b.c

linux中管道的使用示例

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <error.h>
#include <string.h>
#include <fcntl.h>

#define FIFO_INPUT "/tmp/input"
#define FIFO_REVERSE_RESULT "/tmp/result"

int main(int argc, char **argv)
{
    int iFDWrite = -1;
    int iFDRead = -1;
    char szBuffer[200] = {0};
    char szReverseBuffer[200] = {0};

    //create write and read pipe
    if(mkfifo(FIFO_INPUT, O_CREAT|O_EXCL) < 0)
    {
        perror("mkfifo() -- careate input pipe");
        return EXIT_FAILURE;
    }
    if(mkfifo(FIFO_REVERSE_RESULT, O_CREAT|O_EXCL) < 0)
    {
        perror("mkfifo() -- create result pipe");
        return EXIT_FAILURE;
    }

    //1.read data from input pipe 
    //2.reverse data
    //3.write reversed data to result pipe
    iFDRead = open(FIFO_INPUT, O_RDONLY|O_NONBLOCK, 0);    
    if(iFDRead < 0)
    {
        perror("open input pipe");
    }

    printf("Waitting for read data...\n");
    for(;;)
    {
        memset(szBuffer,0,200);
        int iRet = read(iFDRead, szBuffer, 200);
        if(iRet > 0)
        {
            printf("Read \"%s\" from input pipe.\nReverseing string...\n",szBuffer);
            int i = 0;
            for(i = 0; i < iRet; ++i)
            {
                szReverseBuffer[i] = szBuffer[iRet-i-1];  
            }
            iFDWrite = open(FIFO_REVERSE_RESULT, O_WRONLY|O_NONBLOCK, 0);
            if(iFDWrite < 0)
            {
                perror("open output pipe");
            }
            else
            {
                printf("Reversed data:%s\n",szReverseBuffer);
                write(iFDWrite,szReverseBuffer,iRet);
                printf("Write reversed string to output pipe.\n");
            }
            break;
        }
    }

    close(iFDWrite);
    iFDWrite = -1;
    close(iFDRead);
    iFDRead = -1;

    unlink(FIFO_INPUT);
    unlink(FIFO_REVERSE_RESULT);

    return EXIT_SUCCESS;
}