__signal.h

介绍：MySQL是比较出名的数据库软件

#include <sys/feature_tests.h>
#include <sys/signal.h>

/*
typedef struct {  
    unsigned long   __sigbits[4];
} sigset_t;
*/

typedef int sig_atomic_t;

#define sigmask(n)      ((unsigned int)1 << (((n) - 1) & (32 - 1)))
#define sigword(n)      (((unsigned int)((n) - 1))>>5)

#define	__SIGEMPTYSET 		 { 0, 0, 0, 0 };
#define	__SIGFILLSET  		 { 0xffffffff,0xffffffff,0xffffffff,0xffffffff };
#define __SIGADDSET(s, n)     ((s)->__sigbits[sigword(n)] |= sigmask(n))
#define __SIGDELSET(s, n)     ((s)->__sigbits[sigword(n)] &= ~sigmask(n))
#define __SIGISMEMBER(s, n)   (sigmask(n) & (s)->__sigbits[sigword(n)])