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ignore_handler_s set_constraint_handler_s static_assert File input/output clearerr(清除/复位) fclose feof ferror fflush(清空文件缓冲区) fgetc fgetpos fgets fgetwc fgetws File input/output fopen fopen_s fprintf fprintf_s fputc fputs fputwc fputws fread freopen freopen_s fscanf fscanf_s fseek fsetpos ftell fwide fwprintf fwprintf_s fwrite fwscanf fwscanf_s getc getchar gets gets_s getwchar perror printf printf_s putc putchar puts putwc putwchar remove rename rewind scanf scanf_s setbuf setvbuf snprintf sprintf sscanf sscanf_s swprintf swprintf_s swscanf swscanf_s tmpfile tmpfile_s tmpnam tmpnam_s ungetc ungetwc vfprintf vfprintf_s vfscanf vfscanf_s vfwprintf vfwprintf_s vfwscanf vfwscanf_s vprintf vprintf_s vscanf vscanf_s vsnprintf vsprintf vsscanf vsscanf_s vswprintf vswprintf_s vswscanf vswscanf_s vwprintf vwprintf_s vwscanf vwscanf_s wprintf wprintf_s wscanf wscanf_s Localization support lconv LC_ALL LC_COLLATE LC_CTYPE LC_MONETARY LC_NUMERIC LC_TIME localeconv Localization support setlocale Numerics abs acos acosf acosh acoshf acoshl acosl asin asinf asinh asinhf asinhl asinl atan atan2 atan2f atan2l atanf atanh atanhf atanhl atanl cabs cabsf cabsl cacos cacosf cacosh cacoshf cacoshl cacosl carg cargf cargl casin casinf casinh casinhf casinhl casinl catan catanf catanh catanhf catanhl catanl cbrt cbrtf cbrtl ccos ccosf ccosh ccoshf ccoshl ccosl ceil ceilf ceill cexp cexpf cexpl cimag cimagf cimagl clog clogf clogl CMPLX CMPLXF CMPLXL Common mathematical functions complex Complex number arithmetic conj conjf conjl copysign copysignf copysignl cos cosf cosh coshf coshl cosl cpow cpowf cpowl cproj cprojf cprojl creal crealf creall csin csinf csinh csinhf csinhl csinl csqrt csqrtf csqrtl ctan ctanf ctanh ctanhf ctanhl ctanl div double_t erf erfc erfcf erfcl erff erfl exp exp2 exp2f exp2l expf expl expm1 expm1f expm1l fabs fabsf fabsl fdim feclearexcept fegetenv fegetexceptflag fegetround feholdexcept feraiseexcept fesetenv fesetexceptflag fesetround fetestexcept feupdateenv FE_ALL_EXCEPT FE_DFL_ENV FE_DIVBYZERO FE_DOWNWARD FE_INEXACT FE_INVALID FE_OVERFLOW FE_TONEAREST FE_TOWARDZERO FE_UNDERFLOW FE_UPWARD Floating-point environment float_t floor floorf floorl fma fmaf fmal fmax fmaxf fmaxl fmin fminf fminl fmod fmodf fmodl fpclassify FP_INFINITE FP_NAN FP_NORMAL FP_SUBNORMAL FP_ZERO frexp frexpf frexpl HUGE_VAL HUGE_VALF HUGE_VALL hypot hypotf hypotl I ilogb ilogbf ilogbl imaginary imaxabs imaxdiv INFINITY isfinite isgreater isgreaterequal isinf isless islessequal islessgreater isnan isnormal isunordered labs ldexp ldexpf ldexpl ldiv lgamma lgammaf lgammal llabs lldiv llrint llrintf llrintl llround llroundf llroundl log log10 log10f log10l log1p log1pf log1pl log2 log2f log2l logb logbf logbl logf logl lrint lrintf lrintl lround lroundf lroundl MATH_ERREXCEPT math_errhandling MATH_ERRNO modf modff modfl nan NAN nanf nanl nearbyint nearbyintf nearbyintl nextafter nextafterf nextafterl nexttoward nexttowardf nexttowardl Numerics pow powf powl Pseudo-random number generation rand RAND_MAX remainder remainderf remainderl remquo remquof remquol rint rintf rintl round roundf roundl scalbln scalblnf scalblnl scalbn scalbnf scalbnl signbit sin sinf sinh sinhf sinhl sinl sqrt sqrtf sqrtl srand tan tanf tanh tanhf tanhl tanl tgamma tgammaf tgammal trunc truncf truncl Type-generic math _Complex_I _Imaginary_I Program support abort atexit at_quick_exit exit EXIT_FAILURE EXIT_SUCCESS getenv getenv_s jmp_buf longjmp Program support utilities quick_exit raise setjmp SIGABRT SIGFPE SIGILL SIGINT signal SIGSEGV SIGTERM sig_atomic_t SIG_DFL SIG_ERR SIG_IGN system _Exit Strings atof atoi atol atoll btowc c16rtomb c32rtomb char16_t char32_t isalnum isalpha isblank iscntrl isdigit isgraph islower isprint ispunct isspace isupper iswalnum iswalpha iswblank iswcntrl iswctype iswdigit iswgraph iswlower iswprint iswpunct iswspace iswupper iswxdigit isxdigit mblen mbrlen mbrtoc16 mbrtoc32 mbrtowc mbsinit mbsrtowcs mbsrtowcs_s mbstate_t mbstowcs mbstowcs_s mbtowc memchr memcmp memcpy memcpy_s memmove memmove_s memset memset_s Null-terminated byte strings Null-terminated multibyte strings Null-terminated wide strings strcat strcat_s strchr strcmp strcoll strcpy strcpy_s strcspn strerror strerrorlen_s strerror_s Strings library strlen strncat Thread support call_once cnd_broadcast cnd_destroy cnd_init cnd_signal cnd_timedwait cnd_wait mtx_destroy mtx_init mtx_lock mtx_plain mtx_recursive mtx_timed mtx_timedlock mtx_trylock mtx_unlock once_flag ONCE_FLAG_INIT thrd_busy thrd_create thrd_current thrd_detach thrd_equal thrd_error thrd_exit thrd_join thrd_nomem thrd_sleep thrd_success thrd_timedout thrd_yield Thread support library thread_local tss_create tss_delete TSS_DTOR_ITERATIONS tss_get tss_set Type support Boolean type support library Fixed width integer types FLT_EVAL_METHOD FLT_ROUNDS max_align_t NULL Numeric limits offsetof ptrdiff_t size_t Type support Variadic functions Variadic functions va_arg va_copy va_end va_list va_start
文字

在头文件<signal.h>中定义



void(* signal(int sig,void(* handler)(int)))(int);



设置信号sig的错误处理程序。 可以设置信号处理程序,以便进行默认处理,忽略信号或调用用户定义的函数。

当信号处理程序设置为函数并且发生信号时,会执行定义信号处理程序启动之前是否立即执行signal(sig,SIG_DFL)。 此外,该实现可以防止在信号处理程序运行时发生一些实现定义的信号集。

参数

sig

-

将信号处理程序设置为的信号。它可以是实现定义的值或以下值之一:SIGABRTSIGFPESIGILLSIGINTSIGSEGVSIGTERM定义信号类型(宏常量)

SIGABRTSIGFPESIGILLSIGINTSIGSEGVSIGTERM

定义信号类型(宏常量)


SIGABRTSIGFPESIGILLSIGINTSIGSEGVSIGTERM

定义信号类型(宏常量)





handler

-

信号处理程序。这必须是以下之一:SIG_DFL宏。信号处理程序设置为默认信号处理程序。SIG_IGN宏。信号被忽略。指向函数的指针。该函数的签名必须等同于以下内容:void fun(int sig);

void fun(int sig);



void fun(int sig);






  • SIG_DFL宏。信号处理程序设置为默认信号处理程序。

  • SIG_IGN宏。信号被忽略。

  • 指向函数的指针。该功能的签名必须等同于以下内容:

void fun(int sig);

返回值

成功则返回先前的信号处理程序,或失败时返回SIG_ERR(在某些实现中可以禁用信号处理程序)。

信号交易

作为信号处理程序安装的用户定义函数受到以下限制。

如果用户定义的函数在处理时返回SIGFPESIGILL或者SIGSEGV则行为未定义。

如果信号处理程序由于中止或提升而被调用,那么如果信号处理程序调用提升,则行为不确定。

如果信号处理程序由于中止或提升而被调用(换句话说,信号处理程序是异步的),则行为是不确定的。

  • 信号处理程序调用标准库中的任何函数,以下情况除外

    • abort

    • _Exit

    • quick_exit

    • signal 第一个参数是当前处理的信号的数量(异步处理程序可以重新注册自身,但不是其他信号)。

    • 如果原子参数是无锁的,则从stdatomic.h派生原子函数

    • atomic_is_lock_free (有任何种类的原子参数)

  • 信号处理程序引用任何静态或线程本地(自C11)存储持续时间的非锁定原子(自C11开始)以外的任何对象,而不是通过分配给静态volatile std::sig_atomic_t

在进入信号处理程序时,浮点环境的状态和所有对象的值是未指定的,除了。

  • 类型的对象 volatile sig_atomic_t

  • 无锁原子类型的对象(自C11开始)

  • 通过atomic_signal_fence(自C11以来)可见的副作用

从信号处理程序返回时,由信号处理程序修改的非易失性sig_atomic_t或无锁定原子(从C11开始)的任何对象的值都未定义。

如果signal在多线程程序中使用,则行为未定义。它不需要是线程安全的。

注意

POSIX要求这signal是线程安全的,并且指定可以从任何信号处理程序调用的异步信号安全库函数列表。

除了abortraise外,POSIX还指定kill,pthread_kill和sigqueue生成同步信号。

POSIX建议使用sigaction而不是signal,这是由于其信号处理器执行时的信号传递方面的指定行为和重要的实现变化。

#include <signal.h>#include <stdio.h>
 volatile sig_atomic_t gSignalStatus; void signal_handler(int signal){
  gSignalStatus = signal;}
 int main(void){  signal(SIGINT, signal_handler); 
  printf("SignalValue: %d\n", gSignalStatus);  printf("Sending signal: %d\n", SIGINT);  raise(SIGINT);  printf("SignalValue: %d\n", gSignalStatus);}

输出:

SignalValue: 0Sending signal: 2SignalValue: 2

参考

  • C11标准(ISO / IEC 9899:2011):

    • 7.14.1.1信号功能(p:266-267)

  • C99标准(ISO / IEC 9899:1999):

    • 7.14.1.1信号功能(p:247-248)

  • C89 / C90标准(ISO / IEC 9899:1990):

    • 4.7.1.1信号功能

扩展内容

raise

runs the signal handler for particular signal  (function)

| signal的C ++文档 |

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