slang/slsignal.c

   1 #include "config.h"
   2
   3 #include <stdio.h>
   4 #include <signal.h>
   5
   6 #ifdef HAVE_STDLIB_H
   7 # include <stdlib.h>
   8 #endif
   9
  10 #ifdef HAVE_UNISTD_H
  11 # include <unistd.h>
  12 #endif
  13
  14 #include <errno.h>
  15
  16 #include "slang.h"
  17 #include "_slang.h"
  18
  19 /* This function will cause system calls to be restarted after signal if possible */
  20 SLSig_Fun_Type *SLsignal (int sig, SLSig_Fun_Type *f)
  21 {
  22 #ifdef SLANG_POSIX_SIGNALS
  23    struct sigaction old_sa, new_sa;
  24
  25 # ifdef SIGALRM
  26    /* We want system calls to be interrupted by SIGALRM. */
  27    if (sig == SIGALRM) return SLsignal_intr (sig, f);
  28 # endif
  29
  30    sigemptyset (&new_sa.sa_mask);
  31    new_sa.sa_handler = f;
  32
  33    new_sa.sa_flags = 0;
  34 # ifdef SA_RESTART
  35    new_sa.sa_flags |= SA_RESTART;
  36 # endif
  37
  38    if (-1 == sigaction (sig, &new_sa, &old_sa))
  39      return (SLSig_Fun_Type *) SIG_ERR;
  40
  41    return old_sa.sa_handler;
  42 #else
  43    /* Not POSIX. */
  44    return signal (sig, f);
  45 #endif
  46 }
  47
  48 /* This function will NOT cause system calls to be restarted after
  49  * signal if possible
  50  */
  51 SLSig_Fun_Type *SLsignal_intr (int sig, SLSig_Fun_Type *f)
  52 {
  53 #ifdef SLANG_POSIX_SIGNALS
  54    struct sigaction old_sa, new_sa;
  55
  56    sigemptyset (&new_sa.sa_mask);
  57    new_sa.sa_handler = f;
  58
  59    new_sa.sa_flags = 0;
  60 # ifdef SA_INTERRUPT
  61    new_sa.sa_flags |= SA_INTERRUPT;
  62 # endif
  63
  64    if (-1 == sigaction (sig, &new_sa, &old_sa))
  65      return (SLSig_Fun_Type *) SIG_ERR;
  66
  67    return old_sa.sa_handler;
  68 #else
  69    /* Not POSIX. */
  70    return signal (sig, f);
  71 #endif
  72 }
  73
  74
  75 /* We are primarily interested in blocking signals that would cause the
  76  * application to reset the tty.  These include suspend signals and
  77  * possibly interrupt signals.
  78  */
  79 #ifdef SLANG_POSIX_SIGNALS
  80 static sigset_t Old_Signal_Mask;
  81 #endif
  82
  83 static volatile unsigned int Blocked_Depth;
  84
  85 int SLsig_block_signals (void)
  86 {
  87 #ifdef SLANG_POSIX_SIGNALS
  88    sigset_t new_mask;
  89 #endif
  90
  91    Blocked_Depth++;
  92    if (Blocked_Depth != 1)
  93      {
  94         return 0;
  95      }
  96
  97 #ifdef SLANG_POSIX_SIGNALS
  98    sigemptyset (&new_mask);
  99 # ifdef SIGQUIT
 100    sigaddset (&new_mask, SIGQUIT);
 101 # endif
 102 # ifdef SIGTSTP
 103    sigaddset (&new_mask, SIGTSTP);
 104 # endif
 105 # ifdef SIGINT
 106    sigaddset (&new_mask, SIGINT);
 107 # endif
 108 # ifdef SIGTTIN
 109    sigaddset (&new_mask, SIGTTIN);
 110 # endif
 111 # ifdef SIGTTOU
 112    sigaddset (&new_mask, SIGTTOU);
 113 # endif
 114
 115    (void) sigprocmask (SIG_BLOCK, &new_mask, &Old_Signal_Mask);
 116    return 0;
 117 #else
 118    /* Not implemented. */
 119    return -1;
 120 #endif
 121 }
 122
 123 int SLsig_unblock_signals (void)
 124 {
 125    if (Blocked_Depth == 0)
 126      return -1;
 127
 128    Blocked_Depth--;
 129
 130    if (Blocked_Depth != 0)
 131      return 0;
 132
 133 #ifdef SLANG_POSIX_SIGNALS
 134    (void) sigprocmask (SIG_SETMASK, &Old_Signal_Mask, NULL);
 135    return 0;
 136 #else
 137    return -1;
 138 #endif
 139 }