没有这一步内核不会知道应该将信号发送给哪个进程fcntl(STDIN_FILENO, F_SETOWN, getpid());//获得文件的状态标志oflags =fcntl(STDIN_FILENO, F_GETFL);//启动异步通知机制fcntl(STDIN_FILENO, F_SETFL, oflags |FASYNC);while(1);
I found the following code will yield panic output in windows bash: int flags = fcntl(fd, F_GETFL); if (flags == -1) panic("Could not set up async IO"); if (set) flags |= FASYNC; else flags &= ~(FASYNC); if (set) { if (fcntl(fd, F_SETOWN...
在此基础上设置socket 为异步模式,也就是说当I/O操作可执行时,操作系统会向进程发送SIGIO信号 【这个是我们关注的重点】 至于为什么系统内核会向用户进程发送SIGIO信号,可以查看socket源码分析那篇文章sock_fasync这个函数的原理。 #include<iostream>#include<csignal>#include<cstring>#include<unistd.h>#include<fcn...
fcntl(sg_fd, F_SETFL, oflags | FASYNC)www.tldp.org/HOWTO/SCSI-Generic-HOWTO/fcntl.html ...
Flags There are several types of flags associated with each open object. Flags for an object are represented by symbols defined in the <fcntl.h> header file. The followingfile statusflags can be associated with an object: FASYNCTheSIGIOsignal is sent to the process when it is possible to do...
FASYNC A synonym forO_ASYNC. FNDELAY A synonym forO_NDELAY. F_GETFL Get the file status flags and file access modes for the specified file descriptor. These flags are as specified for theoflagargument toopen(), along with the additional values described forF_SETFL. File status flags and fil...
F_SETFD 设置close-on-exec 旗标。该旗标以参数arg 的FD_CLOEXEC位决定。 F_GETFL 取得文件描述词状态旗标,此旗标为open()的参数flags。 F_SETFL 设置文件描述词状态旗标,参数arg为新旗标,但只允许O_APPEND、O_NONBLOCK和O_ASYNC位的改变,其他位的改变将不受影响。
Equivalent to C<qw(FAPPEND FASYNC FCREAT FDEFER FDSYNC FEXCL FLARGEFILE FNDELAY FNONBLOCK FRSYNC FSYNC FTRUNC)>. These only exist for compatibility with old code (if your platform defines them at all) and should not be used in new code. =back =head2 Symbols for use with C<fcntl> ...
而在Linux系统中,实现文件锁的函数之一就是fcntl()函数。fcntl()函数是Unix/Linux系统中的文件控制函数,它可以对文件描述符进行各种控制操作,其中包括文件锁。 在Linux系统中,fcntl()函数的原型是: ``` intfcntl(int fd, int cmd, ... /* str 文件锁...
When theFileDescriptorparameter refers to a shared memory object, thefcntlsubroutine manages only theF_DUPFD,F_DUP2FD,F_GETFD,F_SETFD,F_GETFL, andF_CLOSEMcommands. When using thelibbsd.alibrary, asynchronous I/O is enabled by using theF_SETFLcommand with theFASYNCflag set in theArgumentparam...