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Re: [PATCH 2/3] libio: Update tst-fmemopen2.c


Adhemerval Zanella <azanella@linux.vnet.ibm.com> writes:

> This patch updates tst-fmemopen2 to check for fmemopen with NULL buffer
> inputs and also refactor the code a bit.
>
> --
>
> 	* stdio-common/tst-fmemopen2.c (do_test): Add test for NULL and zero
> 	length buffers.
>
> ---
>
> diff --git a/stdio-common/tst-fmemopen2.c b/stdio-common/tst-fmemopen2.c
> index c2a4baa..652c412 100644
> --- a/stdio-common/tst-fmemopen2.c
> +++ b/stdio-common/tst-fmemopen2.c

[snip]

> +}
> +
> +static int
> +do_test_length_zero (void)
> +{
> +  int result = 0;
> +  FILE *fp;
> +  char buf[] = "";
> +  const size_t nbuf = 0;
> +  int r;
> +
> +  fp = fmemopen (buf, nbuf, "r");
> +  if (fp == NULL)
> +    {
> +      printf ("%s: fmemopen failed\n", __FUNCTION__);
> +      return 1;
> +    }
> +
> +  /* Reading any data on a zero-length buffer should return EOF  */

Missing full stop.

> +  if ((r = fgetc (fp)) != EOF)
> +    {
> +      printf ("%s: fgetc on a zero-lenght returned: %d\n",

s/lenght/length/

> 
> +	      __FUNCTION__, r);
> +      result = 1;
> +    }
> +  off_t o = ftello (fp);
> +  if (o != 0)
> +    {
> +      printf ("%s: first ftello returned %ld, expected 0\n",
> +	      __FUNCTION__, o);
> +      result = 1;
> +    }
> +  fclose (fp);
> +
> +  /* Writing any data shall start at current position and shall not pass
> +     current buffer size beyond the size in fmemopen call.  */
> +  fp = fmemopen (buf, nbuf, "w");
> +  if (fp == NULL)
> +    {
> +      printf ("%s: second fmemopen failed\n", __FUNCTION__);
> +      return 1;
> +    }
> +
> +  static const char str[] = "hello world";
> +  /* Because of buffering, fputs call itself don't fail, however the final
> +     buffer should be not changed because of lenght 0 passed in fmemopen

s/lenght/length/

> +     call.  */
> +  fputs (str, fp);

I think it would be useful to do an fflush(fp) and check that the error
flag is set, and perhaps also to check that errno is set to ENOSPC.

> +  fclose (fp);
> +
> +  if (strcmp (buf, "") != 0)
> +    {
> +      printf ("%s: strcmp (%s, "") failed\n", __FUNCTION__, buf);
> +      return 1;
> +    }
> +

Maybe it would be a bit more robust if buf was declared with a somewhat
larger size than the 1 implied from its initialization with "", so that
if the write test fails, adjacent stack variables are not necessarily
overwritten.


Rasmus

PS: Thanks for allowing len==0 :-)


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