[libgpiod][PATCH] gpiosim: use twalk() instead of twalk_r()

[Bartosz Golaszewski <brgl@xxxxxxxx>]

From: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>

twalk_r() is a GNU extension for the binary search tree API. Musl libc
doesn't provide it and after inquiring with the maintainer it turned out
it won't provide it anytime soon as musl strives to only implement well
standardized functions.

In order to not limit building libgpiosim and tests to glibc only, let's
replace twalk_r() with twalk() and use global variables for the state.
It's not a big deal as we're already using a global root node and a mutex
to protect it.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>
---
 configure.ac            |  2 +-
 tests/gpiosim/gpiosim.c | 54 +++++++++++++++++++----------------------
 2 files changed, 26 insertions(+), 30 deletions(-)

diff --git a/configure.ac b/configure.ac
index 2bd71b0..d42b089 100644
--- a/configure.ac
+++ b/configure.ac
@@ -162,7 +162,7 @@ then
 	AC_CHECK_FUNC([openat], [], [FUNC_NOT_FOUND_LIB([openat])])
 	AC_CHECK_FUNC([mkdirat], [], [FUNC_NOT_FOUND_LIB([mkdirat])])
 	AC_CHECK_FUNC([write], [], [FUNC_NOT_FOUND_LIB([write])])
-	AC_CHECK_FUNC([twalk_r], [], [FUNC_NOT_FOUND_LIB([twalk_r])])
+	AC_CHECK_FUNC([twalk], [], [FUNC_NOT_FOUND_LIB([twalk])])
 	AC_CHECK_FUNC([tsearch], [], [FUNC_NOT_FOUND_LIB([tsearch])])
 	AC_CHECK_FUNC([tdestroy], [], [FUNC_NOT_FOUND_LIB([tdestroy])])
 	AC_CHECK_FUNC([tdelete], [], [FUNC_NOT_FOUND_LIB([tdelete])])
diff --git a/tests/gpiosim/gpiosim.c b/tests/gpiosim/gpiosim.c
index f46adfa..88d79f4 100644
--- a/tests/gpiosim/gpiosim.c
+++ b/tests/gpiosim/gpiosim.c
@@ -23,6 +23,7 @@
 #include "gpiosim.h"
 
 #define GPIOSIM_API		__attribute__((visibility("default")))
+#define UNUSED			__attribute__((unused))
 #define ARRAY_SIZE(x)		(sizeof(x) / sizeof(*(x)))
 #define MIN_KERNEL_VERSION	KERNEL_VERSION(5, 17, 4)
 
@@ -30,15 +31,15 @@ static pthread_mutex_t id_lock = PTHREAD_MUTEX_INITIALIZER;
 static pthread_once_t id_init_once = PTHREAD_ONCE_INIT;
 static void *id_root;
 
-struct id_find_next_ctx {
+struct {
 	int lowest;
 	bool found;
-};
+} id_find_next_ctx;
 
-struct id_del_ctx {
+struct {
 	int id;
 	int *idp;
-};
+} id_del_ctx;
 
 static void id_cleanup(void)
 {
@@ -62,40 +63,38 @@ static int id_compare(const void *p1, const void *p2)
 	return 0;
 }
 
-static void id_find_next(const void *node, VISIT which, void *data)
+static void id_find_next(const void *node, VISIT which, int depth UNUSED)
 {
-	struct id_find_next_ctx *ctx = data;
 	int *id = *(int **)node;
 
-	if (ctx->found)
+	if (id_find_next_ctx.found)
 		return;
 
 	switch (which) {
 	case postorder:
 	case leaf:
-		if (*id != ctx->lowest)
-			ctx->found = true;
+		if (*id != id_find_next_ctx.lowest)
+			id_find_next_ctx.found = true;
 		else
-			ctx->lowest++;
+			id_find_next_ctx.lowest++;
 		break;
 	default:
 		break;
 	};
 }
 
-static void id_del(const void *node, VISIT which, void *data)
+static void id_del(const void *node, VISIT which, int depth UNUSED)
 {
-	struct id_del_ctx *ctx = data;
 	int *id = *(int **)node;
 
-	if (ctx->idp)
+	if (id_del_ctx.idp)
 		return;
 
 	switch (which) {
 	case postorder:
 	case leaf:
-		if (*id == ctx->id)
-			ctx->idp = id;
+		if (*id == id_del_ctx.id)
+			id_del_ctx.idp = id;
 		break;
 	default:
 		break;
@@ -104,18 +103,17 @@ static void id_del(const void *node, VISIT which, void *data)
 
 static int id_alloc(void)
 {
-	struct id_find_next_ctx ctx;
 	void *ret;
 	int *id;
 
 	pthread_once(&id_init_once, id_schedule_cleanup);
 
-	ctx.lowest = 0;
-	ctx.found = false;
-
 	pthread_mutex_lock(&id_lock);
 
-	twalk_r(id_root, id_find_next, &ctx);
+	id_find_next_ctx.lowest = 0;
+	id_find_next_ctx.found = false;
+
+	twalk(id_root, id_find_next);
 
 	id = malloc(sizeof(*id));
 	if (!id) {
@@ -123,7 +121,7 @@ static int id_alloc(void)
 		return -1;
 	}
 
-	*id = ctx.lowest;
+	*id = id_find_next_ctx.lowest;
 
 	ret = tsearch(id, &id_root, id_compare);
 	if (!ret) {
@@ -140,17 +138,15 @@ static int id_alloc(void)
 
 static void id_free(int id)
 {
-	struct id_del_ctx ctx;
-
-	ctx.id = id;
-	ctx.idp = NULL;
+	id_del_ctx.id = id;
+	id_del_ctx.idp = NULL;
 
 	pthread_mutex_lock(&id_lock);
 
-	twalk_r(id_root, id_del, &ctx);
-	if (ctx.idp) {
-		tdelete(ctx.idp, &id_root, id_compare);
-		free(ctx.idp);
+	twalk(id_root, id_del);
+	if (id_del_ctx.idp) {
+		tdelete(id_del_ctx.idp, &id_root, id_compare);
+		free(id_del_ctx.idp);
 	}
 
 	pthread_mutex_unlock(&id_lock);
-- 
2.37.2