portability: add qsort_r

portability/meson.build

@@ -9,6 +9,7 @@ check_functions = [
 	['strlcpy', 'strlcpy.c', 'NEED_STRLCPY', 'string.h'],
 	['pipe2', 'pipe2.c', 'NEED_PIPE2', 'unistd.h'],
 	['mknodat', 'mknodat.c', 'NEED_MKNODAT', 'sys/stat.h'],
+	['qsort_r', 'qsort_r.c', 'NEED_QSORT_R', 'stdlib.h'],
 ]
 
 

portability/qsort_r.c

@@ -0,0 +1,26 @@
+#include <stdlib.h>
+
+struct qsortr_ctx {
+	int (*compar)(const void *, const void *, void *);
+	void *arg;
+};
+
+static __thread struct qsortr_ctx *__ctx;
+
+static int cmp_wrapper(const void *a, const void *b)
+{
+	return __ctx->compar(a, b, __ctx->arg);
+}
+
+void qsort_r(void *base, size_t nmemb, size_t size,
+	int (*compar)(const void *, const void *, void *),
+	void *arg)
+{
+	struct qsortr_ctx ctx = {
+		.compar = compar,
+		.arg = arg,
+	};
+	__ctx = &ctx;
+	qsort(base, nmemb, size, cmp_wrapper);
+	__ctx = 0;
+}

portability/stdlib.h

@@ -0,0 +1,7 @@
+#include_next <stdlib.h>
+
+#ifdef NEED_QSORT_R
+void qsort_r(void *base, size_t nmemb, size_t size,
+	int (*compar)(const void *, const void *, void *),
+	void *arg);
+#endif