第三版str_cli(select加非阻塞I/O)

#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <time.h>
#include <sys/time.h>
#include <errno.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
#include <sys/types.h>
#include <sys/select.h>

#define SERV_ADDR "127.0.0.1"
#define SERV_PORT 5358
#define BUF_LEN 1024

#define MAX(a, b) (a)>(b)?(a):(b)

ssize_t writen(int fd, const void *vptr, size_t n)
{
    size_t nleft;
    ssize_t nwriten;
    const char *ptr;

    ptr = vptr;
    nleft = n;
    while(nleft>0) {
        if((nwriten = write(fd, ptr, nleft)) <= 0) {
            if(nwriten < 0 && errno == EINTR) {
                nwriten = 0;        /*interrupt by signal*/
            } else {
                return -1;
            }
        }

        nleft -= nwriten;
        ptr += nwriten;
    }
    return n;
}

char *gf_time()
{
    struct timeval tv;
    static char str[30];
    char *ptr;

    if(gettimeofday(&tv, NULL) < 0)
        printf("gettimeofday error.\n");

    ptr = ctime(&tv.tv_sec);
    strcpy(str, &ptr[11]);
    snprintf(str+8, sizeof(str)-8, ".%06ld", tv.tv_usec);

    return str;
}

void str_cli(FILE *fp, int sockfd)
{
    int maxfdp1, val, stdineof;
    ssize_t n, nwritten;
    fd_set rset, wset;
    char to[BUF_LEN] = {0}, fr[BUF_LEN] = {0};
    char *toiptr, *tooptr, *froptr, *friptr;

    val = fcntl(sockfd, F_GETFL, 0);
    fcntl(sockfd, F_SETFL, val | O_NONBLOCK);

    val = fcntl(STDIN_FILENO, F_GETFL, 0);
    fcntl(STDIN_FILENO, F_SETFL, val | O_NONBLOCK);

    val = fcntl(STDOUT_FILENO, F_GETFL, 0);
    fcntl(STDOUT_FILENO, F_SETFL, val | O_NONBLOCK);

    toiptr = tooptr = to;
    friptr = froptr = fr;
    stdineof = 0;

    maxfdp1 = MAX(MAX(STDIN_FILENO, STDOUT_FILENO), sockfd) + 1;

    while(1) {
        FD_ZERO(&rset);
        FD_ZERO(&wset);
        if(stdineof == 0 && toiptr < &to[BUF_LEN])
            FD_SET(STDIN_FILENO, &rset);
        if(friptr < &fr[BUF_LEN])
            FD_SET(sockfd, &rset);
        if(tooptr != toiptr)
            FD_SET(sockfd, &wset);
        if(froptr != friptr)
            FD_SET(STDOUT_FILENO, &wset);
        select(maxfdp1, &rset, &wset, NULL, NULL);

        if(FD_ISSET(STDIN_FILENO, &rset)) {
            if((n = read(STDIN_FILENO, toiptr, &to[BUF_LEN] - toiptr)) < 0) {
                if(errno != EAGAIN) {
                    printf("read error\n");
                    return;
                }
            } else if(n == 0) {
                fprintf(stderr, "%s: EOF on stdin\n", gf_time());
                stdineof = 1;
                if(tooptr == toiptr)
                    shutdown(sockfd, SHUT_WR);
            } else {
                fprintf(stderr, "%s: read %d bytes from stdin\n", gf_time(), n);
                toiptr += n;
                FD_SET(sockfd, &wset);
            }
        }
        if(FD_ISSET(sockfd, &rset)) {
            if((n = read(sockfd, friptr, &fr[BUF_LEN] - friptr)) < 0) {
                if(errno != EAGAIN) {
                    printf("read error\n");
                    return;
                }
            } else if(n == 0) {
                fprintf(stderr, "%s: EOF on socket\n", gf_time());
                if(stdineof)
                    return;
                else {
                    printf("strcli: server terminated prematurely!\n");
                    return;
                }
            } else {
                fprintf(stderr, "%s: read %d bytes from socket\n", gf_time(), n);
                friptr += n;
                FD_SET(STDOUT_FILENO, &wset);
            }
        }
        if(FD_ISSET(STDOUT_FILENO, &wset) && ((n = friptr - froptr) > 0)) {
            if((nwritten = write(STDOUT_FILENO, froptr, n)) < 0) {
                if(errno != EWOULDBLOCK)
                    printf("write error to stdout.\n");
            } else {
                fprintf(stderr, "%s: wrote %d bytes to stdout\n", gf_time(), nwritten);
                froptr += nwritten;
                if(froptr == friptr)
                    froptr = friptr = fr;
            }
        }
        if(FD_ISSET(sockfd, &wset) && ((n = toiptr - tooptr) > 0 )) {
            if((nwritten = write(sockfd, tooptr, n)) < 0) {
                if(errno != EWOULDBLOCK)
                    printf("write error to socket.\n");
            } else {
                fprintf(stderr, "%s: wrote %d bytes to socket\n", gf_time(), nwritten);
                tooptr += nwritten;
                if(tooptr == toiptr) {
                    tooptr = toiptr = to;
                    if(stdineof)
                        shutdown(sockfd, SHUT_WR);
                }
            }
        }
    }
    return;
}

int main(int argc, char **argv)
{
    int fd;
    struct sockaddr_in servaddr;

    fd = socket(AF_INET, SOCK_STREAM, 0);

    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = inet_addr(SERV_ADDR);
    servaddr.sin_port = htons(SERV_PORT);

    if (connect(fd, (struct sockaddr *)&servaddr, sizeof(servaddr)) == -1) {
        printf("connect error: %s\n", strerror(errno));
        return 0;
    }

    str_cli(stdin, fd);
    return 0;
}