Add simple pipe syscall and unit test method for linux syscall

[yunwei37]

TODO:

• add syscall
• add test for pipe
  • pipe can be used on single thread now
  • pipe can be used with vfork and execve
  • add unit test and change the makefile
• add document for pipe

it seems unit test on ipc may be complex, so here is just user mode test.

after that, here is some possible improvement for pipe, but need more dependencies:

• add async poll
• try to fix fork...

these can be fix in the future, maybe not in this pull-request.

[coveralls]

Pull Request Test Coverage Report for Build 198586745

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

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• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 5 of 89 (5.62%) changed or added relevant lines in 6 files are covered.
• 17 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.2%) to 32.473%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
linux-object/src/fs/file.rs	0	1	0.0%
linux-syscall/src/lib.rs	0	2	0.0%
linux-object/src/fs/mod.rs	4	8	50.0%
linux-syscall/src/file/fd.rs	0	18	0.0%
linux-object/src/fs/pipe.rs	0	59	0.0%

Files with Coverage Reduction	New Missed Lines	%
../../../../../usr/share/rust/.cargo/registry/src/jackfan.us.kg-1ecc6299db9ec823/async-task-3.0.0/src/waker_fn.rs	4	80.95%
linux-object/src/fs/mod.rs	13	74.36%

Totals
Change from base Build 198552974:	-0.2%
Covered Lines:	4090
Relevant Lines:	12595

---

💛 - Coveralls

[yunwei37]

Test pipe with vfork and execve is success:

testfork:

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

int main()
{
    pid_t pid;
    int cnt = 0;
    int pipefd[2];
    char buf;
    char w[12];
    char r[12];
    if (pipe(pipefd) == -1) {
        printf("pipe");
        exit(-1);
    }
    sprintf(w,"%d",pipefd[1]);
    sprintf(r,"%d",pipefd[0]);
    pid = vfork();
    if(pid<0)
        printf("error in fork!\n");
    else if(pid == 0)
    {	
    	execl("/bin/testec","/bin/testec",r,w,NULL);
    	exit(0);
    }
    else if(pid > 0)
    {	
       close(pipefd[1]);
       while (read(pipefd[0], &buf, 1) > 0)
          write(STDOUT_FILENO, &buf, 1);
       write(STDOUT_FILENO, "\n", 1);
       close(pipefd[0]);  
    }
    return 0;
}

testec:

#include <sys/wait.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>

int main(int argc, char *argv[])
{	
	int writefd, readfd;
	sscanf(argv[2],"%d",&writefd);
	sscanf(argv[1],"%d",&readfd);
	close(readfd);
        write(writefd, "hello pipe", strlen("hello pipe"));
        close(writefd);
        exit(0);
}

[yunwei37]

Currently you can add c language unit test like this:

1. add c files in linux-syscall/test/;
2. add a cargo unit test in linux-loader like ( the program name is the same as source file )

   #[async_std::test]
   async fn test_pipe() {
       test("/bin/testpipe1").await;
   }
   

• if you want to run the unit test locally right away, you can run make rootfs again.
• if you want to inspect the output of program, maybe output the content to a file and read it in rust can be helpful.

[wangrunji0408]

Thanks!