linux 下阻塞睡眠等待poll函数简单实现

/* int poll(struct pollfd *fds, nfds_t nfds, int timeout); */

/*
   struct pollfd {
   int   fd;         // file descriptor
   short events;     // requested events
   short revents;    // returned events
   };
 */
/*
   The  bits that may be set/returned in events and revents are defined in
   <poll.h>:
POLLIN: There is data to read.(数据可读)
POLLOUT:Writing now will not block.（数据可读）
 */

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代码片段(1)

[文件] main.c ~ 2KB    下载(18)

001#include <string.h>

002#include <stdio.h>

003#include <sys/types.h>

004#include <sys/stat.h>

005#include <fcntl.h>

006#include <errno.h>

007#include <poll.h>

008 

009/* int poll(struct pollfd *fds, nfds_t nfds, int timeout); */

010 

011/*

012   struct pollfd {

013   int   fd;         // file descriptor

014   short events;     // requested events

015   short revents;    // returned events

016   };

017 */

018/*

019   The  bits that may be set/returned in events and revents are defined in

020   <poll.h>:

021POLLIN: There is data to read.(数据可读)

022POLLOUT:Writing now will not block.（数据可读）

023 */

024 

025#define OPEN_FLAGS O_RDWR|O_CREAT

026#define OPEN_MODE  00777

027 

028#define W_DATA "howaylee"

029 

030int main(intargc, char* argv[])

031{

032    intret = -1;

033    intfd1 = -1;

034    intfd2 = -1;

035 

036    charr_buf[12] = {0};

037 

038    structpollfd fds[2] = {0};

039 

040    //open fd1

041    fd1 = open(argv[1], OPEN_FLAGS, OPEN_MODE);

042    if(-1 == fd1)

043    {

044        perror("open fd1 failed: ");

045        return-1;

046    }

047    //write fd1

048    ret = write(fd1, W_DATA,sizeof(W_DATA));

049    if(-1 == ret)

050    {

051        perror("write fd1 failed: ");

052        goto_OUT;

053    }

054    //lseek fd1 head

055    ret = lseek(fd1, 0, SEEK_SET);

056    if(-1 == ret)

057    {

058        perror("lseek fd1 failed: ");

059        goto_OUT;

060    }

061 

062    //open fd2

063    fd2 = open(argv[2], OPEN_FLAGS, OPEN_MODE);

064    if(-1 == fd2)

065    {

066        perror("open fd2 failed: ");

067        return-1;

068    }

069 

070    /*阻塞，等待程序读写操作*/

071 

072 

073    while(1)

074    {

075        //初始化pollfd

076        fds[0].fd = fd1;

077        //可读

078        fds[0].events = POLLIN;

079 

080        fds[1].fd = fd2;

081        //可写

082        fds[1].events = POLLOUT;

083 

084        //poll

085        ret = poll(fds,sizeof(fds)/sizeof(fds[0]), -1);

086        if(-1 == ret)

087        {

088            perror("poll failed: ");

089            goto_OUT;

090        }

091 

092        //read fd1

093        if(fds[0].revents & POLLIN )

094        {

095            //清空缓存

096            //memset(r_buf, 0, sizeof(r_buf));

097            ret = read(fd1, r_buf,sizeof(r_buf));

098            if(-1 == ret)

099            {

100                perror("poll read failed: ");

101                goto_OUT;

102            }

103            printf("read = %s\n", r_buf);

104        }

105 

106        //write fd2

107        if(fds[1].revents & POLLOUT )

108        {

109            ret = write(fd2, r_buf,sizeof(r_buf));

110            if(-1 == ret)

111            {

112                perror("poll write failed: ");

113                goto_OUT;

114            }

115            printf("write = %s\n", r_buf);

116        }

117    }

118 

119    //close fd1 fd2

120    close(fd1);

121    close(fd2);

122 

123_OUT:

124    returnret;

125}