/* unistd.h: POSIX constants and functions. */

#ifndef _UNISTD_H
#define _UNISTD_H

#define __need_NULL
#include <stddef.h>

#include <bits/seek.h>
#include <stdint.h>
#include <sys/types.h>

#define STDIN_FILENO 0
#define STDOUT_FILENO 1
#define STDERR_FILENO 2

#ifdef __cplusplus
extern "C"
{
#endif

    /* Create a new process that is a clone of the current one. */
    pid_t fork(void);

    /* Return the current process' process ID. */
    pid_t getpid(void);

    /* Return the current process' parent process ID. */
    pid_t getppid(void);

    /* Return the current process' real user ID. */
    uid_t getuid(void);

    /* Return the current process' effective user ID. */
    uid_t geteuid(void);

    /* Return the current process' real group ID. */
    gid_t getgid(void);

    /* Return the current process' effective group ID. */
    gid_t getegid(void);

    /* Set the current process' user IDs. */
    int setuid(uid_t uid);

    /* Set the current process' effective user ID. */
    int seteuid(uid_t uid);

    /* Set the current process' group IDs. */
    int setgid(gid_t gid);

    /* Set the current process' effective group ID. */
    int setegid(gid_t gid);

    /* Change the mode bits of a file. */
    int chmod(const char* path, mode_t mode);

    /* Change the owner and group of a file. */
    int chown(const char* path, uid_t uid, gid_t gid);

    /* Replace the current process with another one. On success, does not return. */
    int execv(const char* path, char* const* argv);

    /* Replace the current process with another one. On success, does not return. */
    int execl(const char* path, const char* arg, ...);

    /* Replace the current process with another one. On success, does not return. */
    int execve(const char* path, char* const* argv, char* const* envp);

    /* Replace the current process with another one. On success, does not return. */
    int execvp(const char* name, char* const* argv);

    /* Replace the current process with another one. On success, does not return. */
    int execvpe(const char* name, char* const* argv, char* const* envp);

    /* Call the operating system kernel for a specific service. */
    long syscall(long num, ...);

    /* Sleep for X microseconds. */
    int usleep(useconds_t us);

    /* Sleep for X seconds. */
    unsigned long sleep(unsigned long seconds);

    /* Close a file descriptor. */
    int close(int fd);

    /* Read bytes from a file descriptor. */
    ssize_t read(int fd, void* buf, size_t size);

    /* Write bytes to a file descriptor. */
    ssize_t write(int fd, const void* buf, size_t size);

    /* Modify a file descriptor's offset. */
    off_t lseek(int fd, off_t offset, int whence);

    /* Duplicate a file descriptor. */
    int dup(int fd);

#ifdef __cplusplus
}
#endif

#endif