我正在使用管道编写一个协同处理程序。当孩子读取一些数据,处理并输出它时,它工作正常。但是当我读取所有数据并处理它时,它只是挂起。任何机构有一些想法?谢谢你。
这是源代码:
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
int main()
{
#define MAXSIZE 1024
char workload[MAXSIZE];
char result[MAXSIZE];
workload[strlen(workload)] = EOF;
int workload_size = strlen(workload);
int fd1[2], fd2[2];
int n;
pid_t pid;
if (pipe(fd1) < 0 || pipe(fd2) < 0) {
fprintf(stderr, "pipe error: %s\n", strerror(errno));
exit(1);
}
if ((pid = fork()) < 0) {
fprintf(stderr, "fork error: %s\n", strerror(errno));
exit(1);
} else if (pid > 0) {
close(fd1[0]);
close(fd2[1]);
while(fgets(workload, MAXSIZE, stdin) != NULL)
{
workload_size = strlen(workload);
if (write(fd1[1], workload, workload_size) != workload_size) {
fprintf(stderr, "write to pipe error: %s\n", strerror(errno));
exit(1);
}
if ((n = read(fd2[0], result, MAXSIZE)) < 0) {
fprintf(stderr, "read from pipe error: %s\n", strerror(errno));
exit(1);
}
if (n == 0) {
fprintf(stderr, "child closed the pipe\n");
exit(1);
}
result[n] = 0;
if (puts(result) == EOF) {
fprintf(stderr, "fputs error\n");
exit(1);
}
}
} else {
close(fd1[1]);
close(fd2[0]);
if (fd1[0] != STDIN_FILENO) {
if (dup2(fd1[0] ,STDIN_FILENO) != STDIN_FILENO) {
fprintf(stderr, "dup2 error to stdin.\n");
exit(1);
}
close(fd1[0]);
}
if (fd2[1] != STDOUT_FILENO) {
if (dup2(fd2[1] ,STDOUT_FILENO) != STDOUT_FILENO) {
fprintf(stderr, "dup2 error to stdout.\n");
exit(1);
}
close(fd2[1]);
}
if (execl("./a.out", "a.out", NULL) < 0) {
fprintf(stderr, "execl error: %s\n", strerror(errno));
exit(1);
}
exit(0);
}
return 0;
}
这是 a.out 的源代码,它适用于这个:
#include <stdio.h>
#include <string.h>
int main()
{
#define MAXSIZE 1024
char x[MAXSIZE];
int n;
while(scanf("%s", x) != EOF)
{
printf("len:%d %s", strlen(x), x);
fflush(stdout);
}
return 0;
}
但是当我编写这样的代码时,它似乎只是悬而未决:
#include <stdio.h>
#include <string.h>
int main()
{
#define MAXSIZE 1024
char x[MAXSIZE];
int n;
while(scanf("%s", x) != EOF);
printf("Ok\n");
fflush(stdout);
return 0;
}