📄 signal.c
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src/mm/signal.c
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17800 /* This file handles signals, which are asynchronous events and are generally
17801 * a messy and unpleasant business. Signals can be generated by the KILL
17802 * system call, or from the keyboard (SIGINT) or from the clock (SIGALRM).
17803 * In all cases control eventually passes to check_sig() to see which processes
17804 * can be signaled. The actual signaling is done by sig_proc().
17805 *
17806 * The entry points into this file are:
17807 * do_sigaction: perform the SIGACTION system call
17808 * do_sigpending: perform the SIGPENDING system call
17809 * do_sigprocmask: perform the SIGPROCMASK system call
17810 * do_sigreturn: perform the SIGRETURN system call
17811 * do_sigsuspend: perform the SIGSUSPEND system call
17812 * do_kill: perform the KILL system call
17813 * do_ksig: accept a signal originating in the kernel (e.g., SIGINT)
17814 * do_alarm: perform the ALARM system call by calling set_alarm()
17815 * set_alarm: tell the clock task to start or stop a timer
17816 * do_pause: perform the PAUSE system call
17817 * do_reboot: kill all processes, then reboot system
17818 * sig_proc: interrupt or terminate a signaled process
17819 * check_sig: check which processes to signal with sig_proc()
17820 */
17821
17822 #include "mm.h"
17823 #include <sys/stat.h>
17824 #include <minix/callnr.h>
17825 #include <minix/com.h>
17826 #include <signal.h>
17827 #include <sys/sigcontext.h>
17828 #include <string.h>
17829 #include "mproc.h"
17830 #include "param.h"
17831
17832 #define CORE_MODE 0777 /* mode to use on core image files */
17833 #define DUMPED 0200 /* bit set in status when core dumped */
17834 #define DUMP_SIZE ((INT_MAX / BLOCK_SIZE) * BLOCK_SIZE)
17835 /* buffer size for core dumps */
17836
17837 FORWARD _PROTOTYPE( void check_pending, (void) );
17838 FORWARD _PROTOTYPE( void dump_core, (struct mproc *rmp) );
17839 FORWARD _PROTOTYPE( void unpause, (int pro) );
17840
17841
17842 /*===========================================================================*
17843 * do_sigaction *
17844 *===========================================================================*/
17845 PUBLIC int do_sigaction()
17846 {
17847 int r;
17848 struct sigaction svec;
17849 struct sigaction *svp;
17850
17851 if (sig_nr == SIGKILL) return(OK);
17852 if (sig_nr < 1 || sig_nr > _NSIG) return (EINVAL);
17853 svp = &mp->mp_sigact[sig_nr];
17854 if ((struct sigaction *) sig_osa != (struct sigaction *) NULL) {
17855 r = sys_copy(MM_PROC_NR,D, (phys_bytes) svp,
17856 who, D, (phys_bytes) sig_osa, (phys_bytes) sizeof(svec));
17857 if (r != OK) return(r);
17858 }
17859
17860 if ((struct sigaction *) sig_nsa == (struct sigaction *) NULL) return(OK);
17861
17862 /* Read in the sigaction structure. */
17863 r = sys_copy(who, D, (phys_bytes) sig_nsa,
17864 MM_PROC_NR, D, (phys_bytes) &svec, (phys_bytes) sizeof(svec));
17865 if (r != OK) return(r);
17866
17867 if (svec.sa_handler == SIG_IGN) {
17868 sigaddset(&mp->mp_ignore, sig_nr);
17869 sigdelset(&mp->mp_sigpending, sig_nr);
17870 sigdelset(&mp->mp_catch, sig_nr);
17871 } else {
17872 sigdelset(&mp->mp_ignore, sig_nr);
17873 if (svec.sa_handler == SIG_DFL)
17874 sigdelset(&mp->mp_catch, sig_nr);
17875 else
17876 sigaddset(&mp->mp_catch, sig_nr);
17877 }
17878 mp->mp_sigact[sig_nr].sa_handler = svec.sa_handler;
17879 sigdelset(&svec.sa_mask, SIGKILL);
17880 mp->mp_sigact[sig_nr].sa_mask = svec.sa_mask;
17881 mp->mp_sigact[sig_nr].sa_flags = svec.sa_flags;
17882 mp->mp_sigreturn = (vir_bytes) sig_ret;
17883 return(OK);
17884 }
17886 /*===========================================================================*
17887 * do_sigpending *
17888 *===========================================================================*/
17889 PUBLIC int do_sigpending()
17890 {
17891 ret_mask = (long) mp->mp_sigpending;
17892 return OK;
17893 }
17895 /*===========================================================================*
17896 * do_sigprocmask *
17897 *===========================================================================*/
17898 PUBLIC int do_sigprocmask()
17899 {
17900 /* Note that the library interface passes the actual mask in sigmask_set,
17901 * not a pointer to the mask, in order to save a sys_copy. Similarly,
17902 * the old mask is placed in the return message which the library
17903 * interface copies (if requested) to the user specified address.
17904 *
17905 * The library interface must set SIG_INQUIRE if the 'act' argument
17906 * is NULL.
17907 */
17908
17909 int i;
17910
17911 ret_mask = (long) mp->mp_sigmask;
17912
17913 switch (sig_how) {
17914 case SIG_BLOCK:
17915 sigdelset((sigset_t *)&sig_set, SIGKILL);
17916 for (i = 1; i < _NSIG; i++) {
17917 if (sigismember((sigset_t *)&sig_set, i))
17918 sigaddset(&mp->mp_sigmask, i);
17919 }
17920 break;
17921
17922 case SIG_UNBLOCK:
17923 for (i = 1; i < _NSIG; i++) {
17924 if (sigismember((sigset_t *)&sig_set, i))
17925 sigdelset(&mp->mp_sigmask, i);
17926 }
17927 check_pending();
17928 break;
17929
17930 case SIG_SETMASK:
17931 sigdelset((sigset_t *)&sig_set, SIGKILL);
17932 mp->mp_sigmask = (sigset_t)sig_set;
17933 check_pending();
17934 break;
17935
17936 case SIG_INQUIRE:
17937 break;
17938
17939 default:
17940 return(EINVAL);
17941 break;
17942 }
17943 return OK;
17944 }
17946 /*===========================================================================*
17947 * do_sigsuspend *
17948 *===========================================================================*/
17949 PUBLIC int do_sigsuspend()
17950 {
17951 mp->mp_sigmask2 = mp->mp_sigmask; /* save the old mask */
17952 mp->mp_sigmask = (sigset_t) sig_set;
17953 sigdelset(&mp->mp_sigmask, SIGKILL);
17954 mp->mp_flags |= SIGSUSPENDED;
17955 dont_reply = TRUE;
17956 check_pending();
17957 return OK;
17958 }
17961 /*===========================================================================*
17962 * do_sigreturn *
17963 *===========================================================================*/
17964 PUBLIC int do_sigreturn()
17965 {
17966 /* A user signal handler is done. Restore context and check for
17967 * pending unblocked signals.
17968 */
17969
17970 int r;
17971
17972 mp->mp_sigmask = (sigset_t) sig_set;
17973 sigdelset(&mp->mp_sigmask, SIGKILL);
17974
17975 r = sys_sigreturn(who, (vir_bytes)sig_context, sig_flags);
17976 check_pending();
17977 return(r);
17978 }
17980 /*===========================================================================*
17981 * do_kill *
17982 *===========================================================================*/
17983 PUBLIC int do_kill()
17984 {
17985 /* Perform the kill(pid, signo) system call. */
17986
17987 return check_sig(pid, sig_nr);
17988 }
17991 /*===========================================================================*
17992 * do_ksig *
17993 *===========================================================================*/
17994 PUBLIC int do_ksig()
17995 {
17996 /* Certain signals, such as segmentation violations and DEL, originate in the
17997 * kernel. When the kernel detects such signals, it sets bits in a bit map.
17998 * As soon as MM is awaiting new work, the kernel sends MM a message containing
17999 * the process slot and bit map. That message comes here. The File System
18000 * also uses this mechanism to signal writing on broken pipes (SIGPIPE).
18001 */
18002
18003 register struct mproc *rmp;
18004 int i, proc_nr;
18005 pid_t proc_id, id;
18006 sigset_t sig_map;
18007
18008 /* Only kernel may make this call. */
18009 if (who != HARDWARE) return(EPERM);
18010 dont_reply = TRUE; /* don't reply to the kernel */
18011 proc_nr = mm_in.SIG_PROC;
18012 rmp = &mproc[proc_nr];
18013 if ( (rmp->mp_flags & IN_USE) == 0 || (rmp->mp_flags & HANGING) ) return(OK);
18014 proc_id = rmp->mp_pid;
18015 sig_map = (sigset_t) mm_in.SIG_MAP;
18016 mp = &mproc[0]; /* pretend kernel signals are from MM */
18017 mp->mp_procgrp = rmp->mp_procgrp; /* get process group right */
18018
18019 /* Check each bit in turn to see if a signal is to be sent. Unlike
18020 * kill(), the kernel may collect several unrelated signals for a
18021 * process and pass them to MM in one blow. Thus loop on the bit
18022 * map. For SIGINT and SIGQUIT, use proc_id 0 to indicate a broadcast
18023 * to the recipient's process group. For SIGKILL, use proc_id -1 to
18024 * indicate a systemwide broadcast.
18025 */
18026 for (i = 1; i <= _NSIG; i++) {
18027 if (!sigismember(&sig_map, i)) continue;
18028 switch (i) {
18029 case SIGINT:
18030 case SIGQUIT:
18031 id = 0; break; /* broadcast to process group */
18032 case SIGKILL:
18033 id = -1; break; /* broadcast to all except INIT */
18034 case SIGALRM:
18035 /* Disregard SIGALRM when the target process has not
18036 * requested an alarm. This only applies for a KERNEL
18037 * generated signal.
18038 */
18039 if ((rmp->mp_flags & ALARM_ON) == 0) continue;
18040 rmp->mp_flags &= ~ALARM_ON;
18041 /* fall through */
18042 default:
18043 id = proc_id;
18044 break;
18045 }
18046 check_sig(id, i);
18047 sys_endsig(proc_nr); /* tell kernel it's done */
18048 }
18049 return(OK);
18050 }
18053 /*===========================================================================*
18054 * do_alarm *
18055 *===========================================================================*/
18056 PUBLIC int do_alarm()
18057 {
18058 /* Perform the alarm(seconds) system call. */
18059
18060 return(set_alarm(who, seconds));
18061 }
18064 /*===========================================================================*
18065 * set_alarm *
18066 *===========================================================================*/
18067 PUBLIC int set_alarm(proc_nr, sec)
18068 int proc_nr; /* process that wants the alarm */
18069 int sec; /* how many seconds delay before the signal */
18070 {
18071 /* This routine is used by do_alarm() to set the alarm timer. It is also used
18072 * to turn the timer off when a process exits with the timer still on.
18073 */
18074
18075 message m_sig;
18076 int remaining;
18077
18078 if (sec != 0)
18079 mproc[proc_nr].mp_flags |= ALARM_ON;
18080 else
18081 mproc[proc_nr].mp_flags &= ~ALARM_ON;
18082
18083 /* Tell the clock task to provide a signal message when the time comes.
18084 *
18085 * Large delays cause a lot of problems. First, the alarm system call
18086 * takes an unsigned seconds count and the library has cast it to an int.
18087 * That probably works, but on return the library will convert "negative"
18088 * unsigneds to errors. Presumably no one checks for these errors, so
18089 * force this call through. Second, If unsigned and long have the same
18090 * size, converting from seconds to ticks can easily overflow. Finally,
18091 * the kernel has similar overflow bugs adding ticks.
18092 *
18093 * Fixing this requires a lot of ugly casts to fit the wrong interface
18094 * types and to avoid overflow traps. DELTA_TICKS has the right type
18095 * (clock_t) although it is declared as long. How can variables like
18096 * this be declared properly without combinatorial explosion of message
18097 * types?
18098 */
18099 m_sig.m_type = SET_ALARM;
18100 m_sig.CLOCK_PROC_NR = proc_nr;
18101 m_sig.DELTA_TICKS = (clock_t) (HZ * (unsigned long) (unsigned) sec);
18102 if ( (unsigned long) m_sig.DELTA_TICKS / HZ != (unsigned) sec)
18103 m_sig.DELTA_TICKS = LONG_MAX; /* eternity (really CLOCK_T_MAX) */
18104 if (sendrec(CLOCK, &m_sig) != OK) panic("alarm er", NO_NUM);
18105 remaining = (int) m_sig.SECONDS_LEFT;
18106 if (remaining != m_sig.SECONDS_LEFT || remaining < 0)
18107 remaining = INT_MAX; /* true value is not representable */
18108 return(remaining);
18109 }
18112 /*===========================================================================*
18113 * do_pause *
18114 *===========================================================================*/
18115 PUBLIC int do_pause()
18116 {
18117 /* Perform the pause() system call. */
18118
18119 mp->mp_flags |= PAUSED;
18120 dont_reply = TRUE;
18121 return(OK);
18122 }
18125 /*=====================================================================*
18126 * do_reboot *
18127 *=====================================================================*/
18128 PUBLIC int do_reboot()
18129 {
18130 register struct mproc *rmp = mp;
18131 char monitor_code[64];
18132
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