***********我又来求指点了*********

[生活简单到无聊]

#include<stdio.h>
#include<unistd.h>
#include<stdlib.h>
#include<errno.h>
#include<sys/types.h>

int main(int argc, char* argv[])
{
	  
    int i = 0;
    
    pid_t pid = -1;
    
    fprintf(stdout, "parent pid[%d], i[%d]\n", getpid(), i);
    
    if((pid = vfork()) < 0)
    {
        fprintf(stderr, "fork failed!!  errorno = %d\n", errno);
        return 0;
    }
    else if(pid > 0)
    {
        fprintf(stdout, "after fork, parent pid[%d], i[%d]\n", getpid(), i);
    }
    else
    {
        system("find . -type f");
    }
    
    
    fprintf(stdout, "process end. pid[%d], i[%d]\n", getpid(), i);
    
    return 0;
}

运行结果：

parent pid[20000], i[0]
./core.17552
./libshow.a
./dup2.c
./csdn.c
./main
./base/baseMath.o
./base/baseMath.c
./base/libbaseMath.a
./base/libbaseMath.so
./base/baseMath.h
./test.cpp
./stat.c
./power.c
./tag.c
./libshow.so
./unlink
./unlink.c
./book.c
./show.o
./a.bat
./show.c
./reservword.c
./fileop.c
./code.c
process end. pid[20001], i[0]
after fork, parent pid[20000], i[0]
process end. pid[20000], i[0]
Segmentation fault (core dumped)

为什么最后core了。。。。？！

[生活简单到无聊]

GDB结果如下：

(gdb) l
3       #include<stdlib.h>
4       //#include<memory.h>
5       //#include<dirent.h>
6       #include<errno.h>
7       #include<sys/types.h>
8
9       int main(int argc, char* argv[])
10      {
11                
12          int i = 0;
(gdb) 
13          
14          pid_t pid = -1;
15          
16          fprintf(stdout, "parent pid[%d], i[%d]\n", getpid(), i);
17          
18          if((pid = vfork()) < 0)
19          {
20              fprintf(stderr, "fork failed!!  errorno = %d\n", errno);
21              return 0;
22          }
(gdb) 
23          else if(pid > 0)
24          {
25              fprintf(stdout, "after fork, parent pid[%d], i[%d]\n", getpid(), i);
26              //waitpid(pid);
27          }
28          else
29          {
30              /*if(execl("/bin/find", ".", "-type", "f", (char*)NULL) < 0)
31              {
32                  fprintf(stderr, "execl failed!!  errorno = %d\n", errno);
(gdb) 
33              }*/
34              system("find . -type f");
35          }
36          
37          
38          fprintf(stdout, "process end. pid[%d], i[%d]\n", getpid(), i);
39          
40          return 0;
41      }(gdb) b 38
Breakpoint 1 at 0x10000830: file code.c, line 38.
(gdb) run main
Starting program: /data/cyc/cyccode/main main
parent pid[20117], i[0]
./libshow.a
./dup2.c
./csdn.c
./main
./base/baseMath.o
./base/baseMath.c
./base/libbaseMath.a
./base/libbaseMath.so
./base/baseMath.h
./test.cpp
./core.20000
./stat.c
./power.c
./tag.c
./libshow.so
./unlink
./unlink.c
./book.c
./show.o
./a.bat
./show.c
./reservword.c
./fileop.c
./code.c
process end. pid[20120], i[0]
after fork, parent pid[20117], i[0]

Breakpoint 1, main (argc=2, argv=0xffffffff4d8) at code.c:38
38          fprintf(stdout, "process end. pid[%d], i[%d]\n", getpid(), i);
(gdb) p i
$1 = 0
(gdb) p getpid()
$2 = 20117
(gdb) p stdout
$3 = (struct _IO_FILE *) 0xfffb7f606a0 <_IO_2_1_stdout_>
(gdb) s
process end. pid[20117], i[0]
40          return 0;
(gdb) s
41      }(gdb) s
0x00000fffb7ddbd00 in .generic_start_main () from /lib64/libc.so.6
(gdb) s
Single stepping until exit from function .generic_start_main,
which has no line number information.

Program received signal SIGSEGV, Segmentation fault.
0x00000fffb7ddbd04 in .generic_start_main () from /lib64/libc.so.6
(gdb)

[Carl_CCC]

你把最后那个return 0，改成exit(0)就好了，子进程用return 是不安全的。

[Carl_CCC]

还有一种改法就是把vfork改成fork也是安全的。

[生活简单到无聊]

引用 2 楼 Idle_Cloud 的回复:

你把最后那个return 0，改成exit(0)就好了，子进程用return 是不安全的。

额，vfork的问题，vfork不继承父进程的数据，我改成fork就不core了。