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Systemd/src/basic/util.c

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/***
This file is part of systemd.
Copyright 2010 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#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 "build.h"
#include "cgroup-util.h"
#include "def.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 "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"
/* Put this test here for a lack of better place */
assert_cc(EAGAIN == EWOULDBLOCK);
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;
}
static int do_execute(char **directories, usec_t timeout, char *argv[]) {
_cleanup_hashmap_free_free_ Hashmap *pids = NULL;
_cleanup_set_free_free_ Set *seen = NULL;
char **directory;
/* We fork this all off from a child process so that we can
* somewhat cleanly make use of SIGALRM to set a time limit */
(void) reset_all_signal_handlers();
(void) reset_signal_mask();
assert_se(prctl(PR_SET_PDEATHSIG, SIGTERM) == 0);
pids = hashmap_new(NULL);
if (!pids)
return log_oom();
seen = set_new(&string_hash_ops);
if (!seen)
return log_oom();
STRV_FOREACH(directory, directories) {
_cleanup_closedir_ DIR *d;
struct dirent *de;
d = opendir(*directory);
if (!d) {
if (errno == ENOENT)
continue;
return log_error_errno(errno, "Failed to open directory %s: %m", *directory);
}
FOREACH_DIRENT(de, d, break) {
_cleanup_free_ char *path = NULL;
pid_t pid;
int r;
if (!dirent_is_file(de))
continue;
if (set_contains(seen, de->d_name)) {
log_debug("%1$s/%2$s skipped (%2$s was already seen).", *directory, de->d_name);
continue;
}
r = set_put_strdup(seen, de->d_name);
if (r < 0)
return log_oom();
path = strjoin(*directory, "/", de->d_name);
if (!path)
return log_oom();
if (null_or_empty_path(path)) {
log_debug("%s is empty (a mask).", path);
continue;
}
pid = fork();
if (pid < 0) {
log_error_errno(errno, "Failed to fork: %m");
continue;
} else if (pid == 0) {
char *_argv[2];
assert_se(prctl(PR_SET_PDEATHSIG, SIGTERM) == 0);
if (!argv) {
_argv[0] = path;
_argv[1] = NULL;
argv = _argv;
} else
argv[0] = path;
execv(path, argv);
return log_error_errno(errno, "Failed to execute %s: %m", path);
}
log_debug("Spawned %s as " PID_FMT ".", path, pid);
r = hashmap_put(pids, PID_TO_PTR(pid), path);
if (r < 0)
return log_oom();
path = NULL;
}
}
/* Abort execution of this process after the timout. We simply
* rely on SIGALRM as default action terminating the process,
* and turn on alarm(). */
if (timeout != USEC_INFINITY)
alarm((timeout + USEC_PER_SEC - 1) / USEC_PER_SEC);
while (!hashmap_isempty(pids)) {
_cleanup_free_ char *path = NULL;
pid_t pid;
pid = PTR_TO_PID(hashmap_first_key(pids));
assert(pid > 0);
path = hashmap_remove(pids, PID_TO_PTR(pid));
assert(path);
wait_for_terminate_and_warn(path, pid, true);
}
return 0;
}
void execute_directories(const char* const* directories, usec_t timeout, char *argv[]) {
pid_t executor_pid;
int r;
char *name;
char **dirs = (char**) directories;
assert(!strv_isempty(dirs));
name = basename(dirs[0]);
assert(!isempty(name));
/* Executes all binaries in the directories in parallel and waits
* for them to finish. Optionally a timeout is applied. If a file
* with the same name exists in more than one directory, the
* earliest one wins. */
executor_pid = fork();
if (executor_pid < 0) {
log_error_errno(errno, "Failed to fork: %m");
return;
} else if (executor_pid == 0) {
r = do_execute(dirs, timeout, argv);
_exit(r < 0 ? EXIT_FAILURE : EXIT_SUCCESS);
}
wait_for_terminate_and_warn(name, executor_pid, true);
}
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';
}
int socket_from_display(const char *display, char **path) {
size_t k;
char *f, *c;
assert(display);
assert(path);
if (!display_is_local(display))
return -EINVAL;
k = strspn(display+1, "0123456789");
f = new(char, strlen("/tmp/.X11-unix/X") + k + 1);
if (!f)
return -ENOMEM;
c = stpcpy(f, "/tmp/.X11-unix/X");
memcpy(c, display+1, k);
c[k] = 0;
*path = f;
return 0;
}
int block_get_whole_disk(dev_t d, dev_t *ret) {
char *p, *s;
int r;
unsigned n, m;
assert(ret);
/* If it has a queue this is good enough for us */
if (asprintf(&p, "/sys/dev/block/%u:%u/queue", major(d), minor(d)) < 0)
return -ENOMEM;
r = access(p, F_OK);
free(p);
if (r >= 0) {
*ret = d;
return 0;
}
/* If it is a partition find the originating device */
if (asprintf(&p, "/sys/dev/block/%u:%u/partition", major(d), minor(d)) < 0)
return -ENOMEM;
r = access(p, F_OK);
free(p);
if (r < 0)
return -ENOENT;
/* Get parent dev_t */
if (asprintf(&p, "/sys/dev/block/%u:%u/../dev", major(d), minor(d)) < 0)
return -ENOMEM;
r = read_one_line_file(p, &s);
free(p);
if (r < 0)
return r;
r = sscanf(s, "%u:%u", &m, &n);
free(s);
if (r != 2)
return -EINVAL;
/* Only return this if it is really good enough for us. */
if (asprintf(&p, "/sys/dev/block/%u:%u/queue", m, n) < 0)
return -ENOMEM;
r = access(p, F_OK);
free(p);
if (r >= 0) {
*ret = makedev(m, n);
return 0;
}
return -ENOENT;
}
bool kexec_loaded(void) {
bool loaded = false;
char *s;
if (read_one_line_file("/sys/kernel/kexec_loaded", &s) >= 0) {
if (s[0] == '1')
loaded = true;
free(s);
}
return loaded;
}
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;
}
}
int fork_agent(pid_t *pid, const int except[], unsigned n_except, const char *path, ...) {
bool stdout_is_tty, stderr_is_tty;
pid_t parent_pid, agent_pid;
sigset_t ss, saved_ss;
unsigned n, i;
va_list ap;
char **l;
assert(pid);
assert(path);
/* Spawns a temporary TTY agent, making sure it goes away when
* we go away */
parent_pid = getpid();
/* First we temporarily block all signals, so that the new
* child has them blocked initially. This way, we can be sure
* that SIGTERMs are not lost we might send to the agent. */
assert_se(sigfillset(&ss) >= 0);
assert_se(sigprocmask(SIG_SETMASK, &ss, &saved_ss) >= 0);
agent_pid = fork();
if (agent_pid < 0) {
assert_se(sigprocmask(SIG_SETMASK, &saved_ss, NULL) >= 0);
return -errno;
}
if (agent_pid != 0) {
assert_se(sigprocmask(SIG_SETMASK, &saved_ss, NULL) >= 0);
*pid = agent_pid;
return 0;
}
/* In the child:
*
* Make sure the agent goes away when the parent dies */
if (prctl(PR_SET_PDEATHSIG, SIGTERM) < 0)
_exit(EXIT_FAILURE);
/* Make sure we actually can kill the agent, if we need to, in
* case somebody invoked us from a shell script that trapped
* SIGTERM or so... */
(void) reset_all_signal_handlers();
(void) reset_signal_mask();
/* Check whether our parent died before we were able
* to set the death signal and unblock the signals */
if (getppid() != parent_pid)
_exit(EXIT_SUCCESS);
/* Don't leak fds to the agent */
close_all_fds(except, n_except);
stdout_is_tty = isatty(STDOUT_FILENO);
stderr_is_tty = isatty(STDERR_FILENO);
if (!stdout_is_tty || !stderr_is_tty) {
int fd;
/* Detach from stdout/stderr. and reopen
* /dev/tty for them. This is important to
* ensure that when systemctl is started via
* popen() or a similar call that expects to
* read EOF we actually do generate EOF and
* not delay this indefinitely by because we
* keep an unused copy of stdin around. */
fd = open("/dev/tty", O_WRONLY);
if (fd < 0) {
log_error_errno(errno, "Failed to open /dev/tty: %m");
_exit(EXIT_FAILURE);
}
if (!stdout_is_tty && dup2(fd, STDOUT_FILENO) < 0) {
log_error_errno(errno, "Failed to dup2 /dev/tty: %m");
_exit(EXIT_FAILURE);
}
if (!stderr_is_tty && dup2(fd, STDERR_FILENO) < 0) {
log_error_errno(errno, "Failed to dup2 /dev/tty: %m");
_exit(EXIT_FAILURE);
}
if (fd > STDERR_FILENO)
close(fd);
}
/* Count arguments */
va_start(ap, path);
for (n = 0; va_arg(ap, char*); n++)
;
va_end(ap);
/* Allocate strv */
l = alloca(sizeof(char *) * (n + 1));
/* Fill in arguments */
va_start(ap, path);
for (i = 0; i <= n; i++)
l[i] = va_arg(ap, char*);
va_end(ap);
execv(path, l);
_exit(EXIT_FAILURE);
}
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;
l = 0;
u = nmemb;
while (l < u) {
idx = (l + u) / 2;
p = (void *)(((const char *) 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 (errno == ENOENT || errno == 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(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");
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;
/* 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;
if (cg_get_root_path(&root) < 0)
return mem;
if (cg_get_attribute("memory", root, "memory.limit_in_bytes", &value))
return mem;
if (safe_atou64(value, &lim) < 0)
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) {
#if SIZEOF_PID_T == 4
#define TASKS_MAX ((uint64_t) (INT32_MAX-1))
#elif SIZEOF_PID_T == 2
#define TASKS_MAX ((uint64_t) (INT16_MAX-1))
#else
#error "Unknown pid_t size"
#endif
_cleanup_free_ char *value = NULL, *root = NULL;
uint64_t a = TASKS_MAX, b = TASKS_MAX;
/* Determine the maximum number of tasks that may run on this system. We check three sources to determine this
* limit:
*
* a) the maximum value for the pid_t type
* b) the cgroups pids_max attribute for the system
* c) the kernel's configure maximum PID value
*
* And then pick the smallest of the three */
if (read_one_line_file("/proc/sys/kernel/pid_max", &value) >= 0)
(void) safe_atou64(value, &a);
if (cg_get_root_path(&root) >= 0) {
value = mfree(value);
if (cg_get_attribute("pids", root, "pids.max", &value) >= 0)
(void) safe_atou64(value, &b);
}
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 update_reboot_parameter_and_warn(const char *param) {
int r;
if (isempty(param)) {
if (unlink("/run/systemd/reboot-param") < 0) {
if (errno == ENOENT)
return 0;
return log_warning_errno(errno, "Failed to unlink reboot parameter file: %m");
}
return 0;
}
RUN_WITH_UMASK(0022) {
r = write_string_file("/run/systemd/reboot-param", param, WRITE_STRING_FILE_CREATE);
if (r < 0)
return log_warning_errno(r, "Failed to write reboot parameter file: %m");
}
return 0;
}
int version(void) {
puts(PACKAGE_STRING "\n"
SYSTEMD_FEATURES);
return 0;
}
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