xiosignal.c

   1 /* source: xiosignal.c */
   2 /* Copyright Gerhard Rieger and contributors (see file CHANGES) */
   3 /* Published under the GNU General Public License V.2, see file COPYING */
   4
   5 /* this file contains code for handling signals (except SIGCHLD) */
   6
   7 #include "config.h"
   8 #include "xioconfig.h"  /* what features are enabled */
   9
  10 #include "sysincludes.h"
  11
  12 #include "mytypes.h"
  13 #include "compat.h"
  14 #include "error.h"
  15
  16 #include "sycls.h"
  17
  18
  19 #define SOCAT_MAXPIDS 4
  20
  21 struct socat_sig_desc {
  22    int sig_use;
  23    pid_t  sig_pids[SOCAT_MAXPIDS];
  24 } ;
  25
  26 #if 0
  27 size_t socat_sigint_use;        /* how many pids are set in following array */
  28 static pid_t socat_sigint_pids[SOCAT_MAXPIDS];
  29 size_t socat_sigquit_use;       /* how many pids are set in following array */
  30 static pid_t socat_sigquit_pids[SOCAT_MAXPIDS];
  31 #else
  32 static struct socat_sig_desc socat_sighup;
  33 static struct socat_sig_desc socat_sigint;
  34 static struct socat_sig_desc socat_sigquit;
  35 #endif
  36
  37
  38 /* is async-signal-safe */
  39 static struct socat_sig_desc *socat_get_sig_desc(int signum) {
  40    struct socat_sig_desc *sigdesc;
  41    switch (signum) {
  42    case SIGHUP:  sigdesc = &socat_sighup;  break;
  43    case SIGINT:  sigdesc = &socat_sigint;  break;
  44    case SIGQUIT: sigdesc = &socat_sigquit; break;
  45    default: sigdesc = NULL; break;
  46    }
  47    return sigdesc;
  48 }
  49
  50 /* a signal handler that possibly passes the signal to sub processes */
  51 void socatsignalpass(int sig) {
  52    int i;
  53    struct socat_sig_desc *sigdesc;
  54    int _errno;
  55
  56    _errno = errno;
  57    diag_in_handler = 1;
  58    Notice1("socatsignalpass(sig=%d)", sig);
  59    if ((sigdesc = socat_get_sig_desc(sig)) == NULL) {   /* is async-signal-safe */
  60       diag_in_handler = 0;
  61       errno = _errno;
  62       return;
  63    }
  64
  65   { /*debug*/
  66      int n = 0;
  67    for (i=0; i<sigdesc->sig_use; ++i) {
  68       if (sigdesc->sig_pids[i]) {
  69          ++n;
  70          if (Kill(sigdesc->sig_pids[i], sig) < 0) {
  71             Warn2("kill("F_pid", %d): %m",
  72                   sigdesc->sig_pids[i], sig);
  73          }
  74       }
  75    }
  76    if (n >= 0)
  77       Info1("socatsignalpass(): propagated signal to %d sub processes", n);
  78   }
  79 #if !HAVE_SIGACTION
  80    Signal(sig, socatsignalpass);
  81 #endif /* !HAVE_SIGACTION */
  82    Debug("socatsignalpass() ->");
  83    diag_in_handler = 0;
  84    errno = _errno;
  85 }
  86
  87
  88 /* register the sub process pid for passing of signals of type signum.
  89    Only for SIGHUP, SIGINT, and SIGQUIT!
  90    returns 0 on success or <0 if an error occurred */
  91 int xio_opt_signal(pid_t pid, int signum) {
  92    struct socat_sig_desc *sigdesc;
  93
  94    if ((sigdesc = socat_get_sig_desc(signum)) == NULL) {
  95       Error("sub process registered for unsupported signal");
  96       return -1;
  97    }
  98
  99    if (sigdesc->sig_use >= SOCAT_MAXPIDS) {
 100       Error1("too many sub processes registered for signal %d", signum);
 101       return -1;
 102    }
 103    if (sigdesc->sig_use == 0) {
 104       /* the special signal handler has not been registered yet - do it now */
 105 #if HAVE_SIGACTION
 106       struct sigaction act;
 107       memset(&act, 0, sizeof(struct sigaction));
 108       act.sa_flags   = 0/*|SA_RESTART*/;
 109       act.sa_handler = socatsignalpass;
 110       sigfillset(&act.sa_mask);
 111       if (Sigaction(signum, &act, NULL) < 0) {
 112          /*! man does not say that errno is defined */
 113          Warn3("sigaction(%d, %p, NULL): %s", signum, &act, strerror(errno));
 114       }
 115 #else
 116       Signal(signum, socatsignalpass);
 117 #endif /* !HAVE_SIGACTION */
 118    }
 119    sigdesc->sig_pids[sigdesc->sig_use++] = pid;
 120    return 0;
 121 }
 122