From 7119092665e1b771b04b305813be81e9892dfc1b Mon Sep 17 00:00:00 2001
From: Tristan Riehs <tristan.riehs@bordeaux-inp.fr>
Date: Sat, 22 Jun 2024 16:19:05 +0900
Subject: Improve disp API and implement dynamic reload

---
 src/disp.c | 77 ++++++++++++++++++++++++++++++++++++++++++++++----------------
 src/disp.h | 20 +++++++++++++---
 2 files changed, 75 insertions(+), 22 deletions(-)

diff --git a/src/disp.c b/src/disp.c
index 18b6168..c0294fe 100644
--- a/src/disp.c
+++ b/src/disp.c
@@ -25,10 +25,6 @@
 
 #include "disp.h"
 
-/* Reserved return values for the read_input function. */
-#define DISP_ERR INT_MAX
-#define DISP_RELOAD (INT_MAX - 1)
-
 #define dlsym_and_check(dest, name)				\
 	dest->name = dlsym(dest->dl_handle, #name);		\
 	if ((!dest->name) || (dest->name == dest->dl_handle)) {	\
@@ -36,42 +32,85 @@
 		fprintf(stderr, "calculer: %s\n", msg);		\
 		dlclose(dest->dl_handle);			\
 		free(dest);					\
-		return NULL;					\
+		return -1;					\
 	}
 
-struct disp *
-get_disp(char *disp_name)
+static int
+load_symbols(struct disp *disp)
 {
-#ifndef NDEBUG
-	/* displays are shared libraries */
-	char so_path[64] = {0};
-	strcpy(so_path, "./src/.libs/");
-	strcat(so_path, disp_name);
-	strcat(so_path, ".so.0.0.0");
-	void *handle = dlopen(so_path, RTLD_LAZY);
+	void *handle = dlopen(disp->so_path, RTLD_LAZY);
 
 	if (!handle)
 	{
-		char *msg = dlerror();
-		fprintf(stderr, "calculer: %s\n", msg);
+		fprintf(stderr, "calculer: %s\n", dlerror());
 		exit(1);
 	}
 
-	printf("INFO: successfully loaded symbols from \"%s\"\n", so_path);
+#ifndef NDEBUG
+	printf("INFO: successfully loaded symbols from \"%s\"\n", disp->so_path);
+#endif
 
-	struct disp *disp = malloc(sizeof(*disp));
 	disp->dl_handle = handle;
 	dlsym_and_check(disp, init);
 	dlsym_and_check(disp, display_calc);
 	dlsym_and_check(disp, read_input);
 	dlsym_and_check(disp, display_res);
 	dlsym_and_check(disp, destroy);
+#ifndef NDEBUG
 	dlsym_and_check(disp, pre_reload);
 	dlsym_and_check(disp, post_reload);
+#endif
+	return 0;
+}
 
-	return disp;
+struct disp *
+get_disp(char *disp_name)
+{
+#ifndef NDEBUG
+	/* displays are shared libraries */
+	char so_path[64] = {0};
+	strcpy(so_path, "./src/.libs/");
+	strcat(so_path, disp_name);
+	strcat(so_path, ".so.0.0.0");
+	struct disp *disp = malloc(sizeof(*disp));
+	disp->so_path = strdup(so_path);
+
+	return load_symbols(disp) == 0 ? disp : NULL;
 #else
 #  error "not available yet"
 #endif
 	return NULL;
 }
+
+void
+destroy_disp(struct disp *disp)
+{
+	disp->destroy();
+	dlclose(disp->dl_handle);
+	free(disp->so_path);
+	free(disp);
+}
+
+#ifndef NDEBUG
+void
+disp_reload(struct disp *disp)
+{
+	int status;
+	printf("INFO: saving state\n");
+	void *state = disp->pre_reload();
+	printf("INFO: closing shared library\n");
+	dlclose(disp->dl_handle);
+	printf("INFO: reloading symbols\n");
+	status = load_symbols(disp);
+
+	if (status == -1)
+	{
+		printf("calculer: %s\n", dlerror());
+		exit(1);
+	}
+
+	printf("INFO: loading state\n");
+	disp->post_reload(state);
+	printf("INFO: reloading done\n");
+}
+#endif
diff --git a/src/disp.h b/src/disp.h
index d0b2d19..454378d 100644
--- a/src/disp.h
+++ b/src/disp.h
@@ -18,11 +18,19 @@
 #define DISP_H
 
 #include <stdbool.h>
+#include <limits.h>
 
 /* Available display types. */
 #define DISP_CLI "cli"
 #define DISP_RAY "ray"
 
+/* Reserved return values for the read_input function. */
+#ifndef NDEBUG
+#  define DISP_RELOAD INT_MAX
+#endif
+#define DISP_QUIT (INT_MAX - 1)
+#define DISP_ERR (INT_MAX - 2)
+
 struct disp {
 	void *dl_handle;
 	void (*init)(void);
@@ -30,13 +38,19 @@ struct disp {
 	int  (*read_input)(void);
 	void (*display_res)(bool, int);
 	void (*destroy)(void);
+#ifndef NDEBUG
+	char *so_path;
 	void *(*pre_reload)(void);
 	void (*post_reload)(void *);
+#endif
 };
 
 /* Get a display handler for the given display type. */
-struct disp *get_disp(char *disp_name);
+struct disp *get_disp(char *);
+void destroy_disp(struct disp *);
 
-void destroy_disp(void);
+#ifndef NDEBUG
+void disp_reload(struct disp *);
+#endif	/* NDEBUG */
 
-#endif
+#endif	/* DISP_H */
-- 
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