06-file_io.zip_file操作_linux poll

/* multiplex_select.c */ #include <fcntl.h> #include <stdio.h> #include <unistd.h> #include <stdlib.h> #include <time.h> #include <errno.h> #define MAX_BUFFER_SIZE 1024 /* 缓冲区大小*/ #define IN_FILES 3 /* 多路复用输入文件数目*/ #define TIME_DELAY 60 /* 超时时间秒数 */ #define MAX(a, b) ((a > b)?(a):(b)) int main(void) { int fds[IN_FILES]; char buf[MAX_BUFFER_SIZE]; int i, res, real_read, maxfd; struct timeval tv; fd_set inset,tmp_inset; /*首先按一定的权限打开两个源文件*/ fds[0] = 0; if((fds[1] = open ("in1", O_RDONLY|O_NONBLOCK)) < 0) { printf("Open in1 error\n"); return 1; } if((fds[2] = open ("in2", O_RDONLY|O_NONBLOCK)) < 0) { printf("Open in2 error\n"); return 1; } /*取出两个文件描述符中的较大者*/ maxfd = MAX(MAX(fds[0], fds[1]), fds[2]); /*初始化读集合inset，并在读集合中加入相应的描述集*/ FD_ZERO(&inset); for (i = 0; i < IN_FILES; i++) { FD_SET(fds[i], &inset); } FD_SET(0, &inset); tv.tv_sec = TIME_DELAY; tv.tv_usec = 0; /*循环测试该文件描述符是否准备就绪，并调用select函数对相关文件描述符做对应操作*/ while(FD_ISSET(fds[0],&inset) || FD_ISSET(fds[1],&inset) || FD_ISSET(fds[2], &inset)) { tmp_inset = inset; res = select(maxfd + 1, &tmp_inset, NULL, NULL, &tv); switch(res) { case -1: { printf("Select error\n"); return 1; } break; case 0: /* Timeout */ { printf("Time out\n"); return 1; } break; default: { for (i = 0; i < IN_FILES; i++) { if (FD_ISSET(fds[i], &tmp_inset)) { memset(buf, 0, MAX_BUFFER_SIZE); real_read = read(fds[i], buf, MAX_BUFFER_SIZE); if (real_read < 0) { if (errno != EAGAIN) { return 1; } } else if (!real_read) { close(fds[i]); FD_CLR(fds[i], &inset); } else { if (i == 0) { if ((buf[0] == 'q') || (buf[0] == 'Q')) { return 1; } } else { buf[real_read] = '\0'; printf("%s", buf); } } } /* end of if */ } /* end of for */ } break; } /* end of switch */ } /*end of while */ exit(0); }