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