minix/kernel/system/do_fork.c
Jorrit Herder 198c976f7e System processes can be signaled; signals are transformed in SYS_EVENT message
that passes signal map along. This mechanisms is also used for nonuser signals
like SIGKMESS, SIGKSTOP, SIGKSIG.

Revised comments of many system call handlers. Renamed setpriority to nice.
2005-07-19 12:21:36 +00:00

63 lines
1.9 KiB
C

/* The system call implemented in this file:
* m_type: SYS_FORK
*
* The parameters for this system call are:
* m1_i1: PR_PROC_NR (child's process table slot)
* m1_i2: PR_PPROC_NR (parent, process that forked)
* m1_i3: PR_PID (child pid received from PM)
*/
#include "../system.h"
#include <signal.h>
#if (CHIP == INTEL)
#include "../protect.h"
#endif
#if USE_FORK
/*===========================================================================*
* do_fork *
*===========================================================================*/
PUBLIC int do_fork(m_ptr)
register message *m_ptr; /* pointer to request message */
{
/* Handle sys_fork(). PR_PPROC_NR has forked. The child is PR_PROC_NR. */
#if (CHIP == INTEL)
reg_t old_ldt_sel;
#endif
register struct proc *rpc; /* child process pointer */
struct proc *rpp; /* parent process pointer */
rpp = proc_addr(m_ptr->PR_PPROC_NR);
rpc = proc_addr(m_ptr->PR_PROC_NR);
if (isemptyp(rpp) || ! isemptyp(rpc)) return(EINVAL);
/* Copy parent 'proc' struct to child. And reinitialize some fields. */
#if (CHIP == INTEL)
old_ldt_sel = rpc->p_ldt_sel; /* backup local descriptors */
*rpc = *rpp; /* copy 'proc' struct */
rpc->p_ldt_sel = old_ldt_sel; /* restore descriptors */
#else
*rpc = *rpp; /* copy 'proc' struct */
#endif
rpc->p_nr = m_ptr->PR_PROC_NR; /* this was obliterated by copy */
#if TEMP_CODE
rpc->p_ntf_q = NULL; /* remove pending notifications */
#endif
/* Only one in group should have SIGNALED, child doesn't inherit tracing. */
rpc->p_rts_flags |= NO_MAP; /* inhibit process from running */
rpc->p_rts_flags &= ~(SIGNALED | SIG_PENDING | P_STOP);
sigemptyset(&rpc->p_pending);
rpc->p_reg.retreg = 0; /* child sees pid = 0 to know it is child */
rpc->p_user_time = 0; /* set all the accounting times to 0 */
rpc->p_sys_time = 0;
return(OK);
}
#endif /* USE_FORK */