{"id":700,"date":"2017-02-20T16:15:08","date_gmt":"2017-02-20T08:15:08","guid":{"rendered":"http:\/\/www.5x44.cn\/?p=700"},"modified":"2017-02-20T16:15:54","modified_gmt":"2017-02-20T08:15:54","slug":"sigsuspend%e5%87%bd%e6%95%b0","status":"publish","type":"post","link":"https:\/\/www.5x44.cn\/?p=700","title":{"rendered":"sigsuspend\u51fd\u6570"},"content":{"rendered":"

\u6211\u4eec\u5df2\u7ecf\u89c1\u8fc7\u5982\u4f55\u5bf9\u8fdb\u7a0b\u7684\u4fe1\u53f7\u63a9\u7801\u8fdb\u884c\u963b\u585e\u548c\u89e3\u9501\u3002\u6211\u4eec\u53ef\u4ee5\u901a\u8fc7\u8fd9\u79cd\u6280\u672f\u5bf9\u4e0d\u60f3\u88ab\u4fe1\u53f7\u4e2d\u65ad\u7684\u4ee3\u7801\u6bb5\u8fdb\u884c\u4fdd\u62a4\u3002\u5982\u679c\u6211\u4eec\u60f3\u89e3\u9501\u4e00\u4e2a\u4fe1\u53f7\u7136\u540epause\uff0c\u7b49\u5f85\u4e4b\u524d\u963b\u585e\u7684\u4fe1\u53f7\u518d\u6b21\u53d1\u751f\u4f1a\u600e\u4e48\u6837\uff1f\u5047\u8bbe\u6211\u4eec\u7b49\u5f85\u7684\u4fe1\u53f7\u662fSIGINT<\/span>\uff0c\u4e0d\u6b63\u786e\u7684\u65b9\u6cd5\u662f\uff1a<\/span><\/span><\/p>\n\n\n\n
\n
      sigset_t     newmask, oldmask;\r\n\r\n      sigemptyset(&newmask);\r\n      sigaddset(&newmask, SIGINT);\r\n\r\n      \/* block SIGINT and save current signal mask *\/\r\n      if (sigprocmask(SIG_BLOCK, &newmask, &oldmask) < 0)\r\n          err_sys(\"SIG_BLOCK error\");\r\n\r\n      \/* critical region of code *\/\r\n\r\n      \/* reset signal mask, which unblocks SIGINT *\/\r\n      if (sigprocmask(SIG_SETMASK, &oldmask, NULL) < 0)\r\n          err_sys(\"SIG_SETMASK error\");\r\n\r\n      \/* window is open *\/\r\n      pause();  \/* wait for signal to occur *\/\r\n\r\n      \/* continue processing *\/\r\n<\/span><\/pre>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\u5982\u679c\u4fe1\u53f7\u662f\u88ab\u963b\u585e\u72b6\u6001\u65f6\uff0c\u8fdb\u7a0b\u4f1a\u62d2\u6536\u8be5\u4fe1\u53f7\u76f4\u5230\u4fe1\u53f7\u88ab\u89e3\u9501\u3002\u5bf9\u4e8e\u6211\u4eec\u7684\u5e94\u7528\uff0c\u53ef\u4ee5\u770b\u505a\u4fe1\u53f7\u53d1\u751f\u5728\u672a\u89e3\u9501\u548cpause<\/span>\u4e4b\u95f4\uff08\u4f9d\u8d56\u4e8e\u5185\u6838\u5982\u4f55\u5b9e\u73b0\u4fe1\u53f7\uff09\u3002\u5982\u679c\u53d1\u751f\u5728\u8fd9\u4e2a\u65f6\u95f4\u6bb5\u5185\uff0c\u90a3\u4e48\u4f1a\u6709\u4e00\u4e2a\u95ee\u9898\u3002\u4efb\u4f55\u4fe1\u53f7\u53d1\u751f\u5728\u8fd9\u4e2a\u65f6\u95f4\u6bb5\u5185\u90fd\u4f1a\u4e22\u5931\uff0c\u6211\u4eec\u53ef\u80fd\u5c06\u4e0d\u4f1a\u518d\u6b21\u770b\u5230\u8be5\u4fe1\u53f7\u53d1\u751f\uff0c\u540e\u9762\u7684pause()<\/span>\u4f1a\u6c38\u4e45\u7684\u963b\u585e\u7a0b\u5e8f\u3002\u5bf9\u4e8e\u65e9\u671f\u4e0d\u53ef\u9760\u7684\u4fe1\u53f7\u8fd8\u6709\u5176\u5b83\u7684\u95ee\u9898\u3002<\/p>\n
\u6b63\u786e\u89e3\u51b3\u8fd9\u4e2a\u95ee\u9898\uff0c\u6211\u4eec\u987b\u8981\u5373\u91cd\u7f6e\u4fe1\u53f7\u63a9\u7801\u53c8\u80fd\u8ba9\u8fdb\u7a0b\u4f11\u7720\u7684\u539f\u5b50\u64cd\u4f5c\u3002\u8fd9\u4e2a\u529f\u80fd\u7531sigsuspend<\/span>\u51fd\u6570\u63d0\u4f9b\u3002<\/p>\n
 <\/p>\n\n\n\n
\n\n\n\n\n
\n
#include <signal.h>\r\n\r\nint sigsuspend(const sigset_t *sigmask<\/span>);\r\n<\/span><\/pre>\n<\/td>\n<\/tr>\n
\n
Returns: 1 with errno<\/tt> set to EINTR<\/tt><\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\u8fdb\u7a0b\u7684\u4fe1\u53f7\u63a9\u7801\u7531sigmask<\/em>\u53c2\u6570\u6307\u5411\u3002\u7136\u540e\u8fdb\u7a0b\u88ab\u6302\u8d77\u76f4\u5230\u4e00\u4e2a\u4fe1\u53f7\u88ab\u6355\u83b7\u6216\u8005\u76f4\u5230\u4e00\u4e2a\u4fe1\u53f7\u7ec8\u6b62\u4e86\u8fdb\u7a0b\u3002\u5982\u679c\u4e00\u4e2a\u4fe1\u53f7\u88ab\u6355\u83b7\u5e76\u4e14\u8be5\u4fe1\u53f7\u7684\u4fe1\u53f7\u5904\u7406\u51fd\u6570\u8fd4\u56de\uff0c\u4e4b\u540esigsuspend<\/span>\u8fd4\u56de\uff0c\u5e76\u4e14\u8fdb\u7a0b\u7684\u4fe1\u53f7\u63a9\u7801\u88ab\u8bbe\u7f6e\u6210\u8c03\u7528sigsuspend<\/span>\u4e4b\u524d\u7684\u503c\u3002<\/p>\n
\u6ce8\u610f\uff1a\u8fd9\u4e2a\u51fd\u6570\u6267\u884c\u6210\u529f\u540e\u6ca1\u6709\u8fd4\u56de\u503c\u3002\u5982\u679c\u8fd4\u56de\u5230\u8c03\u7528\u8005\uff0c\u5b83\u4e00\u76f4\u90fd\u662f\u8fd4\u56de1\uff0c\u5e76errno<\/span>\u8bbe\u7f6e\u6210EINTR<\/span>\uff08\u6307\u660e\u4e2d\u65ad\u4e86\u4e00\u4e2a\u7cfb\u7edf\u8c03\u7528\uff09<\/p>\n
\u4f8b\u5b50\uff1a<\/h1>\n
Figure10.22\u663e\u793a\u4e86\u4e00\u4e2a\u6b63\u786e\u5904\u7406\u9632\u6b62\u91cd\u8981\u4ee3\u7801\u6bb5\u88ab\u7279\u5b9a\u4fe1\u53f7\u4e2d\u65ad\u7684\u4f8b\u5b50\u3002<\/p>\n
\u6ce8\u610f\uff0c\u5f53sigsuspend<\/span>\u8fd4\u56de\u65f6\uff0c\u5b83\u8bbe\u7f6e\u8fdb\u7a0b\u7684\u4fe1\u53f7\u63a9\u7801\u662f\u8c03\u7528sigsuspend<\/span>\u51fd\u6570\u4e4b\u524d\u7684\u503c\u3002\u5728\u672c\u4f8b\u4e2d\u963b\u585eSIGINT<\/span>\u4fe1\u53f7\u3002\u56e0\u6b64\u6211\u4eec\u91cd\u7f6e\u4fe1\u53f7\u63a9\u7801\u5230\u4e4b\u524d\u4fdd\u5b58\u7684\u503c\uff08oldmask<\/span>\uff09\u3002<\/p>\n
\u8fd0\u884cFigure10.22\u7684\u8f93\u51fa\u5982\u4e0b\uff1a<\/p>\n\n\n\n
\n
   $ .\/a.out<\/span>\r\n   program start:\r\n   in critical region: SIGINT\r\n\r\n   ^?<\/span>                               type the interrupt character<\/span>\r\n   in sig_int: SIGINT SIGUSR1\r\n   after return from sigsuspend: SIGINT\r\n   program exit:\r\n<\/span><\/pre>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\u5f53\u6211\u4eec\u8c03\u7528sigsuspend<\/span>\u65f6\uff0c\u6dfb\u52a0\u4e86SIGUSR1<\/span>\u5230\u4fe1\u53f7\u63a9\u7801\u3002\u6240\u4ee5\u5f53\u4fe1\u53f7\u5904\u7406\u51fd\u6570\u8fd0\u884c\u65f6\uff0c\u6211\u4eec\u80fd\u544a\u4e4b\u4fe1\u53f7\u63a9\u7801\u5b9e\u9645\u4e0a\u5df2\u7ecf\u66f4\u6539\u4e86\u3002\u5f53sigsuspend<\/span>\u8fd4\u56de\u65f6\u6211\u4eec\u80fd\u770b\u5230\u5b83\u6062\u590d\u4e86\u4fe1\u53f7\u63a9\u7801\u5230\u8c03\u7528sigsuspend<\/span>\u4e4b\u524d\u7684\u503c\u3002<\/p>\n\n\n\n
\n
Figure 10.22. Protecting a critical region from a signal<\/h3>\n
#include \"apue.h\"\r\n\r\nstatic void sig_int(int);\r\n\r\nint\r\nmain(void)\r\n{\r\n    sigset_t    newmask, oldmask, waitmask;\r\n\r\n    pr_mask(\"program start: \");\r\n\r\n    if (signal(SIGINT, sig_int) == SIG_ERR)\r\n        err_sys(\"signal(SIGINT) error\");\r\n    sigemptyset(&waitmask);\r\n    sigaddset(&waitmask, SIGUSR1);\r\n    sigemptyset(&newmask);\r\n    sigaddset(&newmask, SIGINT);\r\n\r\n    \/*\r\n     * Block SIGINT and save current signal mask.\r\n     *\/\r\n    if (sigprocmask(SIG_BLOCK, &newmask, &oldmask) < 0)\r\n        err_sys(\"SIG_BLOCK error\");\r\n\r\n    \/*\r\n     * Critical region of code.\r\n     *\/\r\n    pr_mask(\"in critical region: \");\r\n\r\n    \/*\r\n     * Pause, allowing all signals except SIGUSR1.\r\n     *\/\r\n    if (sigsuspend(&waitmask) != -1)\r\n        err_sys(\"sigsuspend error\");\r\n\r\n    pr_mask(\"after return from sigsuspend: \");\r\n\r\n    \/*\r\n     * Reset signal mask which unblocks SIGINT.\r\n     *\/\r\n    if (sigprocmask(SIG_SETMASK, &oldmask, NULL) < 0)\r\n        err_sys(\"SIG_SETMASK error\");\r\n\r\n    \/*\r\n     * And continue processing ...\r\n     *\/\r\n    pr_mask(\"program exit: \");\r\n\r\n    exit(0);\r\n}\r\n\r\nstatic void\r\nsig_int(int signo)\r\n{\r\n    pr_mask(\"\\nin sig_int: \");\r\n<\/span><\/pre>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\u4f8b\u5b50<\/h1>\n
\u53e6\u4e00\u79cd\u4f7f\u7528sigsuspend<\/span>\u7684\u65b9\u6cd5\u662f\u7b49\u5f85\u4fe1\u53f7\u5904\u7406\u51fd\u6570\u8bbe\u7f6e\u5168\u5c40\u53d8\u91cf\u3002\u5728Figure10.23\u7684\u7a0b\u5e8f\u4e2d\u6211\u4eec\u6355\u83b7\u4e86\u4e2d\u65ad\u4fe1\u53f7\u548c\u9000\u51fa\u4fe1\u53f7\uff0c\u4f46\u662f\u6211\u4eec\u60f3\u5728\u6355\u83b7\u9000\u51fa\u4fe1\u53f7\u65f6\u5524\u9192\u4e3b\u51fd\u6570\u3002<\/p>\n
\u8be5\u7a0b\u5e8f\u7684\u7b80\u5355\u8f93\u51fa\u662f\uff1a<\/p>\n\n\n\n
\n
   $ .\/a.out<\/span>\r\n\r\n   ^?<\/span>                type the interrupt character<\/span>\r\n   interrupt\r\n\r\n   ^?<\/span>                type the interrupt character again<\/span>\r\n   interrupt\r\n\r\n   ^?<\/span>                and again<\/span>\r\n   interrupt\r\n\r\n   ^?<\/span>                and again<\/span>\r\n   interrupt\r\n\r\n   ^?<\/span>                and again<\/span>\r\n   interrupt\r\n\r\n   ^?<\/span>                and again<\/span>\r\n   interrupt\r\n\r\n   ^?<\/span>                and again<\/span>\r\n   interrupt\r\n\r\n   ^\\<\/span> $              now terminate with quit character<\/span><\/span><\/pre>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
 <\/p>\n\n\n\n
\n
Figure 10.23. Using sigsuspend<\/tt> to wait for a global variable to be set<\/h3>\n
#include \"apue.h\"\r\n\r\nvolatile sig_atomic_t    quitflag;    \/* set nonzero by signal handler *\/\r\n\r\nstatic void\r\nsig_int(int signo)  \/* one signal handler for SIGINT and SIGQUIT *\/\r\n{\r\n    if (signo == SIGINT)\r\n        printf(\"\\ninterrupt\\n\");\r\n    else if (signo == SIGQUIT)\r\n        quitflag = 1;   \/* set flag for main loop *\/\r\n}\r\n\r\nint\r\nmain(void)\r\n{\r\n     sigset_t     newmask, oldmask, zeromask;\r\n\r\n     if (signal(SIGINT, sig_int) == SIG_ERR)\r\n         err_sys(\"signal(SIGINT) error\");\r\n     if (signal(SIGQUIT, sig_int) == SIG_ERR)\r\n         err_sys(\"signal(SIGQUIT) error\");\r\n\r\n     sigemptyset(&zeromask);\r\n     sigemptyset(&newmask);\r\n     sigaddset(&newmask, SIGQUIT);\r\n\r\n     \/*\r\n      * Block SIGQUIT and save current signal mask.\r\n      *\/\r\n     if (sigprocmask(SIG_BLOCK, &newmask, &oldmask) < 0)\r\n         err_sys(\"SIG_BLOCK error\");\r\n\r\n     while (quitflag == 0)\r\n         sigsuspend(&zeromask);\r\n\r\n     \/*\r\n      * SIGQUIT has been caught and is now blocked; do whatever.\r\n      *\/\r\n     quitflag = 0;\r\n\r\n     \/*\r\n      * Reset signal mask which unblocks SIGQUIT.\r\n      *\/\r\n     if (sigprocmask(SIG_SETMASK, &oldmask, NULL) < 0)\r\n         err_sys(\"SIG_SETMASK error\");\r\n\r\n     exit(0);\r\n}\r\n<\/span><\/pre>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\u4e3a\u4e86\u5728\u652f\u6301ISO C\u7684\u975ePOSIX\u7cfb\u7edf\u548cPOSIX.1\u7cfb\u7edf\u95f4\u7684\u517c\u5bb9\u6027\uff0c\u6211\u4eec\u53ea\u8981\u5728\u4fe1\u53f7\u5904\u7406\u51fd\u6570\u4e2d\u505a\u4e00\u4ef6\u4e8b\u60c5\uff0c\u90a3\u5c31\u662f\u7ed9\u53d8\u91cf\u6dfb\u52a0\u4e00\u4e2asig_atomic_t<\/span>\u7684\u9650\u5b9a\u7b26\uff0c\u5176\u5b83\u7684\u4ec0\u4e48\u4e5f\u4e0d\u7528\u505a\u3002\u5728Figure10.4\u8fd9\u4e2a\u51fd\u6570\u5217\u8868\u4e2d\u7684\u51fd\u6570\u53ef\u4ee5\u5b89\u5168\u7684\u8fd0\u884c\u5728\u4fe1\u53f7\u51fd\u6570\u51fd\u6570\u4e2d\uff0c\u4f46\u662f\u5982\u679c\u6211\u4eec\u4f7f\u7528\u4e86sig_atomic_t<\/span>\u7684\u8bdd\uff0c\u6211\u4eec\u7684\u4ee3\u7801\u5c31\u53ef\u80fd\u5728\u975ePOSIX\u7684\u7cfb\u7edf\u4e0a\u6b63\u786e\u8fd0\u884c\u3002<\/p>\n\n\n\n
\n\n\n\n\n\n\n<\/colgroup>\n<\/thead>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
\n
Figure 10.4. Reentrant functions that may be called from a signal handler<\/h4>\n<\/caption>\n
\n
accept<\/tt><\/p>\n<\/td>\n
\n
fchmod<\/tt><\/p>\n<\/td>\n
\n
lseek<\/tt><\/p>\n<\/td>\n
\n
sendto<\/tt><\/p>\n<\/td>\n
\n
stat<\/tt><\/p>\n<\/td>\n<\/tr>\n
\n
access<\/tt><\/p>\n<\/td>\n
\n
fchown<\/tt><\/p>\n<\/td>\n
\n
lstat<\/tt><\/p>\n<\/td>\n
\n
setgid<\/tt><\/p>\n<\/td>\n
\n
symlink<\/tt><\/p>\n<\/td>\n<\/tr>\n
\n
aio_error<\/tt><\/p>\n<\/td>\n
\n
fcntl<\/tt><\/p>\n<\/td>\n
\n
mkdir<\/tt><\/p>\n<\/td>\n
\n
setpgid<\/tt><\/p>\n<\/td>\n
\n
sysconf<\/tt><\/p>\n<\/td>\n<\/tr>\n
\n
aio_return<\/tt><\/p>\n<\/td>\n
\n
fdatasync<\/tt><\/p>\n<\/td>\n
\n
mkfifo<\/tt><\/p>\n<\/td>\n
\n
setsid<\/tt><\/p>\n<\/td>\n
\n
tcdrain<\/tt><\/p>\n<\/td>\n<\/tr>\n
\n
aio_suspend<\/tt><\/p>\n<\/td>\n
\n
fork<\/tt><\/p>\n<\/td>\n
\n
open<\/tt><\/p>\n<\/td>\n
\n
setsockopt<\/tt><\/p>\n<\/td>\n
\n
tcflow<\/tt><\/p>\n<\/td>\n<\/tr>\n
\n
alarm<\/tt><\/p>\n<\/td>\n
\n
fpathconf<\/tt><\/p>\n<\/td>\n
\n
pathconf<\/tt><\/p>\n<\/td>\n
\n
setuid<\/tt><\/p>\n<\/td>\n
\n
tcflush<\/tt><\/p>\n<\/td>\n<\/tr>\n
\n
bind<\/tt><\/p>\n<\/td>\n
\n
fstat<\/tt><\/p>\n<\/td>\n
\n
pause<\/tt><\/p>\n<\/td>\n
\n
shutdown<\/tt><\/p>\n<\/td>\n
\n
tcgetattr<\/tt><\/p>\n<\/td>\n<\/tr>\n
\n
cfgetispeed<\/tt><\/p>\n<\/td>\n
\n
fsync<\/tt><\/p>\n<\/td>\n
\n
pipe<\/tt><\/p>\n<\/td>\n
\n
sigaction<\/tt><\/p>\n<\/td>\n
\n
tcgetpgrp<\/tt><\/p>\n<\/td>\n<\/tr>\n
\n
cfgetospeed<\/tt><\/p>\n<\/td>\n
\n
ftruncate<\/tt><\/p>\n<\/td>\n
\n
poll<\/tt><\/p>\n<\/td>\n
\n
sigaddset<\/tt><\/p>\n<\/td>\n
\n
tcsendbreak<\/tt><\/p>\n<\/td>\n<\/tr>\n
\n
cfsetispeed<\/tt><\/p>\n<\/td>\n
\n
getegid<\/tt><\/p>\n<\/td>\n
\n
posix_trace_event<\/tt><\/p>\n<\/td>\n
\n
sigdelset<\/tt><\/p>\n<\/td>\n
\n
tcsetattr<\/tt><\/p>\n<\/td>\n<\/tr>\n
\n
cfsetospeed<\/tt><\/p>\n<\/td>\n
\n
geteuid<\/tt><\/p>\n<\/td>\n
\n
pselect<\/tt><\/p>\n<\/td>\n
\n
sigemptyset<\/tt><\/p>\n<\/td>\n
\n
tcsetpgrp<\/tt><\/p>\n<\/td>\n<\/tr>\n
\n
chdir<\/tt><\/p>\n<\/td>\n
\n
getgid<\/tt><\/p>\n<\/td>\n
\n
raise<\/tt><\/p>\n<\/td>\n
\n
sigfillset<\/tt><\/p>\n<\/td>\n
\n
time<\/tt><\/p>\n<\/td>\n<\/tr>\n
\n
chmod<\/tt><\/p>\n<\/td>\n
\n
getgroups<\/tt><\/p>\n<\/td>\n
\n
read<\/tt><\/p>\n<\/td>\n
\n
sigismember<\/tt><\/p>\n<\/td>\n
\n
timer_getoverrun<\/tt><\/p>\n<\/td>\n<\/tr>\n
\n
chown<\/tt><\/p>\n<\/td>\n
\n
getpeername<\/tt><\/p>\n<\/td>\n
\n
readlink<\/tt><\/p>\n<\/td>\n
\n
signal<\/tt><\/p>\n<\/td>\n
\n
timer_gettime<\/tt><\/p>\n<\/td>\n<\/tr>\n
\n
clock_gettime<\/tt><\/p>\n<\/td>\n
\n
getpgrp<\/tt><\/p>\n<\/td>\n
\n
recv<\/tt><\/p>\n<\/td>\n
\n
sigpause<\/tt><\/p>\n<\/td>\n
\n
timer_settime<\/tt><\/p>\n<\/td>\n<\/tr>\n
\n
close<\/tt><\/p>\n<\/td>\n
\n
getpid<\/tt><\/p>\n<\/td>\n
\n
recvfrom<\/tt><\/p>\n<\/td>\n
\n
sigpending<\/tt><\/p>\n<\/td>\n
\n
times<\/tt><\/p>\n<\/td>\n<\/tr>\n
\n
connect<\/tt><\/p>\n<\/td>\n
\n
getppid<\/tt><\/p>\n<\/td>\n
\n
recvmsg<\/tt><\/p>\n<\/td>\n
\n
sigprocmask<\/tt><\/p>\n<\/td>\n
\n
umask<\/tt><\/p>\n<\/td>\n<\/tr>\n
\n
creat<\/tt><\/p>\n<\/td>\n
\n
getsockname<\/tt><\/p>\n<\/td>\n
\n
rename<\/tt><\/p>\n<\/td>\n
\n
sigqueue<\/tt><\/p>\n<\/td>\n
\n
uname<\/tt><\/p>\n<\/td>\n<\/tr>\n
\n
dup<\/tt><\/p>\n<\/td>\n
\n
getsockopt<\/tt><\/p>\n<\/td>\n
\n
rmdir<\/tt><\/p>\n<\/td>\n
\n
sigset<\/tt><\/p>\n<\/td>\n
\n
unlink<\/tt><\/p>\n<\/td>\n<\/tr>\n
\n
dup2<\/tt><\/p>\n<\/td>\n
\n
getuid<\/tt><\/p>\n<\/td>\n
\n
select<\/tt><\/p>\n<\/td>\n
\n
sigsuspend<\/tt><\/p>\n<\/td>\n
\n
utime<\/tt><\/p>\n<\/td>\n<\/tr>\n
\n
execle<\/tt><\/p>\n<\/td>\n
\n
kill<\/tt><\/p>\n<\/td>\n
\n
sem_post<\/tt><\/p>\n<\/td>\n
\n
sleep<\/tt><\/p>\n<\/td>\n
\n
wait<\/tt><\/p>\n<\/td>\n<\/tr>\n
\n
execve<\/tt><\/p>\n<\/td>\n
\n
link<\/tt><\/p>\n<\/td>\n
\n
send<\/tt><\/p>\n<\/td>\n
\n
socket<\/tt><\/p>\n<\/td>\n
\n
waitpid<\/tt><\/p>\n<\/td>\n<\/tr>\n
\n
_Exit & _exit<\/tt><\/p>\n<\/td>\n
\n
listen<\/tt><\/p>\n<\/td>\n
\n
sendmsg<\/tt><\/p>\n<\/td>\n
\n
socketpair<\/tt><\/p>\n<\/td>\n
\n
write<\/tt><\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\u4f8b\u5b50<\/h1>\n
\u53e6\u4e00\u4e2a\u4fe1\u53f7\u7684\u4f8b\u5b50\uff0c\u6211\u4eec\u663e\u793a\u4e86\u4fe1\u53f7\u66fe\u7ecf\u80fd\u7528\u4e8e\u540c\u6b65\u7236\u5b50\u8fdb\u7a0b\u3002Figure10.24\u663e\u793a\u4e868.9\u8282\u4e2d\u4e94\u4e2a\u4f8b\u7a0b\u7684\u5b9e\u73b0\uff1aTELL_WAIT<\/span>\uff0cTELL_PARENT<\/span>\uff0cTELL_CHILD<\/span>\uff0cWAIT_PARENT<\/span>\u548cWAIT_CHILD<\/span>\u3002<\/p>\n
\u6211\u4eec\u4f7f\u7528\u4e24\u4e2a\u7528\u6237\u5b9a\u4e49\u4fe1\u53f7\uff1aSIGUSR1<\/span>\u4fe1\u53f7\u662f\u7528\u6765\u4ece\u7236\u8fdb\u7a0b\u53d1\u5411\u5b50\u8fdb\u7a0b\u7684\uff0cSIGUSR2<\/span>\u662f\u7531\u5b50\u8fdb\u7a0b\u53d1\u5f80\u7236\u8fdb\u7a0b\u7684\u3002\u5728\u4e4b\u524dFigure15.7\u4e2d\u663e\u793a\u4e86\u8fd9\u4e94\u4e2a\u51fd\u6570\u4eba\u4f7f\u7528\u7ba1\u9053\u7684\u5b9e\u73b0\u3002<\/p>\n\n\n\n
\n
Figure 10.24. Routines to allow a parent and child to synchronize<\/h4>\n
#include \"apue.h\"\r\n\r\nstatic volatile sig_atomic_t sigflag; \/* set nonzero by sig handler *\/\r\nstatic sigset_t newmask, oldmask, zeromask;\r\n\r\nstatic void\r\nsig_usr(int signo)   \/* one signal handler for SIGUSR1 and SIGUSR2 *\/\r\n{\r\n    sigflag = 1;\r\n}\r\n\r\nvoid\r\nTELL_WAIT(void)\r\n{\r\n    if (signal(SIGUSR1, sig_usr) == SIG_ERR)\r\n        err_sys(\"signal(SIGUSR1) error\");\r\n    if (signal(SIGUSR2, sig_usr) == SIG_ERR)\r\n        err_sys(\"signal(SIGUSR2) error\");\r\n    sigemptyset(&zeromask);\r\n    sigemptyset(&newmask);\r\n    sigaddset(&newmask, SIGUSR1);\r\n    sigaddset(&newmask, SIGUSR2);\r\n\r\n    \/*\r\n     * Block SIGUSR1 and SIGUSR2, and save current signal mask.\r\n     *\/\r\n    if (sigprocmask(SIG_BLOCK, &newmask, &oldmask) < 0)\r\n        err_sys(\"SIG_BLOCK error\");\r\n}\r\n\r\nvoid\r\nTELL_PARENT(pid_t pid)\r\n{\r\n    kill(pid, SIGUSR2);              \/* tell parent we're done *\/\r\n}\r\n\r\nvoid\r\nWAIT_PARENT(void)\r\n{\r\n    while (sigflag == 0)\r\n        sigsuspend(&zeromask);   \/* and wait for parent *\/\r\n    sigflag = 0;\r\n\r\n    \/*\r\n     * Reset signal mask to original value.\r\n     *\/\r\n    if (sigprocmask(SIG_SETMASK, &oldmask, NULL) < 0)\r\n        err_sys(\"SIG_SETMASK error\");\r\n}\r\n\r\nvoid\r\nTELL_CHILD(pid_t pid)\r\n{\r\n    kill(pid, SIGUSR1);             \/* tell child we're done *\/\r\n}\r\n\r\nvoid\r\nWAIT_CHILD(void)\r\n{\r\n    while (sigflag == 0)\r\n        sigsuspend(&zeromask);  \/* and wait for child *\/\r\n    sigflag = 0;\r\n\r\n    \/*\r\n     * Reset signal mask to original value.\r\n     *\/\r\n    if (sigprocmask(SIG_SETMASK, &oldmask, NULL) < 0)\r\n        err_sys(\"SIG_SETMASK error\");\r\n}\r\n<\/span><\/pre>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\u5982\u679c\u6211\u4eec\u60f3\u8ba9\u8fdb\u7a0b\u4f11\u7720\u5e76\u7b49\u5f85\u4fe1\u53f7\u53d1\u751fsigsuspend<\/span>\u51fd\u6570\u5f88\u9002\u5408\uff0c\u4f46\u662f\u5982\u679c\u6211\u4eec\u60f3\u5728\u7b49\u5f85\u7684\u540c\u65f6\u8c03\u7528\u5176\u5b83\u7cfb\u7edf\u51fd\u6570\u4f1a\u53d1\u751f\u4ec0\u4e48\uff1f\u5f88\u4e0d\u5e78\uff0c\u6211\u4eec\u6ca1\u6709\u89e3\u51b3\u65b9\u6cd5\uff0c\u9664\u975e\u4f7f\u7528\u591a\u7ebf\u7a0b\u65f6\u8ba9\u4e00\u4e2a\u5355\u72ec\u7684\u7ebf\u7a0b\u5904\u7406\u4fe1\u53f7\uff0c\u6211\u4eec\u5c06\u4f1a\u5728APUE12.8\u8282\u770b\u5230\u3002<\/p>\n
\u5728\u6ca1\u6709\u4f7f\u7528\u7ebf\u7a0b\u65f6\uff0c\u6211\u4eec\u6700\u597d\u662f\u5728\u5f53\u4fe1\u53f7\u53d1\u751f\u65f6\u5728\u4fe1\u53f7\u5904\u7406\u51fd\u6570\u4e2d\u8bbe\u7f6e\u4e00\u4e2a\u5168\u5c40\u53d8\u91cf\u3002\u4f8b\u5982\uff1a\u5982\u4f55\u6211\u4eec\u8981\u6355\u83b7SIGINT<\/span>\u548cSIGALRM<\/span>\uff0c\u5e76\u4e14\u4f7f\u7528signal_intr<\/span>\u51fd\u6570\u5b89\u88c5\u4fe1\u53f7\u5904\u7406\u51fd\u6570\uff0c\u4fe1\u53f7\u4f1a\u4e2d\u65ad\u4efb\u4f55\u6162\u7cfb\u7edf\u8c03\u7528\uff0c\u4f7f\u5176\u88ab\u963b\u585e\u3002\u4fe1\u53f7\u591a\u6570\u4f1a\u53d1\u751f\u5728\u5f53\u6211\u4eec\u88ab\u963b\u585e\u5728select<\/span>\u51fd\u6570\u4e2d\u7b49\u5f85\u4e00\u4e2a\u6162\u8bbe\u5907\u8f93\u5165\u65f6\u3002\uff08\u7279\u522b\u662f\u5bf9\u4e8eSIGALRM<\/span>\uff0c\u56e0\u4e3a\u6211\u4eec\u8bbe\u7f6e\u4e00\u4e2a\u8b66\u544a\u65f6\u949f\u9632\u6b62\u6211\u4eec\u4e00\u76f4\u7b49\u5f85\u90a3\u4e2a\u8f93\u5165\u3002\uff09\u4ee3\u7801\u770b\u8d77\u6765\u50cf\u5982\u4e0b\uff1a<\/p>\n\n\n\n
\n
       if (intr_flag)       \/* flag set by our SIGINT handler *\/\r\n           handle_intr();\r\n       if (alrm_flag)       \/* flag set by our SIGALRM handler *\/\r\n           handle_alrm();\r\n\r\n       \/* signals occurring in here are lost *\/\r\n\r\n       while (select( ... ) < 0) {\r\n           if (errno == EINTR) {\r\n               if (alrm_flag)\r\n                   handle_alrm();\r\n               else if (intr_flag)\r\n                   handle_intr();\r\n          } else {\r\n              \/* some other error *\/\r\n          }\r\n      }\r\n<\/span><\/pre>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\u5982\u679cselect<\/span>\u8fd4\u56de\u4e00\u4e2a\u7cfb\u7edf\u8c03\u7528\u9519\u8bef\uff0c\u90a3\u4e48\u6211\u4eec\u5728\u8c03\u7528select<\/span>\u4e4b\u524d\u518d\u6b21\u6d4b\u8bd5\u5168\u5c40\u6807\u8bb0\u3002\u5982\u679c\u4fe1\u53f7\u5728\u524d\u4e24\u4e2aif<\/span>\u548c\u968f\u540e\u7684select<\/span>\u4e4b\u95f4\u5c31\u4f1a\u6709\u95ee\u9898\u53d1\u751f\u3002\u5df2\u7ecf\u5728\u7a0b\u5e8f\u7684\u6ce8\u91ca\u5904\u5199\u660e\u3002\u4fe1\u53f7\u5904\u7406\u51fd\u6570\u88ab\u8c03\u7528\uff0c\u5e76\u4e14\u5b83\u4eec\u8bbe\u7f6e\u9002\u5f53\u7684\u5168\u5c40\u51fd\u6570\uff0c\u4f46\u662fselect\u7edd\u5bf9\u4e0d\u4f1a\u8fd4\u56de\uff08\u9664\u975e\u6709\u4e00\u4e9b\u6570\u636e\u51c6\u5907\u8bfb\u53d6\uff09\u3002<\/p>\n
\u4e0b\u9762\u7684\u6b65\u9aa4\u662f\u6211\u4eec\u5e94\u8be5\u80fd\u53bb\u505a\u7684\uff0c\u987a\u5e8f\u662f\uff1a<\/p>\n
    \n
  1. \u963b\u585eSIGINT<\/span>\u548cSIGALRM<\/span>\u3002<\/li>\n
  2. \u6d4b\u8bd5\u4e24\u4e2a\u5168\u5c40\u53d8\u91cf\uff0c\u5e76\u67e5\u770b\u5b83\u4eec\u662f\u5426\u67d0\u4e2a\u4fe1\u53f7\u5df2\u7ecf\u53d1\u751f\u4e86\uff0c\u5982\u679c\u53d1\u751f\u4e86\uff0c\u5904\u7406\u8fd9\u4e2a\u6761\u4ef6\u3002<\/li>\n
  3. \u8c03\u7528select<\/span>\uff08\u6216\u4efb\u4f55\u5176\u5b83\u7cfb\u7edf\u51fd\u6570\uff0c\u7c7b\u4f3cread<\/span>\uff09\u5e76\u89e3\u9501\u4e24\u4e2a\u4fe1\u53f7\uff0c\u7c7b\u4f3c\u4e00\u4e2a\u539f\u5b50\u64cd\u4f5c\u3002<\/li>\n<\/ol>\n
    \u53ea\u6709\u5f53\u7b2c\u4e09\u6b65\u662f\u4e00\u4e2apause<\/span>\u64cd\u4f5c\u65f6\uff0csigsuspend<\/span>\u51fd\u6570\u624d\u5bf9\u6211\u4eec\u6709\u7528\u3002\uff08The sigsuspend function helps us only if step 3 is a pause operation.\uff09<\/p>\n","protected":false},"excerpt":{"rendered":"
    \u6211\u4eec\u5df2\u7ecf\u89c1\u8fc7\u5982\u4f55\u5bf9\u8fdb\u7a0b\u7684\u4fe1\u53f7\u63a9\u7801\u8fdb\u884c\u963b\u585e\u548c\u89e3\u9501\u3002\u6211\u4eec\u53ef\u4ee5\u901a\u8fc7\u8fd9\u79cd\u6280\u672f\u5bf9\u4e0d\u60f3\u88ab\u4fe1\u53f7\u4e2d\u65ad\u7684\u4ee3\u7801\u6bb5\u8fdb\u884c\u4fdd\u62a4\u3002\u5982\u679c\u6211\u4eec\u60f3\u89e3\u9501\u4e00\u4e2a\u4fe1\u53f7\u7136\u540epause\uff0c\u7b49\u5f85\u4e4b\u524d\u963b\u585e\u7684\u4fe1\u53f7\u518d…<\/p>\n
     Read More  Read More<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[18],"tags":[],"class_list":["post-700","post","type-post","status-publish","format-standard","hentry","category-apue"],"_links":{"self":[{"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/posts\/700","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=700"}],"version-history":[{"count":9,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/posts\/700\/revisions"}],"predecessor-version":[{"id":709,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/posts\/700\/revisions\/709"}],"wp:attachment":[{"href":"https:\/\/www.5x44.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=700"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=700"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=700"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}