From: Björn Ketelaars <bjorn.ketelaars@hydroxide.nl>
Date: Thu, 5 Apr 2018 05:17:17 +0000 (+0200)
Subject: zstd requires a stable sort.
X-Git-Tag: v1.3.5~3^2~81^2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=462aed68112c814815c832f921d056db5a3d4289;p=thirdparty%2Fzstd.git

zstd requires a stable sort.

On OpenBSD qsort() is not guaranteed to be stable, their mergesort() is.
This fixes issue #1088. All the hard work has been done by @terrelln.
---

diff --git a/lib/dictBuilder/cover.c b/lib/dictBuilder/cover.c
index b5a3957a9..6d473624d 100644
--- a/lib/dictBuilder/cover.c
+++ b/lib/dictBuilder/cover.c
@@ -581,10 +581,17 @@ static int COVER_ctx_init(COVER_ctx_t *ctx, const void *samplesBuffer,
     for (i = 0; i < ctx->suffixSize; ++i) {
       ctx->suffix[i] = i;
     }
-    /* qsort doesn't take an opaque pointer, so pass as a global */
+    /* qsort doesn't take an opaque pointer, so pass as a global.
+     * On OpenBSD qsort() is not guaranteed to be stable, their mergesort() is.
+     */
     g_ctx = ctx;
+#if defined(__OpenBSD__)
+    mergesort(ctx->suffix, ctx->suffixSize, sizeof(U32),
+          (ctx->d <= 8 ? &COVER_strict_cmp8 : &COVER_strict_cmp));
+#else
     qsort(ctx->suffix, ctx->suffixSize, sizeof(U32),
           (ctx->d <= 8 ? &COVER_strict_cmp8 : &COVER_strict_cmp));
+#endif
   }
   DISPLAYLEVEL(2, "Computing frequencies\n");
   /* For each dmer group (group of positions with the same first d bytes):