select函数监控一个或多个文件描述符状态程序

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/* 一个文件描述符监控 */#include <stdio.h>#include <sys/time.h>#include <sys/types.h>#include <unistd.h>#include <sys/types.h>#include <sys/stat.h>#include <fcntl.h>#include <errno.h>#define PATH "/tmp/test_file"int main (void){int fd = 0;int fd_max = 0;fd_set fd_sets;fd_set handle_sets;int rs = 0;char buff[128] = {0};int i = 0;fd = open (PATH, O_RDWR | O_CREAT, 0664);if (fd <= 0)perror ("open:");FD_ZERO (&fd_sets);FD_SET (fd, &handle_sets);if (fd > fd_max) {fd_max = fd;}while (1) {if (i >= 1)break;fd_sets = handle_sets; // 保存handle_setsrs = select (fd_max + 1, &fd_sets, NULL, NULL, NULL);if(rs < 0){if(errno == EINTR){continue;}else{break;}}else if(rs == 0){continue;}else{if (FD_ISSET (fd, &fd_sets)) {rs = read (fd, buff, sizeof (buff));if (rs <= 0) {continue;}printf ("buff = %s\n", buff);lseek (fd, 0, SEEK_SET);i++;}}}return 0;}

/* 三个(多个)文件描述符监控 */#include <stdio.h>#include <sys/time.h>#include <sys/types.h>#include <unistd.h>#include <sys/types.h>#include <sys/stat.h>#include <fcntl.h>#include <errno.h>#define PATH1 "/tmp/test_file1"#define PATH2 "/tmp/test_file2"#define PATH3 "/tmp/test_file3"typedef struct device_file {char *file_name;int  fd;} device_file_t;static device_file_t g_device_file[] ={{PATH1, 0},{PATH2, 0},{PATH3, 0},};int main (void){int fd = 0;int fd_max = 0;fd_set fd_sets;fd_set handle_sets;int rs = 0;int i = 0;int index = 0;char buff[128] = {0};FD_ZERO (&fd_sets);for (index = 0; index < sizeof (g_device_file)/sizeof (device_file_t); index++){fd = 0;fd = open (g_device_file[index].file_name, O_RDWR | O_CREAT, 0664);if (fd <= 0)perror ("open:");g_device_file[index].fd = fd;FD_SET (fd, &handle_sets);if (fd > fd_max) {fd_max = fd;}}while (1) {if (i >= 1)break;fd_sets = handle_sets; rs = select (fd_max + 1, &fd_sets, NULL, NULL, NULL);if(rs < 0){if(errno == EINTR){continue;}else{break;}}else if(rs == 0){continue;}else{for (index = 0; index < sizeof (g_device_file)/sizeof (device_file_t); index++) {fd = g_device_file[index].fd;if (FD_ISSET (fd, &fd_sets)) {rs = read (fd, buff, sizeof (buff));if (rs <= 0) {continue;}printf ("buff = %s\n", buff);lseek (fd, 0, SEEK_SET);i++;}}}}return 0;}

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