Merge pull request #4312 from Cyan4973/musl_ci

introduce ZSTD_USE_C90_QSORT

.github/workflows/dev-short-tests.yml

@@ -684,6 +684,17 @@ jobs:
         make -C programs zstd-pgo
         ./programs/zstd -b
 
+  musl-build:
+    runs-on: ubuntu-22.04
+    steps:
+      - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # tag=v4.1.1
+      - name: Install musl-tools
+        run: |
+          sudo apt install -y musl-tools
+      - name: Compile the project with musl-gcc
+        run: |
+          CC=musl-gcc CPPFLAGS=-DZSTD_USE_C90_QSORT make -j V=1 zstd
+
   intel-cet-compatibility:
     runs-on: ubuntu-latest
     steps:

lib/README.md

@@ -193,6 +193,10 @@ The file structure is designed to make this selection manually achievable for an
   and assembly decoding loops. You may want to use this macro if these loops are
   slower on your platform.
 
+- The macro `ZSTD_USE_C90_QSORT` forces usage of C90's `qsort()`,
+  for situations where the code cannot determine that `qsort_r()` is not supported,
+  such as, for example, older versions of `musl`.
+
 #### Windows : using MinGW+MSYS to create DLL
 
 DLL can be created using MinGW+MSYS with the `make libzstd` command.

lib/dictBuilder/cover.c

@@ -241,8 +241,9 @@ typedef struct {
   unsigned d;
 } COVER_ctx_t;
 
-#if !defined(_GNU_SOURCE) && !defined(__APPLE__) && !defined(_MSC_VER)
-/* C90 only offers qsort() that needs a global context. */
+#if defined(ZSTD_USE_C90_QSORT) \
+  || (!defined(_GNU_SOURCE) && !defined(__APPLE__) && !defined(_MSC_VER))
+/* Use global context for non-reentrant sort functions */
 static COVER_ctx_t *g_coverCtx = NULL;
 #endif
 
@@ -328,7 +329,7 @@ static void stableSort(COVER_ctx_t *ctx) {
     qsort_r(ctx->suffix, ctx->suffixSize, sizeof(U32),
             ctx,
             (ctx->d <= 8 ? &COVER_strict_cmp8 : &COVER_strict_cmp));
-#elif defined(_GNU_SOURCE)
+#elif defined(_GNU_SOURCE) && !defined(ZSTD_USE_C90_QSORT)
     qsort_r(ctx->suffix, ctx->suffixSize, sizeof(U32),
             (ctx->d <= 8 ? &COVER_strict_cmp8 : &COVER_strict_cmp),
             ctx);
@@ -342,7 +343,7 @@ static void stableSort(COVER_ctx_t *ctx) {
           (ctx->d <= 8 ? &COVER_strict_cmp8 : &COVER_strict_cmp));
 #else /* C90 fallback.*/
     g_coverCtx = ctx;
-    /* TODO(cavalcanti): implement a reentrant qsort() when is not available. */
+    /* TODO(cavalcanti): implement a reentrant qsort() when _r is not available. */
     qsort(ctx->suffix, ctx->suffixSize, sizeof(U32),
           (ctx->d <= 8 ? &COVER_strict_cmp8 : &COVER_strict_cmp));
 #endif