user.h

struct stat;

// system calls
int fork (void);
int exit (void) __attribute__ ((noreturn));
int wait (void);
int pipe (int *);
int write (int, void *, int);
int read (int, void *, int);
int close (int);
int kill (int);
int exec (char *, char **);
int open (char *, int);
int mknod (char *, short, short);
int unlink (char *);
int fstat (int fd, struct stat *);
int link (char *, char *);
int mkdir (char *);
int chdir (char *);
int dup (int);
int getpid (void);
char *sbrk (int);
int sleep (int);
int uptime (void);

// ulib.c
int stat (char *, struct stat *);
char *strcpy (char *, char *);
void *memmove (void *, void *, int);
char *strchr (const char *, char c);
int strcmp (const char *, const char *);
void printf (int, char *, ...);
char *gets (char *, int max);
uint strlen (char *);
void *memset (void *, int, uint);
void *malloc (uint);
void free (void *);
int atoi (const char *);