如何使用 fork/exec 和 libcheck 对程序进行单元测试？

问题描述 投票：0回答：1

我正在尝试测试一个程序，

fork
和
exec
与libcheck（https://github.com/libcheck/check）。

当我正常运行程序时，它可以创建子进程，稍等一下，然后用 

kill
来完成它，没有问题。但是，如果我在测试中执行相同的操作，则测试会失败并显示 
SIGTERM
。看起来测试进程被杀死了。
当使用 
Received signal 15 (Terminated)
 运行测试时，我什至没有看到 
strace
 正在执行。
当使用
kill
和
strace
运行测试时，执行了kill，但程序在
CK_FORK=no
期间中止。
另外我现在真的不知道如何正确调试它。


测试.c
：
wait


我已经从代码中删除了错误检查。


这可以使用 
#include <check.h>

#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/wait.h>
#include <paths.h>
#include <unistd.h>

START_TEST(test)
{
    int process;

    /* prevent duplicate output from the child process */
    if (0 != fflush (NULL)) abort ();

    process = fork ();
    if (0 > process) abort ();

    /* child process */
    if (0 == process)
    {
        int null_fd;

        /* reset signals */
        if (SIG_ERR == signal (SIGTERM, SIG_DFL))
        {
            exit (EXIT_FAILURE);
        }

        /* Replace stderr with /dev/null, because SoX will
         * spam the output with current status data. */
        null_fd = open (_PATH_DEVNULL, O_WRONLY);
        if (0 > null_fd)
        {
            exit (EXIT_FAILURE);
        }

        if (0 > dup2 (null_fd, STDERR_FILENO))
        {
            exit (EXIT_FAILURE);
        }

        if (0 > close (null_fd))
        {
            exit (EXIT_FAILURE);
        }

        execlp ("/usr/bin/play", (char *) NULL);

        /* execvp failed */
        exit (EXIT_FAILURE);
    }


    printf("kill: %d\n", process);

    if (0 > kill (process, SIGTERM)) abort ();

    if (0 > waitpid (process, NULL, 0)) abort ();
}
END_TEST


Suite * suite (void)
{
    Suite *s;
    TCase *tc_core;

    s = suite_create ("Test");

    /* Core test case */
    tc_core = tcase_create ("Test");

    tcase_add_test (tc_core, test);
    suite_add_tcase (s, tc_core);

    return s;
}

int main (void)
{
    int number_failed;
    Suite *s;
    SRunner *sr;

    s = suite ();
    sr = srunner_create (s);

    srunner_run_all (sr, CK_NORMAL);
    number_failed = srunner_ntests_failed (sr);
    srunner_free (sr);

    return (number_failed == 0) ? EXIT_SUCCESS : EXIT_FAILURE;
}

 进行编译



执行：
    

  • 

    • gcc test.c -lcheck_pic -pthread -lrt -lm -lsubunit


与
    $ ./a.out 
Running suite(s): Test
kill: 7047
0%: Checks: 1, Failures: 0, Errors: 1
test.c:11:E:Test:test:0: (after this point) Received signal 15 (Terminated)

  • 

    • strace


奇怪的是，偶尔它确实可以工作，这似乎与当前系统负载相关。如果我的 CPU 几乎空闲，成功率约为 50%，当我的 CPU 处于负载状态时，则几乎总是失败。
成功后，看起来像这样：




执行：
    

  • 

    • $ strace -fe trace=%process,%signal ./a.out 
execve("./a.out", ["./a.out"], 0x7ffc8a157ef0 /* 47 vars */) = 0
rt_sigaction(SIGRTMIN, {sa_handler=0x7fd6fd8c9690, sa_mask=[], sa_flags=SA_RESTORER|SA_SIGINFO, sa_restorer=0x7fd6fd8d6140}, NULL, 8) = 0
rt_sigaction(SIGRT_1, {sa_handler=0x7fd6fd8c9730, sa_mask=[], sa_flags=SA_RESTORER|SA_RESTART|SA_SIGINFO, sa_restorer=0x7fd6fd8d6140}, NULL, 8) = 0
rt_sigprocmask(SIG_UNBLOCK, [RTMIN RT_1], NULL, 8) = 0
rt_sigaction(SIGALRM, {sa_handler=0x5638b7e93b50, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fd6fd8d6140}, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGINT, {sa_handler=0x5638b7e93b50, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fd6fd8d6140}, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGTERM, {sa_handler=0x5638b7e93b50, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fd6fd8d6140}, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
Running suite(s): Test
clone(child_stack=NULL, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7fd6fd5a0550) = 6995
strace: Process 6995 attached
[pid  6994] wait4(6995,  <unfinished ...>
[pid  6995] clone(child_stack=NULL, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7fd6fd5a0550) = 6996
strace: Process 6996 attached
kill: 6996
[pid  6995] kill(6996, SIGTERM)         = 0
[pid  6996] --- SIGTERM {si_signo=SIGTERM, si_code=SI_USER, si_pid=6995, si_uid=1001} ---
[pid  6995] wait4(6996,  <unfinished ...>
[pid  6996] rt_sigaction(SIGTERM, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fd6fd8d6140}, NULL, 8) = 0
[pid  6996] kill(-6995, SIGTERM)        = 0
[pid  6995] <... wait4 resumed>NULL, 0, NULL) = ? ERESTARTSYS (To be restarted if SA_RESTART is set)
[pid  6995] --- SIGTERM {si_signo=SIGTERM, si_code=SI_USER, si_pid=6996, si_uid=1001} ---
[pid  6996] kill(-6995, SIGTERM)        = 0
[pid  6996] rt_sigreturn({mask=[]} <unfinished ...>
[pid  6995] rt_sigaction(SIGTERM, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fd6fd8d6140},  <unfinished ...>
[pid  6996] <... rt_sigreturn resumed>) = 140561350264128
[pid  6996] --- SIGTERM {si_signo=SIGTERM, si_code=SI_USER, si_pid=6996, si_uid=1001} ---
[pid  6995] <... rt_sigaction resumed>NULL, 8) = 0
[pid  6995] kill(-6995, SIGTERM)        = 0
[pid  6995] kill(-6995, SIGTERM)        = 0
[pid  6995] rt_sigreturn({mask=[]} <unfinished ...>
[pid  6996] +++ killed by SIGTERM +++
[pid  6995] <... rt_sigreturn resumed>) = -1 EINTR (Interrupted system call)
[pid  6995] --- SIGTERM {si_signo=SIGTERM, si_code=SI_USER, si_pid=6996, si_uid=1001} ---
[pid  6995] +++ killed by SIGTERM +++
<... wait4 resumed>[{WIFSIGNALED(s) && WTERMSIG(s) == SIGTERM}], 0, NULL) = 6995
--- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_KILLED, si_pid=6995, si_uid=1001, si_status=SIGTERM, si_utime=0, si_stime=0} ---
kill(-6995, SIGKILL)                    = -1 ESRCH (No such process)
0%: Checks: 1, Failures: 0, Errors: 1
test.c:11:E:Test:test:0: (after this point) Received signal 15 (Terminated)
rt_sigaction(SIGALRM, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fd6fd8d6140}, NULL, 8) = 0
rt_sigaction(SIGINT, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fd6fd8d6140}, NULL, 8) = 0
rt_sigaction(SIGTERM, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7fd6fd8d6140}, NULL, 8) = 0
exit_group(1)                           = ?
+++ exited with 1 +++



与
    Running suite(s): Test
kill: 7074
100%: Checks: 1, Failures: 0, Errors: 0

  • 

    • strace

    
	




c

unit-testing

fork

kill


1个回答




    
    
    

        

            

                

                    
0
投票

                    
                

            

        

        
execve("./a.out", ["./a.out"], 0x7ffd0a5de0d0 /* 47 vars */) = 0
rt_sigaction(SIGRTMIN, {sa_handler=0x7f216e4fa690, sa_mask=[], sa_flags=SA_RESTORER|SA_SIGINFO, sa_restorer=0x7f216e507140}, NULL, 8) = 0
rt_sigaction(SIGRT_1, {sa_handler=0x7f216e4fa730, sa_mask=[], sa_flags=SA_RESTORER|SA_RESTART|SA_SIGINFO, sa_restorer=0x7f216e507140}, NULL, 8) = 0
rt_sigprocmask(SIG_UNBLOCK, [RTMIN RT_1], NULL, 8) = 0
rt_sigaction(SIGALRM, {sa_handler=0x55988f29db50, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7f216e507140}, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGINT, {sa_handler=0x55988f29db50, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7f216e507140}, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGTERM, {sa_handler=0x55988f29db50, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7f216e507140}, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
Running suite(s): Test
clone(child_stack=NULL, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7f216e31f450) = 137654
wait4(137654, strace: Process 137654 attached
 <unfinished ...>
[pid 137654] clone(child_stack=NULL, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7f216e31f450) = 137655
strace: Process 137655 attached
kill: 137655
[pid 137655] rt_sigaction(SIGTERM, {sa_handler=SIG_DFL, sa_mask=[TERM], sa_flags=SA_RESTORER|SA_RESTART, sa_restorer=0x7f216e358d60}, {sa_handler=0x55988f29db50, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7f216e507140}, 8) = 0
[pid 137654] kill(137655, SIGTERM)      = 0
[pid 137655] --- SIGTERM {si_signo=SIGTERM, si_code=SI_USER, si_pid=137654, si_uid=1001} ---
[pid 137654] wait4(137655,  <unfinished ...>
[pid 137655] +++ killed by SIGTERM +++
[pid 137654] <... wait4 resumed>NULL, 0, NULL) = 137655
[pid 137654] --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_KILLED, si_pid=137655, si_uid=1001, si_status=SIGTERM, si_utime=0, si_stime=0} ---
[pid 137654] exit_group(0)              = ?
[pid 137654] +++ exited with 0 +++
<... wait4 resumed>[{WIFEXITED(s) && WEXITSTATUS(s) == 0}], 0, NULL) = 137654
--- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=137654, si_uid=1001, si_status=0, si_utime=0, si_stime=0} ---
kill(-137654, SIGKILL)                  = -1 ESRCH (No such process)
100%: Checks: 1, Failures: 0, Errors: 0
rt_sigaction(SIGALRM, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7f216e507140}, NULL, 8) = 0
rt_sigaction(SIGINT, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7f216e507140}, NULL, 8) = 0
rt_sigaction(SIGTERM, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7f216e507140}, NULL, 8) = 0
exit_group(0)                           = ?
+++ exited with 0 +++

 
安装一个 SIGTERM 处理程序
，它会杀死整个进程组。  该处理程序由孙进程继承，该进程在 exec 您实际想要运行的进程之前被终止。
您的分叉运行包含三个进程：


libcheck


进程 
C
 在 A: a.out
    \
B:   (forked test suite)
      \
C:     (forked process in test case)
 之前被 B 杀死，这意味着它继承了 
exec
 安装的信号配置。再次，它捕获 SIGTERM 并杀死整个进程组。
    

	

    

    


  

  

    
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