On Fri, Feb 02, 2018 at 12:00:58PM +0000, Bruce Richardson wrote:
> Coverity flags an issue where the resources used by the FILE object for
> the temporary input file are leaked. This is a very minor issue, but is
> easily fixed, while also avoiding later problems where we try to close
> an invalid file descriptor in the failure case.
>
> The fix is to use "dup()" to get a new file descriptor number rather than
> using the value directly from fileno. This allows us to close the file
> opened with tmpfile() within in scope block, while allowing the duplicate
> to pass to the outer block and be closed when the function terminates.
>
> As a side-effect I/O in the function is therefore changed from using stdio
> fread/fwrite to read/write system calls.
>
> Coverity issue: 260399
> Fixes: 0d68533617e3 ("pmdinfogen: allow using stdin and stdout")
>
> Signed-off-by: Bruce Richardson <bruce.richard...@intel.com>
> ---
> buildtools/pmdinfogen/pmdinfogen.c | 16 ++++++++++------
> 1 file changed, 10 insertions(+), 6 deletions(-)
>
> diff --git a/buildtools/pmdinfogen/pmdinfogen.c
> b/buildtools/pmdinfogen/pmdinfogen.c
> index 45b267346..0f35ca46b 100644
> --- a/buildtools/pmdinfogen/pmdinfogen.c
> +++ b/buildtools/pmdinfogen/pmdinfogen.c
> @@ -50,20 +50,24 @@ static void *grab_file(const char *filename, unsigned
> long *size)
> /* from stdin, use a temporary file to mmap */
> FILE *infile;
> char buffer[1024];
> - size_t n;
> + int n;
>
> infile = tmpfile();
> if (infile == NULL) {
> perror("tmpfile");
> return NULL;
> }
> - while (!feof(stdin)) {
> - n = fread(buffer, 1, sizeof(buffer), stdin);
> - if (fwrite(buffer, 1, n, infile) != n)
> + fd = dup(fileno(infile));
> + fclose(infile);
> + if (fd < 0)
> + return NULL;
> +
> + n = read(STDIN_FILENO, buffer, sizeof(buffer));
> + while (n > 0) {
> + if (write(fd, buffer, n) != n)
> goto failed;
> + n = read(STDIN_FILENO, buffer, sizeof(buffer));
> }
> - fflush(infile);
> - fd = fileno(infile);
> }
>
> if (fstat(fd, &st))
> --
> 2.14.3
>
>
Wouldn't it be just as good, and easier to check fd for == -1 as a condition of
calling close?
like
failed:
if (fd >= 0)
close(fd);
