src/basic/process-util.h

/* SPDX-License-Identifier: LGPL-2.1+ */
#pragma once

/***
  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 <sched.h>
#include <signal.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdio.h>
#include <string.h>
#include <sys/resource.h>
#include <sys/types.h>

#include "format-util.h"
#include "ioprio.h"
#include "macro.h"
#include "time-util.h"

#define procfs_file_alloca(pid, field)                                  \
        ({                                                              \
                pid_t _pid_ = (pid);                                    \
                const char *_r_;                                        \
                if (_pid_ == 0) {                                       \
                        _r_ = ("/proc/self/" field);                    \
                } else {                                                \
                        _r_ = alloca(STRLEN("/proc/") + DECIMAL_STR_MAX(pid_t) + 1 + sizeof(field)); \
                        sprintf((char*) _r_, "/proc/"PID_FMT"/" field, _pid_);                       \
                }                                                       \
                _r_;                                                    \
        })

int get_process_state(pid_t pid);
int get_process_comm(pid_t pid, char **name);
int get_process_cmdline(pid_t pid, size_t max_length, bool comm_fallback, char **line);
int get_process_exe(pid_t pid, char **name);
int get_process_uid(pid_t pid, uid_t *uid);
int get_process_gid(pid_t pid, gid_t *gid);
int get_process_capeff(pid_t pid, char **capeff);
int get_process_cwd(pid_t pid, char **cwd);
int get_process_root(pid_t pid, char **root);
int get_process_environ(pid_t pid, char **environ);
int get_process_ppid(pid_t pid, pid_t *ppid);

int wait_for_terminate(pid_t pid, siginfo_t *status);

typedef enum WaitFlags {
        WAIT_LOG_ABNORMAL             = 1U << 0,
        WAIT_LOG_NON_ZERO_EXIT_STATUS = 1U << 1,

        /* A shortcut for requesting the most complete logging */
        WAIT_LOG = WAIT_LOG_ABNORMAL|WAIT_LOG_NON_ZERO_EXIT_STATUS,
} WaitFlags;

int wait_for_terminate_and_check(const char *name, pid_t pid, WaitFlags flags);
int wait_for_terminate_with_timeout(pid_t pid, usec_t timeout);

void sigkill_wait(pid_t pid);
void sigkill_waitp(pid_t *pid);

int kill_and_sigcont(pid_t pid, int sig);

int rename_process(const char name[]);
int is_kernel_thread(pid_t pid);

int getenv_for_pid(pid_t pid, const char *field, char **_value);

bool pid_is_alive(pid_t pid);
bool pid_is_unwaited(pid_t pid);
int pid_from_same_root_fs(pid_t pid);

bool is_main_thread(void);

noreturn void freeze(void);

bool oom_score_adjust_is_valid(int oa);

#ifndef PERSONALITY_INVALID
/* personality(7) documents that 0xffffffffUL is used for querying the
 * current personality, hence let's use that here as error
 * indicator. */
#define PERSONALITY_INVALID 0xffffffffLU
#endif

unsigned long personality_from_string(const char *p);
const char *personality_to_string(unsigned long);

int safe_personality(unsigned long p);
int opinionated_personality(unsigned long *ret);

int ioprio_class_to_string_alloc(int i, char **s);
int ioprio_class_from_string(const char *s);

const char *sigchld_code_to_string(int i) _const_;
int sigchld_code_from_string(const char *s) _pure_;

int sched_policy_to_string_alloc(int i, char **s);
int sched_policy_from_string(const char *s);

static inline pid_t PTR_TO_PID(const void *p) {
        return (pid_t) ((uintptr_t) p);
}

static inline void* PID_TO_PTR(pid_t pid) {
        return (void*) ((uintptr_t) pid);
}

void valgrind_summary_hack(void);

int pid_compare_func(const void *a, const void *b);

static inline bool nice_is_valid(int n) {
        return n >= PRIO_MIN && n < PRIO_MAX;
}

static inline bool sched_policy_is_valid(int i) {
        return IN_SET(i, SCHED_OTHER, SCHED_BATCH, SCHED_IDLE, SCHED_FIFO, SCHED_RR);
}

static inline bool sched_priority_is_valid(int i) {
        return i >= 0 && i <= sched_get_priority_max(SCHED_RR);
}

static inline bool ioprio_class_is_valid(int i) {
        return IN_SET(i, IOPRIO_CLASS_NONE, IOPRIO_CLASS_RT, IOPRIO_CLASS_BE, IOPRIO_CLASS_IDLE);
}

static inline bool ioprio_priority_is_valid(int i) {
        return i >= 0 && i < IOPRIO_BE_NR;
}

static inline bool pid_is_valid(pid_t p) {
        return p > 0;
}

static inline int sched_policy_to_string_alloc_with_check(int n, char **s) {
        if (!sched_policy_is_valid(n))
                return -EINVAL;

        return sched_policy_to_string_alloc(n, s);
}

int ioprio_parse_priority(const char *s, int *ret);

pid_t getpid_cached(void);
void reset_cached_pid(void);

int must_be_root(void);

typedef enum ForkFlags {
        FORK_RESET_SIGNALS = 1U << 0,
        FORK_CLOSE_ALL_FDS = 1U << 1,
        FORK_DEATHSIG      = 1U << 2,
        FORK_NULL_STDIO    = 1U << 3,
        FORK_REOPEN_LOG    = 1U << 4,
        FORK_LOG           = 1U << 5,
        FORK_WAIT          = 1U << 6,
        FORK_NEW_MOUNTNS   = 1U << 7,
} ForkFlags;

int safe_fork_full(const char *name, const int except_fds[], size_t n_except_fds, ForkFlags flags, pid_t *ret_pid);

static inline int safe_fork(const char *name, ForkFlags flags, pid_t *ret_pid) {
        return safe_fork_full(name, NULL, 0, flags, ret_pid);
}

int fork_agent(const char *name, const int except[], unsigned n_except, pid_t *pid, const char *path, ...);

#if SIZEOF_PID_T == 4
/* The highest possibly (theoretic) pid_t value on this architecture. */
#define PID_T_MAX ((pid_t) INT32_MAX)
/* The maximum number of concurrent processes Linux allows on this architecture, as well as the highest valid PID value
 * the kernel will potentially assign. This reflects a value compiled into the kernel (PID_MAX_LIMIT), and sets the
 * upper boundary on what may be written to the /proc/sys/kernel/pid_max sysctl (but do note that the sysctl is off by
 * 1, since PID 0 can never exist and there can hence only be one process less than the limit would suggest). Since
 * these values are documented in proc(5) we feel quite confident that they are stable enough for the near future at
 * least to define them here too. */
#define TASKS_MAX 4194303U
#elif SIZEOF_PID_T == 2
#define PID_T_MAX ((pid_t) INT16_MAX)
#define TASKS_MAX 32767U
#else
#error "Unknown pid_t size"
#endif

assert_cc(TASKS_MAX <= (unsigned long) PID_T_MAX)