Initial revision
This commit is contained in:
Ben Gras
227
kernel/system/sigctl.c
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227
kernel/system/sigctl.c
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/* The system call that is implemented in this file:
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* SYS_SIGCTL # signal handling functionality
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*
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* The parameters and types for this system call are:
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* SIG_REQUEST # request to perform (long)
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* SIG_PROC # process to signal/ pending (int)
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* SIG_CTXT_PTR # pointer to sigcontext structure (pointer)
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* SIG_FLAGS # flags for S_SIGRETURN call (int)
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* SIG_MAP # bit map with pending signals (long)
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* SIG_NUMBER # signal number to send to process (int)
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*
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* Supported request types are in the parameter SIG_REQUEST:
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* S_GETSIG # get a pending kernel signal
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* S_ENDSIG # signal has been processed
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* S_SENDSIG # deliver a POSIX-style signal
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* S_SIGRETURN # return from a POSIX-style signal
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* S_KILL # send a signal to a process
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*/
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#include "../kernel.h"
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#include "../system.h"
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#include <signal.h>
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#include <sys/sigcontext.h>
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INIT_ASSERT
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/*===========================================================================*
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* do_sigctl *
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*===========================================================================*/
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PUBLIC int do_sigctl(m_ptr)
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message *m_ptr; /* pointer to request message */
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{
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/* Only the MM and FS are allowed to use signal control operations. */
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if (m_ptr->m_source != MM_PROC_NR && m_ptr->m_source != FS_PROC_NR)
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return(EPERM);
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/* Now see what request we got. The supported requests are S_GETSIG,
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* S_ENDSIG, S_SENDSIG, S_SIGRETURN, and S_KILL. Unsupported requests
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* result in an EINVAL error.
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*/
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switch(m_ptr->SIG_REQUEST) {
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/* MM is ready to accept signals and repeatedly does a system call to get
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* one. Find a process with pending signals. If no signals are available,
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* return NONE in the process number field.
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*/
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case S_GETSIG: {
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register struct proc *rp;
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/* Find the next process with pending signals. */
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for (rp = BEG_USER_ADDR; rp < END_PROC_ADDR; rp++) {
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if (rp->p_flags & PENDING) {
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m_ptr->SIG_PROC = proc_number(rp);
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m_ptr->SIG_MAP = rp->p_pending;
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sigemptyset(&rp->p_pending); /* ball is in MM's court */
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rp->p_flags &= ~PENDING; /* blocked by SIG_PENDING */
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return(OK);
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}
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}
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/* No process with pending signals was found. */
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m_ptr->SIG_PROC = NONE;
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return(OK);
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}
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/* Finish up after a KSIG-type signal, caused by a SYS_KILL message or a
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* call to cause_sig by a task
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*/
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case S_ENDSIG: {
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register struct proc *rp;
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rp = proc_addr(m_ptr->SIG_PROC);
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if (isemptyp(rp)) return(EINVAL); /* process already dead? */
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assert(isuserp(rp));
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/* MM has finished one KSIG. Perhaps process is ready now? */
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if (rp->p_pendcount != 0 && --rp->p_pendcount == 0
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&& (rp->p_flags &= ~SIG_PENDING) == 0)
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lock_ready(rp);
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return(OK);
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}
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/* Handle sys_sendsig, POSIX-style signal handling.
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*/
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case S_SENDSIG: {
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struct sigmsg smsg;
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register struct proc *rp;
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phys_bytes src_phys, dst_phys;
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struct sigcontext sc, *scp;
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struct sigframe fr, *frp;
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rp = proc_addr(m_ptr->SIG_PROC);
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assert(isuserp(rp));
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/* Get the sigmsg structure into our address space. */
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src_phys = umap_local(proc_addr(MM_PROC_NR), D, (vir_bytes)
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m_ptr->SIG_CTXT_PTR, (vir_bytes) sizeof(struct sigmsg));
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assert(src_phys != 0);
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phys_copy(src_phys,vir2phys(&smsg),(phys_bytes) sizeof(struct sigmsg));
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/* Compute the user stack pointer where sigcontext will be stored. */
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scp = (struct sigcontext *) smsg.sm_stkptr - 1;
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/* Copy the registers to the sigcontext structure. */
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kmemcpy(&sc.sc_regs, &rp->p_reg, sizeof(struct sigregs));
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/* Finish the sigcontext initialization. */
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sc.sc_flags = SC_SIGCONTEXT;
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sc.sc_mask = smsg.sm_mask;
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/* Copy the sigcontext structure to the user's stack. */
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dst_phys = umap_local(rp, D, (vir_bytes) scp,
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(vir_bytes) sizeof(struct sigcontext));
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if (dst_phys == 0) return(EFAULT);
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phys_copy(vir2phys(&sc), dst_phys,
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(phys_bytes) sizeof(struct sigcontext));
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/* Initialize the sigframe structure. */
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frp = (struct sigframe *) scp - 1;
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fr.sf_scpcopy = scp;
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fr.sf_retadr2= (void (*)()) rp->p_reg.pc;
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fr.sf_fp = rp->p_reg.fp;
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rp->p_reg.fp = (reg_t) &frp->sf_fp;
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fr.sf_scp = scp;
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fr.sf_code = 0; /* XXX - should be used for type of FP exception */
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fr.sf_signo = smsg.sm_signo;
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fr.sf_retadr = (void (*)()) smsg.sm_sigreturn;
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/* Copy the sigframe structure to the user's stack. */
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dst_phys = umap_local(rp, D, (vir_bytes) frp,
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(vir_bytes) sizeof(struct sigframe));
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if (dst_phys == 0) return(EFAULT);
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phys_copy(vir2phys(&fr), dst_phys,
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(phys_bytes) sizeof(struct sigframe));
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/* Reset user registers to execute the signal handler. */
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rp->p_reg.sp = (reg_t) frp;
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rp->p_reg.pc = (reg_t) smsg.sm_sighandler;
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return(OK);
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}
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/* POSIX style signals require sys_sigreturn to put things in order before
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* the signalled process can resume execution
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*/
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case S_SIGRETURN: {
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struct sigcontext sc;
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register struct proc *rp;
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phys_bytes src_phys;
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rp = proc_addr(m_ptr->SIG_PROC);
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if (! isuserp(rp)) {
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kprintf("S_SIGRETURN: message source: %d; ", m_ptr->m_source);
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kprintf("got non-user process rp: %d\n", rp->p_nr);
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}
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assert(isuserp(rp));
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/* Copy in the sigcontext structure. */
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src_phys = umap_local(rp, D, (vir_bytes) m_ptr->SIG_CTXT_PTR,
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(vir_bytes) sizeof(struct sigcontext));
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if (src_phys == 0) return(EFAULT);
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phys_copy(src_phys, vir2phys(&sc),
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(phys_bytes) sizeof(struct sigcontext));
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/* Make sure that this is not just a jmp_buf. */
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if ((sc.sc_flags & SC_SIGCONTEXT) == 0) return(EINVAL);
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/* Fix up only certain key registers if the compiler doesn't use
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* register variables within functions containing setjmp.
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*/
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if (sc.sc_flags & SC_NOREGLOCALS) {
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rp->p_reg.retreg = sc.sc_retreg;
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rp->p_reg.fp = sc.sc_fp;
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rp->p_reg.pc = sc.sc_pc;
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rp->p_reg.sp = sc.sc_sp;
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return(OK);
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}
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sc.sc_psw = rp->p_reg.psw;
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#if (CHIP == INTEL)
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/* Don't panic kernel if user gave bad selectors. */
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sc.sc_cs = rp->p_reg.cs;
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sc.sc_ds = rp->p_reg.ds;
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sc.sc_es = rp->p_reg.es;
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#if _WORD_SIZE == 4
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sc.sc_fs = rp->p_reg.fs;
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sc.sc_gs = rp->p_reg.gs;
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#endif
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#endif
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/* Restore the registers. */
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kmemcpy(&rp->p_reg, (char *)&sc.sc_regs, sizeof(struct sigregs));
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return(OK);
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}
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/* Handle sys_kill(). Cause a signal to be sent to a process via MM.
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* Note that this has nothing to do with the kill(2) system call, this
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* is how the FS (and possibly other servers) get access to cause_sig.
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*/
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case S_KILL: {
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cause_sig(m_ptr->SIG_PROC, m_ptr->SIG_NUMBER);
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return(OK);
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}
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default:
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return(EINVAL);
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}
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}
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PUBLIC int do_kill(m_ptr)
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message *m_ptr; /* pointer to request message */
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{
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/* Handle sys_kill(). Cause a signal to be sent to a process via MM.
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* Note that this has nothing to do with the kill (2) system call, this
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* is how the FS (and possibly other servers) get access to cause_sig.
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*/
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cause_sig(m_ptr->SIG_PROC, m_ptr->SIG_NUMBER);
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return(OK);
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}
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