libs/fvwmsignal.h

   1 /* -*-c-*- */
   2 #ifndef FVWMSIGNAL_H
   3 #define FVWMSIGNAL_H
   4
   5 /* This module provides wrappers around system functions that could
   6  * potentially block, e.g. select(). These wrappers will check that
   7  * the "terminate" flag is still clear and then call the system
   8  * function in one atomic operation. This ensures that fvwm will not
   9  * block in a system function once it has received the signal to quit.
  10  *
  11  * This module was written by Chris Rankin,  rankinc@zipworld.com.au
  12  */
  13 /* This module is intended to use POSIX.1 signal semantics, since most
  14  * modern systems can reasonably be expected to support POSIX and since
  15  * the semantics of the old "signal()" function vary from system to system.
  16  * If POSIX.1 is not available then the module can provide BSD signal
  17  * semantics, which can be summarised as follows:
  18  *  - the signal handler will NOT uninstall itself once it has been called
  19  *  - a signal will be temporarily blocked from further delivery so long
  20  *    as its handler is running
  21  *  - certain system calls will be automatically restarted if interrupted
  22  *    by a signal
  23  */
  24
  25 #if !defined(HAVE_SIGACTION) \
  26     && defined(HAVE_SIGBLOCK) && defined(HAVE_SIGSETMASK)
  27 #  define USE_BSD_SIGNALS
  28 #endif
  29
  30 #ifdef USE_BSD_SIGNALS
  31 #  define BSD_BLOCK_SIGNALS      int old_mask = sigblock( fvwmGetSignalMask() )
  32 #  define BSB_BLOCK_ALL_SIGNALS  int old_mask = sigblock( ~0 )
  33 #  define BSD_UNBLOCK_SIGNALS    sigsetmask( old_mask )
  34 #else
  35 #  define BSD_BLOCK_SIGNALS
  36 #  define BSD_BLOCK_ALL_SIGNALS
  37 #  define BSD_UNBLOCK_SIGNALS
  38 #endif
  39
  40 #include <signal.h>
  41 #include "ftime.h"
  42 #if HAVE_SYS_SELECT_H
  43 #  include <sys/select.h>
  44 #endif
  45
  46 /*
  47  * Global variables
  48  */
  49 extern volatile sig_atomic_t isTerminated;
  50
  51
  52 /*
  53  * Module prototypes
  54  */
  55 RETSIGTYPE fvwmReapChildren(int sig);
  56 extern void fvwmSetTerminate(int sig);
  57
  58 #ifdef USE_BSD_SIGNALS
  59 extern void fvwmSetSignalMask(int);
  60 extern int fvwmGetSignalMask(void);
  61 #endif
  62
  63 #ifdef  HAVE_SELECT
  64 extern int fvwmSelect(
  65         fd_set_size_t nfds, fd_set *readfds, fd_set *writefds,
  66         fd_set *exceptfds, struct timeval *timeout);
  67 #endif
  68
  69 #endif /* FVWMSIGNAL_H */
  70