sys.c

LINUX 1.0 内核c源代码,是一份精简的linux内核源代码

		put_fs_long(current->cutime,(unsigned long *)&tbuf->tms_cutime);
		put_fs_long(current->cstime,(unsigned long *)&tbuf->tms_cstime);
	}
	return jiffies;
}

asmlinkage int sys_brk(unsigned long brk)
{
	int freepages;
	unsigned long rlim;
	unsigned long newbrk, oldbrk;

	if (brk < current->end_code)
		return current->brk;
	newbrk = PAGE_ALIGN(brk);
	oldbrk = PAGE_ALIGN(current->brk);
	if (oldbrk == newbrk)
		return current->brk = brk;

	/*
	 * Always allow shrinking brk
	 */
	if (brk <= current->brk) {
		current->brk = brk;
		do_munmap(newbrk, oldbrk-newbrk);
		return brk;
	}
	/*
	 * Check against rlimit and stack..
	 */
	rlim = current->rlim[RLIMIT_DATA].rlim_cur;
	if (rlim >= RLIM_INFINITY)
		rlim = ~0;
	if (brk - current->end_code > rlim || brk >= current->start_stack - 16384)
		return current->brk;
	/*
	 * stupid algorithm to decide if we have enough memory: while
	 * simple, it hopefully works in most obvious cases.. Easy to
	 * fool it, but this should catch most mistakes.
	 */
	freepages = buffermem >> 12;
	freepages += nr_free_pages;
	freepages += nr_swap_pages;
	freepages -= (high_memory - 0x100000) >> 16;
	freepages -= (newbrk-oldbrk) >> 12;
	if (freepages < 0)
		return current->brk;
#if 0
	freepages += current->rss;
	freepages -= oldbrk >> 12;
	if (freepages < 0)
		return current->brk;
#endif
	/*
	 * Ok, we have probably got enough memory - let it rip.
	 */
	current->brk = brk;
	do_mmap(NULL, oldbrk, newbrk-oldbrk,
		PROT_READ|PROT_WRITE|PROT_EXEC,
		MAP_FIXED|MAP_PRIVATE, 0);
	return brk;
}

/*
 * This needs some heave checking ...
 * I just haven't get the stomach for it. I also don't fully
 * understand sessions/pgrp etc. Let somebody who does explain it.
 *
 * OK, I think I have the protection semantics right.... this is really
 * only important on a multi-user system anyway, to make sure one user
 * can't send a signal to a process owned by another.  -TYT, 12/12/91
 *
 * Auch. Had to add the 'did_exec' flag to conform completely to POSIX.
 * LBT 04.03.94
 */
asmlinkage int sys_setpgid(pid_t pid, pid_t pgid)
{
	struct task_struct * p;

	if (!pid)
		pid = current->pid;
	if (!pgid)
		pgid = pid;
	if (pgid < 0)
		return -EINVAL;
	for_each_task(p) {
		if (p->pid == pid)
			goto found_task;
	}
	return -ESRCH;

found_task:
	if (p->p_pptr == current || p->p_opptr == current) {
		if (p->session != current->session)
			return -EPERM;
		if (p->did_exec)
			return -EACCES;
	} else if (p != current)
		return -ESRCH;
	if (p->leader)
		return -EPERM;
	if (pgid != pid) {
		struct task_struct * tmp;
		for_each_task (tmp) {
			if (tmp->pgrp == pgid &&
			 tmp->session == current->session)
				goto ok_pgid;
		}
		return -EPERM;
	}

ok_pgid:
	p->pgrp = pgid;
	return 0;
}

asmlinkage int sys_getpgid(pid_t pid)
{
	struct task_struct * p;

	if (!pid)
		return current->pgrp;
	for_each_task(p) {
		if (p->pid == pid)
			return p->pgrp;
	}
	return -ESRCH;
}

asmlinkage int sys_getpgrp(void)
{
	return current->pgrp;
}

asmlinkage int sys_setsid(void)
{
	if (current->leader)
		return -EPERM;
	current->leader = 1;
	current->session = current->pgrp = current->pid;
	current->tty = -1;
	return current->pgrp;
}

/*
 * Supplementary group ID's
 */
asmlinkage int sys_getgroups(int gidsetsize, gid_t *grouplist)
{
	int i;

	if (gidsetsize) {
		i = verify_area(VERIFY_WRITE, grouplist, sizeof(gid_t) * gidsetsize);
		if (i)
			return i;
	}
	for (i = 0 ; (i < NGROUPS) && (current->groups[i] != NOGROUP) ; i++) {
		if (!gidsetsize)
			continue;
		if (i >= gidsetsize)
			break;
		put_fs_word(current->groups[i], (short *) grouplist);
		grouplist++;
	}
	return(i);
}

asmlinkage int sys_setgroups(int gidsetsize, gid_t *grouplist)
{
	int	i;

	if (!suser())
		return -EPERM;
	if (gidsetsize > NGROUPS)
		return -EINVAL;
	for (i = 0; i < gidsetsize; i++, grouplist++) {
		current->groups[i] = get_fs_word((unsigned short *) grouplist);
	}
	if (i < NGROUPS)
		current->groups[i] = NOGROUP;
	return 0;
}

int in_group_p(gid_t grp)
{
	int	i;

	if (grp == current->egid)
		return 1;

	for (i = 0; i < NGROUPS; i++) {
		if (current->groups[i] == NOGROUP)
			break;
		if (current->groups[i] == grp)
			return 1;
	}
	return 0;
}

asmlinkage int sys_newuname(struct new_utsname * name)
{
	int error;

	if (!name)
		return -EFAULT;
	error = verify_area(VERIFY_WRITE, name, sizeof *name);
	if (!error)
		memcpy_tofs(name,&system_utsname,sizeof *name);
	return error;
}

asmlinkage int sys_uname(struct old_utsname * name)
{
	int error;
	if (!name)
		return -EFAULT;
	error = verify_area(VERIFY_WRITE, name,sizeof *name);
	if (error)
		return error;
	memcpy_tofs(&name->sysname,&system_utsname.sysname,
		sizeof (system_utsname.sysname));
	memcpy_tofs(&name->nodename,&system_utsname.nodename,
		sizeof (system_utsname.nodename));
	memcpy_tofs(&name->release,&system_utsname.release,
		sizeof (system_utsname.release));
	memcpy_tofs(&name->version,&system_utsname.version,
		sizeof (system_utsname.version));
	memcpy_tofs(&name->machine,&system_utsname.machine,
		sizeof (system_utsname.machine));
	return 0;
}

asmlinkage int sys_olduname(struct oldold_utsname * name)
{
	int error;
	if (!name)
		return -EFAULT;
	error = verify_area(VERIFY_WRITE, name,sizeof *name);
	if (error)
		return error;
	memcpy_tofs(&name->sysname,&system_utsname.sysname,__OLD_UTS_LEN);
	put_fs_byte(0,name->sysname+__OLD_UTS_LEN);
	memcpy_tofs(&name->nodename,&system_utsname.nodename,__OLD_UTS_LEN);
	put_fs_byte(0,name->nodename+__OLD_UTS_LEN);
	memcpy_tofs(&name->release,&system_utsname.release,__OLD_UTS_LEN);
	put_fs_byte(0,name->release+__OLD_UTS_LEN);
	memcpy_tofs(&name->version,&system_utsname.version,__OLD_UTS_LEN);
	put_fs_byte(0,name->version+__OLD_UTS_LEN);
	memcpy_tofs(&name->machine,&system_utsname.machine,__OLD_UTS_LEN);
	put_fs_byte(0,name->machine+__OLD_UTS_LEN);
	return 0;
}

/*
 * Only sethostname; gethostname can be implemented by calling uname()
 */
asmlinkage int sys_sethostname(char *name, int len)
{
	int	i;
	
	if (!suser())
		return -EPERM;
	if (len > __NEW_UTS_LEN)
		return -EINVAL;
	for (i=0; i < len; i++) {
		if ((system_utsname.nodename[i] = get_fs_byte(name+i)) == 0)
			return 0;
	}
	system_utsname.nodename[i] = 0;
	return 0;
}

/*
 * Only setdomainname; getdomainname can be implemented by calling
 * uname()
 */
asmlinkage int sys_setdomainname(char *name, int len)
{
	int	i;
	
	if (!suser())
		return -EPERM;
	if (len > __NEW_UTS_LEN)
		return -EINVAL;
	for (i=0; i < len; i++) {
		if ((system_utsname.domainname[i] = get_fs_byte(name+i)) == 0)
			return 0;
	}
	system_utsname.domainname[i] = 0;
	return 0;
}

asmlinkage int sys_getrlimit(unsigned int resource, struct rlimit *rlim)
{
	int error;

	if (resource >= RLIM_NLIMITS)
		return -EINVAL;
	error = verify_area(VERIFY_WRITE,rlim,sizeof *rlim);
	if (error)
		return error;
	put_fs_long(current->rlim[resource].rlim_cur, 
		    (unsigned long *) rlim);
	put_fs_long(current->rlim[resource].rlim_max, 
		    ((unsigned long *) rlim)+1);
	return 0;	
}

asmlinkage int sys_setrlimit(unsigned int resource, struct rlimit *rlim)
{
	struct rlimit new_rlim, *old_rlim;

	if (resource >= RLIM_NLIMITS)
		return -EINVAL;
	old_rlim = current->rlim + resource;
	new_rlim.rlim_cur = get_fs_long((unsigned long *) rlim);
	new_rlim.rlim_max = get_fs_long(((unsigned long *) rlim)+1);
	if (((new_rlim.rlim_cur > old_rlim->rlim_max) ||
	     (new_rlim.rlim_max > old_rlim->rlim_max)) &&
	    !suser())
		return -EPERM;
	*old_rlim = new_rlim;
	return 0;
}

/*
 * It would make sense to put struct rusuage in the task_struct,
 * except that would make the task_struct be *really big*.  After
 * task_struct gets moved into malloc'ed memory, it would
 * make sense to do this.  It will make moving the rest of the information
 * a lot simpler!  (Which we're not doing right now because we're not
 * measuring them yet).
 */
int getrusage(struct task_struct *p, int who, struct rusage *ru)
{
	int error;
	struct rusage r;
	unsigned long	*lp, *lpend, *dest;

	error = verify_area(VERIFY_WRITE, ru, sizeof *ru);
	if (error)
		return error;
	memset((char *) &r, 0, sizeof(r));
	switch (who) {
		case RUSAGE_SELF:
			r.ru_utime.tv_sec = CT_TO_SECS(p->utime);
			r.ru_utime.tv_usec = CT_TO_USECS(p->utime);
			r.ru_stime.tv_sec = CT_TO_SECS(p->stime);
			r.ru_stime.tv_usec = CT_TO_USECS(p->stime);
			r.ru_minflt = p->min_flt;
			r.ru_majflt = p->maj_flt;
			break;
		case RUSAGE_CHILDREN:
			r.ru_utime.tv_sec = CT_TO_SECS(p->cutime);
			r.ru_utime.tv_usec = CT_TO_USECS(p->cutime);
			r.ru_stime.tv_sec = CT_TO_SECS(p->cstime);
			r.ru_stime.tv_usec = CT_TO_USECS(p->cstime);
			r.ru_minflt = p->cmin_flt;
			r.ru_majflt = p->cmaj_flt;
			break;
		default:
			r.ru_utime.tv_sec = CT_TO_SECS(p->utime + p->cutime);
			r.ru_utime.tv_usec = CT_TO_USECS(p->utime + p->cutime);
			r.ru_stime.tv_sec = CT_TO_SECS(p->stime + p->cstime);
			r.ru_stime.tv_usec = CT_TO_USECS(p->stime + p->cstime);
			r.ru_minflt = p->min_flt + p->cmin_flt;
			r.ru_majflt = p->maj_flt + p->cmaj_flt;
			break;
	}
	lp = (unsigned long *) &r;
	lpend = (unsigned long *) (&r+1);
	dest = (unsigned long *) ru;
	for (; lp < lpend; lp++, dest++) 
		put_fs_long(*lp, dest);
	return 0;
}

asmlinkage int sys_getrusage(int who, struct rusage *ru)
{
	if (who != RUSAGE_SELF && who != RUSAGE_CHILDREN)
		return -EINVAL;
	return getrusage(current, who, ru);
}

asmlinkage int sys_umask(int mask)
{
	int old = current->umask;

	current->umask = mask & S_IRWXUGO;
	return (old);
}