On Tue, Nov 9, 2021 at 8:50 AM Xi Ruoyao via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> POSIX says:
>
> On some implementations, if buf is a null pointer, getcwd() may obtain
> size bytes of memory using malloc(). In this case, the pointer returned
> by getcwd() may be used as the argument in a subsequent call to free().
> Invoking getcwd() with buf as a null pointer is not recommended in
> conforming applications.
>
> This produces an error building GCC with --enable-werror-always:
>
> ../../../fixincludes/fixincl.c: In function ‘process’:
> ../../../fixincludes/fixincl.c:1356:7: error: argument 1 is null but
> the corresponding size argument 2 value is 4096 [-Werror=nonnull]
>
> And, at least we've been leaking memory even if getcwd() supports this
> non-standard extension.
>
> fixincludes/ChangeLog:
>
> * fixincl.c (process): Allocate and deallocate the buffer for
> getcwd() explicitly.
> ---
> fixincludes/fixincl.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/fixincludes/fixincl.c b/fixincludes/fixincl.c
> index 6dba2f6e830..b4b1e38ede7 100644
> --- a/fixincludes/fixincl.c
> +++ b/fixincludes/fixincl.c
> @@ -1353,9 +1353,11 @@ process (void)
> if (access (pz_curr_file, R_OK) != 0)
> {
> int erno = errno;
> + char *buf = xmalloc (MAXPATHLEN);
> fprintf (stderr, "Cannot access %s from %s\n\terror %d (%s)\n",
> - pz_curr_file, getcwd ((char *) NULL, MAXPATHLEN),
> + pz_curr_file, getcwd (buf, MAXPATHLEN),
> erno, xstrerror (erno));
> + free (buf);
> return;
> }
>
> --
> 2.33.1
This seems to contradict bug 21823:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=21823
It would fix bug 80047, though:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80047
