Re: [LTP] [PATCH 2/3] mq_open/16-1: use tmp file to share info

[Jan Stancek <jstancek@redhat.com>]

----- Original Message -----
> From: "Kang Kai" <kai.kang@windriver.com>
> To: ltp-list@lists.sourceforge.net
> Cc: "Zhenfeng Zhao" <Zhenfeng.Zhao@windriver.com>
> Sent: Thursday, 9 August, 2012 12:30:57 PM
> Subject: [LTP] [PATCH 2/3] mq_open/16-1: use tmp file to share info
> 
> In this test case, it uses a variable to share data between child and
> parent processes. But after fork there is a copy of the variable in
> child process and modify it will not affect the variable in the
> parent
> process. Then when the child process call mq_open() before parent
> process,
> the case will fail.
> 
> Use tmp file to replace the variable. Any modification in child
> process
> can be seen in parent process.
> 
> Signed-off-by: Kang Kai <kai.kang@windriver.com>
> ---
>  .../conformance/interfaces/mq_open/16-1.c          |   38
>  +++++++++++++++++--
>  1 files changed, 34 insertions(+), 4 deletions(-)
> 
> diff --git
> a/testcases/open_posix_testsuite/conformance/interfaces/mq_open/16-1.c
> b/testcases/open_posix_testsuite/conformance/interfaces/mq_open/16-1.c
> index b9a3215..ebd697b 100644
> ---
> a/testcases/open_posix_testsuite/conformance/interfaces/mq_open/16-1.c
> +++
> b/testcases/open_posix_testsuite/conformance/interfaces/mq_open/16-1.c
> @@ -20,9 +20,11 @@
>   * this is fine (will have some false positives, but no false
>   negatives).
>   */
>  
> +#include <sys/mman.h>
>  #include <sys/stat.h>
>  #include <sys/types.h>
>  #include <sys/wait.h>
> +#include <errno.h>
>  #include <fcntl.h>
>  #include <mqueue.h>
>  #include <signal.h>
> @@ -32,11 +34,15 @@
>  #include "posixtest.h"
>  
>  #define NAMESIZE 50
> +#define TNAME "mq_open/16-1.c"
>  
>  int main()
>  {
>         	char qname[NAMESIZE];
> +	char fname[NAMESIZE];
>  	int pid, succeeded=0;
> +	int fd;
> +	void *pa = NULL;
>  	mqd_t childqueue, queue;
>  
>  	/*
> @@ -47,6 +53,26 @@ int main()
>  
>         	sprintf(qname, "/mq_open_16-1_%d", getpid());
>  
> +	sprintf(fname, "/tmp/pts_mq_open_16_1_%d", getpid());
> +	unlink(fname);
> +	fd = open(fname, O_CREAT | O_RDWR | O_EXCL,
> +		 S_IRUSR | S_IWUSR);
> +	if (fd == -1) {
> +		printf(TNAME " Error at open(): %s\n", strerror(errno));
> +		exit(PTS_UNRESOLVED);
> +	}
> +	/* file is empty now, will cause "Bus error" */
> +	write(fd, "\0", 1);

Isn't there a risk of SIGBUS, when the file length is just 1 byte
and it's mapped to sizeof(int)?

   SIGBUS Attempted access to a portion of the buffer that does not correspond to the file (for  example,  beyond
          the end of the file, including the case where another process has truncated the file).

Regards,
Jan

> +	unlink(fname);
> +
> +	pa = mmap(NULL, sizeof(int), PROT_READ | PROT_WRITE, MAP_SHARED,
> fd, 0);
> +	if (pa == MAP_FAILED) {
> +		printf(TNAME " Error at mmap: %s\n", strerror(errno));
> +		close(fd);
> +		exit(PTS_FAIL);
> +	}
> +	*(int *)pa = 0;
> +
>  	if ((pid = fork()) == 0) {
>  		sigset_t mask;
>  		int sig;
> @@ -62,7 +88,7 @@ int main()
>          	childqueue = mq_open(qname, O_CREAT|O_EXCL|O_RDWR,
>  				S_IRUSR | S_IWUSR, NULL);
>          	if (childqueue != (mqd_t)-1) {
> -			succeeded++;
> +			++*(int *)pa;
>  #ifdef DEBUG
>  			printf("mq_open() in child succeeded\n");
>  		} else {
> @@ -79,7 +105,7 @@ int main()
>          	queue = mq_open(qname, O_CREAT | O_EXCL |O_RDWR,
>  				S_IRUSR | S_IWUSR, NULL);
>          	if (queue != (mqd_t)-1) {
> -			succeeded++;
> +			++*(int *)pa;
>  #ifdef DEBUG
>  			printf("mq_open() in parent succeeded\n");
>  		} else {
> @@ -93,13 +119,15 @@ int main()
>  			mq_close(queue);
>  			mq_close(childqueue);
>  			mq_unlink(qname);
> +			close(fd);
> +			munmap(pa, sizeof(int));
>  			return PTS_UNRESOLVED;
>  		}
>  
>  		mq_close(queue);
>  		mq_close(childqueue);
>  		mq_unlink(qname);
> -
> +		succeeded = *(int *)pa;
>  		if (succeeded==0) {
>  			printf("Test FAILED - mq_open() never succeeded\n");
>  			return PTS_FAIL;
> @@ -111,8 +139,10 @@ int main()
>  		}
>  
>          	printf("Test PASSED\n");
> +		close(fd);
> +		munmap(pa, sizeof(int));
>          	return PTS_PASS;
>  	}
>  
>  	return PTS_UNRESOLVED;
> -}
> \ No newline at end of file
> +}
> --
> 1.7.5.4
> 
> 
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