我正在尝试编写一个递归程序，以便使用fork构建一个进程树。我想我会根据级别数和子项数正确构建树。但是，当我想要退出时，我继续在树上建造，我超过了孩子和水平的数量，因此我最终没有正确退出。
这是我的代码和示例输入和输出。请注意，需要在命令行参数中指定子级数和级别数。
代码：
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <errno.h>
int level;
static void run_process(const char *child, int lev)
{
fprintf(stderr, "ALIVE: Level %d process with pid= %ld child of ppid=%ld\n",
lev, (long)getpid(), (long)getppid());
}
int fork_level (int l, int c){
int i;
pid_t rightchild;
if (l>=level){
fprintf(stderr, "Exiting: Level %d with pid= %ld, child of ppid= %ld\n",l, (long)getpid(), (long)getppid());
exit (1) ;
}
else {
for (i=0; i<c; i++){
if ((rightchild = fork()) < 0)
{
fprintf(stderr, "can't fork, error %d\n", errno);
return 0;
}
else if (rightchild == 0)
{
run_process("Right", l);
fork_level (++l, c);
}
}
for (i=0; i<c; i++){
wait (NULL);
}
fprintf(stderr, "Exiting: Level %d with pid= %ld, child of ppid= %ld\n",l, (long)getpid(), (long)getppid());
}
}
main(int argc, char *argv[])
{
int i, N=0, M=0, I=0, pflag=0, uflag =0;
char Nchar [3], Mchar [3], ichar [3];
for (i = 1; i < argc; i++) {
if (strcmp (argv[i], "-u")==0 ){
uflag=1;
}
else if (strcmp (argv[i], "-N")==0){
i++;
strcpy (Nchar, argv[i]);
N= atoi (Nchar);
}
else if (strcmp (argv[i], "-M")==0){
i++;
strcpy (Nchar, argv[i]);
level= atoi (Nchar);
}
else if (strcmp (argv[i], "-p")==0){
pflag=1;
}
else if (strcmp (argv[i], "-s")==0){
i++;
strcpy (ichar, argv[i]);
I= atoi (ichar);
}
}
if (uflag==1){
printf ("u.....\n");
}
fork_level (0, N);
}
以下是我运行代码./main -u -N 2 -M 2的方法
这是样本输出：
ALIVE: Level 0 process with pid= 26534 child of ppid=26533
ALIVE: Level 0 process with pid= 26535 child of ppid=26533
ALIVE: Level 1 process with pid= 26536 child of ppid=26534
ALIVE: Level 1 process with pid= 26538 child of ppid=26534
ALIVE: Level 1 process with pid= 26537 child of ppid=26535
Exiting: Level 2 with pid= 26536, child of ppid= 26534
Exiting: Level 2 with pid= 26538, child of ppid= 26534
Exiting: Level 2 with pid= 26537, child of ppid= 26535
ALIVE: Level 1 process with pid= 26539 child of ppid=26535
Exiting: Level 2 with pid= 26539, child of ppid= 26535
Exiting: Level 1 with pid= 26534, child of ppid= 26533
Exiting: Level 1 with pid= 26535, child of ppid= 26533
Exiting: Level 1 with pid= 26535, child of ppid= 26533
ALIVE: Level 1 process with pid= 26540 child of ppid=26534
Exiting: Level 2 with pid= 26540, child of ppid= 26534
Exiting: Level 1 with pid= 26534, child of ppid= 26533
Exiting: Level 0 with pid= 26533, child of ppid= 25113