[glibc] stdlib: Fix heapsort for cases with exactly two elements

[glibc] stdlib: Fix heapsort for cases with exactly two elements

[Adhemerval Zanella]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=74d2731a5fb2676b64092bc25e7f193db1b17b2b

commit 74d2731a5fb2676b64092bc25e7f193db1b17b2b
Author: Kuan-Wei Chiu <visitorckw@gmail.com>
Date:   Tue Jan 16 10:16:56 2024 +0800

    stdlib: Fix heapsort for cases with exactly two elements
    
    When malloc fails to allocate a buffer and falls back to heapsort, the
    current heapsort implementation does not perform sorting when there are
    exactly two elements. Heapsort is now skipped only when there is
    exactly one element.
    
    Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
    Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

Diff:
---
 stdlib/qsort.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/stdlib/qsort.c b/stdlib/qsort.c
index b29882388e..45af8da80c 100644
--- a/stdlib/qsort.c
+++ b/stdlib/qsort.c
@@ -162,7 +162,7 @@ get_swap_type (void *const pbase, size_t size)
 static void
 heapsort_r (void *base, size_t n, size_t size, __compar_d_fn_t cmp, void *arg)
 {
-  if (n <= 1)
+  if (n == 0)
     return;
 
   enum swap_type_t swap_type = get_swap_type (base, size);