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fault.c

/***********************************************************************
*                                                                      *
*               This software is part of the ast package               *
*          Copyright (c) 1982-2008 AT&T Intellectual Property          *
*                      and is licensed under the                       *
*                  Common Public License, Version 1.0                  *
*                    by AT&T Intellectual Property                     *
*                                                                      *
*                A copy of the License is available at                 *
*            http://www.opensource.org/licenses/cpl1.0.txt             *
*         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
*                                                                      *
*              Information and Software Systems Research               *
*                            AT&T Research                             *
*                           Florham Park NJ                            *
*                                                                      *
*                  David Korn <dgk@research.att.com>                   *
*                                                                      *
***********************************************************************/
#pragma prototyped
/*
 * Fault handling routines
 *
 *   David Korn
 *   AT&T Labs
 *
 */

#include    "defs.h"
#include    <fcin.h>
#include    "io.h"
#include    "history.h"
#include    "shnodes.h"
#include    "variables.h"
#include    "jobs.h"
#include    "path.h"

#define abortsig(sig)   (sig==SIGABRT || sig==SIGBUS || sig==SIGILL || sig==SIGSEGV)

static char indone;

#if !_std_malloc
#   include <vmalloc.h>
#endif
#if  defined(VMFL) && (VMALLOC_VERSION>=20031205L)
    /*
     * This exception handler is called after vmalloc() unlocks the region
     */
    static int malloc_done(Vmalloc_t* vm, int type, Void_t* val, Vmdisc_t* dp)
    {
      dp->exceptf = 0;
      sh_exit(SH_EXITSIG);
      return(0);
    }
#endif

/*
 * Most signals caught or ignored by the shell come here
*/
void  sh_fault(register int sig)
{
      register Shell_t  *shp = sh_getinterp();
      register int            flag=0;
      register char           *trap;
      register struct checkpt *pp = (struct checkpt*)shp->jmplist;
      int   action=0;
      /* reset handler */
      if(!(sig&SH_TRAP))
            signal(sig, sh_fault);
      sig &= ~SH_TRAP;
#ifdef SIGWINCH
      if(sig==SIGWINCH)
      {
            int rows=0, cols=0;
            int32_t v;
            astwinsize(2,&rows,&cols);
            if(v = cols)
                  nv_putval(COLUMNS, (char*)&v, NV_INT32);
            if(v = rows)
                  nv_putval(LINES, (char*)&v, NV_INT32);
      }
#endif  /* SIGWINCH */
      if(shp->savesig)
      {
            /* critical region, save and process later */
            shp->savesig = sig;
            return;
      }

      /* handle ignored signals */
      if((trap=shp->st.trapcom[sig]) && *trap==0)
            return;
      flag = shp->sigflag[sig]&~SH_SIGOFF;
      if(!trap)
      {
            if(sig==SIGINT && (shp->trapnote&SH_SIGIGNORE))
                  return;
            if(flag&SH_SIGIGNORE)
                  return;
            if(flag&SH_SIGDONE)
            {
                  void *ptr=0;
                  if((flag&SH_SIGINTERACTIVE) && sh_isstate(SH_INTERACTIVE) && !sh_isstate(SH_FORKED) && ! shp->subshell)
                  {
                        /* check for TERM signal between fork/exec */
                        if(sig==SIGTERM && job.in_critical)
                              shp->trapnote |= SH_SIGTERM;
                        return;
                  }
                  shp->lastsig = sig;
                  sigrelease(sig);
                  if(pp->mode < SH_JMPFUN)
                        pp->mode = SH_JMPFUN;
                  else
                        pp->mode = SH_JMPEXIT;
                  if(sig==SIGABRT || (abortsig(sig) && (ptr = malloc(1))))
                  {
                        if(ptr)
                              free(ptr);
                        if(!shp->subshell)
                              sh_done(sig);
                        sh_exit(SH_EXITSIG);
                  }
                  /* mark signal and continue */
                  shp->trapnote |= SH_SIGSET;
                  if(sig < shp->sigmax)
                        shp->sigflag[sig] |= SH_SIGSET;
#if  defined(VMFL) && (VMALLOC_VERSION>=20031205L)
                  if(abortsig(sig))
                  {
                        /* abort inside malloc, process when malloc returns */
                        /* VMFL defined when using vmalloc() */
                        Vmdisc_t* dp = vmdisc(Vmregion,0);
                        if(dp)
                              dp->exceptf = malloc_done;
                  }
#endif
                  return;
            }
      }
      errno = 0;
      if(pp->mode==SH_JMPCMD)
            shp->lastsig = sig;
      if(trap)
      {
            /*
             * propogate signal to foreground group
             */
            if(sig==SIGHUP && job.curpgid)
                  killpg(job.curpgid,SIGHUP);
            flag = SH_SIGTRAP;
      }
      else
      {
            shp->lastsig = sig;
            flag = SH_SIGSET;
#ifdef SIGTSTP
            if(sig==SIGTSTP)
            {
                  shp->trapnote |= SH_SIGTSTP;
                  if(pp->mode==SH_JMPCMD && sh_isstate(SH_STOPOK))
                  {
                        sigrelease(sig);
                        sh_exit(SH_EXITSIG);
                        flag = 0;
                  }
            }
#endif /* SIGTSTP */
      }
#ifdef ERROR_NOTIFY
      /* This is obsolete */
      if((error_info.flags&ERROR_NOTIFY) && shp->bltinfun)
            action = (*shp->bltinfun)(-sig,(char**)0,(void*)0);
      if(action>0)
            return;
#endif
      if(shp->bltinfun && shp->bltindata.notify)
      {
            shp->bltindata.sigset = 1;
            return;
      }
      shp->trapnote |= flag;
      if(sig < shp->sigmax)
            shp->sigflag[sig] |= flag;
      if(pp->mode==SH_JMPCMD && sh_isstate(SH_STOPOK))
      {
            if(action<0)
                  return;
            sigrelease(sig);
            sh_exit(SH_EXITSIG);
      }
}

/*
 * initialize signal handling
 */
void sh_siginit(void)
{
      register int sig, n=SIGTERM+1;
      register const struct shtable2      *tp = shtab_signals;
      sig_begin();
      /* find the largest signal number in the table */
#ifdef SIGRTMIN
      sh.sigruntime[SH_SIGRTMIN] = SIGRTMIN;
#endif /* SIGRTMIN */
#ifdef SIGRTMAX
      sh.sigruntime[SH_SIGRTMAX] = SIGRTMAX;
#endif /* SIGRTMAX */
      while(*tp->sh_name)
      {
            sig = tp->sh_number&((1<<SH_SIGBITS)-1);
            if ((tp->sh_number>>SH_SIGBITS) & SH_SIGRUNTIME)
                  sig = sh.sigruntime[sig-1];
            if(sig>n && sig<SH_TRAP)
                  n = sig;
            tp++;
      }
      sh.sigmax = n++;
      sh.st.trapcom = (char**)calloc(n,sizeof(char*));
      sh.sigflag = (unsigned char*)calloc(n,1);
      sh.sigmsg = (char**)calloc(n,sizeof(char*));
      for(tp=shtab_signals; sig=tp->sh_number; tp++)
      {
            n = (sig>>SH_SIGBITS);
            if((sig &= ((1<<SH_SIGBITS)-1)) > sh.sigmax)
                  continue;
            sig--;
            if(n&SH_SIGRUNTIME)
                  sig = sh.sigruntime[sig];
            if(sig>=0)
            {
                  sh.sigflag[sig] = n;
                  if(*tp->sh_name)
                        sh.sigmsg[sig] = (char*)tp->sh_value;
            }
      }
}

/*
 * Turn on trap handler for signal <sig>
 */
void  sh_sigtrap(register int sig)
{
      register int flag;
      void (*fun)(int);
      sh.st.otrapcom = 0;
      if(sig==0)
            sh_sigdone();
      else if(!((flag=sh.sigflag[sig])&(SH_SIGFAULT|SH_SIGOFF)))
      {
            /* don't set signal if already set or off by parent */
            if((fun=signal(sig,sh_fault))==SIG_IGN) 
            {
                  signal(sig,SIG_IGN);
                  flag |= SH_SIGOFF;
            }
            else
            {
                  flag |= SH_SIGFAULT;
                  if(sig==SIGALRM && fun!=SIG_DFL && fun!=sh_fault)
                        signal(sig,fun);
            }
            flag &= ~(SH_SIGSET|SH_SIGTRAP);
            sh.sigflag[sig] = flag;
      }
}

/*
 * set signal handler so sh_done is called for all caught signals
 */
void  sh_sigdone(void)
{
      register int      flag, sig = sh.sigmax;
      sh.sigflag[0] |= SH_SIGFAULT;
      while(--sig>0)
      {
            flag = sh.sigflag[sig];
            if((flag&(SH_SIGDONE|SH_SIGIGNORE|SH_SIGINTERACTIVE)) && !(flag&(SH_SIGFAULT|SH_SIGOFF)))
                  sh_sigtrap(sig);
      }
}

/*
 * Restore to default signals
 * Free the trap strings if mode is non-zero
 * If mode>1 then ignored traps cause signal to be ignored 
 */
void  sh_sigreset(register int mode)
{
      register char     *trap;
      register int      flag, sig=sh.st.trapmax;
      while(sig-- > 0)
      {
            if(trap=sh.st.trapcom[sig])
            {
                  flag  = sh.sigflag[sig]&~(SH_SIGTRAP|SH_SIGSET);
                  if(*trap)
                  {
                        if(mode)
                              free(trap);
                        sh.st.trapcom[sig] = 0;
                  }
                  else if(sig && mode>1)
                  {
                        signal(sig,SIG_IGN);
                        flag &= ~SH_SIGFAULT;
                        flag |= SH_SIGOFF;
                  }
                  sh.sigflag[sig] = flag;
            }
      }
      for(sig=SH_DEBUGTRAP;sig>=0;sig--)
      {
            if(trap=sh.st.trap[sig])
            {
                  if(mode)
                        free(trap);
                  sh.st.trap[sig] = 0;
            }
            
      }
      sh.st.trapcom[0] = 0;
      if(mode)
            sh.st.trapmax = 0;
      sh.trapnote=0;
}

/*
 * free up trap if set and restore signal handler if modified
 */
void  sh_sigclear(register int sig)
{
      register int flag = sh.sigflag[sig];
      register char *trap;
      sh.st.otrapcom=0;
      if(!(flag&SH_SIGFAULT))
            return;
      flag &= ~(SH_SIGTRAP|SH_SIGSET);
      if(trap=sh.st.trapcom[sig])
      {
            free(trap);
            sh.st.trapcom[sig]=0;
      }
      sh.sigflag[sig] = flag;
}

/*
 * check for traps
 */

void  sh_chktrap(void)
{
      register int      sig=sh.st.trapmax;
      register char *trap;
      if(!(sh.trapnote&~SH_SIGIGNORE))
            sig=0;
      sh.trapnote &= ~SH_SIGTRAP;
      /* execute errexit trap first */
      if(sh_isstate(SH_ERREXIT) && sh.exitval)
      {
            int   sav_trapnote = sh.trapnote;
            sh.trapnote &= ~SH_SIGSET;
            if(sh.st.trap[SH_ERRTRAP])
            {
                  trap = sh.st.trap[SH_ERRTRAP];
                  sh.st.trap[SH_ERRTRAP] = 0;
                  sh_trap(trap,0);
                  sh.st.trap[SH_ERRTRAP] = trap;
            }
            sh.trapnote = sav_trapnote;
            if(sh_isoption(SH_ERREXIT))
            {
                  struct checkpt    *pp = (struct checkpt*)sh.jmplist;
                  pp->mode = SH_JMPEXIT;
                  sh_exit(sh.exitval);
            }
      }
      if(sh.sigflag[SIGALRM]&SH_SIGALRM)
            sh_timetraps();
      while(--sig>=0)
      {
            if(sh.sigflag[sig]&SH_SIGTRAP)
            {
                  sh.sigflag[sig] &= ~SH_SIGTRAP;
                  if(trap=sh.st.trapcom[sig])
                        sh_trap(trap,0);
            }
      }
}


/*
 * parse and execute the given trap string, stream or tree depending on mode
 * mode==0 for string, mode==1 for stream, mode==2 for parse tree
 */
int sh_trap(const char *trap, int mode)
{
      int   jmpval, savxit = sh.exitval;
      int   was_history = sh_isstate(SH_HISTORY);
      int   was_verbose = sh_isstate(SH_VERBOSE);
      int   staktop = staktell();
      char  *savptr = stakfreeze(0);
      struct      checkpt buff;
      Fcin_t      savefc;
      fcsave(&savefc);
      sh_offstate(SH_HISTORY);
      sh_offstate(SH_VERBOSE);
      sh.intrap++;
      sh_pushcontext(&buff,SH_JMPTRAP);
      jmpval = sigsetjmp(buff.buff,0);
      if(jmpval == 0)
      {
            if(mode==2)
                  sh_exec((Shnode_t*)trap,sh_isstate(SH_ERREXIT));
            else
            {
                  Sfio_t *sp;
                  if(mode)
                        sp = (Sfio_t*)trap;
                  else
                        sp = sfopen(NIL(Sfio_t*),trap,"s");
                  sh_eval(sp,0);
            }
      }
      else if(indone)
      {
            if(jmpval==SH_JMPSCRIPT)
                  indone=0;
            else
            {
                  if(jmpval==SH_JMPEXIT)
                        savxit = sh.exitval;
                  jmpval=SH_JMPTRAP;
            }
      }
      sh_popcontext(&buff);
      sh.intrap--;
      sfsync(sh.outpool);
      if(jmpval!=SH_JMPEXIT && jmpval!=SH_JMPFUN)
            sh.exitval=savxit;
      stakset(savptr,staktop);
      fcrestore(&savefc);
      if(was_history)
            sh_onstate(SH_HISTORY);
      if(was_verbose)
            sh_onstate(SH_VERBOSE);
      exitset();
      if(jmpval>SH_JMPTRAP)
            siglongjmp(*sh.jmplist,jmpval);
      return(sh.exitval);
}

/*
 * exit the current scope and jump to an earlier one based on pp->mode
 */
void sh_exit(register int xno)
{
      register struct checkpt *pp = (struct checkpt*)sh.jmplist;
      register int            sig=0;
      register Sfio_t*  pool;
      sh.exitval=xno;
      if(xno==SH_EXITSIG)
            sh.exitval |= (sig=sh.lastsig);
#ifdef SIGTSTP
      if(sh.trapnote&SH_SIGTSTP)
      {
            /* ^Z detected by the shell */
            sh.trapnote = 0;
            sh.sigflag[SIGTSTP] = 0;
            if(!sh.subshell && sh_isstate(SH_MONITOR) && !sh_isstate(SH_STOPOK))
                  return;
            if(sh_isstate(SH_TIMING))
                  return;
            /* Handles ^Z for shell builtins, subshells, and functs */
            sh.lastsig = 0;
            sh_onstate(SH_MONITOR);
            sh_offstate(SH_STOPOK);
            sh.trapnote = 0;
            if(!sh.subshell && (sig=sh_fork(0,NIL(int*))))
            {
                  job.curpgid = 0;
                  job.parent = (pid_t)-1;
                  job_wait(sig);
                  job.parent = 0;
                  sh.sigflag[SIGTSTP] = 0;
                  /* wait for child to stop */
                  sh.exitval = (SH_EXITSIG|SIGTSTP);
                  /* return to prompt mode */
                  pp->mode = SH_JMPERREXIT;
            }
            else
            {
                  if(sh.subshell)
                        sh_subfork();
                  /* child process, put to sleep */
                  sh_offstate(SH_STOPOK);
                  sh_offstate(SH_MONITOR);
                  sh.sigflag[SIGTSTP] = 0;
                  /* stop child job */
                  killpg(job.curpgid,SIGTSTP);
                  /* child resumes */
                  job_clear();
                  sh.forked = 1;
                  sh.exitval = (xno&SH_EXITMASK);
                  return;
            }
      }
#endif /* SIGTSTP */
      /* unlock output pool */
      sh_offstate(SH_NOTRACK);
      if(!(pool=sfpool(NIL(Sfio_t*),sh.outpool,SF_WRITE)))
            pool = sh.outpool; /* can't happen? */
      sfclrlock(pool);
#ifdef SIGPIPE
      if(sh.lastsig==SIGPIPE)
            sfpurge(pool);
#endif /* SIGPIPE */
      sfclrlock(sfstdin);
      if(!pp)
            sh_done(sig);
      sh.prefix = 0;
      if(pp->mode == SH_JMPSCRIPT && !pp->prev) 
            sh_done(sig);
      siglongjmp(pp->buff,pp->mode);
}

/*
 * This is the exit routine for the shell
 */

void sh_done(register int sig)
{
      register char *t;
      register int savxit = sh.exitval;
      sh.trapnote = 0;
      indone=1;
      if(sig==0)
            sig = sh.lastsig;
      if(sh.userinit)
            (*sh.userinit)(-1);
      if(t=sh.st.trapcom[0])
      {
            sh.st.trapcom[0]=0; /*should free but not long */
            sh.oldexit = savxit;
            sh_trap(t,0);
            savxit = sh.exitval;
      }
      else
      {
            /* avoid recursive call for set -e */
            sh_offstate(SH_ERREXIT);
            sh_chktrap();
      }
      sh_freeup();
#if SHOPT_ACCT
      sh_accend();
#endif      /* SHOPT_ACCT */
#if SHOPT_VSH || SHOPT_ESH
      if(sh_isoption(SH_EMACS)||sh_isoption(SH_VI)||sh_isoption(SH_GMACS))
            tty_cooked(-1);
#endif
#ifdef JOBS
      if((sh_isoption(SH_INTERACTIVE) && sh.login_sh) || (!sh_isoption(SH_INTERACTIVE) && (sig==SIGHUP)))
            job_walk(sfstderr,job_terminate,SIGHUP,NIL(char**));
#endif      /* JOBS */
      job_close();
      if(nv_search("VMTRACE", sh.var_tree,0))
            strmatch((char*)0,(char*)0);
      sfsync((Sfio_t*)sfstdin);
      sfsync((Sfio_t*)sh.outpool);
      sfsync((Sfio_t*)sfstdout);
      if(sig)
      {
            /* generate fault termination code */
            signal(sig,SIG_DFL);
            sigrelease(sig);
            kill(getpid(),sig);
            pause();
      }
#if SHOPT_KIA
      if(sh_isoption(SH_NOEXEC))
            kiaclose();
#endif /* SHOPT_KIA */
      exit(savxit&SH_EXITMASK);
}


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