我有两个程序,服务器和客户端。服务器应该读取一个文件,然后通过命名管道将其内容发送给客户端。但是我的服务器只从文件中读取两个字符,然后退出。这段代码有什么问题?
服务器.c:
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#define FIFO_NAME "american_maid"
int main(void)
{
char line[300];
int num, fd;
FILE *fp;
fp = fopen("out.txt","r");
mknod(FIFO_NAME, S_IFIFO | 0666, 0);
printf("waiting for readers...\n");
fd = open(FIFO_NAME, O_WRONLY);
printf("got a reader--type some stuff\n");
while (fgets(line, sizeof(line), fp)) {
if ((num = write(fd, line, strlen(line))) == -1)
perror("write");
else
printf("speak: wrote %d bytes\n", num);
}
fclose(fp);
return 0;
}
客户端.c:
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#define FIFO_NAME "american_maid"
int main(void)
{
char s[300];
int num, fd;
mknod(FIFO_NAME, S_IFIFO | 0666, 0);
printf("waiting for writers...\n");
fd = open(FIFO_NAME, O_RDONLY);
printf("got a writer\n");
do {
if ((num = read(fd, s, 300)) == -1)
perror("read");
else {
s[num] = '\0';
printf("tick: read %d bytes: \"%s\"\n", num, s);
}
} while (num > 0);
return 0;
}
最佳答案
当我使用命令序列运行下面显示的代码时:
$ ln -s server.c out.txt
$ ./client &
$ ./server
$
我得到一份由客户端程序打印的源代码。同样,当我使用以下命令运行命令时:
$ ./server &
$ ./client
$
修改后的代码并没有太大的修改。它避免了 do { } while(...)
循环——它们很少真正有益——并且非常小心不要溢出缓冲区。该代码还删除了多余的 header 。
服务器.c
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#define FIFO_NAME "american_maid"
int main(void)
{
const char infile[] = "out.txt";
FILE *fp = fopen(infile, "r");
if (fp == 0)
{
fprintf(stderr, "Failed to open %s for reading", infile);
return(1);
}
mknod(FIFO_NAME, S_IFIFO | 0666, 0);
printf("waiting for readers...\n");
int fd = open(FIFO_NAME, O_WRONLY);
if (fd > 0)
{
char line[300];
printf("got a reader--type some stuff\n");
while (fgets(line, sizeof(line), fp))
{
int len = strlen(line);
int num = write(fd, line, len);
if (num != len)
perror("write");
else
printf("speak: wrote %d bytes\n", num);
}
close(fd);
}
fclose(fp);
return 0;
}
客户端.c
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#define FIFO_NAME "american_maid"
int main(void)
{
const char outfile[] = "client.out";
FILE *fp = fopen(outfile, "w");
if (fp == 0)
{
fprintf(stderr, "Failed to open %s for writing\n", outfile);
return 1;
}
printf("waiting for writers...\n");
mknod(FIFO_NAME, S_IFIFO | 0666, 0);
int fd = open(FIFO_NAME, O_RDONLY);
if (fd > 0)
{
int num;
char s[300];
printf("got a writer\n");
while ((num = read(fd, s, sizeof(s))) > 0)
{
printf("tick: read %d bytes: \"%.*s\"\n", num, num, s);
fprintf(fp, "%.*s", num, s);
}
close(fd);
}
fclose(fp);
return 0;
}
请注意,此版本将其输出写入文件 client.out
;即使给定一个包含一些非常长的行要处理的文件(2049 字节,包括末尾的换行符),client.out
中的输出与 out.txt
中的输入完全匹配>.
关于c - 如何通过 C 中的命名管道发送文件?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/15957195/