Re: [PATCH] stdlib: Fix BZ #26241 testcase on GNU/Hurd

[Adhemerval Zanella]

On 23/03/2021 21:38, Samuel Thibault wrote:

GNU/Hurd's readlink system call is partly implemented in userspace, which
also allocates a buffer on the stack for the result, and thus needs one
more path.

LGTM, thanks.

Reviewed-by: Adhemerval Zanella  <adhemerval.zane...@linaro.org>

---
  stdlib/tst-canon-bz26341.c | 3 ++-
  1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/stdlib/tst-canon-bz26341.c b/stdlib/tst-canon-bz26341.c
index 6d054596b5..0ddd9aed15 100644
--- a/stdlib/tst-canon-bz26341.c
+++ b/stdlib/tst-canon-bz26341.c
@@ -72,10 +72,11 @@ do_realpath (void *arg)
       If realpath uses more than 2 * PATH_MAX plus some slack it will trigger
       a stackoverflow.  */

+ const size_t syscall_usage = 1 * PATH_MAX + 1024;

Could you also add a comment from where this come from on the description
above?

    const size_t realpath_usage = 2 * PATH_MAX + 1024;
    const size_t thread_usage = 1 * PATH_MAX + 1024;
    size_t stack_size = support_small_thread_stack_size ()
-                     - realpath_usage - thread_usage;
+                     - syscall_usage - realpath_usage - thread_usage;
    char stack[stack_size];
    char *resolved = stack + stack_size - thread_usage + 1024;