}
bool in_initrd(void) {
struct statfs s;
if (saved_in_initrd >= 0)
return saved_in_initrd;
/* We make two checks here:
*
* 1. the flag file /etc/initrd-release must exist
* 2. the root file system must be a memory file system
*
* The second check is extra paranoia, since misdetecting an
* initrd can have bad consequences due the initrd
* emptying when transititioning to the main systemd.
*/
saved_in_initrd = access("/etc/initrd-release", F_OK) >= 0 &&
statfs("/", &s) >= 0 &&
is_temporary_fs(&s);
return saved_in_initrd;
}
void in_initrd_force(bool value) {
saved_in_initrd = value;
}
/* hey glibc, APIs with callbacks without a user pointer are so useless */
void *xbsearch_r(const void *key, const void *base, size_t nmemb, size_t size,
int (*compar) (const void *, const void *, void *), void *arg) {
size_t l, u, idx;
const void *p;
int comparison;
assert(!size_multiply_overflow(nmemb, size));
l = 0;
u = nmemb;
while (l < u) {
idx = (l + u) / 2;
p = (const uint8_t*) base + idx * size;
comparison = compar(key, p, arg);
if (comparison < 0)
u = idx;
else if (comparison > 0)
l = idx + 1;
else
return (void *)p;
}
return NULL;
}
int on_ac_power(void) {
bool found_offline = false, found_online = false;
_cleanup_closedir_ DIR *d = NULL;
struct dirent *de;
d = opendir("/sys/class/power_supply");
if (!d)
return errno == ENOENT ? true : -errno;
FOREACH_DIRENT(de, d, return -errno) {
_cleanup_close_ int fd = -1, device = -1;
char contents[6];
ssize_t n;
device = openat(dirfd(d), de->d_name, O_DIRECTORY|O_RDONLY|O_CLOEXEC|O_NOCTTY);
if (device < 0) {
if (IN_SET(errno, ENOENT, ENOTDIR))
continue;
return -errno;
}
fd = openat(device, "type", O_RDONLY|O_CLOEXEC|O_NOCTTY);
if (fd < 0) {
if (errno == ENOENT)
continue;
return -errno;
}
n = read(fd, contents, sizeof(contents));
if (n < 0)
return -errno;
if (n != 6 || memcmp(contents, "Mains\n", 6))
continue;
safe_close(fd);
fd = openat(device, "online", O_RDONLY|O_CLOEXEC|O_NOCTTY);
if (fd < 0) {
if (errno == ENOENT)
continue;
return -errno;
}
n = read(fd, contents, sizeof(contents));
if (n < 0)
return -errno;
if (n != 2 || contents[1] != '\n')
return -EIO;
if (contents[0] == '1') {
found_online = true;
break;
} else if (contents[0] == '0')
found_offline = true;
else
return -EIO;
}
return found_online || !found_offline;
}
int container_get_leader(const char *machine, pid_t *pid) {
_cleanup_free_ char *s = NULL, *class = NULL;
const char *p;
pid_t leader;
int r;
assert(machine);
assert(pid);
if (!machine_name_is_valid(machine))
return -EINVAL;
p = strjoina("/run/systemd/machines/", machine);
r = parse_env_file(NULL, p, NEWLINE, "LEADER", &s, "CLASS", &class, NULL);
if (r == -ENOENT)
return -EHOSTDOWN;
if (r < 0)
return r;
if (!s)
return -EIO;
if (!streq_ptr(class, "container"))
return -EIO;
r = parse_pid(s, &leader);
if (r < 0)
return r;
if (leader <= 1)
return -EIO;
*pid = leader;
return 0;
}
int namespace_open(pid_t pid, int *pidns_fd, int *mntns_fd, int *netns_fd, int *userns_fd, int *root_fd) {
_cleanup_close_ int pidnsfd = -1, mntnsfd = -1, netnsfd = -1, usernsfd = -1;
int rfd = -1;
assert(pid >= 0);
if (mntns_fd) {
const char *mntns;
mntns = procfs_file_alloca(pid, "ns/mnt");
mntnsfd = open(mntns, O_RDONLY|O_NOCTTY|O_CLOEXEC);
if (mntnsfd < 0)
return -errno;
}
if (pidns_fd) {
const char *pidns;
pidns = procfs_file_alloca(pid, "ns/pid");
pidnsfd = open(pidns, O_RDONLY|O_NOCTTY|O_CLOEXEC);
if (pidnsfd < 0)
return -errno;
}
if (netns_fd) {
const char *netns;
netns = procfs_file_alloca(pid, "ns/net");
netnsfd = open(netns, O_RDONLY|O_NOCTTY|O_CLOEXEC);
if (netnsfd < 0)
return -errno;
}
if (userns_fd) {
const char *userns;
userns = procfs_file_alloca(pid, "ns/user");
usernsfd = open(userns, O_RDONLY|O_NOCTTY|O_CLOEXEC);
if (usernsfd < 0 && errno != ENOENT)
return -errno;
}
if (root_fd) {
const char *root;
root = procfs_file_alloca(pid, "root");
rfd = open(root, O_RDONLY|O_NOCTTY|O_CLOEXEC|O_DIRECTORY);
if (rfd < 0)
return -errno;
}
if (pidns_fd)
*pidns_fd = pidnsfd;
if (mntns_fd)
*mntns_fd = mntnsfd;
if (netns_fd)
*netns_fd = netnsfd;
if (userns_fd)
*userns_fd = usernsfd;
if (root_fd)
*root_fd = rfd;
pidnsfd = mntnsfd = netnsfd = usernsfd = -1;
return 0;
}
int namespace_enter(int pidns_fd, int mntns_fd, int netns_fd, int userns_fd, int root_fd) {
if (userns_fd >= 0) {
/* Can't setns to your own userns, since then you could
* escalate from non-root to root in your own namespace, so
* check if namespaces equal before attempting to enter. */
_cleanup_free_ char *userns_fd_path = NULL;
int r;
if (asprintf(&userns_fd_path, "/proc/self/fd/%d", userns_fd) < 0)
return -ENOMEM;
r = files_same(userns_fd_path, "/proc/self/ns/user", 0);
if (r < 0)
return r;
if (r)
userns_fd = -1;
}
if (pidns_fd >= 0)
if (setns(pidns_fd, CLONE_NEWPID) < 0)
return -errno;
if (mntns_fd >= 0)
if (setns(mntns_fd, CLONE_NEWNS) < 0)
return -errno;
if (netns_fd >= 0)
if (setns(netns_fd, CLONE_NEWNET) < 0)
return -errno;
if (userns_fd >= 0)
if (setns(userns_fd, CLONE_NEWUSER) < 0)
return -errno;
if (root_fd >= 0) {
if (fchdir(root_fd) < 0)
return -errno;
if (chroot(".") < 0)
return -errno;
}
return reset_uid_gid();
}
uint64_t physical_memory(void) {
_cleanup_free_ char *root = NULL, *value = NULL;
uint64_t mem, lim;
size_t ps;
long sc;
int r;
/* We return this as uint64_t in case we are running as 32bit process on a 64bit kernel with huge amounts of
* memory.
*
* In order to support containers nicely that have a configured memory limit we'll take the minimum of the
* physically reported amount of memory and the limit configured for the root cgroup, if there is any. */
sc = sysconf(_SC_PHYS_PAGES);
assert(sc > 0);
ps = page_size();
mem = (uint64_t) sc * (uint64_t) ps;
r = cg_get_root_path(&root);
if (r < 0) {
log_debug_errno(r, "Failed to determine root cgroup, ignoring cgroup memory limit: %m");
return mem;
}
r = cg_all_unified();
if (r < 0) {
log_debug_errno(r, "Failed to determine root unified mode, ignoring cgroup memory limit: %m");
return mem;
}
if (r > 0) {
r = cg_get_attribute("memory", root, "memory.max", &value);
if (r < 0) {
log_debug_errno(r, "Failed to read memory.max cgroup attribute, ignoring cgroup memory limit: %m");
return mem;
}
if (streq(value, "max"))
return mem;
} else {
r = cg_get_attribute("memory", root, "memory.limit_in_bytes", &value);
if (r < 0) {
log_debug_errno(r, "Failed to read memory.limit_in_bytes cgroup attribute, ignoring cgroup memory limit: %m");
return mem;
}
}
r = safe_atou64(value, &lim);
if (r < 0) {
log_debug_errno(r, "Failed to parse cgroup memory limit '%s', ignoring: %m", value);
return mem;
}
if (lim == UINT64_MAX)
return mem;
/* Make sure the limit is a multiple of our own page size */
lim /= ps;
lim *= ps;
return MIN(mem, lim);
}
uint64_t physical_memory_scale(uint64_t v, uint64_t max) {
uint64_t p, m, ps, r;
assert(max > 0);
/* Returns the physical memory size, multiplied by v divided by max. Returns UINT64_MAX on overflow. On success
* the result is a multiple of the page size (rounds down). */
ps = page_size();
assert(ps > 0);
p = physical_memory() / ps;
assert(p > 0);
m = p * v;
if (m / p != v)
return UINT64_MAX;
m /= max;
r = m * ps;
if (r / ps != m)
return UINT64_MAX;
return r;
}
uint64_t system_tasks_max(void) {
uint64_t a = TASKS_MAX, b = TASKS_MAX;
_cleanup_free_ char *root = NULL;
int r;
/* Determine the maximum number of tasks that may run on this system. We check three sources to determine this
* limit:
*
* a) the maximum tasks value the kernel allows on this architecture
* b) the cgroups pids_max attribute for the system
* c) the kernel's configured maximum PID value
*
* And then pick the smallest of the three */
r = procfs_tasks_get_limit(&a);
if (r < 0)
log_debug_errno(r, "Failed to read maximum number of tasks from /proc, ignoring: %m");
r = cg_get_root_path(&root);
if (r < 0)
log_debug_errno(r, "Failed to determine cgroup root path, ignoring: %m");
else {
_cleanup_free_ char *value = NULL;
r = cg_get_attribute("pids", root, "pids.max", &value);
if (r < 0)
log_debug_errno(r, "Failed to read pids.max attribute of cgroup root, ignoring: %m");
else if (!streq(value, "max")) {
r = safe_atou64(value, &b);
if (r < 0)
log_debug_errno(r, "Failed to parse pids.max attribute of cgroup root, ignoring: %m");
}
}
return MIN3(TASKS_MAX,
a <= 0 ? TASKS_MAX : a,
b <= 0 ? TASKS_MAX : b);
}
uint64_t system_tasks_max_scale(uint64_t v, uint64_t max) {
uint64_t t, m;
assert(max > 0);
/* Multiply the system's task value by the fraction v/max. Hence, if max==100 this calculates percentages
* relative to the system's maximum number of tasks. Returns UINT64_MAX on overflow. */
t = system_tasks_max();
assert(t > 0);
m = t * v;
if (m / t != v) /* overflow? */
return UINT64_MAX;
return m / max;
}
int version(void) {
puts(PACKAGE_STRING "\n"
SYSTEMD_FEATURES);
return 0;
}
/* This is a direct translation of str_verscmp from boot.c */
static bool is_digit(int c) {
return c >= '0' && c <= '9';
}
static int c_order(int c) {
if (c == 0 || is_digit(c))
return 0;
if ((c >= 'a') && (c <= 'z'))
return c;
return c + 0x10000;
}
int str_verscmp(const char *s1, const char *s2) {
const char *os1, *os2;
assert(s1);
assert(s2);
os1 = s1;
os2 = s2;
while (*s1 || *s2) {
int first;
while ((*s1 && !is_digit(*s1)) || (*s2 && !is_digit(*s2))) {
int order;
order = c_order(*s1) - c_order(*s2);
if (order != 0)
return order;
s1++;
s2++;
}
while (*s1 == '0')
s1++;
while (*s2 == '0')
s2++;
first = 0;
while (is_digit(*s1) && is_digit(*s2)) {
if (first == 0)
first = *s1 - *s2;
s1++;
s2++;
}
if (is_digit(*s1))
return 1;
if (is_digit(*s2))
return -1;
if (first != 0)
return first;
}
return strcmp(os1, os2);
}
/* Turn off core dumps but only if we're running outside of a container. */
void disable_coredumps(void) {
int r;
if (detect_container() > 0)
return;
r = write_string_file("/proc/sys/kernel/core_pattern", "|/bin/false", 0);
if (r < 0)
log_debug_errno(r, "Failed to turn off coredumps, ignoring: %m");
}
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