Re: Fix BZ 18756 (fmemopen(..., 0, ...) does not fail)

[Adhemerval Zanella <adhemerval dot zanella at linaro dot org>]

Hi,

Thanks for the patch, it straightforward enough. Only a comment below.

On 02-08-2015 17:16, Paul Pluzhnikov wrote:
> Greetings,
> 
> Attached trivial patch fixes BZ 18756 and adds a test case for it.
> Since this is new breakage in 2.22, I say it should go in despite the
> hard freeze.
> 
> Thanks,
> 
> 2015-08-02  Paul Pluzhnikov  <ppluzhnikov@google.com>
> 
>         [BZ #18756]
>         * libio/fmemopen.c (__fmemopen): Check for 0 len.
>         * libio/test-fmemopen.c (do_bz18756): New test.
> 
> -- Paul Pluzhnikov
> 
> 
> bz18756-20150802.txt
> 
> 
> diff --git a/libio/fmemopen.c b/libio/fmemopen.c
> index 3ab3e8d..c58f376 100644
> --- a/libio/fmemopen.c
> +++ b/libio/fmemopen.c
> @@ -150,6 +150,12 @@ __fmemopen (void *buf, size_t len, const char *mode)
>    cookie_io_functions_t iof;
>    fmemopen_cookie_t *c;
>  
> +  if (__glibc_unlikely (len == 0))
> +    {
> +      __set_errno (EINVAL);
> +      return NULL;
> +    }
> +
>    c = (fmemopen_cookie_t *) calloc (sizeof (fmemopen_cookie_t), 1);
>    if (c == NULL)
>      return NULL;
> diff --git a/libio/test-fmemopen.c b/libio/test-fmemopen.c
> index 63ca89f..81371fa 100644
> --- a/libio/test-fmemopen.c
> +++ b/libio/test-fmemopen.c
> @@ -24,6 +24,27 @@ static char buffer[] = "foobar";
>  #include <errno.h>
>  
>  static int
> +do_bz18756 (void)
> +{
> +  int ch;
> +  int ret = 0;
> +  FILE *stream;
> +
> +  errno = 0;
> +  stream = fmemopen (&ch, 0, "w");
> +  if (stream != NULL || errno != EINVAL)
> +    {
> +      printf ("fmemopen zero-sized buffer: stream = %p, %m\n", stream);
> +      ret = 1;
> +    }

I would use the 'FAIL:' message pattern to follow recent GLIBC testcases
here.

> +
> +  if (stream != NULL)
> +    fclose (stream);
> +
> +  return ret;
> +}
> +
> +static int
>  do_test (void)
>  {
>    int ch;
> @@ -44,7 +65,7 @@ do_test (void)
>  
>    fclose (stream);
>  
> -  return ret;
> +  return ret + do_bz18756 ();
>  }
>  
>  #define TEST_FUNCTION do_test ()